Auto merge of #118970 - aliemjay:rollup-or33al2, r=aliemjay

Rollup of 2 pull requests

Successful merges:

 - #118927 (Erase late bound regions from `Instance::fn_sig()` and add a few more details to StableMIR APIs)
 - #118964 (Opportunistically resolve region var in canonicalizer (instead of resolving root var))

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_infer/src/infer/mod.rs

@@ -381,17 +381,13 @@ impl<'tcx> ty::InferCtxtLike for InferCtxt<'tcx> {
         self.probe_ty_var(vid).ok()
     }
 
-    fn root_lt_var(&self, vid: ty::RegionVid) -> ty::RegionVid {
-        self.root_region_var(vid)
-    }
-
-    fn probe_lt_var(&self, vid: ty::RegionVid) -> Option<ty::Region<'tcx>> {
+    fn opportunistic_resolve_lt_var(&self, vid: ty::RegionVid) -> Option<ty::Region<'tcx>> {
         let re = self
             .inner
             .borrow_mut()
             .unwrap_region_constraints()
             .opportunistic_resolve_var(self.tcx, vid);
-        if re.is_var() { None } else { Some(re) }
+        if *re == ty::ReVar(vid) { None } else { Some(re) }
     }
 
     fn root_ct_var(&self, vid: ConstVid) -> ConstVid {
@@ -1367,10 +1363,6 @@ impl<'tcx> InferCtxt<'tcx> {
         self.inner.borrow_mut().type_variables().root_var(var)
     }
 
-    pub fn root_region_var(&self, var: ty::RegionVid) -> ty::RegionVid {
-        self.inner.borrow_mut().unwrap_region_constraints().root_var(var)
-    }
-
     pub fn root_const_var(&self, var: ty::ConstVid) -> ty::ConstVid {
         self.inner.borrow_mut().const_unification_table().find(var).vid
     }

compiler/rustc_infer/src/infer/region_constraints/mod.rs

@@ -623,11 +623,6 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
         }
     }
 
-    pub fn root_var(&mut self, vid: ty::RegionVid) -> ty::RegionVid {
-        let mut ut = self.unification_table_mut(); // FIXME(rust-lang/ena#42): unnecessary mut
-        ut.find(vid).vid
-    }
-
     fn combine_map(&mut self, t: CombineMapType) -> &mut CombineMap<'tcx> {
         match t {
             Glb => &mut self.glbs,

compiler/rustc_next_trait_solver/src/canonicalizer.rs

@@ -242,16 +242,10 @@ impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> TypeFolder<I>
 
             ty::ReVar(vid) => {
                 assert_eq!(
-                    self.infcx.root_lt_var(vid),
-                    vid,
-                    "region vid should have been resolved fully before canonicalization"
-                );
-                assert_eq!(
-                    self.infcx.probe_lt_var(vid),
+                    self.infcx.opportunistic_resolve_lt_var(vid),
                     None,
                     "region vid should have been resolved fully before canonicalization"
                 );
-
                 match self.canonicalize_mode {
                     CanonicalizeMode::Input => CanonicalVarKind::Region(ty::UniverseIndex::ROOT),
                     CanonicalizeMode::Response { .. } => {

compiler/rustc_smir/src/rustc_smir/context.rs

@@ -5,7 +5,9 @@
 
 use rustc_middle::ty;
 use rustc_middle::ty::print::{with_forced_trimmed_paths, with_no_trimmed_paths};
-use rustc_middle::ty::{GenericPredicates, Instance, ParamEnv, ScalarInt, ValTree};
+use rustc_middle::ty::{
+    GenericPredicates, Instance, ParamEnv, ScalarInt, TypeVisitableExt, ValTree,
+};
 use rustc_span::def_id::LOCAL_CRATE;
 use stable_mir::compiler_interface::Context;
 use stable_mir::mir::alloc::GlobalAlloc;
@@ -324,7 +326,8 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
     fn instance_ty(&self, def: InstanceDef) -> stable_mir::ty::Ty {
         let mut tables = self.0.borrow_mut();
         let instance = tables.instances[def];
-        instance.ty(tables.tcx, ParamEnv::empty()).stable(&mut *tables)
+        assert!(!instance.has_non_region_param(), "{instance:?} needs further substitution");
+        instance.ty(tables.tcx, ParamEnv::reveal_all()).stable(&mut *tables)
     }
 
     fn instance_def_id(&self, def: InstanceDef) -> stable_mir::DefId {

compiler/rustc_smir/src/rustc_smir/convert/mir.rs

@@ -36,6 +36,7 @@ impl<'tcx> Stable<'tcx> for mir::Body<'tcx> {
                 .collect(),
             self.arg_count,
             self.var_debug_info.iter().map(|info| info.stable(tables)).collect(),
+            self.spread_arg.stable(tables),
         )
     }
 }

compiler/rustc_smir/src/rustc_smir/convert/mod.rs

@@ -57,7 +57,9 @@ impl<'tcx> Stable<'tcx> for rustc_hir::CoroutineKind {
                 stable_mir::mir::CoroutineKind::Gen(source.stable(tables))
             }
             CoroutineKind::Coroutine => stable_mir::mir::CoroutineKind::Coroutine,
-            CoroutineKind::AsyncGen(_) => todo!(),
+            CoroutineKind::AsyncGen(source) => {
+                stable_mir::mir::CoroutineKind::AsyncGen(source.stable(tables))
+            }
         }
     }
 }

compiler/rustc_type_ir/src/debug.rs

@@ -32,11 +32,7 @@ impl<I: Interner> InferCtxtLike for NoInfcx<I> {
         None
     }
 
-    fn root_lt_var(&self, vid: I::InferRegion) -> I::InferRegion {
-        vid
-    }
-
-    fn probe_lt_var(&self, _vid: I::InferRegion) -> Option<I::Region> {
+    fn opportunistic_resolve_lt_var(&self, _vid: I::InferRegion) -> Option<I::Region> {
         None
     }
 

compiler/rustc_type_ir/src/infcx.rs

@@ -18,14 +18,14 @@ pub trait InferCtxtLike {
         lt: <Self::Interner as Interner>::InferRegion,
     ) -> Option<UniverseIndex>;
 
-    /// Resolve `InferRegion` to its root `InferRegion`.
-    fn root_lt_var(
-        &self,
-        vid: <Self::Interner as Interner>::InferRegion,
-    ) -> <Self::Interner as Interner>::InferRegion;
-
-    /// Resolve `InferRegion` to its inferred region, if it has been equated with a non-infer region.
-    fn probe_lt_var(
+    /// Resolve `InferRegion` to its inferred region, if it has been equated with
+    /// a non-infer region.
+    ///
+    /// FIXME: This has slightly different semantics than `{probe,resolve}_{ty,ct}_var`,
+    /// that has to do with the fact unlike `Ty` or `Const` vars, in rustc, we may
+    /// not always be able to *name* the root region var from the universe of the
+    /// var we're trying to resolve. That's why it's called *opportunistic*.
+    fn opportunistic_resolve_lt_var(
         &self,
         vid: <Self::Interner as Interner>::InferRegion,
     ) -> Option<<Self::Interner as Interner>::Region>;

compiler/stable_mir/src/mir/body.rs

@@ -22,6 +22,11 @@ pub struct Body {
 
     /// Debug information pertaining to user variables, including captures.
     pub var_debug_info: Vec<VarDebugInfo>,
+
+    /// Mark an argument (which must be a tuple) as getting passed as its individual components.
+    ///
+    /// This is used for the "rust-call" ABI such as closures.
+    pub(super) spread_arg: Option<Local>,
 }
 
 pub type BasicBlockIdx = usize;
@@ -36,14 +41,15 @@ impl Body {
         locals: LocalDecls,
         arg_count: usize,
         var_debug_info: Vec<VarDebugInfo>,
+        spread_arg: Option<Local>,
     ) -> Self {
         // If locals doesn't contain enough entries, it can lead to panics in
         // `ret_local`, `arg_locals`, and `inner_locals`.
         assert!(
             locals.len() > arg_count,
             "A Body must contain at least a local for the return value and each of the function's arguments"
         );
-        Self { blocks, locals, arg_count, var_debug_info }
+        Self { blocks, locals, arg_count, var_debug_info, spread_arg }
     }
 
     /// Return local that holds this function's return value.
@@ -75,6 +81,11 @@ impl Body {
         self.locals.get(local)
     }
 
+    /// Get an iterator for all local declarations.
+    pub fn local_decls(&self) -> impl Iterator<Item = (Local, &LocalDecl)> {
+        self.locals.iter().enumerate()
+    }
+
     pub fn dump<W: io::Write>(&self, w: &mut W) -> io::Result<()> {
         writeln!(w, "{}", function_body(self))?;
         self.blocks
@@ -98,6 +109,10 @@ impl Body {
             .collect::<Result<Vec<_>, _>>()?;
         Ok(())
     }
+
+    pub fn spread_arg(&self) -> Option<Local> {
+        self.spread_arg
+    }
 }
 
 type LocalDecls = Vec<LocalDecl>;
@@ -248,6 +263,57 @@ pub enum AssertMessage {
     MisalignedPointerDereference { required: Operand, found: Operand },
 }
 
+impl AssertMessage {
+    pub fn description(&self) -> Result<&'static str, Error> {
+        match self {
+            AssertMessage::Overflow(BinOp::Add, _, _) => Ok("attempt to add with overflow"),
+            AssertMessage::Overflow(BinOp::Sub, _, _) => Ok("attempt to subtract with overflow"),
+            AssertMessage::Overflow(BinOp::Mul, _, _) => Ok("attempt to multiply with overflow"),
+            AssertMessage::Overflow(BinOp::Div, _, _) => Ok("attempt to divide with overflow"),
+            AssertMessage::Overflow(BinOp::Rem, _, _) => {
+                Ok("attempt to calculate the remainder with overflow")
+            }
+            AssertMessage::OverflowNeg(_) => Ok("attempt to negate with overflow"),
+            AssertMessage::Overflow(BinOp::Shr, _, _) => Ok("attempt to shift right with overflow"),
+            AssertMessage::Overflow(BinOp::Shl, _, _) => Ok("attempt to shift left with overflow"),
+            AssertMessage::Overflow(op, _, _) => Err(error!("`{:?}` cannot overflow", op)),
+            AssertMessage::DivisionByZero(_) => Ok("attempt to divide by zero"),
+            AssertMessage::RemainderByZero(_) => {
+                Ok("attempt to calculate the remainder with a divisor of zero")
+            }
+            AssertMessage::ResumedAfterReturn(CoroutineKind::Coroutine) => {
+                Ok("coroutine resumed after completion")
+            }
+            AssertMessage::ResumedAfterReturn(CoroutineKind::Async(_)) => {
+                Ok("`async fn` resumed after completion")
+            }
+            AssertMessage::ResumedAfterReturn(CoroutineKind::Gen(_)) => {
+                Ok("`async gen fn` resumed after completion")
+            }
+            AssertMessage::ResumedAfterReturn(CoroutineKind::AsyncGen(_)) => {
+                Ok("`gen fn` should just keep returning `AssertMessage::None` after completion")
+            }
+            AssertMessage::ResumedAfterPanic(CoroutineKind::Coroutine) => {
+                Ok("coroutine resumed after panicking")
+            }
+            AssertMessage::ResumedAfterPanic(CoroutineKind::Async(_)) => {
+                Ok("`async fn` resumed after panicking")
+            }
+            AssertMessage::ResumedAfterPanic(CoroutineKind::Gen(_)) => {
+                Ok("`async gen fn` resumed after panicking")
+            }
+            AssertMessage::ResumedAfterPanic(CoroutineKind::AsyncGen(_)) => {
+                Ok("`gen fn` should just keep returning `AssertMessage::None` after panicking")
+            }
+
+            AssertMessage::BoundsCheck { .. } => Ok("index out of bounds"),
+            AssertMessage::MisalignedPointerDereference { .. } => {
+                Ok("misaligned pointer dereference")
+            }
+        }
+    }
+}
+
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum BinOp {
     Add,
@@ -325,6 +391,7 @@ pub enum CoroutineKind {
     Async(CoroutineSource),
     Coroutine,
     Gen(CoroutineSource),
+    AsyncGen(CoroutineSource),
 }
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]

compiler/stable_mir/src/mir/mono.rs

@@ -1,6 +1,6 @@
 use crate::crate_def::CrateDef;
 use crate::mir::Body;
-use crate::ty::{Allocation, ClosureDef, ClosureKind, FnDef, FnSig, GenericArgs, IndexedVal, Ty};
+use crate::ty::{Allocation, ClosureDef, ClosureKind, FnDef, GenericArgs, IndexedVal, Ty};
 use crate::{with, CrateItem, DefId, Error, ItemKind, Opaque, Symbol};
 use std::fmt::{Debug, Formatter};
 
@@ -115,11 +115,6 @@ impl Instance {
         })
     }
 
-    /// Get this function signature with all types already instantiated.
-    pub fn fn_sig(&self) -> FnSig {
-        self.ty().kind().fn_sig().unwrap().skip_binder()
-    }
-
     /// Check whether this instance is an empty shim.
     ///
     /// Allow users to check if this shim can be ignored when called directly.

compiler/stable_mir/src/mir/pretty.rs

@@ -260,6 +260,7 @@ pub fn pretty_assert_message(msg: &AssertMessage) -> String {
             );
             pretty
         }
+        AssertMessage::Overflow(op, _, _) => unreachable!("`{:?}` cannot overflow", op),
         AssertMessage::OverflowNeg(op) => {
             let pretty_op = pretty_operand(op);
             pretty.push_str(
@@ -279,17 +280,15 @@ pub fn pretty_assert_message(msg: &AssertMessage) -> String {
             );
             pretty
         }
-        AssertMessage::ResumedAfterReturn(_) => {
-            format!("attempt to resume a generator after completion")
-        }
-        AssertMessage::ResumedAfterPanic(_) => format!("attempt to resume a panicked generator"),
         AssertMessage::MisalignedPointerDereference { required, found } => {
             let pretty_required = pretty_operand(required);
             let pretty_found = pretty_operand(found);
             pretty.push_str(format!("\"misaligned pointer dereference: address must be a multiple of {{}} but is {{}}\",{pretty_required}, {pretty_found}").as_str());
             pretty
         }
-        _ => todo!(),
+        AssertMessage::ResumedAfterReturn(_) | AssertMessage::ResumedAfterPanic(_) => {
+            msg.description().unwrap().to_string()
+        }
     }
 }
 

compiler/stable_mir/src/mir/visit.rs

@@ -133,7 +133,7 @@ pub trait MirVisitor {
     }
 
     fn super_body(&mut self, body: &Body) {
-        let Body { blocks, locals: _, arg_count, var_debug_info } = body;
+        let Body { blocks, locals: _, arg_count, var_debug_info, spread_arg: _ } = body;
 
         for bb in blocks {
             self.visit_basic_block(bb);

compiler/stable_mir/src/ty.rs

@@ -22,9 +22,7 @@ impl Debug for Ty {
 /// Constructors for `Ty`.
 impl Ty {
     /// Create a new type from a given kind.
-    ///
-    /// Note that not all types may be supported at this point.
-    fn from_rigid_kind(kind: RigidTy) -> Ty {
+    pub fn from_rigid_kind(kind: RigidTy) -> Ty {
         with(|cx| cx.new_rigid_ty(kind))
     }
 
@@ -77,6 +75,16 @@ impl Ty {
     pub fn bool_ty() -> Ty {
         Ty::from_rigid_kind(RigidTy::Bool)
     }
+
+    /// Create a type representing a signed integer.
+    pub fn signed_ty(inner: IntTy) -> Ty {
+        Ty::from_rigid_kind(RigidTy::Int(inner))
+    }
+
+    /// Create a type representing an unsigned integer.
+    pub fn unsigned_ty(inner: UintTy) -> Ty {
+        Ty::from_rigid_kind(RigidTy::Uint(inner))
+    }
 }
 
 impl Ty {

tests/ui-fulldeps/stable-mir/check_defs.rs

@@ -69,7 +69,7 @@ fn extract_elem_ty(ty: Ty) -> Ty {
 
 /// Check signature and type of `Vec::<u8>::new` and its generic version.
 fn test_vec_new(instance: mir::mono::Instance) {
-    let sig = instance.fn_sig();
+    let sig = instance.ty().kind().fn_sig().unwrap().skip_binder();
     assert_matches!(sig.inputs(), &[]);
     let elem_ty = extract_elem_ty(sig.output());
     assert_matches!(elem_ty.kind(), TyKind::RigidTy(RigidTy::Uint(UintTy::U8)));

tests/ui/traits/next-solver/issue-118950-root-region.rs

@@ -0,0 +1,22 @@
+// compile-flags: -Znext-solver
+//
+// This is a gnarly test but I don't know how to minimize it, frankly.
+
+#![feature(lazy_type_alias)]
+//~^ WARN the feature `lazy_type_alias` is incomplete
+
+trait ToUnit<'a> {
+    type Unit;
+}
+
+trait Overlap<T> {}
+
+type Assoc<'a, T> = <*const T as ToUnit<'a>>::Unit;
+
+impl<T> Overlap<T> for T {}
+
+impl<T> Overlap<for<'a> fn(Assoc<'a, T>)> for T where Missing: Overlap<T> {}
+//~^ ERROR conflicting implementations of trait `Overlap<fn(_)>` for type `fn(_)`
+//~| ERROR cannot find type `Missing` in this scope
+
+fn main() {}