diff --git a/src/doc/unstable-book/src/language-features/plugin.md b/src/doc/unstable-book/src/language-features/plugin.md
index f19b39daca3ef..8be4d16998276 100644
--- a/src/doc/unstable-book/src/language-features/plugin.md
+++ b/src/doc/unstable-book/src/language-features/plugin.md
@@ -59,7 +59,6 @@ extern crate rustc_plugin;
 use syntax::parse::token::{self, Token};
 use syntax::tokenstream::TokenTree;
 use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacEager};
-use syntax::ext::build::AstBuilder;  // A trait for expr_usize.
 use syntax_pos::Span;
 use rustc_plugin::Registry;
 
@@ -164,13 +163,6 @@ can continue and find further errors.
 To print syntax fragments for debugging, you can use `span_note` together with
 `syntax::print::pprust::*_to_string`.
 
-The example above produced an integer literal using `AstBuilder::expr_usize`.
-As an alternative to the `AstBuilder` trait, `libsyntax` provides a set of
-quasiquote macros. They are undocumented and very rough around the edges.
-However, the implementation may be a good starting point for an improved
-quasiquote as an ordinary plugin library.
-
-
 # Lint plugins
 
 Plugins can extend [Rust's lint
diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 026c3cc6f95b2..ff35c3aa3a5eb 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -5168,7 +5168,7 @@ impl<'a> LoweringContext<'a> {
                         let uc_nested = attr::mk_nested_word_item(uc_ident);
                         attr::mk_list_item(e.span, allow_ident, vec![uc_nested])
                     };
-                    attr::mk_spanned_attr_outer(e.span, attr::mk_attr_id(), allow)
+                    attr::mk_attr_outer(allow)
                 };
                 let attrs = vec![attr];
 
diff --git a/src/librustc/infer/canonical/canonicalizer.rs b/src/librustc/infer/canonical/canonicalizer.rs
index 3d57a89493e1e..db724875b8aa3 100644
--- a/src/librustc/infer/canonical/canonicalizer.rs
+++ b/src/librustc/infer/canonical/canonicalizer.rs
@@ -693,7 +693,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         const_var: &'tcx ty::Const<'tcx>
     ) -> &'tcx ty::Const<'tcx> {
         let infcx = self.infcx.expect("encountered const-var without infcx");
-        let bound_to = infcx.resolve_const_var(const_var);
+        let bound_to = infcx.shallow_resolve(const_var);
         if bound_to != const_var {
             self.fold_const(bound_to)
         } else {
diff --git a/src/librustc/infer/mod.rs b/src/librustc/infer/mod.rs
index 663acd67dcd83..e1d77a97c1160 100644
--- a/src/librustc/infer/mod.rs
+++ b/src/librustc/infer/mod.rs
@@ -1351,23 +1351,6 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         }
     }
 
-    pub fn resolve_const_var(
-        &self,
-        ct: &'tcx ty::Const<'tcx>
-    ) -> &'tcx ty::Const<'tcx> {
-        if let ty::Const { val: ConstValue::Infer(InferConst::Var(v)), .. } = ct {
-            self.const_unification_table
-                .borrow_mut()
-                .probe_value(*v)
-                .val
-                .known()
-                .map(|c| self.resolve_const_var(c))
-                .unwrap_or(ct)
-        } else {
-            ct
-        }
-    }
-
     pub fn fully_resolve<T: TypeFoldable<'tcx>>(&self, value: &T) -> FixupResult<'tcx, T> {
         /*!
          * Attempts to resolve all type/region/const variables in
@@ -1586,7 +1569,7 @@ impl<'a, 'tcx> ShallowResolver<'a, 'tcx> {
                 // it can be resolved to an int/float variable, which
                 // can then be recursively resolved, hence the
                 // recursion. Note though that we prevent type
-                // variables from unifyxing to other type variables
+                // variables from unifying to other type variables
                 // directly (though they may be embedded
                 // structurally), and we prevent cycles in any case,
                 // so this recursion should always be of very limited
@@ -1626,17 +1609,15 @@ impl<'a, 'tcx> TypeFolder<'tcx> for ShallowResolver<'a, 'tcx> {
     }
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
-        match ct {
-            ty::Const { val: ConstValue::Infer(InferConst::Var(vid)), .. } => {
+        if let ty::Const { val: ConstValue::Infer(InferConst::Var(vid)), .. } = ct {
                 self.infcx.const_unification_table
                     .borrow_mut()
                     .probe_value(*vid)
                     .val
                     .known()
-                    .map(|c| self.fold_const(c))
                     .unwrap_or(ct)
-            }
-            _ => ct,
+        } else {
+            ct
         }
     }
 }
diff --git a/src/librustc/ty/relate.rs b/src/librustc/ty/relate.rs
index a6bfc2dee613b..ca54f63b83afe 100644
--- a/src/librustc/ty/relate.rs
+++ b/src/librustc/ty/relate.rs
@@ -594,13 +594,11 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
                 ty: a.ty,
             }))
         }
-        (ConstValue::ByRef { .. }, _) => {
-            bug!(
-                "non-Scalar ConstValue encountered in super_relate_consts {:?} {:?}",
-                a,
-                b,
-            );
-        }
+
+        // FIXME(const_generics): we should either handle `Scalar::Ptr` or add a comment
+        // saying that we're not handling it intentionally.
+
+        // FIXME(const_generics): handle `ConstValue::ByRef` and `ConstValue::Slice`.
 
         // FIXME(const_generics): this is wrong, as it is a projection
         (ConstValue::Unevaluated(a_def_id, a_substs),
diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index 77b8ebba21669..14da3875cdd79 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -1863,6 +1863,12 @@ impl<'tcx> TyS<'tcx> {
         }
     }
 
+    /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
+    #[inline]
+    pub fn is_any_ptr(&self) -> bool {
+        self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
+    }
+
     /// Returns `true` if this type is an `Arc<T>`.
     #[inline]
     pub fn is_arc(&self) -> bool {
diff --git a/src/librustc_metadata/decoder.rs b/src/librustc_metadata/decoder.rs
index 8e76dbb882e3b..9668e68e90a3e 100644
--- a/src/librustc_metadata/decoder.rs
+++ b/src/librustc_metadata/decoder.rs
@@ -980,14 +980,7 @@ impl<'a, 'tcx> CrateMetadata {
     }
 
     fn get_attributes(&self, item: &Entry<'tcx>, sess: &Session) -> Vec<ast::Attribute> {
-        item.attributes
-            .decode((self, sess))
-            .map(|mut attr| {
-                // Need new unique IDs: old thread-local IDs won't map to new threads.
-                attr.id = attr::mk_attr_id();
-                attr
-            })
-            .collect()
+        item.attributes.decode((self, sess)).collect()
     }
 
     // Translate a DefId from the current compilation environment to a DefId
diff --git a/src/librustc_mir/const_eval.rs b/src/librustc_mir/const_eval.rs
index 37d4c5b2f09ce..b54fe5e09bef6 100644
--- a/src/librustc_mir/const_eval.rs
+++ b/src/librustc_mir/const_eval.rs
@@ -20,10 +20,10 @@ use rustc_data_structures::fx::FxHashMap;
 use syntax::source_map::{Span, DUMMY_SP};
 
 use crate::interpret::{self,
-    PlaceTy, MPlaceTy, OpTy, ImmTy, Immediate, Scalar,
+    PlaceTy, MPlaceTy, OpTy, ImmTy, Immediate, Scalar, Pointer,
     RawConst, ConstValue,
     InterpResult, InterpErrorInfo, InterpError, GlobalId, InterpCx, StackPopCleanup,
-    Allocation, AllocId, MemoryKind,
+    Allocation, AllocId, MemoryKind, Memory,
     snapshot, RefTracking, intern_const_alloc_recursive,
 };
 
@@ -397,7 +397,16 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         )
     }
 
-    fn ptr_op(
+    fn ptr_to_int(
+        _mem: &Memory<'mir, 'tcx, Self>,
+        _ptr: Pointer,
+    ) -> InterpResult<'tcx, u64> {
+        Err(
+            ConstEvalError::NeedsRfc("pointer-to-integer cast".to_string()).into(),
+        )
+    }
+
+    fn binary_ptr_op(
         _ecx: &InterpCx<'mir, 'tcx, Self>,
         _bin_op: mir::BinOp,
         _left: ImmTy<'tcx>,
diff --git a/src/librustc_mir/interpret/cast.rs b/src/librustc_mir/interpret/cast.rs
index 980697360eb75..ac146eaaf25a6 100644
--- a/src/librustc_mir/interpret/cast.rs
+++ b/src/librustc_mir/interpret/cast.rs
@@ -7,22 +7,13 @@ use syntax::symbol::sym;
 use rustc_apfloat::ieee::{Single, Double};
 use rustc_apfloat::{Float, FloatConvert};
 use rustc::mir::interpret::{
-    Scalar, InterpResult, Pointer, PointerArithmetic, InterpError,
+    Scalar, InterpResult, PointerArithmetic, InterpError,
 };
 use rustc::mir::CastKind;
 
-use super::{InterpCx, Machine, PlaceTy, OpTy, Immediate, FnVal};
+use super::{InterpCx, Machine, PlaceTy, OpTy, ImmTy, Immediate, FnVal};
 
 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
-    fn type_is_fat_ptr(&self, ty: Ty<'tcx>) -> bool {
-        match ty.sty {
-            ty::RawPtr(ty::TypeAndMut { ty, .. }) |
-            ty::Ref(_, ty, _) => !self.type_is_sized(ty),
-            ty::Adt(def, _) if def.is_box() => !self.type_is_sized(ty.boxed_ty()),
-            _ => false,
-        }
-    }
-
     pub fn cast(
         &mut self,
         src: OpTy<'tcx, M::PointerTag>,
@@ -37,40 +28,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
             Misc | Pointer(PointerCast::MutToConstPointer) => {
                 let src = self.read_immediate(src)?;
-
-                if self.type_is_fat_ptr(src.layout.ty) {
-                    match (*src, self.type_is_fat_ptr(dest.layout.ty)) {
-                        // pointers to extern types
-                        (Immediate::Scalar(_),_) |
-                        // slices and trait objects to other slices/trait objects
-                        (Immediate::ScalarPair(..), true) => {
-                            // No change to immediate
-                            self.write_immediate(*src, dest)?;
-                        }
-                        // slices and trait objects to thin pointers (dropping the metadata)
-                        (Immediate::ScalarPair(data, _), false) => {
-                            self.write_scalar(data, dest)?;
-                        }
-                    }
-                } else {
-                    match src.layout.variants {
-                        layout::Variants::Single { index } => {
-                            if let Some(discr) =
-                                src.layout.ty.discriminant_for_variant(*self.tcx, index)
-                            {
-                                // Cast from a univariant enum
-                                assert!(src.layout.is_zst());
-                                return self.write_scalar(
-                                    Scalar::from_uint(discr.val, dest.layout.size),
-                                    dest);
-                            }
-                        }
-                        layout::Variants::Multiple { .. } => {},
-                    }
-
-                    let dest_val = self.cast_scalar(src.to_scalar()?, src.layout, dest.layout)?;
-                    self.write_scalar(dest_val, dest)?;
-                }
+                let res = self.cast_immediate(src, dest.layout)?;
+                self.write_immediate(res, dest)?;
             }
 
             Pointer(PointerCast::ReifyFnPointer) => {
@@ -126,36 +85,76 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         Ok(())
     }
 
-    fn cast_scalar(
+    fn cast_immediate(
         &self,
-        val: Scalar<M::PointerTag>,
-        src_layout: TyLayout<'tcx>,
+        src: ImmTy<'tcx, M::PointerTag>,
         dest_layout: TyLayout<'tcx>,
-    ) -> InterpResult<'tcx, Scalar<M::PointerTag>> {
+    ) -> InterpResult<'tcx, Immediate<M::PointerTag>> {
         use rustc::ty::TyKind::*;
-        trace!("Casting {:?}: {:?} to {:?}", val, src_layout.ty, dest_layout.ty);
+        trace!("Casting {:?}: {:?} to {:?}", *src, src.layout.ty, dest_layout.ty);
 
-        match src_layout.ty.sty {
+        match src.layout.ty.sty {
             // Floating point
-            Float(FloatTy::F32) => self.cast_from_float(val.to_f32()?, dest_layout.ty),
-            Float(FloatTy::F64) => self.cast_from_float(val.to_f64()?, dest_layout.ty),
-            // Integer(-like), including fn ptr casts and casts from enums that
-            // are represented as integers (this excludes univariant enums, which
-            // are handled in `cast` directly).
-            _ => {
+            Float(FloatTy::F32) =>
+                return Ok(self.cast_from_float(src.to_scalar()?.to_f32()?, dest_layout.ty)?.into()),
+            Float(FloatTy::F64) =>
+                return Ok(self.cast_from_float(src.to_scalar()?.to_f64()?, dest_layout.ty)?.into()),
+            // The rest is integer/pointer-"like", including fn ptr casts and casts from enums that
+            // are represented as integers.
+            _ =>
                 assert!(
-                    src_layout.ty.is_bool()       || src_layout.ty.is_char()     ||
-                    src_layout.ty.is_enum()       || src_layout.ty.is_integral() ||
-                    src_layout.ty.is_unsafe_ptr() || src_layout.ty.is_fn_ptr()   ||
-                    src_layout.ty.is_region_ptr(),
-                    "Unexpected cast from type {:?}", src_layout.ty
-                );
-                match val.to_bits_or_ptr(src_layout.size, self) {
-                    Err(ptr) => self.cast_from_ptr(ptr, src_layout, dest_layout),
-                    Ok(data) => self.cast_from_int(data, src_layout, dest_layout),
+                    src.layout.ty.is_bool()       || src.layout.ty.is_char()     ||
+                    src.layout.ty.is_enum()       || src.layout.ty.is_integral() ||
+                    src.layout.ty.is_any_ptr(),
+                    "Unexpected cast from type {:?}", src.layout.ty
+                )
+        }
+
+        // Handle cast from a univariant (ZST) enum.
+        match src.layout.variants {
+            layout::Variants::Single { index } => {
+                if let Some(discr) =
+                    src.layout.ty.discriminant_for_variant(*self.tcx, index)
+                {
+                    assert!(src.layout.is_zst());
+                    return Ok(Scalar::from_uint(discr.val, dest_layout.size).into());
                 }
             }
+            layout::Variants::Multiple { .. } => {},
+        }
+
+        // Handle casting the metadata away from a fat pointer.
+        if src.layout.ty.is_unsafe_ptr() && dest_layout.ty.is_unsafe_ptr() &&
+            dest_layout.size != src.layout.size
+        {
+            assert_eq!(src.layout.size, 2*self.memory.pointer_size());
+            assert_eq!(dest_layout.size, self.memory.pointer_size());
+            assert!(dest_layout.ty.is_unsafe_ptr());
+            match *src {
+                Immediate::ScalarPair(data, _) =>
+                    return Ok(data.into()),
+                Immediate::Scalar(..) =>
+                    bug!(
+                        "{:?} input to a fat-to-thin cast ({:?} -> {:?})",
+                        *src, src.layout.ty, dest_layout.ty
+                    ),
+            };
+        }
+
+        // Handle casting any ptr to raw ptr (might be a fat ptr).
+        if src.layout.ty.is_any_ptr() && dest_layout.ty.is_unsafe_ptr()
+        {
+            // The only possible size-unequal case was handled above.
+            assert_eq!(src.layout.size, dest_layout.size);
+            return Ok(*src);
         }
+
+        // For all remaining casts, we either
+        // (a) cast a raw ptr to usize, or
+        // (b) cast from an integer-like (including bool, char, enums).
+        // In both cases we want the bits.
+        let bits = self.force_bits(src.to_scalar()?, src.layout.size)?;
+        Ok(self.cast_from_int(bits, src.layout, dest_layout)?.into())
     }
 
     fn cast_from_int(
@@ -236,31 +235,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
-    fn cast_from_ptr(
-        &self,
-        ptr: Pointer<M::PointerTag>,
-        src_layout: TyLayout<'tcx>,
-        dest_layout: TyLayout<'tcx>,
-    ) -> InterpResult<'tcx, Scalar<M::PointerTag>> {
-        use rustc::ty::TyKind::*;
-
-        match dest_layout.ty.sty {
-            // Casting to a reference or fn pointer is not permitted by rustc,
-            // no need to support it here.
-            RawPtr(_) => Ok(ptr.into()),
-            Int(_) | Uint(_) => {
-                let size = self.memory.pointer_size();
-
-                match self.force_bits(Scalar::Ptr(ptr), size) {
-                    Ok(bits) => self.cast_from_int(bits, src_layout, dest_layout),
-                    Err(_) if dest_layout.size == size => Ok(ptr.into()),
-                    Err(e) => Err(e),
-                }
-            }
-            _ => bug!("invalid MIR: ptr to {:?} cast", dest_layout.ty)
-        }
-    }
-
     fn unsize_into_ptr(
         &mut self,
         src: OpTy<'tcx, M::PointerTag>,
diff --git a/src/librustc_mir/interpret/machine.rs b/src/librustc_mir/interpret/machine.rs
index e3f16a3c9ea45..be8ad49bb3385 100644
--- a/src/librustc_mir/interpret/machine.rs
+++ b/src/librustc_mir/interpret/machine.rs
@@ -165,11 +165,10 @@ pub trait Machine<'mir, 'tcx>: Sized {
         def_id: DefId,
     ) -> InterpResult<'tcx, Cow<'tcx, Allocation>>;
 
-    /// Called for all binary operations on integer(-like) types when one operand is a pointer
-    /// value, and for the `Offset` operation that is inherently about pointers.
+    /// Called for all binary operations where the LHS has pointer type.
     ///
     /// Returns a (value, overflowed) pair if the operation succeeded
-    fn ptr_op(
+    fn binary_ptr_op(
         ecx: &InterpCx<'mir, 'tcx, Self>,
         bin_op: mir::BinOp,
         left: ImmTy<'tcx, Self::PointerTag>,
@@ -234,7 +233,6 @@ pub trait Machine<'mir, 'tcx>: Sized {
         extra: Self::FrameExtra,
     ) -> InterpResult<'tcx>;
 
-    #[inline(always)]
     fn int_to_ptr(
         _mem: &Memory<'mir, 'tcx, Self>,
         int: u64,
@@ -246,11 +244,8 @@ pub trait Machine<'mir, 'tcx>: Sized {
         }).into())
     }
 
-    #[inline(always)]
     fn ptr_to_int(
         _mem: &Memory<'mir, 'tcx, Self>,
         _ptr: Pointer<Self::PointerTag>,
-    ) -> InterpResult<'tcx, u64> {
-        err!(ReadPointerAsBytes)
-    }
+    ) -> InterpResult<'tcx, u64>;
 }
diff --git a/src/librustc_mir/interpret/operand.rs b/src/librustc_mir/interpret/operand.rs
index 1816171d7b127..b5289187ef08f 100644
--- a/src/librustc_mir/interpret/operand.rs
+++ b/src/librustc_mir/interpret/operand.rs
@@ -33,12 +33,21 @@ pub enum Immediate<Tag=(), Id=AllocId> {
     ScalarPair(ScalarMaybeUndef<Tag, Id>, ScalarMaybeUndef<Tag, Id>),
 }
 
-impl<'tcx, Tag> Immediate<Tag> {
-    #[inline]
-    pub fn from_scalar(val: Scalar<Tag>) -> Self {
-        Immediate::Scalar(ScalarMaybeUndef::Scalar(val))
+impl<Tag> From<ScalarMaybeUndef<Tag>> for Immediate<Tag> {
+    #[inline(always)]
+    fn from(val: ScalarMaybeUndef<Tag>) -> Self {
+        Immediate::Scalar(val)
     }
+}
 
+impl<Tag> From<Scalar<Tag>> for Immediate<Tag> {
+    #[inline(always)]
+    fn from(val: Scalar<Tag>) -> Self {
+        Immediate::Scalar(val.into())
+    }
+}
+
+impl<'tcx, Tag> Immediate<Tag> {
     pub fn new_slice(
         val: Scalar<Tag>,
         len: u64,
@@ -183,7 +192,7 @@ impl<'tcx, Tag: Copy> ImmTy<'tcx, Tag>
 {
     #[inline]
     pub fn from_scalar(val: Scalar<Tag>, layout: TyLayout<'tcx>) -> Self {
-        ImmTy { imm: Immediate::from_scalar(val), layout }
+        ImmTy { imm: val.into(), layout }
     }
 
     #[inline]
@@ -241,7 +250,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let ptr = match self.check_mplace_access(mplace, None)? {
             Some(ptr) => ptr,
             None => return Ok(Some(ImmTy { // zero-sized type
-                imm: Immediate::Scalar(Scalar::zst().into()),
+                imm: Scalar::zst().into(),
                 layout: mplace.layout,
             })),
         };
@@ -252,7 +261,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     .get(ptr.alloc_id)?
                     .read_scalar(self, ptr, mplace.layout.size)?;
                 Ok(Some(ImmTy {
-                    imm: Immediate::Scalar(scalar),
+                    imm: scalar.into(),
                     layout: mplace.layout,
                 }))
             }
@@ -354,7 +363,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let field = field.try_into().unwrap();
         let field_layout = op.layout.field(self, field)?;
         if field_layout.is_zst() {
-            let immediate = Immediate::Scalar(Scalar::zst().into());
+            let immediate = Scalar::zst().into();
             return Ok(OpTy { op: Operand::Immediate(immediate), layout: field_layout });
         }
         let offset = op.layout.fields.offset(field);
@@ -364,7 +373,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             // extract fields from types with `ScalarPair` ABI
             Immediate::ScalarPair(a, b) => {
                 let val = if offset.bytes() == 0 { a } else { b };
-                Immediate::Scalar(val)
+                Immediate::from(val)
             },
             Immediate::Scalar(val) =>
                 bug!("field access on non aggregate {:#?}, {:#?}", val, op.layout),
@@ -401,7 +410,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             Deref => self.deref_operand(base)?.into(),
             Subslice { .. } | ConstantIndex { .. } | Index(_) => if base.layout.is_zst() {
                 OpTy {
-                    op: Operand::Immediate(Immediate::Scalar(Scalar::zst().into())),
+                    op: Operand::Immediate(Scalar::zst().into()),
                     // the actual index doesn't matter, so we just pick a convenient one like 0
                     layout: base.layout.field(self, 0)?,
                 }
@@ -425,7 +434,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let layout = self.layout_of_local(frame, local, layout)?;
         let op = if layout.is_zst() {
             // Do not read from ZST, they might not be initialized
-            Operand::Immediate(Immediate::Scalar(Scalar::zst().into()))
+            Operand::Immediate(Scalar::zst().into())
         } else {
             frame.locals[local].access()?
         };
@@ -553,7 +562,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 Operand::Indirect(MemPlace::from_ptr(ptr, align))
             },
             ConstValue::Scalar(x) =>
-                Operand::Immediate(Immediate::Scalar(tag_scalar(x).into())),
+                Operand::Immediate(tag_scalar(x).into()),
             ConstValue::Slice { data, start, end } => {
                 // We rely on mutability being set correctly in `data` to prevent writes
                 // where none should happen.
diff --git a/src/librustc_mir/interpret/operator.rs b/src/librustc_mir/interpret/operator.rs
index b4edee72a4d19..a893f8012db99 100644
--- a/src/librustc_mir/interpret/operator.rs
+++ b/src/librustc_mir/interpret/operator.rs
@@ -290,30 +290,29 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     FloatTy::F64 => self.binary_float_op(bin_op, left.to_f64()?, right.to_f64()?),
                 })
             }
-            _ => {
-                // Must be integer(-like) types.  Don't forget about == on fn pointers.
-                assert!(
-                    left.layout.ty.is_integral()   ||
-                    left.layout.ty.is_unsafe_ptr() || left.layout.ty.is_fn_ptr(),
-                    "Unexpected LHS type {:?} for BinOp {:?}", left.layout.ty, bin_op);
+            _ if left.layout.ty.is_integral() => {
+                // the RHS type can be different, e.g. for shifts -- but it has to be integral, too
                 assert!(
-                    right.layout.ty.is_integral()   ||
-                    right.layout.ty.is_unsafe_ptr() || right.layout.ty.is_fn_ptr(),
-                    "Unexpected RHS type {:?} for BinOp {:?}", right.layout.ty, bin_op);
-
-                // Handle operations that support pointer values
-                if left.to_scalar_ptr()?.is_ptr() ||
-                    right.to_scalar_ptr()?.is_ptr() ||
-                    bin_op == mir::BinOp::Offset
-                {
-                    return M::ptr_op(self, bin_op, left, right);
-                }
+                    right.layout.ty.is_integral(),
+                    "Unexpected types for BinOp: {:?} {:?} {:?}",
+                    left.layout.ty, bin_op, right.layout.ty
+                );
 
-                // Everything else only works with "proper" bits
-                let l = left.to_bits().expect("we checked is_ptr");
-                let r = right.to_bits().expect("we checked is_ptr");
+                let l = self.force_bits(left.to_scalar()?, left.layout.size)?;
+                let r = self.force_bits(right.to_scalar()?, right.layout.size)?;
                 self.binary_int_op(bin_op, l, left.layout, r, right.layout)
             }
+            _ if left.layout.ty.is_any_ptr() => {
+                // The RHS type must be the same *or an integer type* (for `Offset`).
+                assert!(
+                    right.layout.ty == left.layout.ty || right.layout.ty.is_integral(),
+                    "Unexpected types for BinOp: {:?} {:?} {:?}",
+                    left.layout.ty, bin_op, right.layout.ty
+                );
+
+                M::binary_ptr_op(self, bin_op, left, right)
+            }
+            _ => bug!("Invalid MIR: bad LHS type for binop: {:?}", left.layout.ty),
         }
     }
 
diff --git a/src/librustc_mir/interpret/terminator.rs b/src/librustc_mir/interpret/terminator.rs
index 27bd0f8889634..8258192db4fdb 100644
--- a/src/librustc_mir/interpret/terminator.rs
+++ b/src/librustc_mir/interpret/terminator.rs
@@ -8,7 +8,7 @@ use rustc_target::spec::abi::Abi;
 
 use super::{
     InterpResult, PointerArithmetic, InterpError, Scalar,
-    InterpCx, Machine, Immediate, OpTy, ImmTy, PlaceTy, MPlaceTy, StackPopCleanup, FnVal,
+    InterpCx, Machine, OpTy, ImmTy, PlaceTy, MPlaceTy, StackPopCleanup, FnVal,
 };
 
 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
@@ -462,7 +462,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 // Adjust receiver argument.
                 args[0] = OpTy::from(ImmTy {
                     layout: this_receiver_ptr,
-                    imm: Immediate::Scalar(receiver_place.ptr.into())
+                    imm: receiver_place.ptr.into()
                 });
                 trace!("Patched self operand to {:#?}", args[0]);
                 // recurse with concrete function
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index b633705a65f5d..2938487393dc7 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -2104,9 +2104,7 @@ pub enum AttrStyle {
     Inner,
 }
 
-#[derive(
-    Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, PartialOrd, Ord, Copy,
-)]
+#[derive(Clone, PartialEq, Eq, Hash, Debug, PartialOrd, Ord, Copy)]
 pub struct AttrId(pub usize);
 
 impl Idx for AttrId {
@@ -2118,6 +2116,18 @@ impl Idx for AttrId {
     }
 }
 
+impl rustc_serialize::Encodable for AttrId {
+    fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
+        s.emit_unit()
+    }
+}
+
+impl rustc_serialize::Decodable for AttrId {
+    fn decode<D: Decoder>(d: &mut D) -> Result<AttrId, D::Error> {
+        d.read_nil().map(|_| crate::attr::mk_attr_id())
+    }
+}
+
 /// Metadata associated with an item.
 /// Doc-comments are promoted to attributes that have `is_sugared_doc = true`.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
diff --git a/src/libsyntax/attr/builtin.rs b/src/libsyntax/attr/builtin.rs
index dbf31ad014832..5fb513783fbaa 100644
--- a/src/libsyntax/attr/builtin.rs
+++ b/src/libsyntax/attr/builtin.rs
@@ -3,7 +3,6 @@
 use crate::ast::{self, Attribute, MetaItem, NestedMetaItem};
 use crate::early_buffered_lints::BufferedEarlyLintId;
 use crate::ext::base::ExtCtxt;
-use crate::ext::build::AstBuilder;
 use crate::feature_gate::{Features, GatedCfg};
 use crate::parse::ParseSess;
 
@@ -929,7 +928,7 @@ pub fn find_transparency(
 pub fn check_builtin_macro_attribute(ecx: &ExtCtxt<'_>, meta_item: &MetaItem, name: Symbol) {
     // All the built-in macro attributes are "words" at the moment.
     let template = AttributeTemplate { word: true, list: None, name_value_str: None };
-    let attr = ecx.attribute(meta_item.span, meta_item.clone());
+    let attr = ecx.attribute(meta_item.clone());
     check_builtin_attribute(ecx.parse_sess, &attr, name, template);
 }
 
diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs
index 7be21ff9029a5..3e56136b17108 100644
--- a/src/libsyntax/attr/mod.rs
+++ b/src/libsyntax/attr/mod.rs
@@ -6,9 +6,10 @@ pub use builtin::*;
 pub use IntType::*;
 pub use ReprAttr::*;
 pub use StabilityLevel::*;
+pub use crate::ast::Attribute;
 
 use crate::ast;
-use crate::ast::{AttrId, Attribute, AttrStyle, Name, Ident, Path, PathSegment};
+use crate::ast::{AttrId, AttrStyle, Name, Ident, Path, PathSegment};
 use crate::ast::{MetaItem, MetaItemKind, NestedMetaItem};
 use crate::ast::{Lit, LitKind, Expr, Item, Local, Stmt, StmtKind, GenericParam};
 use crate::mut_visit::visit_clobber;
@@ -328,13 +329,14 @@ impl Attribute {
             let meta = mk_name_value_item_str(
                 Ident::with_empty_ctxt(sym::doc),
                 dummy_spanned(Symbol::intern(&strip_doc_comment_decoration(&comment.as_str()))));
-            let mut attr = if self.style == ast::AttrStyle::Outer {
-                mk_attr_outer(self.span, self.id, meta)
-            } else {
-                mk_attr_inner(self.span, self.id, meta)
-            };
-            attr.is_sugared_doc = true;
-            f(&attr)
+            f(&Attribute {
+                id: self.id,
+                style: self.style,
+                path: meta.path,
+                tokens: meta.node.tokens(meta.span),
+                is_sugared_doc: true,
+                span: self.span,
+            })
         } else {
             f(self)
         }
@@ -376,46 +378,36 @@ pub fn mk_attr_id() -> AttrId {
     AttrId(id)
 }
 
-/// Returns an inner attribute with the given value.
-pub fn mk_attr_inner(span: Span, id: AttrId, item: MetaItem) -> Attribute {
-    mk_spanned_attr_inner(span, id, item)
-}
-
 /// Returns an inner attribute with the given value and span.
-pub fn mk_spanned_attr_inner(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
+pub fn mk_attr_inner(item: MetaItem) -> Attribute {
     Attribute {
-        id,
+        id: mk_attr_id(),
         style: ast::AttrStyle::Inner,
         path: item.path,
         tokens: item.node.tokens(item.span),
         is_sugared_doc: false,
-        span: sp,
+        span: item.span,
     }
 }
 
-/// Returns an outer attribute with the given value.
-pub fn mk_attr_outer(span: Span, id: AttrId, item: MetaItem) -> Attribute {
-    mk_spanned_attr_outer(span, id, item)
-}
-
 /// Returns an outer attribute with the given value and span.
-pub fn mk_spanned_attr_outer(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
+pub fn mk_attr_outer(item: MetaItem) -> Attribute {
     Attribute {
-        id,
+        id: mk_attr_id(),
         style: ast::AttrStyle::Outer,
         path: item.path,
         tokens: item.node.tokens(item.span),
         is_sugared_doc: false,
-        span: sp,
+        span: item.span,
     }
 }
 
-pub fn mk_sugared_doc_attr(id: AttrId, text: Symbol, span: Span) -> Attribute {
+pub fn mk_sugared_doc_attr(text: Symbol, span: Span) -> Attribute {
     let style = doc_comment_style(&text.as_str());
     let lit_kind = LitKind::Str(text, ast::StrStyle::Cooked);
     let lit = Lit::from_lit_kind(lit_kind, span);
     Attribute {
-        id,
+        id: mk_attr_id(),
         style,
         path: Path::from_ident(Ident::with_empty_ctxt(sym::doc).with_span_pos(span)),
         tokens: MetaItemKind::NameValue(lit).tokens(span),
diff --git a/src/libsyntax/diagnostics/plugin.rs b/src/libsyntax/diagnostics/plugin.rs
index e5e55a6444a2e..80591ad304df0 100644
--- a/src/libsyntax/diagnostics/plugin.rs
+++ b/src/libsyntax/diagnostics/plugin.rs
@@ -4,7 +4,6 @@ use std::env;
 use crate::ast::{self, Ident, Name};
 use crate::source_map;
 use crate::ext::base::{ExtCtxt, MacEager, MacResult};
-use crate::ext::build::AstBuilder;
 use crate::parse::token::{self, Token};
 use crate::ptr::P;
 use crate::symbol::kw;
diff --git a/src/libsyntax/ext/build.rs b/src/libsyntax/ext/build.rs
index b30fefe5b9676..b4b15ba31b713 100644
--- a/src/libsyntax/ext/build.rs
+++ b/src/libsyntax/ext/build.rs
@@ -9,295 +9,20 @@ use crate::ThinVec;
 use rustc_target::spec::abi::Abi;
 use syntax_pos::{Pos, Span};
 
-pub trait AstBuilder {
-    // Paths
-    fn path(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path;
-    fn path_ident(&self, span: Span, id: ast::Ident) -> ast::Path;
-    fn path_global(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path;
-    fn path_all(&self, sp: Span,
-                global: bool,
-                idents: Vec<ast::Ident>,
-                args: Vec<ast::GenericArg>,
-                constraints: Vec<ast::AssocTyConstraint>)
-        -> ast::Path;
-
-    fn qpath(&self, self_type: P<ast::Ty>,
-             trait_path: ast::Path,
-             ident: ast::Ident)
-             -> (ast::QSelf, ast::Path);
-    fn qpath_all(&self, self_type: P<ast::Ty>,
-                trait_path: ast::Path,
-                ident: ast::Ident,
-                args: Vec<ast::GenericArg>,
-                constraints: Vec<ast::AssocTyConstraint>)
-                -> (ast::QSelf, ast::Path);
-
-    // types and consts
-    fn ty_mt(&self, ty: P<ast::Ty>, mutbl: ast::Mutability) -> ast::MutTy;
-
-    fn ty(&self, span: Span, ty: ast::TyKind) -> P<ast::Ty>;
-    fn ty_path(&self, path: ast::Path) -> P<ast::Ty>;
-    fn ty_ident(&self, span: Span, idents: ast::Ident) -> P<ast::Ty>;
-    fn anon_const(&self, span: Span, expr: ast::ExprKind) -> ast::AnonConst;
-    fn const_ident(&self, span: Span, idents: ast::Ident) -> ast::AnonConst;
-
-    fn ty_rptr(&self, span: Span,
-               ty: P<ast::Ty>,
-               lifetime: Option<ast::Lifetime>,
-               mutbl: ast::Mutability) -> P<ast::Ty>;
-    fn ty_ptr(&self, span: Span,
-              ty: P<ast::Ty>,
-              mutbl: ast::Mutability) -> P<ast::Ty>;
-
-    fn ty_infer(&self, sp: Span) -> P<ast::Ty>;
-
-    fn typaram(&self,
-               span: Span,
-               id: ast::Ident,
-               attrs: Vec<ast::Attribute>,
-               bounds: ast::GenericBounds,
-               default: Option<P<ast::Ty>>) -> ast::GenericParam;
-
-    fn trait_ref(&self, path: ast::Path) -> ast::TraitRef;
-    fn poly_trait_ref(&self, span: Span, path: ast::Path) -> ast::PolyTraitRef;
-    fn trait_bound(&self, path: ast::Path) -> ast::GenericBound;
-    fn lifetime(&self, span: Span, ident: ast::Ident) -> ast::Lifetime;
-    fn lifetime_def(&self,
-                    span: Span,
-                    ident: ast::Ident,
-                    attrs: Vec<ast::Attribute>,
-                    bounds: ast::GenericBounds)
-                    -> ast::GenericParam;
-
-    // Statements
-    fn stmt_expr(&self, expr: P<ast::Expr>) -> ast::Stmt;
-    fn stmt_semi(&self, expr: P<ast::Expr>) -> ast::Stmt;
-    fn stmt_let(&self, sp: Span, mutbl: bool, ident: ast::Ident, ex: P<ast::Expr>) -> ast::Stmt;
-    fn stmt_let_typed(&self,
-                      sp: Span,
-                      mutbl: bool,
-                      ident: ast::Ident,
-                      typ: P<ast::Ty>,
-                      ex: P<ast::Expr>)
-                      -> ast::Stmt;
-    fn stmt_let_type_only(&self, span: Span, ty: P<ast::Ty>) -> ast::Stmt;
-    fn stmt_item(&self, sp: Span, item: P<ast::Item>) -> ast::Stmt;
-
-    // Blocks
-    fn block(&self, span: Span, stmts: Vec<ast::Stmt>) -> P<ast::Block>;
-    fn block_expr(&self, expr: P<ast::Expr>) -> P<ast::Block>;
-
-    // Expressions
-    fn expr(&self, span: Span, node: ast::ExprKind) -> P<ast::Expr>;
-    fn expr_path(&self, path: ast::Path) -> P<ast::Expr>;
-    fn expr_qpath(&self, span: Span, qself: ast::QSelf, path: ast::Path) -> P<ast::Expr>;
-    fn expr_ident(&self, span: Span, id: ast::Ident) -> P<ast::Expr>;
-
-    fn expr_self(&self, span: Span) -> P<ast::Expr>;
-    fn expr_binary(&self, sp: Span, op: ast::BinOpKind,
-                   lhs: P<ast::Expr>, rhs: P<ast::Expr>) -> P<ast::Expr>;
-    fn expr_deref(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr>;
-    fn expr_unary(&self, sp: Span, op: ast::UnOp, e: P<ast::Expr>) -> P<ast::Expr>;
-
-    fn expr_addr_of(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr>;
-    fn expr_mut_addr_of(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr>;
-    fn expr_field_access(&self, span: Span, expr: P<ast::Expr>, ident: ast::Ident) -> P<ast::Expr>;
-    fn expr_tup_field_access(&self, sp: Span, expr: P<ast::Expr>,
-                             idx: usize) -> P<ast::Expr>;
-    fn expr_call(&self, span: Span, expr: P<ast::Expr>, args: Vec<P<ast::Expr>>) -> P<ast::Expr>;
-    fn expr_call_ident(&self, span: Span, id: ast::Ident, args: Vec<P<ast::Expr>>) -> P<ast::Expr>;
-    fn expr_call_global(&self, sp: Span, fn_path: Vec<ast::Ident>,
-                        args: Vec<P<ast::Expr>> ) -> P<ast::Expr>;
-    fn expr_method_call(&self, span: Span,
-                        expr: P<ast::Expr>, ident: ast::Ident,
-                        args: Vec<P<ast::Expr>> ) -> P<ast::Expr>;
-    fn expr_block(&self, b: P<ast::Block>) -> P<ast::Expr>;
-    fn expr_cast(&self, sp: Span, expr: P<ast::Expr>, ty: P<ast::Ty>) -> P<ast::Expr>;
-
-    fn field_imm(&self, span: Span, name: Ident, e: P<ast::Expr>) -> ast::Field;
-    fn expr_struct(&self, span: Span, path: ast::Path, fields: Vec<ast::Field>) -> P<ast::Expr>;
-    fn expr_struct_ident(&self, span: Span, id: ast::Ident,
-                         fields: Vec<ast::Field>) -> P<ast::Expr>;
-
-    fn expr_lit(&self, sp: Span, lit: ast::LitKind) -> P<ast::Expr>;
-
-    fn expr_usize(&self, span: Span, i: usize) -> P<ast::Expr>;
-    fn expr_isize(&self, sp: Span, i: isize) -> P<ast::Expr>;
-    fn expr_u8(&self, sp: Span, u: u8) -> P<ast::Expr>;
-    fn expr_u16(&self, sp: Span, u: u16) -> P<ast::Expr>;
-    fn expr_u32(&self, sp: Span, u: u32) -> P<ast::Expr>;
-    fn expr_bool(&self, sp: Span, value: bool) -> P<ast::Expr>;
-
-    fn expr_vec(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr>;
-    fn expr_vec_ng(&self, sp: Span) -> P<ast::Expr>;
-    fn expr_vec_slice(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr>;
-    fn expr_str(&self, sp: Span, s: Symbol) -> P<ast::Expr>;
-
-    fn expr_some(&self, sp: Span, expr: P<ast::Expr>) -> P<ast::Expr>;
-    fn expr_none(&self, sp: Span) -> P<ast::Expr>;
-
-    fn expr_break(&self, sp: Span) -> P<ast::Expr>;
-
-    fn expr_tuple(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr>;
-
-    fn expr_fail(&self, span: Span, msg: Symbol) -> P<ast::Expr>;
-    fn expr_unreachable(&self, span: Span) -> P<ast::Expr>;
-
-    fn expr_ok(&self, span: Span, expr: P<ast::Expr>) -> P<ast::Expr>;
-    fn expr_err(&self, span: Span, expr: P<ast::Expr>) -> P<ast::Expr>;
-    fn expr_try(&self, span: Span, head: P<ast::Expr>) -> P<ast::Expr>;
-
-    fn pat(&self, span: Span, pat: PatKind) -> P<ast::Pat>;
-    fn pat_wild(&self, span: Span) -> P<ast::Pat>;
-    fn pat_lit(&self, span: Span, expr: P<ast::Expr>) -> P<ast::Pat>;
-    fn pat_ident(&self, span: Span, ident: ast::Ident) -> P<ast::Pat>;
-
-    fn pat_ident_binding_mode(&self,
-                              span: Span,
-                              ident: ast::Ident,
-                              bm: ast::BindingMode) -> P<ast::Pat>;
-    fn pat_path(&self, span: Span, path: ast::Path) -> P<ast::Pat>;
-    fn pat_tuple_struct(&self, span: Span, path: ast::Path,
-                        subpats: Vec<P<ast::Pat>>) -> P<ast::Pat>;
-    fn pat_struct(&self, span: Span, path: ast::Path,
-                  field_pats: Vec<Spanned<ast::FieldPat>>) -> P<ast::Pat>;
-    fn pat_tuple(&self, span: Span, pats: Vec<P<ast::Pat>>) -> P<ast::Pat>;
-
-    fn pat_some(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat>;
-    fn pat_none(&self, span: Span) -> P<ast::Pat>;
-
-    fn pat_ok(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat>;
-    fn pat_err(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat>;
-
-    fn arm(&self, span: Span, pats: Vec<P<ast::Pat>>, expr: P<ast::Expr>) -> ast::Arm;
-    fn arm_unreachable(&self, span: Span) -> ast::Arm;
-
-    fn expr_match(&self, span: Span, arg: P<ast::Expr>, arms: Vec<ast::Arm> ) -> P<ast::Expr>;
-    fn expr_if(&self, span: Span,
-               cond: P<ast::Expr>, then: P<ast::Expr>, els: Option<P<ast::Expr>>) -> P<ast::Expr>;
-    fn expr_loop(&self, span: Span, block: P<ast::Block>) -> P<ast::Expr>;
-
-    fn lambda_fn_decl(&self,
-                      span: Span,
-                      fn_decl: P<ast::FnDecl>,
-                      body: P<ast::Expr>,
-                      fn_decl_span: Span)
-                      -> P<ast::Expr>;
-
-    fn lambda(&self, span: Span, ids: Vec<ast::Ident>, body: P<ast::Expr>) -> P<ast::Expr>;
-    fn lambda0(&self, span: Span, body: P<ast::Expr>) -> P<ast::Expr>;
-    fn lambda1(&self, span: Span, body: P<ast::Expr>, ident: ast::Ident) -> P<ast::Expr>;
-
-    fn lambda_stmts(&self, span: Span, ids: Vec<ast::Ident>,
-                    blk: Vec<ast::Stmt>) -> P<ast::Expr>;
-    fn lambda_stmts_0(&self, span: Span, stmts: Vec<ast::Stmt>) -> P<ast::Expr>;
-    fn lambda_stmts_1(&self, span: Span, stmts: Vec<ast::Stmt>,
-                      ident: ast::Ident) -> P<ast::Expr>;
-
-    // Items
-    fn item(&self, span: Span,
-            name: Ident, attrs: Vec<ast::Attribute> , node: ast::ItemKind) -> P<ast::Item>;
-
-    fn arg(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> ast::Arg;
-    // FIXME: unused `self`
-    fn fn_decl(&self, inputs: Vec<ast::Arg> , output: ast::FunctionRetTy) -> P<ast::FnDecl>;
-
-    fn item_fn_poly(&self,
-                    span: Span,
-                    name: Ident,
-                    inputs: Vec<ast::Arg> ,
-                    output: P<ast::Ty>,
-                    generics: Generics,
-                    body: P<ast::Block>) -> P<ast::Item>;
-    fn item_fn(&self,
-               span: Span,
-               name: Ident,
-               inputs: Vec<ast::Arg> ,
-               output: P<ast::Ty>,
-               body: P<ast::Block>) -> P<ast::Item>;
-
-    fn variant(&self, span: Span, name: Ident, tys: Vec<P<ast::Ty>> ) -> ast::Variant;
-    fn item_enum_poly(&self,
-                      span: Span,
-                      name: Ident,
-                      enum_definition: ast::EnumDef,
-                      generics: Generics) -> P<ast::Item>;
-    fn item_enum(&self, span: Span, name: Ident, enum_def: ast::EnumDef) -> P<ast::Item>;
-
-    fn item_struct_poly(&self,
-                        span: Span,
-                        name: Ident,
-                        struct_def: ast::VariantData,
-                        generics: Generics) -> P<ast::Item>;
-    fn item_struct(&self, span: Span, name: Ident, struct_def: ast::VariantData) -> P<ast::Item>;
-
-    fn item_mod(&self, span: Span, inner_span: Span,
-                name: Ident, attrs: Vec<ast::Attribute>,
-                items: Vec<P<ast::Item>>) -> P<ast::Item>;
-
-    fn item_extern_crate(&self, span: Span, name: Ident) -> P<ast::Item>;
-
-    fn item_static(&self,
-                   span: Span,
-                   name: Ident,
-                   ty: P<ast::Ty>,
-                   mutbl: ast::Mutability,
-                   expr: P<ast::Expr>)
-                   -> P<ast::Item>;
-
-    fn item_const(&self,
-                   span: Span,
-                   name: Ident,
-                   ty: P<ast::Ty>,
-                   expr: P<ast::Expr>)
-                   -> P<ast::Item>;
-
-    fn item_ty_poly(&self,
-                    span: Span,
-                    name: Ident,
-                    ty: P<ast::Ty>,
-                    generics: Generics) -> P<ast::Item>;
-    fn item_ty(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> P<ast::Item>;
-
-    fn attribute(&self, sp: Span, mi: ast::MetaItem) -> ast::Attribute;
-
-    fn meta_word(&self, sp: Span, w: ast::Name) -> ast::MetaItem;
-
-    fn meta_list_item_word(&self, sp: Span, w: ast::Name) -> ast::NestedMetaItem;
-
-    fn meta_list(&self,
-                 sp: Span,
-                 name: ast::Name,
-                 mis: Vec<ast::NestedMetaItem> )
-                 -> ast::MetaItem;
-    fn meta_name_value(&self,
-                       sp: Span,
-                       name: ast::Name,
-                       value: ast::LitKind)
-                       -> ast::MetaItem;
-
-    fn item_use(&self, sp: Span,
-                vis: ast::Visibility, vp: P<ast::UseTree>) -> P<ast::Item>;
-    fn item_use_simple(&self, sp: Span, vis: ast::Visibility, path: ast::Path) -> P<ast::Item>;
-    fn item_use_simple_(&self, sp: Span, vis: ast::Visibility,
-                        ident: Option<ast::Ident>, path: ast::Path) -> P<ast::Item>;
-    fn item_use_list(&self, sp: Span, vis: ast::Visibility,
-                     path: Vec<ast::Ident>, imports: &[ast::Ident]) -> P<ast::Item>;
-    fn item_use_glob(&self, sp: Span,
-                     vis: ast::Visibility, path: Vec<ast::Ident>) -> P<ast::Item>;
-}
+// Left so that Cargo tests don't break, this can be removed once those no longer use it
+pub trait AstBuilder {}
 
-impl<'a> AstBuilder for ExtCtxt<'a> {
-    fn path(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path {
+impl<'a> ExtCtxt<'a> {
+    pub fn path(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path {
         self.path_all(span, false, strs, vec![], vec![])
     }
-    fn path_ident(&self, span: Span, id: ast::Ident) -> ast::Path {
+    pub fn path_ident(&self, span: Span, id: ast::Ident) -> ast::Path {
         self.path(span, vec![id])
     }
-    fn path_global(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path {
+    pub fn path_global(&self, span: Span, strs: Vec<ast::Ident> ) -> ast::Path {
         self.path_all(span, true, strs, vec![], vec![])
     }
-    fn path_all(&self,
+    pub fn path_all(&self,
                 span: Span,
                 global: bool,
                 mut idents: Vec<ast::Ident> ,
@@ -330,7 +55,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
     /// Constructs a qualified path.
     ///
     /// Constructs a path like `<self_type as trait_path>::ident`.
-    fn qpath(&self,
+    pub fn qpath(&self,
              self_type: P<ast::Ty>,
              trait_path: ast::Path,
              ident: ast::Ident)
@@ -341,7 +66,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
     /// Constructs a qualified path.
     ///
     /// Constructs a path like `<self_type as trait_path>::ident<'a, T, A = Bar>`.
-    fn qpath_all(&self,
+    pub fn qpath_all(&self,
                  self_type: P<ast::Ty>,
                  trait_path: ast::Path,
                  ident: ast::Ident,
@@ -363,14 +88,14 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }, path)
     }
 
-    fn ty_mt(&self, ty: P<ast::Ty>, mutbl: ast::Mutability) -> ast::MutTy {
+    pub fn ty_mt(&self, ty: P<ast::Ty>, mutbl: ast::Mutability) -> ast::MutTy {
         ast::MutTy {
             ty,
             mutbl,
         }
     }
 
-    fn ty(&self, span: Span, ty: ast::TyKind) -> P<ast::Ty> {
+    pub fn ty(&self, span: Span, ty: ast::TyKind) -> P<ast::Ty> {
         P(ast::Ty {
             id: ast::DUMMY_NODE_ID,
             span,
@@ -378,18 +103,18 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         })
     }
 
-    fn ty_path(&self, path: ast::Path) -> P<ast::Ty> {
+    pub fn ty_path(&self, path: ast::Path) -> P<ast::Ty> {
         self.ty(path.span, ast::TyKind::Path(None, path))
     }
 
     // Might need to take bounds as an argument in the future, if you ever want
     // to generate a bounded existential trait type.
-    fn ty_ident(&self, span: Span, ident: ast::Ident)
+    pub fn ty_ident(&self, span: Span, ident: ast::Ident)
         -> P<ast::Ty> {
         self.ty_path(self.path_ident(span, ident))
     }
 
-    fn anon_const(&self, span: Span, expr: ast::ExprKind) -> ast::AnonConst {
+    pub fn anon_const(&self, span: Span, expr: ast::ExprKind) -> ast::AnonConst {
         ast::AnonConst {
             id: ast::DUMMY_NODE_ID,
             value: P(ast::Expr {
@@ -401,11 +126,11 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn const_ident(&self, span: Span, ident: ast::Ident) -> ast::AnonConst {
+    pub fn const_ident(&self, span: Span, ident: ast::Ident) -> ast::AnonConst {
         self.anon_const(span, ast::ExprKind::Path(None, self.path_ident(span, ident)))
     }
 
-    fn ty_rptr(&self,
+    pub fn ty_rptr(&self,
                span: Span,
                ty: P<ast::Ty>,
                lifetime: Option<ast::Lifetime>,
@@ -415,7 +140,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                 ast::TyKind::Rptr(lifetime, self.ty_mt(ty, mutbl)))
     }
 
-    fn ty_ptr(&self,
+    pub fn ty_ptr(&self,
               span: Span,
               ty: P<ast::Ty>,
               mutbl: ast::Mutability)
@@ -424,11 +149,11 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                 ast::TyKind::Ptr(self.ty_mt(ty, mutbl)))
     }
 
-    fn ty_infer(&self, span: Span) -> P<ast::Ty> {
+    pub fn ty_infer(&self, span: Span) -> P<ast::Ty> {
         self.ty(span, ast::TyKind::Infer)
     }
 
-    fn typaram(&self,
+    pub fn typaram(&self,
                span: Span,
                ident: ast::Ident,
                attrs: Vec<ast::Attribute>,
@@ -445,14 +170,14 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn trait_ref(&self, path: ast::Path) -> ast::TraitRef {
+    pub fn trait_ref(&self, path: ast::Path) -> ast::TraitRef {
         ast::TraitRef {
             path,
             ref_id: ast::DUMMY_NODE_ID,
         }
     }
 
-    fn poly_trait_ref(&self, span: Span, path: ast::Path) -> ast::PolyTraitRef {
+    pub fn poly_trait_ref(&self, span: Span, path: ast::Path) -> ast::PolyTraitRef {
         ast::PolyTraitRef {
             bound_generic_params: Vec::new(),
             trait_ref: self.trait_ref(path),
@@ -460,16 +185,16 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn trait_bound(&self, path: ast::Path) -> ast::GenericBound {
+    pub fn trait_bound(&self, path: ast::Path) -> ast::GenericBound {
         ast::GenericBound::Trait(self.poly_trait_ref(path.span, path),
                                  ast::TraitBoundModifier::None)
     }
 
-    fn lifetime(&self, span: Span, ident: ast::Ident) -> ast::Lifetime {
+    pub fn lifetime(&self, span: Span, ident: ast::Ident) -> ast::Lifetime {
         ast::Lifetime { id: ast::DUMMY_NODE_ID, ident: ident.with_span_pos(span) }
     }
 
-    fn lifetime_def(&self,
+    pub fn lifetime_def(&self,
                     span: Span,
                     ident: ast::Ident,
                     attrs: Vec<ast::Attribute>,
@@ -485,7 +210,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn stmt_expr(&self, expr: P<ast::Expr>) -> ast::Stmt {
+    pub fn stmt_expr(&self, expr: P<ast::Expr>) -> ast::Stmt {
         ast::Stmt {
             id: ast::DUMMY_NODE_ID,
             span: expr.span,
@@ -493,7 +218,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn stmt_semi(&self, expr: P<ast::Expr>) -> ast::Stmt {
+    pub fn stmt_semi(&self, expr: P<ast::Expr>) -> ast::Stmt {
         ast::Stmt {
             id: ast::DUMMY_NODE_ID,
             span: expr.span,
@@ -501,7 +226,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn stmt_let(&self, sp: Span, mutbl: bool, ident: ast::Ident,
+    pub fn stmt_let(&self, sp: Span, mutbl: bool, ident: ast::Ident,
                 ex: P<ast::Expr>) -> ast::Stmt {
         let pat = if mutbl {
             let binding_mode = ast::BindingMode::ByValue(ast::Mutability::Mutable);
@@ -524,7 +249,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn stmt_let_typed(&self,
+    pub fn stmt_let_typed(&self,
                       sp: Span,
                       mutbl: bool,
                       ident: ast::Ident,
@@ -553,7 +278,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
     }
 
     // Generates `let _: Type;`, which is usually used for type assertions.
-    fn stmt_let_type_only(&self, span: Span, ty: P<ast::Ty>) -> ast::Stmt {
+    pub fn stmt_let_type_only(&self, span: Span, ty: P<ast::Ty>) -> ast::Stmt {
         let local = P(ast::Local {
             pat: self.pat_wild(span),
             ty: Some(ty),
@@ -569,7 +294,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn stmt_item(&self, sp: Span, item: P<ast::Item>) -> ast::Stmt {
+    pub fn stmt_item(&self, sp: Span, item: P<ast::Item>) -> ast::Stmt {
         ast::Stmt {
             id: ast::DUMMY_NODE_ID,
             node: ast::StmtKind::Item(item),
@@ -577,14 +302,14 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn block_expr(&self, expr: P<ast::Expr>) -> P<ast::Block> {
+    pub fn block_expr(&self, expr: P<ast::Expr>) -> P<ast::Block> {
         self.block(expr.span, vec![ast::Stmt {
             id: ast::DUMMY_NODE_ID,
             span: expr.span,
             node: ast::StmtKind::Expr(expr),
         }])
     }
-    fn block(&self, span: Span, stmts: Vec<ast::Stmt>) -> P<ast::Block> {
+    pub fn block(&self, span: Span, stmts: Vec<ast::Stmt>) -> P<ast::Block> {
         P(ast::Block {
            stmts,
            id: ast::DUMMY_NODE_ID,
@@ -593,7 +318,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         })
     }
 
-    fn expr(&self, span: Span, node: ast::ExprKind) -> P<ast::Expr> {
+    pub fn expr(&self, span: Span, node: ast::ExprKind) -> P<ast::Expr> {
         P(ast::Expr {
             id: ast::DUMMY_NODE_ID,
             node,
@@ -602,61 +327,65 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         })
     }
 
-    fn expr_path(&self, path: ast::Path) -> P<ast::Expr> {
+    pub fn expr_path(&self, path: ast::Path) -> P<ast::Expr> {
         self.expr(path.span, ast::ExprKind::Path(None, path))
     }
 
     /// Constructs a `QPath` expression.
-    fn expr_qpath(&self, span: Span, qself: ast::QSelf, path: ast::Path) -> P<ast::Expr> {
+    pub fn expr_qpath(&self, span: Span, qself: ast::QSelf, path: ast::Path) -> P<ast::Expr> {
         self.expr(span, ast::ExprKind::Path(Some(qself), path))
     }
 
-    fn expr_ident(&self, span: Span, id: ast::Ident) -> P<ast::Expr> {
+    pub fn expr_ident(&self, span: Span, id: ast::Ident) -> P<ast::Expr> {
         self.expr_path(self.path_ident(span, id))
     }
-    fn expr_self(&self, span: Span) -> P<ast::Expr> {
+    pub fn expr_self(&self, span: Span) -> P<ast::Expr> {
         self.expr_ident(span, Ident::with_empty_ctxt(kw::SelfLower))
     }
 
-    fn expr_binary(&self, sp: Span, op: ast::BinOpKind,
+    pub fn expr_binary(&self, sp: Span, op: ast::BinOpKind,
                    lhs: P<ast::Expr>, rhs: P<ast::Expr>) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::Binary(Spanned { node: op, span: sp }, lhs, rhs))
     }
 
-    fn expr_deref(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn expr_deref(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr> {
         self.expr_unary(sp, UnOp::Deref, e)
     }
-    fn expr_unary(&self, sp: Span, op: ast::UnOp, e: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn expr_unary(&self, sp: Span, op: ast::UnOp, e: P<ast::Expr>) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::Unary(op, e))
     }
 
-    fn expr_field_access(&self, sp: Span, expr: P<ast::Expr>, ident: ast::Ident) -> P<ast::Expr> {
+    pub fn expr_field_access(
+        &self, sp: Span, expr: P<ast::Expr>, ident: ast::Ident,
+    ) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::Field(expr, ident.with_span_pos(sp)))
     }
-    fn expr_tup_field_access(&self, sp: Span, expr: P<ast::Expr>, idx: usize) -> P<ast::Expr> {
+    pub fn expr_tup_field_access(&self, sp: Span, expr: P<ast::Expr>, idx: usize) -> P<ast::Expr> {
         let ident = Ident::from_str(&idx.to_string()).with_span_pos(sp);
         self.expr(sp, ast::ExprKind::Field(expr, ident))
     }
-    fn expr_addr_of(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn expr_addr_of(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::AddrOf(ast::Mutability::Immutable, e))
     }
-    fn expr_mut_addr_of(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn expr_mut_addr_of(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::AddrOf(ast::Mutability::Mutable, e))
     }
 
-    fn expr_call(&self, span: Span, expr: P<ast::Expr>, args: Vec<P<ast::Expr>>) -> P<ast::Expr> {
+    pub fn expr_call(
+        &self, span: Span, expr: P<ast::Expr>, args: Vec<P<ast::Expr>>,
+    ) -> P<ast::Expr> {
         self.expr(span, ast::ExprKind::Call(expr, args))
     }
-    fn expr_call_ident(&self, span: Span, id: ast::Ident,
+    pub fn expr_call_ident(&self, span: Span, id: ast::Ident,
                        args: Vec<P<ast::Expr>>) -> P<ast::Expr> {
         self.expr(span, ast::ExprKind::Call(self.expr_ident(span, id), args))
     }
-    fn expr_call_global(&self, sp: Span, fn_path: Vec<ast::Ident> ,
+    pub fn expr_call_global(&self, sp: Span, fn_path: Vec<ast::Ident> ,
                       args: Vec<P<ast::Expr>> ) -> P<ast::Expr> {
         let pathexpr = self.expr_path(self.path_global(sp, fn_path));
         self.expr_call(sp, pathexpr, args)
     }
-    fn expr_method_call(&self, span: Span,
+    pub fn expr_method_call(&self, span: Span,
                         expr: P<ast::Expr>,
                         ident: ast::Ident,
                         mut args: Vec<P<ast::Expr>> ) -> P<ast::Expr> {
@@ -664,10 +393,10 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         let segment = ast::PathSegment::from_ident(ident.with_span_pos(span));
         self.expr(span, ast::ExprKind::MethodCall(segment, args))
     }
-    fn expr_block(&self, b: P<ast::Block>) -> P<ast::Expr> {
+    pub fn expr_block(&self, b: P<ast::Block>) -> P<ast::Expr> {
         self.expr(b.span, ast::ExprKind::Block(b, None))
     }
-    fn field_imm(&self, span: Span, ident: Ident, e: P<ast::Expr>) -> ast::Field {
+    pub fn field_imm(&self, span: Span, ident: Ident, e: P<ast::Expr>) -> ast::Field {
         ast::Field {
             ident: ident.with_span_pos(span),
             expr: e,
@@ -676,23 +405,25 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
             attrs: ThinVec::new(),
         }
     }
-    fn expr_struct(&self, span: Span, path: ast::Path, fields: Vec<ast::Field>) -> P<ast::Expr> {
+    pub fn expr_struct(
+        &self, span: Span, path: ast::Path, fields: Vec<ast::Field>
+    ) -> P<ast::Expr> {
         self.expr(span, ast::ExprKind::Struct(path, fields, None))
     }
-    fn expr_struct_ident(&self, span: Span,
+    pub fn expr_struct_ident(&self, span: Span,
                          id: ast::Ident, fields: Vec<ast::Field>) -> P<ast::Expr> {
         self.expr_struct(span, self.path_ident(span, id), fields)
     }
 
-    fn expr_lit(&self, span: Span, lit_kind: ast::LitKind) -> P<ast::Expr> {
+    pub fn expr_lit(&self, span: Span, lit_kind: ast::LitKind) -> P<ast::Expr> {
         let lit = ast::Lit::from_lit_kind(lit_kind, span);
         self.expr(span, ast::ExprKind::Lit(lit))
     }
-    fn expr_usize(&self, span: Span, i: usize) -> P<ast::Expr> {
+    pub fn expr_usize(&self, span: Span, i: usize) -> P<ast::Expr> {
         self.expr_lit(span, ast::LitKind::Int(i as u128,
                                               ast::LitIntType::Unsigned(ast::UintTy::Usize)))
     }
-    fn expr_isize(&self, sp: Span, i: isize) -> P<ast::Expr> {
+    pub fn expr_isize(&self, sp: Span, i: isize) -> P<ast::Expr> {
         if i < 0 {
             let i = (-i) as u128;
             let lit_ty = ast::LitIntType::Signed(ast::IntTy::Isize);
@@ -703,59 +434,59 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                                                 ast::LitIntType::Signed(ast::IntTy::Isize)))
         }
     }
-    fn expr_u32(&self, sp: Span, u: u32) -> P<ast::Expr> {
+    pub fn expr_u32(&self, sp: Span, u: u32) -> P<ast::Expr> {
         self.expr_lit(sp, ast::LitKind::Int(u as u128,
                                             ast::LitIntType::Unsigned(ast::UintTy::U32)))
     }
-    fn expr_u16(&self, sp: Span, u: u16) -> P<ast::Expr> {
+    pub fn expr_u16(&self, sp: Span, u: u16) -> P<ast::Expr> {
         self.expr_lit(sp, ast::LitKind::Int(u as u128,
                                             ast::LitIntType::Unsigned(ast::UintTy::U16)))
     }
-    fn expr_u8(&self, sp: Span, u: u8) -> P<ast::Expr> {
+    pub fn expr_u8(&self, sp: Span, u: u8) -> P<ast::Expr> {
         self.expr_lit(sp, ast::LitKind::Int(u as u128, ast::LitIntType::Unsigned(ast::UintTy::U8)))
     }
-    fn expr_bool(&self, sp: Span, value: bool) -> P<ast::Expr> {
+    pub fn expr_bool(&self, sp: Span, value: bool) -> P<ast::Expr> {
         self.expr_lit(sp, ast::LitKind::Bool(value))
     }
 
-    fn expr_vec(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr> {
+    pub fn expr_vec(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::Array(exprs))
     }
-    fn expr_vec_ng(&self, sp: Span) -> P<ast::Expr> {
+    pub fn expr_vec_ng(&self, sp: Span) -> P<ast::Expr> {
         self.expr_call_global(sp, self.std_path(&[sym::vec, sym::Vec, sym::new]),
                               Vec::new())
     }
-    fn expr_vec_slice(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr> {
+    pub fn expr_vec_slice(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr> {
         self.expr_addr_of(sp, self.expr_vec(sp, exprs))
     }
-    fn expr_str(&self, sp: Span, s: Symbol) -> P<ast::Expr> {
+    pub fn expr_str(&self, sp: Span, s: Symbol) -> P<ast::Expr> {
         self.expr_lit(sp, ast::LitKind::Str(s, ast::StrStyle::Cooked))
     }
 
-    fn expr_cast(&self, sp: Span, expr: P<ast::Expr>, ty: P<ast::Ty>) -> P<ast::Expr> {
+    pub fn expr_cast(&self, sp: Span, expr: P<ast::Expr>, ty: P<ast::Ty>) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::Cast(expr, ty))
     }
 
-    fn expr_some(&self, sp: Span, expr: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn expr_some(&self, sp: Span, expr: P<ast::Expr>) -> P<ast::Expr> {
         let some = self.std_path(&[sym::option, sym::Option, sym::Some]);
         self.expr_call_global(sp, some, vec![expr])
     }
 
-    fn expr_none(&self, sp: Span) -> P<ast::Expr> {
+    pub fn expr_none(&self, sp: Span) -> P<ast::Expr> {
         let none = self.std_path(&[sym::option, sym::Option, sym::None]);
         let none = self.path_global(sp, none);
         self.expr_path(none)
     }
 
-    fn expr_break(&self, sp: Span) -> P<ast::Expr> {
+    pub fn expr_break(&self, sp: Span) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::Break(None, None))
     }
 
-    fn expr_tuple(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr> {
+    pub fn expr_tuple(&self, sp: Span, exprs: Vec<P<ast::Expr>>) -> P<ast::Expr> {
         self.expr(sp, ast::ExprKind::Tup(exprs))
     }
 
-    fn expr_fail(&self, span: Span, msg: Symbol) -> P<ast::Expr> {
+    pub fn expr_fail(&self, span: Span, msg: Symbol) -> P<ast::Expr> {
         let loc = self.source_map().lookup_char_pos(span.lo());
         let expr_file = self.expr_str(span, Symbol::intern(&loc.file.name.to_string()));
         let expr_line = self.expr_u32(span, loc.line as u32);
@@ -770,21 +501,21 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                 expr_loc_ptr])
     }
 
-    fn expr_unreachable(&self, span: Span) -> P<ast::Expr> {
+    pub fn expr_unreachable(&self, span: Span) -> P<ast::Expr> {
         self.expr_fail(span, Symbol::intern("internal error: entered unreachable code"))
     }
 
-    fn expr_ok(&self, sp: Span, expr: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn expr_ok(&self, sp: Span, expr: P<ast::Expr>) -> P<ast::Expr> {
         let ok = self.std_path(&[sym::result, sym::Result, sym::Ok]);
         self.expr_call_global(sp, ok, vec![expr])
     }
 
-    fn expr_err(&self, sp: Span, expr: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn expr_err(&self, sp: Span, expr: P<ast::Expr>) -> P<ast::Expr> {
         let err = self.std_path(&[sym::result, sym::Result, sym::Err]);
         self.expr_call_global(sp, err, vec![expr])
     }
 
-    fn expr_try(&self, sp: Span, head: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn expr_try(&self, sp: Span, head: P<ast::Expr>) -> P<ast::Expr> {
         let ok = self.std_path(&[sym::result, sym::Result, sym::Ok]);
         let ok_path = self.path_global(sp, ok);
         let err = self.std_path(&[sym::result, sym::Result, sym::Err]);
@@ -814,67 +545,67 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
     }
 
 
-    fn pat(&self, span: Span, pat: PatKind) -> P<ast::Pat> {
+    pub fn pat(&self, span: Span, pat: PatKind) -> P<ast::Pat> {
         P(ast::Pat { id: ast::DUMMY_NODE_ID, node: pat, span })
     }
-    fn pat_wild(&self, span: Span) -> P<ast::Pat> {
+    pub fn pat_wild(&self, span: Span) -> P<ast::Pat> {
         self.pat(span, PatKind::Wild)
     }
-    fn pat_lit(&self, span: Span, expr: P<ast::Expr>) -> P<ast::Pat> {
+    pub fn pat_lit(&self, span: Span, expr: P<ast::Expr>) -> P<ast::Pat> {
         self.pat(span, PatKind::Lit(expr))
     }
-    fn pat_ident(&self, span: Span, ident: ast::Ident) -> P<ast::Pat> {
+    pub fn pat_ident(&self, span: Span, ident: ast::Ident) -> P<ast::Pat> {
         let binding_mode = ast::BindingMode::ByValue(ast::Mutability::Immutable);
         self.pat_ident_binding_mode(span, ident, binding_mode)
     }
 
-    fn pat_ident_binding_mode(&self,
+    pub fn pat_ident_binding_mode(&self,
                               span: Span,
                               ident: ast::Ident,
                               bm: ast::BindingMode) -> P<ast::Pat> {
         let pat = PatKind::Ident(bm, ident.with_span_pos(span), None);
         self.pat(span, pat)
     }
-    fn pat_path(&self, span: Span, path: ast::Path) -> P<ast::Pat> {
+    pub fn pat_path(&self, span: Span, path: ast::Path) -> P<ast::Pat> {
         self.pat(span, PatKind::Path(None, path))
     }
-    fn pat_tuple_struct(&self, span: Span, path: ast::Path,
+    pub fn pat_tuple_struct(&self, span: Span, path: ast::Path,
                         subpats: Vec<P<ast::Pat>>) -> P<ast::Pat> {
         self.pat(span, PatKind::TupleStruct(path, subpats))
     }
-    fn pat_struct(&self, span: Span, path: ast::Path,
+    pub fn pat_struct(&self, span: Span, path: ast::Path,
                   field_pats: Vec<Spanned<ast::FieldPat>>) -> P<ast::Pat> {
         self.pat(span, PatKind::Struct(path, field_pats, false))
     }
-    fn pat_tuple(&self, span: Span, pats: Vec<P<ast::Pat>>) -> P<ast::Pat> {
+    pub fn pat_tuple(&self, span: Span, pats: Vec<P<ast::Pat>>) -> P<ast::Pat> {
         self.pat(span, PatKind::Tuple(pats))
     }
 
-    fn pat_some(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat> {
+    pub fn pat_some(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat> {
         let some = self.std_path(&[sym::option, sym::Option, sym::Some]);
         let path = self.path_global(span, some);
         self.pat_tuple_struct(span, path, vec![pat])
     }
 
-    fn pat_none(&self, span: Span) -> P<ast::Pat> {
+    pub fn pat_none(&self, span: Span) -> P<ast::Pat> {
         let some = self.std_path(&[sym::option, sym::Option, sym::None]);
         let path = self.path_global(span, some);
         self.pat_path(span, path)
     }
 
-    fn pat_ok(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat> {
+    pub fn pat_ok(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat> {
         let some = self.std_path(&[sym::result, sym::Result, sym::Ok]);
         let path = self.path_global(span, some);
         self.pat_tuple_struct(span, path, vec![pat])
     }
 
-    fn pat_err(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat> {
+    pub fn pat_err(&self, span: Span, pat: P<ast::Pat>) -> P<ast::Pat> {
         let some = self.std_path(&[sym::result, sym::Result, sym::Err]);
         let path = self.path_global(span, some);
         self.pat_tuple_struct(span, path, vec![pat])
     }
 
-    fn arm(&self, span: Span, pats: Vec<P<ast::Pat>>, expr: P<ast::Expr>) -> ast::Arm {
+    pub fn arm(&self, span: Span, pats: Vec<P<ast::Pat>>, expr: P<ast::Expr>) -> ast::Arm {
         ast::Arm {
             attrs: vec![],
             pats,
@@ -884,25 +615,25 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }
     }
 
-    fn arm_unreachable(&self, span: Span) -> ast::Arm {
+    pub fn arm_unreachable(&self, span: Span) -> ast::Arm {
         self.arm(span, vec![self.pat_wild(span)], self.expr_unreachable(span))
     }
 
-    fn expr_match(&self, span: Span, arg: P<ast::Expr>, arms: Vec<ast::Arm>) -> P<Expr> {
+    pub fn expr_match(&self, span: Span, arg: P<ast::Expr>, arms: Vec<ast::Arm>) -> P<Expr> {
         self.expr(span, ast::ExprKind::Match(arg, arms))
     }
 
-    fn expr_if(&self, span: Span, cond: P<ast::Expr>,
+    pub fn expr_if(&self, span: Span, cond: P<ast::Expr>,
                then: P<ast::Expr>, els: Option<P<ast::Expr>>) -> P<ast::Expr> {
         let els = els.map(|x| self.expr_block(self.block_expr(x)));
         self.expr(span, ast::ExprKind::If(cond, self.block_expr(then), els))
     }
 
-    fn expr_loop(&self, span: Span, block: P<ast::Block>) -> P<ast::Expr> {
+    pub fn expr_loop(&self, span: Span, block: P<ast::Block>) -> P<ast::Expr> {
         self.expr(span, ast::ExprKind::Loop(block, None))
     }
 
-    fn lambda_fn_decl(&self,
+    pub fn lambda_fn_decl(&self,
                       span: Span,
                       fn_decl: P<ast::FnDecl>,
                       body: P<ast::Expr>,
@@ -916,7 +647,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                                                fn_decl_span))
     }
 
-    fn lambda(&self,
+    pub fn lambda(&self,
               span: Span,
               ids: Vec<ast::Ident>,
               body: P<ast::Expr>)
@@ -937,30 +668,30 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                                                span))
     }
 
-    fn lambda0(&self, span: Span, body: P<ast::Expr>) -> P<ast::Expr> {
+    pub fn lambda0(&self, span: Span, body: P<ast::Expr>) -> P<ast::Expr> {
         self.lambda(span, Vec::new(), body)
     }
 
-    fn lambda1(&self, span: Span, body: P<ast::Expr>, ident: ast::Ident) -> P<ast::Expr> {
+    pub fn lambda1(&self, span: Span, body: P<ast::Expr>, ident: ast::Ident) -> P<ast::Expr> {
         self.lambda(span, vec![ident], body)
     }
 
-    fn lambda_stmts(&self,
+    pub fn lambda_stmts(&self,
                     span: Span,
                     ids: Vec<ast::Ident>,
                     stmts: Vec<ast::Stmt>)
                     -> P<ast::Expr> {
         self.lambda(span, ids, self.expr_block(self.block(span, stmts)))
     }
-    fn lambda_stmts_0(&self, span: Span, stmts: Vec<ast::Stmt>) -> P<ast::Expr> {
+    pub fn lambda_stmts_0(&self, span: Span, stmts: Vec<ast::Stmt>) -> P<ast::Expr> {
         self.lambda0(span, self.expr_block(self.block(span, stmts)))
     }
-    fn lambda_stmts_1(&self, span: Span, stmts: Vec<ast::Stmt>,
+    pub fn lambda_stmts_1(&self, span: Span, stmts: Vec<ast::Stmt>,
                       ident: ast::Ident) -> P<ast::Expr> {
         self.lambda1(span, self.expr_block(self.block(span, stmts)), ident)
     }
 
-    fn arg(&self, span: Span, ident: ast::Ident, ty: P<ast::Ty>) -> ast::Arg {
+    pub fn arg(&self, span: Span, ident: ast::Ident, ty: P<ast::Ty>) -> ast::Arg {
         let arg_pat = self.pat_ident(span, ident);
         ast::Arg {
             attrs: ThinVec::default(),
@@ -972,7 +703,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
     }
 
     // FIXME: unused `self`
-    fn fn_decl(&self, inputs: Vec<ast::Arg>, output: ast::FunctionRetTy) -> P<ast::FnDecl> {
+    pub fn fn_decl(&self, inputs: Vec<ast::Arg>, output: ast::FunctionRetTy) -> P<ast::FnDecl> {
         P(ast::FnDecl {
             inputs,
             output,
@@ -980,7 +711,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         })
     }
 
-    fn item(&self, span: Span, name: Ident,
+    pub fn item(&self, span: Span, name: Ident,
             attrs: Vec<ast::Attribute>, node: ast::ItemKind) -> P<ast::Item> {
         // FIXME: Would be nice if our generated code didn't violate
         // Rust coding conventions
@@ -995,7 +726,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         })
     }
 
-    fn item_fn_poly(&self,
+    pub fn item_fn_poly(&self,
                     span: Span,
                     name: Ident,
                     inputs: Vec<ast::Arg> ,
@@ -1016,7 +747,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                               body))
     }
 
-    fn item_fn(&self,
+    pub fn item_fn(&self,
                span: Span,
                name: Ident,
                inputs: Vec<ast::Arg> ,
@@ -1032,7 +763,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
             body)
     }
 
-    fn variant(&self, span: Span, ident: Ident, tys: Vec<P<ast::Ty>> ) -> ast::Variant {
+    pub fn variant(&self, span: Span, ident: Ident, tys: Vec<P<ast::Ty>> ) -> ast::Variant {
         let fields: Vec<_> = tys.into_iter().map(|ty| {
             ast::StructField {
                 span: ty.span,
@@ -1060,19 +791,19 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
                })
     }
 
-    fn item_enum_poly(&self, span: Span, name: Ident,
+    pub fn item_enum_poly(&self, span: Span, name: Ident,
                       enum_definition: ast::EnumDef,
                       generics: Generics) -> P<ast::Item> {
         self.item(span, name, Vec::new(), ast::ItemKind::Enum(enum_definition, generics))
     }
 
-    fn item_enum(&self, span: Span, name: Ident,
+    pub fn item_enum(&self, span: Span, name: Ident,
                  enum_definition: ast::EnumDef) -> P<ast::Item> {
         self.item_enum_poly(span, name, enum_definition,
                             Generics::default())
     }
 
-    fn item_struct(&self, span: Span, name: Ident,
+    pub fn item_struct(&self, span: Span, name: Ident,
                    struct_def: ast::VariantData) -> P<ast::Item> {
         self.item_struct_poly(
             span,
@@ -1082,12 +813,12 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         )
     }
 
-    fn item_struct_poly(&self, span: Span, name: Ident,
+    pub fn item_struct_poly(&self, span: Span, name: Ident,
         struct_def: ast::VariantData, generics: Generics) -> P<ast::Item> {
         self.item(span, name, Vec::new(), ast::ItemKind::Struct(struct_def, generics))
     }
 
-    fn item_mod(&self, span: Span, inner_span: Span, name: Ident,
+    pub fn item_mod(&self, span: Span, inner_span: Span, name: Ident,
                 attrs: Vec<ast::Attribute>,
                 items: Vec<P<ast::Item>>) -> P<ast::Item> {
         self.item(
@@ -1102,11 +833,11 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         )
     }
 
-    fn item_extern_crate(&self, span: Span, name: Ident) -> P<ast::Item> {
+    pub fn item_extern_crate(&self, span: Span, name: Ident) -> P<ast::Item> {
         self.item(span, name, Vec::new(), ast::ItemKind::ExternCrate(None))
     }
 
-    fn item_static(&self,
+    pub fn item_static(&self,
                    span: Span,
                    name: Ident,
                    ty: P<ast::Ty>,
@@ -1116,7 +847,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         self.item(span, name, Vec::new(), ast::ItemKind::Static(ty, mutbl, expr))
     }
 
-    fn item_const(&self,
+    pub fn item_const(&self,
                   span: Span,
                   name: Ident,
                   ty: P<ast::Ty>,
@@ -1125,39 +856,39 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         self.item(span, name, Vec::new(), ast::ItemKind::Const(ty, expr))
     }
 
-    fn item_ty_poly(&self, span: Span, name: Ident, ty: P<ast::Ty>,
+    pub fn item_ty_poly(&self, span: Span, name: Ident, ty: P<ast::Ty>,
                     generics: Generics) -> P<ast::Item> {
         self.item(span, name, Vec::new(), ast::ItemKind::Ty(ty, generics))
     }
 
-    fn item_ty(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> P<ast::Item> {
+    pub fn item_ty(&self, span: Span, name: Ident, ty: P<ast::Ty>) -> P<ast::Item> {
         self.item_ty_poly(span, name, ty, Generics::default())
     }
 
-    fn attribute(&self, sp: Span, mi: ast::MetaItem) -> ast::Attribute {
-        attr::mk_spanned_attr_outer(sp, attr::mk_attr_id(), mi)
+    pub fn attribute(&self, mi: ast::MetaItem) -> ast::Attribute {
+        attr::mk_attr_outer(mi)
     }
 
-    fn meta_word(&self, sp: Span, w: ast::Name) -> ast::MetaItem {
-        attr::mk_word_item(Ident::with_empty_ctxt(w).with_span_pos(sp))
+    pub fn meta_word(&self, sp: Span, w: ast::Name) -> ast::MetaItem {
+        attr::mk_word_item(Ident::new(w, sp))
     }
 
-    fn meta_list_item_word(&self, sp: Span, w: ast::Name) -> ast::NestedMetaItem {
-        attr::mk_nested_word_item(Ident::with_empty_ctxt(w).with_span_pos(sp))
+    pub fn meta_list_item_word(&self, sp: Span, w: ast::Name) -> ast::NestedMetaItem {
+        attr::mk_nested_word_item(Ident::new(w, sp))
     }
 
-    fn meta_list(&self, sp: Span, name: ast::Name, mis: Vec<ast::NestedMetaItem>)
+    pub fn meta_list(&self, sp: Span, name: ast::Name, mis: Vec<ast::NestedMetaItem>)
                  -> ast::MetaItem {
-        attr::mk_list_item(sp, Ident::with_empty_ctxt(name).with_span_pos(sp), mis)
+        attr::mk_list_item(sp, Ident::new(name, sp), mis)
     }
 
-    fn meta_name_value(&self, span: Span, name: ast::Name, lit_kind: ast::LitKind)
+    pub fn meta_name_value(&self, span: Span, name: ast::Name, lit_kind: ast::LitKind)
                        -> ast::MetaItem {
-        attr::mk_name_value_item(span, Ident::with_empty_ctxt(name).with_span_pos(span),
+        attr::mk_name_value_item(span, Ident::new(name, span),
                                  lit_kind, span)
     }
 
-    fn item_use(&self, sp: Span,
+    pub fn item_use(&self, sp: Span,
                 vis: ast::Visibility, vp: P<ast::UseTree>) -> P<ast::Item> {
         P(ast::Item {
             id: ast::DUMMY_NODE_ID,
@@ -1170,11 +901,11 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         })
     }
 
-    fn item_use_simple(&self, sp: Span, vis: ast::Visibility, path: ast::Path) -> P<ast::Item> {
+    pub fn item_use_simple(&self, sp: Span, vis: ast::Visibility, path: ast::Path) -> P<ast::Item> {
         self.item_use_simple_(sp, vis, None, path)
     }
 
-    fn item_use_simple_(&self, sp: Span, vis: ast::Visibility,
+    pub fn item_use_simple_(&self, sp: Span, vis: ast::Visibility,
                         rename: Option<ast::Ident>, path: ast::Path) -> P<ast::Item> {
         self.item_use(sp, vis, P(ast::UseTree {
             span: sp,
@@ -1183,7 +914,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }))
     }
 
-    fn item_use_list(&self, sp: Span, vis: ast::Visibility,
+    pub fn item_use_list(&self, sp: Span, vis: ast::Visibility,
                      path: Vec<ast::Ident>, imports: &[ast::Ident]) -> P<ast::Item> {
         let imports = imports.iter().map(|id| {
             (ast::UseTree {
@@ -1200,7 +931,7 @@ impl<'a> AstBuilder for ExtCtxt<'a> {
         }))
     }
 
-    fn item_use_glob(&self, sp: Span,
+    pub fn item_use_glob(&self, sp: Span,
                      vis: ast::Visibility, path: Vec<ast::Ident>) -> P<ast::Item> {
         self.item_use(sp, vis, P(ast::UseTree {
             span: sp,
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index cd602d08c5baa..1e9e16d72f829 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -1340,10 +1340,14 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
             }
 
             let meta = attr::mk_list_item(DUMMY_SP, Ident::with_empty_ctxt(sym::doc), items);
-            match at.style {
-                ast::AttrStyle::Inner => *at = attr::mk_spanned_attr_inner(at.span, at.id, meta),
-                ast::AttrStyle::Outer => *at = attr::mk_spanned_attr_outer(at.span, at.id, meta),
-            }
+            *at = attr::Attribute {
+                span: at.span,
+                id: at.id,
+                style: at.style,
+                path: meta.path,
+                tokens: meta.node.tokens(meta.span),
+                is_sugared_doc: false,
+            };
         } else {
             noop_visit_attribute(at, self)
         }
diff --git a/src/libsyntax/ext/proc_macro.rs b/src/libsyntax/ext/proc_macro.rs
index 425b9813f5904..ec708994fad86 100644
--- a/src/libsyntax/ext/proc_macro.rs
+++ b/src/libsyntax/ext/proc_macro.rs
@@ -2,7 +2,6 @@ use crate::ast::{self, ItemKind, Attribute, Mac};
 use crate::attr::{mark_used, mark_known, HasAttrs};
 use crate::errors::{Applicability, FatalError};
 use crate::ext::base::{self, *};
-use crate::ext::build::AstBuilder;
 use crate::ext::proc_macro_server;
 use crate::parse::{self, token};
 use crate::parse::parser::PathStyle;
@@ -239,11 +238,11 @@ crate fn add_derived_markers<T: HasAttrs>(
     item.visit_attrs(|attrs| {
         if names.contains(&sym::Eq) && names.contains(&sym::PartialEq) {
             let meta = cx.meta_word(span, sym::structural_match);
-            attrs.push(cx.attribute(span, meta));
+            attrs.push(cx.attribute(meta));
         }
         if names.contains(&sym::Copy) {
             let meta = cx.meta_word(span, sym::rustc_copy_clone_marker);
-            attrs.push(cx.attribute(span, meta));
+            attrs.push(cx.attribute(meta));
         }
     });
 }
diff --git a/src/libsyntax/parse/attr.rs b/src/libsyntax/parse/attr.rs
index af484c886ab35..a42da1123600a 100644
--- a/src/libsyntax/parse/attr.rs
+++ b/src/libsyntax/parse/attr.rs
@@ -53,7 +53,7 @@ impl<'a> Parser<'a> {
                     just_parsed_doc_comment = false;
                 }
                 token::DocComment(s) => {
-                    let attr = attr::mk_sugared_doc_attr(attr::mk_attr_id(), s, self.token.span);
+                    let attr = attr::mk_sugared_doc_attr(s, self.token.span);
                     if attr.style != ast::AttrStyle::Outer {
                         let mut err = self.fatal("expected outer doc comment");
                         err.note("inner doc comments like this (starting with \
@@ -239,7 +239,7 @@ impl<'a> Parser<'a> {
                 }
                 token::DocComment(s) => {
                     // we need to get the position of this token before we bump.
-                    let attr = attr::mk_sugared_doc_attr(attr::mk_attr_id(), s, self.token.span);
+                    let attr = attr::mk_sugared_doc_attr(s, self.token.span);
                     if attr.style == ast::AttrStyle::Inner {
                         attrs.push(attr);
                         self.bump();
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 7096d6799e2cd..442cc784f7aaa 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -6393,15 +6393,8 @@ impl<'a> Parser<'a> {
                     self.eval_src_mod(path, directory_ownership, id.to_string(), id_span)?;
                 // Record that we fetched the mod from an external file
                 if warn {
-                    let attr = Attribute {
-                        id: attr::mk_attr_id(),
-                        style: ast::AttrStyle::Outer,
-                        path: ast::Path::from_ident(
-                            Ident::with_empty_ctxt(sym::warn_directory_ownership)),
-                        tokens: TokenStream::empty(),
-                        is_sugared_doc: false,
-                        span: DUMMY_SP,
-                    };
+                    let attr = attr::mk_attr_outer(
+                        attr::mk_word_item(Ident::with_empty_ctxt(sym::warn_directory_ownership)));
                     attr::mark_known(&attr);
                     attrs.push(attr);
                 }
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 88ff6ee907101..372f6fef5e3bd 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -123,12 +123,12 @@ pub fn print_crate<'a>(cm: &'a SourceMap,
         let pi_nested = attr::mk_nested_word_item(ast::Ident::with_empty_ctxt(sym::prelude_import));
         let list = attr::mk_list_item(
             DUMMY_SP, ast::Ident::with_empty_ctxt(sym::feature), vec![pi_nested]);
-        let fake_attr = attr::mk_attr_inner(DUMMY_SP, attr::mk_attr_id(), list);
+        let fake_attr = attr::mk_attr_inner(list);
         s.print_attribute(&fake_attr);
 
         // #![no_std]
         let no_std_meta = attr::mk_word_item(ast::Ident::with_empty_ctxt(sym::no_std));
-        let fake_attr = attr::mk_attr_inner(DUMMY_SP, attr::mk_attr_id(), no_std_meta);
+        let fake_attr = attr::mk_attr_inner(no_std_meta);
         s.print_attribute(&fake_attr);
     }
 
diff --git a/src/libsyntax_ext/assert.rs b/src/libsyntax_ext/assert.rs
index 235565314f5e2..b10d8fcd357c4 100644
--- a/src/libsyntax_ext/assert.rs
+++ b/src/libsyntax_ext/assert.rs
@@ -3,7 +3,6 @@ use errors::{Applicability, DiagnosticBuilder};
 use syntax::ast::{self, *};
 use syntax::source_map::Spanned;
 use syntax::ext::base::*;
-use syntax::ext::build::AstBuilder;
 use syntax::parse::token::{self, TokenKind};
 use syntax::parse::parser::Parser;
 use syntax::print::pprust;
diff --git a/src/libsyntax_ext/cfg.rs b/src/libsyntax_ext/cfg.rs
index 2b64f558be0a0..84830e6ddda1a 100644
--- a/src/libsyntax_ext/cfg.rs
+++ b/src/libsyntax_ext/cfg.rs
@@ -6,7 +6,6 @@ use errors::DiagnosticBuilder;
 
 use syntax::ast;
 use syntax::ext::base::{self, *};
-use syntax::ext::build::AstBuilder;
 use syntax::attr;
 use syntax::tokenstream;
 use syntax::parse::token;
diff --git a/src/libsyntax_ext/concat.rs b/src/libsyntax_ext/concat.rs
index dbc985fd8599a..f1d079eb05379 100644
--- a/src/libsyntax_ext/concat.rs
+++ b/src/libsyntax_ext/concat.rs
@@ -1,6 +1,5 @@
 use syntax::ast;
 use syntax::ext::base;
-use syntax::ext::build::AstBuilder;
 use syntax::symbol::Symbol;
 use syntax::tokenstream;
 
diff --git a/src/libsyntax_ext/deriving/clone.rs b/src/libsyntax_ext/deriving/clone.rs
index 9a890a06e0396..2340238aaea41 100644
--- a/src/libsyntax_ext/deriving/clone.rs
+++ b/src/libsyntax_ext/deriving/clone.rs
@@ -5,7 +5,6 @@ use crate::deriving::generic::ty::*;
 use syntax::ast::{self, Expr, GenericArg, Generics, ItemKind, MetaItem, VariantData};
 use syntax::attr;
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax_pos::Span;
@@ -77,7 +76,7 @@ pub fn expand_deriving_clone(cx: &mut ExtCtxt<'_>,
     }
 
     let inline = cx.meta_word(span, sym::inline);
-    let attrs = vec![cx.attribute(span, inline)];
+    let attrs = vec![cx.attribute(inline)];
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
diff --git a/src/libsyntax_ext/deriving/cmp/eq.rs b/src/libsyntax_ext/deriving/cmp/eq.rs
index 1d981e0ff7906..0c34599814a79 100644
--- a/src/libsyntax_ext/deriving/cmp/eq.rs
+++ b/src/libsyntax_ext/deriving/cmp/eq.rs
@@ -4,7 +4,6 @@ use crate::deriving::generic::ty::*;
 
 use syntax::ast::{self, Expr, MetaItem, GenericArg};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::{sym, Symbol};
 use syntax_pos::Span;
@@ -17,7 +16,7 @@ pub fn expand_deriving_eq(cx: &mut ExtCtxt<'_>,
     let inline = cx.meta_word(span, sym::inline);
     let hidden = cx.meta_list_item_word(span, sym::hidden);
     let doc = cx.meta_list(span, sym::doc, vec![hidden]);
-    let attrs = vec![cx.attribute(span, inline), cx.attribute(span, doc)];
+    let attrs = vec![cx.attribute(inline), cx.attribute(doc)];
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
diff --git a/src/libsyntax_ext/deriving/cmp/ord.rs b/src/libsyntax_ext/deriving/cmp/ord.rs
index 844865d57c7ad..885cfee35658a 100644
--- a/src/libsyntax_ext/deriving/cmp/ord.rs
+++ b/src/libsyntax_ext/deriving/cmp/ord.rs
@@ -4,7 +4,6 @@ use crate::deriving::generic::ty::*;
 
 use syntax::ast::{self, Expr, MetaItem};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::sym;
 use syntax_pos::Span;
@@ -15,7 +14,7 @@ pub fn expand_deriving_ord(cx: &mut ExtCtxt<'_>,
                            item: &Annotatable,
                            push: &mut dyn FnMut(Annotatable)) {
     let inline = cx.meta_word(span, sym::inline);
-    let attrs = vec![cx.attribute(span, inline)];
+    let attrs = vec![cx.attribute(inline)];
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
diff --git a/src/libsyntax_ext/deriving/cmp/partial_eq.rs b/src/libsyntax_ext/deriving/cmp/partial_eq.rs
index 732bb234389a0..337f7c5cfe238 100644
--- a/src/libsyntax_ext/deriving/cmp/partial_eq.rs
+++ b/src/libsyntax_ext/deriving/cmp/partial_eq.rs
@@ -4,7 +4,6 @@ use crate::deriving::generic::ty::*;
 
 use syntax::ast::{BinOpKind, Expr, MetaItem};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::sym;
 use syntax_pos::Span;
@@ -63,7 +62,7 @@ pub fn expand_deriving_partial_eq(cx: &mut ExtCtxt<'_>,
     macro_rules! md {
         ($name:expr, $f:ident) => { {
             let inline = cx.meta_word(span, sym::inline);
-            let attrs = vec![cx.attribute(span, inline)];
+            let attrs = vec![cx.attribute(inline)];
             MethodDef {
                 name: $name,
                 generics: LifetimeBounds::empty(),
diff --git a/src/libsyntax_ext/deriving/cmp/partial_ord.rs b/src/libsyntax_ext/deriving/cmp/partial_ord.rs
index a30a7d78222f4..0ec30f5924fbe 100644
--- a/src/libsyntax_ext/deriving/cmp/partial_ord.rs
+++ b/src/libsyntax_ext/deriving/cmp/partial_ord.rs
@@ -6,7 +6,6 @@ use crate::deriving::generic::ty::*;
 
 use syntax::ast::{self, BinOpKind, Expr, MetaItem};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::{sym, Symbol};
 use syntax_pos::Span;
@@ -19,7 +18,7 @@ pub fn expand_deriving_partial_ord(cx: &mut ExtCtxt<'_>,
     macro_rules! md {
         ($name:expr, $op:expr, $equal:expr) => { {
             let inline = cx.meta_word(span, sym::inline);
-            let attrs = vec![cx.attribute(span, inline)];
+            let attrs = vec![cx.attribute(inline)];
             MethodDef {
                 name: $name,
                 generics: LifetimeBounds::empty(),
@@ -43,7 +42,7 @@ pub fn expand_deriving_partial_ord(cx: &mut ExtCtxt<'_>,
                                     PathKind::Std));
 
     let inline = cx.meta_word(span, sym::inline);
-    let attrs = vec![cx.attribute(span, inline)];
+    let attrs = vec![cx.attribute(inline)];
 
     let partial_cmp_def = MethodDef {
         name: "partial_cmp",
diff --git a/src/libsyntax_ext/deriving/debug.rs b/src/libsyntax_ext/deriving/debug.rs
index 44ddbb98809b4..0f709630bf41e 100644
--- a/src/libsyntax_ext/deriving/debug.rs
+++ b/src/libsyntax_ext/deriving/debug.rs
@@ -7,7 +7,6 @@ use rustc_data_structures::thin_vec::ThinVec;
 use syntax::ast::{self, Ident};
 use syntax::ast::{Expr, MetaItem};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::sym;
 use syntax_pos::{DUMMY_SP, Span};
diff --git a/src/libsyntax_ext/deriving/decodable.rs b/src/libsyntax_ext/deriving/decodable.rs
index 4c0641d08a92a..293c5a1e7e71b 100644
--- a/src/libsyntax_ext/deriving/decodable.rs
+++ b/src/libsyntax_ext/deriving/decodable.rs
@@ -7,7 +7,6 @@ use crate::deriving::generic::ty::*;
 use syntax::ast;
 use syntax::ast::{Expr, MetaItem, Mutability};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
diff --git a/src/libsyntax_ext/deriving/default.rs b/src/libsyntax_ext/deriving/default.rs
index fd8e87e2fefd1..2fdea10b76f51 100644
--- a/src/libsyntax_ext/deriving/default.rs
+++ b/src/libsyntax_ext/deriving/default.rs
@@ -4,7 +4,6 @@ use crate::deriving::generic::ty::*;
 
 use syntax::ast::{Expr, MetaItem};
 use syntax::ext::base::{Annotatable, DummyResult, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::{kw, sym};
 use syntax::span_err;
@@ -16,7 +15,7 @@ pub fn expand_deriving_default(cx: &mut ExtCtxt<'_>,
                                item: &Annotatable,
                                push: &mut dyn FnMut(Annotatable)) {
     let inline = cx.meta_word(span, sym::inline);
-    let attrs = vec![cx.attribute(span, inline)];
+    let attrs = vec![cx.attribute(inline)];
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
diff --git a/src/libsyntax_ext/deriving/encodable.rs b/src/libsyntax_ext/deriving/encodable.rs
index a964a0970f091..6d0d3b96a56d6 100644
--- a/src/libsyntax_ext/deriving/encodable.rs
+++ b/src/libsyntax_ext/deriving/encodable.rs
@@ -88,7 +88,6 @@ use crate::deriving::generic::ty::*;
 
 use syntax::ast::{Expr, ExprKind, MetaItem, Mutability};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
diff --git a/src/libsyntax_ext/deriving/generic/mod.rs b/src/libsyntax_ext/deriving/generic/mod.rs
index 7f27769f236e2..4a0c4a39f785b 100644
--- a/src/libsyntax_ext/deriving/generic/mod.rs
+++ b/src/libsyntax_ext/deriving/generic/mod.rs
@@ -187,7 +187,6 @@ use syntax::ast::{self, BinOpKind, EnumDef, Expr, Generics, Ident, PatKind};
 use syntax::ast::{VariantData, GenericParamKind, GenericArg};
 use syntax::attr;
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::source_map::{self, respan};
 use syntax::util::map_in_place::MapInPlace;
 use syntax::ptr::P;
@@ -666,14 +665,13 @@ impl<'a> TraitDef<'a> {
         let path = cx.path_all(self.span, false, vec![type_ident], self_params, vec![]);
         let self_type = cx.ty_path(path);
 
-        let attr = cx.attribute(self.span,
-                                cx.meta_word(self.span, sym::automatically_derived));
+        let attr = cx.attribute(cx.meta_word(self.span, sym::automatically_derived));
         // Just mark it now since we know that it'll end up used downstream
         attr::mark_used(&attr);
         let opt_trait_ref = Some(trait_ref);
         let unused_qual = {
             let word = cx.meta_list_item_word(self.span, Symbol::intern("unused_qualifications"));
-            cx.attribute(self.span, cx.meta_list(self.span, sym::allow, vec![word]))
+            cx.attribute(cx.meta_list(self.span, sym::allow, vec![word]))
         };
 
         let mut a = vec![attr, unused_qual];
diff --git a/src/libsyntax_ext/deriving/generic/ty.rs b/src/libsyntax_ext/deriving/generic/ty.rs
index 394beb141712d..399829eaefd14 100644
--- a/src/libsyntax_ext/deriving/generic/ty.rs
+++ b/src/libsyntax_ext/deriving/generic/ty.rs
@@ -6,7 +6,6 @@ pub use Ty::*;
 
 use syntax::ast::{self, Expr, GenericParamKind, Generics, Ident, SelfKind, GenericArg};
 use syntax::ext::base::ExtCtxt;
-use syntax::ext::build::AstBuilder;
 use syntax::source_map::{respan, DUMMY_SP};
 use syntax::ptr::P;
 use syntax_pos::Span;
diff --git a/src/libsyntax_ext/deriving/hash.rs b/src/libsyntax_ext/deriving/hash.rs
index 7ad04aebf6e2e..9787722e81dd0 100644
--- a/src/libsyntax_ext/deriving/hash.rs
+++ b/src/libsyntax_ext/deriving/hash.rs
@@ -4,7 +4,6 @@ use crate::deriving::generic::ty::*;
 
 use syntax::ast::{Expr, MetaItem, Mutability};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::sym;
 use syntax_pos::Span;
diff --git a/src/libsyntax_ext/deriving/mod.rs b/src/libsyntax_ext/deriving/mod.rs
index cad79917af284..8cd2853e5383d 100644
--- a/src/libsyntax_ext/deriving/mod.rs
+++ b/src/libsyntax_ext/deriving/mod.rs
@@ -2,7 +2,6 @@
 
 use syntax::ast::{self, MetaItem};
 use syntax::ext::base::{Annotatable, ExtCtxt, MultiItemModifier};
-use syntax::ext::build::AstBuilder;
 use syntax::ptr::P;
 use syntax::symbol::{Symbol, sym};
 use syntax_pos::Span;
diff --git a/src/libsyntax_ext/env.rs b/src/libsyntax_ext/env.rs
index 03c60e3f11f03..39fc90decc92a 100644
--- a/src/libsyntax_ext/env.rs
+++ b/src/libsyntax_ext/env.rs
@@ -5,7 +5,6 @@
 
 use syntax::ast::{self, Ident, GenericArg};
 use syntax::ext::base::{self, *};
-use syntax::ext::build::AstBuilder;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax_pos::Span;
 use syntax::tokenstream;
diff --git a/src/libsyntax_ext/format.rs b/src/libsyntax_ext/format.rs
index e53660b656865..f1e6cb027ca7a 100644
--- a/src/libsyntax_ext/format.rs
+++ b/src/libsyntax_ext/format.rs
@@ -8,7 +8,6 @@ use errors::Applicability;
 
 use syntax::ast;
 use syntax::ext::base::{self, *};
-use syntax::ext::build::AstBuilder;
 use syntax::parse::token;
 use syntax::ptr::P;
 use syntax::symbol::{Symbol, sym};
diff --git a/src/libsyntax_ext/global_allocator.rs b/src/libsyntax_ext/global_allocator.rs
index 33072487e19f4..f788b51380433 100644
--- a/src/libsyntax_ext/global_allocator.rs
+++ b/src/libsyntax_ext/global_allocator.rs
@@ -3,7 +3,6 @@ use syntax::ast::{self, Arg, Attribute, Expr, FnHeader, Generics, Ident};
 use syntax::attr::check_builtin_macro_attribute;
 use syntax::ext::allocator::{AllocatorKind, AllocatorMethod, AllocatorTy, ALLOCATOR_METHODS};
 use syntax::ext::base::{Annotatable, ExtCtxt};
-use syntax::ext::build::AstBuilder;
 use syntax::ext::hygiene::SyntaxContext;
 use syntax::ptr::P;
 use syntax::symbol::{kw, sym, Symbol};
@@ -110,7 +109,7 @@ impl AllocFnFactory<'_, '_> {
     fn attrs(&self) -> Vec<Attribute> {
         let special = sym::rustc_std_internal_symbol;
         let special = self.cx.meta_word(self.span, special);
-        vec![self.cx.attribute(self.span, special)]
+        vec![self.cx.attribute(special)]
     }
 
     fn arg_ty(
diff --git a/src/libsyntax_ext/plugin_macro_defs.rs b/src/libsyntax_ext/plugin_macro_defs.rs
index 2fd1a42db95f3..a725f5e46ad1c 100644
--- a/src/libsyntax_ext/plugin_macro_defs.rs
+++ b/src/libsyntax_ext/plugin_macro_defs.rs
@@ -16,14 +16,8 @@ use syntax_pos::hygiene::{ExpnId, ExpnInfo, ExpnKind, MacroKind};
 use std::mem;
 
 fn plugin_macro_def(name: Name, span: Span) -> P<Item> {
-    let rustc_builtin_macro = Attribute {
-        id: attr::mk_attr_id(),
-        style: AttrStyle::Outer,
-        path: Path::from_ident(Ident::new(sym::rustc_builtin_macro, span)),
-        tokens: TokenStream::empty(),
-        is_sugared_doc: false,
-        span,
-    };
+    let rustc_builtin_macro = attr::mk_attr_outer(
+        attr::mk_word_item(Ident::new(sym::rustc_builtin_macro, span)));
 
     let parens: TreeAndJoint = TokenTree::Delimited(
         DelimSpan::from_single(span), token::Paren, TokenStream::empty()
diff --git a/src/libsyntax_ext/proc_macro_harness.rs b/src/libsyntax_ext/proc_macro_harness.rs
index fc6cd5dc94cd5..7913a7442edc7 100644
--- a/src/libsyntax_ext/proc_macro_harness.rs
+++ b/src/libsyntax_ext/proc_macro_harness.rs
@@ -4,7 +4,6 @@ use syntax::ast::{self, Ident};
 use syntax::attr;
 use syntax::source_map::{ExpnInfo, ExpnKind, respan};
 use syntax::ext::base::{ExtCtxt, MacroKind};
-use syntax::ext::build::AstBuilder;
 use syntax::ext::expand::ExpansionConfig;
 use syntax::ext::hygiene::ExpnId;
 use syntax::ext::proc_macro::is_proc_macro_attr;
@@ -337,7 +336,7 @@ fn mk_decls(
 
     let hidden = cx.meta_list_item_word(span, sym::hidden);
     let doc = cx.meta_list(span, sym::doc, vec![hidden]);
-    let doc_hidden = cx.attribute(span, doc);
+    let doc_hidden = cx.attribute(doc);
 
     let proc_macro = Ident::with_empty_ctxt(sym::proc_macro);
     let krate = cx.item(span,
@@ -394,7 +393,7 @@ fn mk_decls(
         cx.expr_vec_slice(span, decls),
     ).map(|mut i| {
         let attr = cx.meta_word(span, sym::rustc_proc_macro_decls);
-        i.attrs.push(cx.attribute(span, attr));
+        i.attrs.push(cx.attribute(attr));
         i.vis = respan(span, ast::VisibilityKind::Public);
         i
     });
diff --git a/src/libsyntax_ext/source_util.rs b/src/libsyntax_ext/source_util.rs
index 8ecfd4ddda7bf..2c8d53a231550 100644
--- a/src/libsyntax_ext/source_util.rs
+++ b/src/libsyntax_ext/source_util.rs
@@ -1,6 +1,5 @@
 use syntax::{ast, panictry};
 use syntax::ext::base::{self, *};
-use syntax::ext::build::AstBuilder;
 use syntax::parse::{self, token, DirectoryOwnership};
 use syntax::print::pprust;
 use syntax::ptr::P;
diff --git a/src/libsyntax_ext/standard_library_imports.rs b/src/libsyntax_ext/standard_library_imports.rs
index 81bb32d79a2aa..68b13bdd171a9 100644
--- a/src/libsyntax_ext/standard_library_imports.rs
+++ b/src/libsyntax_ext/standard_library_imports.rs
@@ -4,7 +4,6 @@ use syntax::ext::hygiene::{ExpnId, MacroKind};
 use syntax::ptr::P;
 use syntax::source_map::{ExpnInfo, ExpnKind, dummy_spanned, respan};
 use syntax::symbol::{Ident, Symbol, kw, sym};
-use syntax::tokenstream::TokenStream;
 use syntax_pos::DUMMY_SP;
 
 use std::iter;
@@ -41,8 +40,6 @@ pub fn inject(
         };
         krate.module.items.insert(0, P(ast::Item {
             attrs: vec![attr::mk_attr_outer(
-                DUMMY_SP,
-                attr::mk_attr_id(),
                 attr::mk_word_item(ast::Ident::with_empty_ctxt(sym::macro_use))
             )],
             vis: dummy_spanned(ast::VisibilityKind::Inherited),
@@ -64,14 +61,8 @@ pub fn inject(
     ));
 
     krate.module.items.insert(0, P(ast::Item {
-        attrs: vec![ast::Attribute {
-            style: ast::AttrStyle::Outer,
-            path: ast::Path::from_ident(ast::Ident::new(sym::prelude_import, span)),
-            tokens: TokenStream::empty(),
-            id: attr::mk_attr_id(),
-            is_sugared_doc: false,
-            span,
-        }],
+        attrs: vec![attr::mk_attr_outer(
+            attr::mk_word_item(ast::Ident::new(sym::prelude_import, span)))],
         vis: respan(span.shrink_to_lo(), ast::VisibilityKind::Inherited),
         node: ast::ItemKind::Use(P(ast::UseTree {
             prefix: ast::Path {
diff --git a/src/libsyntax_ext/test.rs b/src/libsyntax_ext/test.rs
index a2d93d01cec56..993ef25752757 100644
--- a/src/libsyntax_ext/test.rs
+++ b/src/libsyntax_ext/test.rs
@@ -4,7 +4,6 @@
 use syntax::ast;
 use syntax::attr::{self, check_builtin_macro_attribute};
 use syntax::ext::base::*;
-use syntax::ext::build::AstBuilder;
 use syntax::ext::hygiene::SyntaxContext;
 use syntax::print::pprust;
 use syntax::source_map::respan;
@@ -36,8 +35,7 @@ pub fn expand_test_case(
         item.vis = respan(item.vis.span, ast::VisibilityKind::Public);
         item.ident = item.ident.gensym();
         item.attrs.push(
-            ecx.attribute(sp,
-                ecx.meta_word(sp, sym::rustc_test_marker))
+            ecx.attribute(ecx.meta_word(sp, sym::rustc_test_marker))
         );
         item
     });
@@ -150,11 +148,11 @@ pub fn expand_test_or_bench(
     let mut test_const = cx.item(sp, ast::Ident::new(item.ident.name, sp).gensym(),
         vec![
             // #[cfg(test)]
-            cx.attribute(attr_sp, cx.meta_list(attr_sp, sym::cfg, vec![
+            cx.attribute(cx.meta_list(attr_sp, sym::cfg, vec![
                 cx.meta_list_item_word(attr_sp, sym::test)
             ])),
             // #[rustc_test_marker]
-            cx.attribute(attr_sp, cx.meta_word(attr_sp, sym::rustc_test_marker)),
+            cx.attribute(cx.meta_word(attr_sp, sym::rustc_test_marker)),
         ],
         // const $ident: test::TestDescAndFn =
         ast::ItemKind::Const(cx.ty(sp, ast::TyKind::Path(None, test_path("TestDescAndFn"))),
diff --git a/src/libsyntax_ext/test_harness.rs b/src/libsyntax_ext/test_harness.rs
index 848c797856ea9..4b3903c7ad7d3 100644
--- a/src/libsyntax_ext/test_harness.rs
+++ b/src/libsyntax_ext/test_harness.rs
@@ -6,7 +6,6 @@ use syntax::ast::{self, Ident};
 use syntax::attr;
 use syntax::entry::{self, EntryPointType};
 use syntax::ext::base::{ExtCtxt, Resolver};
-use syntax::ext::build::AstBuilder;
 use syntax::ext::expand::ExpansionConfig;
 use syntax::ext::hygiene::{ExpnId, MacroKind};
 use syntax::feature_gate::Features;
@@ -160,9 +159,7 @@ impl MutVisitor for EntryPointCleaner {
                     let dc_nested = attr::mk_nested_word_item(Ident::from_str("dead_code"));
                     let allow_dead_code_item = attr::mk_list_item(DUMMY_SP, allow_ident,
                                                                   vec![dc_nested]);
-                    let allow_dead_code = attr::mk_attr_outer(DUMMY_SP,
-                                                              attr::mk_attr_id(),
-                                                              allow_dead_code_item);
+                    let allow_dead_code = attr::mk_attr_outer(allow_dead_code_item);
 
                     ast::Item {
                         id,
@@ -295,7 +292,7 @@ fn mk_main(cx: &mut TestCtxt<'_>) -> P<ast::Item> {
 
     // #![main]
     let main_meta = ecx.meta_word(sp, sym::main);
-    let main_attr = ecx.attribute(sp, main_meta);
+    let main_attr = ecx.attribute(main_meta);
 
     // extern crate test as test_gensym
     let test_extern_stmt = ecx.stmt_item(sp, ecx.item(sp,
diff --git a/src/test/mir-opt/const_prop/reify_fn_ptr.rs b/src/test/mir-opt/const_prop/reify_fn_ptr.rs
index 809eb19ade899..7e36b2a6b1b39 100644
--- a/src/test/mir-opt/const_prop/reify_fn_ptr.rs
+++ b/src/test/mir-opt/const_prop/reify_fn_ptr.rs
@@ -19,7 +19,7 @@ fn main() {
 //      _3 = const Scalar(AllocId(1).0x0) : fn();
 //      _2 = move _3 as usize (Misc);
 //      ...
-//      _1 = const Scalar(AllocId(1).0x0) : *const fn();
+//      _1 = move _2 as *const fn() (Misc);
 //      ...
 //  }
 // END rustc.main.ConstProp.after.mir
diff --git a/src/test/ui-fulldeps/auxiliary/plugin-args.rs b/src/test/ui-fulldeps/auxiliary/plugin-args.rs
index 36cee82893a06..f3cd2397b28fe 100644
--- a/src/test/ui-fulldeps/auxiliary/plugin-args.rs
+++ b/src/test/ui-fulldeps/auxiliary/plugin-args.rs
@@ -11,7 +11,6 @@ extern crate rustc_driver;
 
 use std::borrow::ToOwned;
 use syntax::ast;
-use syntax::ext::build::AstBuilder;
 use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind};
 use syntax::ext::base::{TTMacroExpander, ExtCtxt, MacResult, MacEager};
 use syntax::print::pprust;
diff --git a/src/test/ui-fulldeps/auxiliary/roman-numerals.rs b/src/test/ui-fulldeps/auxiliary/roman-numerals.rs
index 07302b6e68b31..77fa5c2cd7898 100644
--- a/src/test/ui-fulldeps/auxiliary/roman-numerals.rs
+++ b/src/test/ui-fulldeps/auxiliary/roman-numerals.rs
@@ -18,7 +18,6 @@ extern crate rustc_driver;
 use syntax::parse::token::{self, Token};
 use syntax::tokenstream::TokenTree;
 use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacEager};
-use syntax::ext::build::AstBuilder;  // A trait for expr_usize.
 use syntax_pos::Span;
 use rustc_plugin::Registry;
 
diff --git a/src/test/ui/consts/const-eval/const_raw_ptr_ops.rs b/src/test/ui/consts/const-eval/const_raw_ptr_ops.rs
index 44266682a5c6c..9be1374f85d99 100644
--- a/src/test/ui/consts/const-eval/const_raw_ptr_ops.rs
+++ b/src/test/ui/consts/const-eval/const_raw_ptr_ops.rs
@@ -4,8 +4,8 @@ fn main() {}
 
 // unconst and bad, will thus error in miri
 const X: bool = unsafe { &1 as *const i32 == &2 as *const i32 }; //~ ERROR any use of this
-// unconst and fine
-const X2: bool = unsafe { 42 as *const i32 == 43 as *const i32 };
+// unconst and bad, will thus error in miri
+const X2: bool = unsafe { 42 as *const i32 == 43 as *const i32 }; //~ ERROR any use of this
 // unconst and fine
 const Y: usize = unsafe { 42usize as *const i32 as usize + 1 };
 // unconst and bad, will thus error in miri
diff --git a/src/test/ui/consts/const-eval/const_raw_ptr_ops.stderr b/src/test/ui/consts/const-eval/const_raw_ptr_ops.stderr
index a12575b3975b6..2cba833a74896 100644
--- a/src/test/ui/consts/const-eval/const_raw_ptr_ops.stderr
+++ b/src/test/ui/consts/const-eval/const_raw_ptr_ops.stderr
@@ -8,13 +8,21 @@ LL | const X: bool = unsafe { &1 as *const i32 == &2 as *const i32 };
    |
    = note: `#[deny(const_err)]` on by default
 
+error: any use of this value will cause an error
+  --> $DIR/const_raw_ptr_ops.rs:8:27
+   |
+LL | const X2: bool = unsafe { 42 as *const i32 == 43 as *const i32 };
+   | --------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   |                           |
+   |                           "pointer arithmetic or comparison" needs an rfc before being allowed inside constants
+
 error: any use of this value will cause an error
   --> $DIR/const_raw_ptr_ops.rs:12:28
    |
 LL | const Y2: usize = unsafe { &1 as *const i32 as usize + 1 };
-   | ---------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   | ---------------------------^^^^^^^^^^^^^^^^^^^^^^^^^-------
    |                            |
-   |                            "pointer arithmetic or comparison" needs an rfc before being allowed inside constants
+   |                            "pointer-to-integer cast" needs an rfc before being allowed inside constants
 
 error: any use of this value will cause an error
   --> $DIR/const_raw_ptr_ops.rs:16:26
@@ -32,5 +40,5 @@ LL | const Z3: i32 = unsafe { *(44 as *const i32) };
    |                          |
    |                          a memory access tried to interpret some bytes as a pointer
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors
 
diff --git a/src/test/ui/consts/const-eval/issue-52442.rs b/src/test/ui/consts/const-eval/issue-52442.rs
index 2989b200b2fc4..ea24578c7dd0c 100644
--- a/src/test/ui/consts/const-eval/issue-52442.rs
+++ b/src/test/ui/consts/const-eval/issue-52442.rs
@@ -1,5 +1,5 @@
 fn main() {
     [();  { &loop { break } as *const _ as usize } ];
     //~^ ERROR casting pointers to integers in constants is unstable
-    //~| ERROR it is undefined behavior to use this value
+    //~| ERROR evaluation of constant value failed
 }
diff --git a/src/test/ui/consts/const-eval/issue-52442.stderr b/src/test/ui/consts/const-eval/issue-52442.stderr
index 88c94d917fe0e..5bd4979bdb33c 100644
--- a/src/test/ui/consts/const-eval/issue-52442.stderr
+++ b/src/test/ui/consts/const-eval/issue-52442.stderr
@@ -7,13 +7,11 @@ LL |     [();  { &loop { break } as *const _ as usize } ];
    = note: for more information, see https://github.com/rust-lang/rust/issues/51910
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/issue-52442.rs:2:11
+error[E0080]: evaluation of constant value failed
+  --> $DIR/issue-52442.rs:2:13
    |
 LL |     [();  { &loop { break } as *const _ as usize } ];
-   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected initialized plain (non-pointer) bytes
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ "pointer-to-integer cast" needs an rfc before being allowed inside constants
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/consts/const-eval/match-test-ptr-null.rs b/src/test/ui/consts/const-eval/match-test-ptr-null.rs
index 50757afaf5651..5b89b0262aca5 100644
--- a/src/test/ui/consts/const-eval/match-test-ptr-null.rs
+++ b/src/test/ui/consts/const-eval/match-test-ptr-null.rs
@@ -5,11 +5,9 @@ fn main() {
     let _: [u8; 0] = [4; {
         match &1 as *const i32 as usize {
             //~^ ERROR casting pointers to integers in constants
-            //~| NOTE for more information, see
             //~| ERROR constant contains unimplemented expression type
-            0 => 42, //~ ERROR constant contains unimplemented expression type
-            //~^ NOTE "pointer arithmetic or comparison" needs an rfc before being allowed
             //~| ERROR evaluation of constant value failed
+            0 => 42, //~ ERROR constant contains unimplemented expression type
             n => n,
         }
     }];
diff --git a/src/test/ui/consts/const-eval/match-test-ptr-null.stderr b/src/test/ui/consts/const-eval/match-test-ptr-null.stderr
index d8a3bac5ce689..3d34ac4266270 100644
--- a/src/test/ui/consts/const-eval/match-test-ptr-null.stderr
+++ b/src/test/ui/consts/const-eval/match-test-ptr-null.stderr
@@ -20,10 +20,10 @@ LL |             0 => 42,
    |             ^
 
 error[E0080]: evaluation of constant value failed
-  --> $DIR/match-test-ptr-null.rs:10:13
+  --> $DIR/match-test-ptr-null.rs:6:15
    |
-LL |             0 => 42,
-   |             ^ "pointer arithmetic or comparison" needs an rfc before being allowed inside constants
+LL |         match &1 as *const i32 as usize {
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^ "pointer-to-integer cast" needs an rfc before being allowed inside constants
 
 error: aborting due to 4 previous errors
 
diff --git a/src/test/ui/consts/issue-51559.rs b/src/test/ui/consts/issue-51559.rs
index 429947269385b..69f0d8df0aa4a 100644
--- a/src/test/ui/consts/issue-51559.rs
+++ b/src/test/ui/consts/issue-51559.rs
@@ -2,6 +2,6 @@
 
 const BAR: *mut () = ((|| 3) as fn() -> i32) as *mut ();
 pub const FOO: usize = unsafe { BAR as usize };
-//~^ ERROR it is undefined behavior to use this value
+//~^ ERROR any use of this value will cause an error
 
 fn main() {}
diff --git a/src/test/ui/consts/issue-51559.stderr b/src/test/ui/consts/issue-51559.stderr
index 917c54ddaef1e..4d50ec818bce7 100644
--- a/src/test/ui/consts/issue-51559.stderr
+++ b/src/test/ui/consts/issue-51559.stderr
@@ -1,11 +1,12 @@
-error[E0080]: it is undefined behavior to use this value
-  --> $DIR/issue-51559.rs:4:1
+error: any use of this value will cause an error
+  --> $DIR/issue-51559.rs:4:33
    |
 LL | pub const FOO: usize = unsafe { BAR as usize };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected initialized plain (non-pointer) bytes
+   | --------------------------------^^^^^^^^^^^^---
+   |                                 |
+   |                                 "pointer-to-integer cast" needs an rfc before being allowed inside constants
    |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
+   = note: `#[deny(const_err)]` on by default
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0080`.
diff --git a/src/test/ui/issues/issue-52023-array-size-pointer-cast.rs b/src/test/ui/issues/issue-52023-array-size-pointer-cast.rs
index 63f1128f10642..d12b483ba4473 100644
--- a/src/test/ui/issues/issue-52023-array-size-pointer-cast.rs
+++ b/src/test/ui/issues/issue-52023-array-size-pointer-cast.rs
@@ -1,4 +1,4 @@
 fn main() {
     let _ = [0; (&0 as *const i32) as usize]; //~ ERROR casting pointers to integers in constants
-    //~^ ERROR it is undefined behavior to use this value
+    //~^ ERROR evaluation of constant value failed
 }
diff --git a/src/test/ui/issues/issue-52023-array-size-pointer-cast.stderr b/src/test/ui/issues/issue-52023-array-size-pointer-cast.stderr
index 2db6f42405c17..68ee53754161c 100644
--- a/src/test/ui/issues/issue-52023-array-size-pointer-cast.stderr
+++ b/src/test/ui/issues/issue-52023-array-size-pointer-cast.stderr
@@ -7,13 +7,11 @@ LL |     let _ = [0; (&0 as *const i32) as usize];
    = note: for more information, see https://github.com/rust-lang/rust/issues/51910
    = help: add `#![feature(const_raw_ptr_to_usize_cast)]` to the crate attributes to enable
 
-error[E0080]: it is undefined behavior to use this value
+error[E0080]: evaluation of constant value failed
   --> $DIR/issue-52023-array-size-pointer-cast.rs:2:17
    |
 LL |     let _ = [0; (&0 as *const i32) as usize];
-   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a pointer, but expected initialized plain (non-pointer) bytes
-   |
-   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ "pointer-to-integer cast" needs an rfc before being allowed inside constants
 
 error: aborting due to 2 previous errors