Rollup of 6 pull requests

compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs

@@ -516,7 +516,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     self_ty,
                     trait_segment,
                     false,
-                    ty::BoundConstness::NotConst,
                 );
 
                 // SUBTLE: As noted at the end of `try_append_return_type_notation_params`

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -336,14 +336,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         def_id: DefId,
         item_segment: &hir::PathSegment<'tcx>,
     ) -> GenericArgsRef<'tcx> {
-        let (args, _) = self.lower_generic_args_of_path(
-            span,
-            def_id,
-            &[],
-            item_segment,
-            None,
-            ty::BoundConstness::NotConst,
-        );
+        let (args, _) = self.lower_generic_args_of_path(span, def_id, &[], item_segment, None);
         if let Some(c) = item_segment.args().constraints.first() {
             prohibit_assoc_item_constraint(self, c, Some((def_id, item_segment, span)));
         }
@@ -392,7 +385,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         parent_args: &[ty::GenericArg<'tcx>],
         segment: &hir::PathSegment<'tcx>,
         self_ty: Option<Ty<'tcx>>,
-        constness: ty::BoundConstness,
     ) -> (GenericArgsRef<'tcx>, GenericArgCountResult) {
         // If the type is parameterized by this region, then replace this
         // region with the current anon region binding (in other words,
@@ -415,7 +407,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             assert!(self_ty.is_none());
         }
 
-        let mut arg_count = check_generic_arg_count(
+        let arg_count = check_generic_arg_count(
             self,
             def_id,
             segment,
@@ -573,16 +565,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 }
             }
         }
-        if let ty::BoundConstness::Const | ty::BoundConstness::ConstIfConst = constness
-            && generics.has_self
-            && !tcx.is_const_trait(def_id)
-        {
-            let reported = self.dcx().emit_err(crate::errors::ConstBoundForNonConstTrait {
-                span,
-                modifier: constness.as_str(),
-            });
-            arg_count.correct = Err(GenericArgCountMismatch { reported, invalid_args: vec![] });
-        }
 
         let mut args_ctx = GenericArgsCtxt {
             lowerer: self,
@@ -614,14 +596,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         parent_args: GenericArgsRef<'tcx>,
     ) -> GenericArgsRef<'tcx> {
         debug!(?span, ?item_def_id, ?item_segment);
-        let (args, _) = self.lower_generic_args_of_path(
-            span,
-            item_def_id,
-            parent_args,
-            item_segment,
-            None,
-            ty::BoundConstness::NotConst,
-        );
+        let (args, _) =
+            self.lower_generic_args_of_path(span, item_def_id, parent_args, item_segment, None);
         if let Some(c) = item_segment.args().constraints.first() {
             prohibit_assoc_item_constraint(self, c, Some((item_def_id, item_segment, span)));
         }
@@ -647,7 +623,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             self_ty,
             trait_ref.path.segments.last().unwrap(),
             true,
-            ty::BoundConstness::NotConst,
         )
     }
 
@@ -700,9 +675,17 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             &[],
             trait_segment,
             Some(self_ty),
-            constness,
         );
 
+        if let ty::BoundConstness::Const | ty::BoundConstness::ConstIfConst = constness
+            && !self.tcx().is_const_trait(trait_def_id)
+        {
+            self.dcx().emit_err(crate::errors::ConstBoundForNonConstTrait {
+                span: trait_ref.path.span,
+                modifier: constness.as_str(),
+            });
+        }
+
         let tcx = self.tcx();
         let bound_vars = tcx.late_bound_vars(trait_ref.hir_ref_id);
         debug!(?bound_vars);
@@ -762,19 +745,11 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         self_ty: Ty<'tcx>,
         trait_segment: &hir::PathSegment<'tcx>,
         is_impl: bool,
-        // FIXME(effects): Move all host param things in HIR ty lowering to AST lowering.
-        constness: ty::BoundConstness,
     ) -> ty::TraitRef<'tcx> {
         self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, is_impl);
 
-        let (generic_args, _) = self.lower_generic_args_of_path(
-            span,
-            trait_def_id,
-            &[],
-            trait_segment,
-            Some(self_ty),
-            constness,
-        );
+        let (generic_args, _) =
+            self.lower_generic_args_of_path(span, trait_def_id, &[], trait_segment, Some(self_ty));
         if let Some(c) = trait_segment.args().constraints.first() {
             prohibit_assoc_item_constraint(self, c, Some((trait_def_id, trait_segment, span)));
         }
@@ -1542,7 +1517,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         item_def_id: DefId,
         trait_segment: &hir::PathSegment<'tcx>,
         item_segment: &hir::PathSegment<'tcx>,
-        constness: ty::BoundConstness,
     ) -> Ty<'tcx> {
         let tcx = self.tcx();
 
@@ -1555,7 +1529,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         debug!(?self_ty);
 
         let trait_ref =
-            self.lower_mono_trait_ref(span, trait_def_id, self_ty, trait_segment, false, constness);
+            self.lower_mono_trait_ref(span, trait_def_id, self_ty, trait_segment, false);
         debug!(?trait_ref);
 
         let item_args =
@@ -1918,7 +1892,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     def_id,
                     &path.segments[path.segments.len() - 2],
                     path.segments.last().unwrap(),
-                    ty::BoundConstness::NotConst,
                 )
             }
             Res::PrimTy(prim_ty) => {
@@ -2151,7 +2124,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     &[],
                     &hir::PathSegment::invalid(),
                     None,
-                    ty::BoundConstness::NotConst,
                 );
                 tcx.at(span).type_of(def_id).instantiate(tcx, args)
             }

compiler/rustc_lint/src/types.rs

@@ -18,6 +18,8 @@ use rustc_target::spec::abi::Abi as SpecAbi;
 use tracing::debug;
 use {rustc_ast as ast, rustc_hir as hir};
 
+mod improper_ctypes;
+
 use crate::lints::{
     AmbiguousWidePointerComparisons, AmbiguousWidePointerComparisonsAddrMetadataSuggestion,
     AmbiguousWidePointerComparisonsAddrSuggestion, AtomicOrderingFence, AtomicOrderingLoad,
@@ -983,15 +985,6 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                             // Empty enums are okay... although sort of useless.
                             return FfiSafe;
                         }
-
-                        if def.is_variant_list_non_exhaustive() && !def.did().is_local() {
-                            return FfiUnsafe {
-                                ty,
-                                reason: fluent::lint_improper_ctypes_non_exhaustive,
-                                help: None,
-                            };
-                        }
-
                         // Check for a repr() attribute to specify the size of the
                         // discriminant.
                         if !def.repr().c() && !def.repr().transparent() && def.repr().int.is_none()
@@ -1010,21 +1003,23 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                             };
                         }
 
+                        use improper_ctypes::{
+                            check_non_exhaustive_variant, non_local_and_non_exhaustive,
+                        };
+
+                        let non_local_def = non_local_and_non_exhaustive(def);
                         // Check the contained variants.
-                        for variant in def.variants() {
-                            let is_non_exhaustive = variant.is_field_list_non_exhaustive();
-                            if is_non_exhaustive && !variant.def_id.is_local() {
-                                return FfiUnsafe {
-                                    ty,
-                                    reason: fluent::lint_improper_ctypes_non_exhaustive_variant,
-                                    help: None,
-                                };
-                            }
+                        let ret = def.variants().iter().try_for_each(|variant| {
+                            check_non_exhaustive_variant(non_local_def, variant)
+                                .map_break(|reason| FfiUnsafe { ty, reason, help: None })?;
 
                             match self.check_variant_for_ffi(acc, ty, def, variant, args) {
-                                FfiSafe => (),
-                                r => return r,
+                                FfiSafe => ControlFlow::Continue(()),
+                                r => ControlFlow::Break(r),
                             }
+                        });
+                        if let ControlFlow::Break(result) = ret {
+                            return result;
                         }
 
                         FfiSafe

compiler/rustc_lint/src/types/improper_ctypes.rs

@@ -0,0 +1,51 @@
+use std::ops::ControlFlow;
+
+use rustc_errors::DiagMessage;
+use rustc_hir::def::CtorKind;
+use rustc_middle::ty;
+
+use crate::fluent_generated as fluent;
+
+/// Check a variant of a non-exhaustive enum for improper ctypes
+///
+/// We treat `#[non_exhaustive] enum` as "ensure that code will compile if new variants are added".
+/// This includes linting, on a best-effort basis. There are valid additions that are unlikely.
+///
+/// Adding a data-carrying variant to an existing C-like enum that is passed to C is "unlikely",
+/// so we don't need the lint to account for it.
+/// e.g. going from enum Foo { A, B, C } to enum Foo { A, B, C, D(u32) }.
+pub(crate) fn check_non_exhaustive_variant(
+    non_local_def: bool,
+    variant: &ty::VariantDef,
+) -> ControlFlow<DiagMessage, ()> {
+    // non_exhaustive suggests it is possible that someone might break ABI
+    // see: https://github.com/rust-lang/rust/issues/44109#issuecomment-537583344
+    // so warn on complex enums being used outside their crate
+    if non_local_def {
+        // which is why we only warn about really_tagged_union reprs from https://rust.tf/rfc2195
+        // with an enum like `#[repr(u8)] enum Enum { A(DataA), B(DataB), }`
+        // but exempt enums with unit ctors like C's (e.g. from rust-bindgen)
+        if variant_has_complex_ctor(variant) {
+            return ControlFlow::Break(fluent::lint_improper_ctypes_non_exhaustive);
+        }
+    }
+
+    let non_exhaustive_variant_fields = variant.is_field_list_non_exhaustive();
+    if non_exhaustive_variant_fields && !variant.def_id.is_local() {
+        return ControlFlow::Break(fluent::lint_improper_ctypes_non_exhaustive_variant);
+    }
+
+    ControlFlow::Continue(())
+}
+
+fn variant_has_complex_ctor(variant: &ty::VariantDef) -> bool {
+    // CtorKind::Const means a "unit" ctor
+    !matches!(variant.ctor_kind(), Some(CtorKind::Const))
+}
+
+// non_exhaustive suggests it is possible that someone might break ABI
+// see: https://github.com/rust-lang/rust/issues/44109#issuecomment-537583344
+// so warn on complex enums being used outside their crate
+pub(crate) fn non_local_and_non_exhaustive(def: ty::AdtDef<'_>) -> bool {
+    def.is_variant_list_non_exhaustive() && !def.did().is_local()
+}

config.example.toml

@@ -414,6 +414,9 @@
 # Specify the location of the Android NDK. Used when targeting Android.
 #android-ndk = "/path/to/android-ndk-r26d"
 
+# What custom diff tool to use for displaying compiletest tests.
+#compiletest-diff-tool = <none>
+
 # =============================================================================
 # General install configuration options
 # =============================================================================

library/std/src/sys/pal/unix/fs.rs

@@ -189,7 +189,7 @@ cfg_has_statx! {{
             // See: https://github.com/rust-lang/rust/issues/65662
             //
             // FIXME what about transient conditions like `ENOMEM`?
-            let err2 = cvt(statx(0, ptr::null(), 0, libc::STATX_ALL, ptr::null_mut()))
+            let err2 = cvt(statx(0, ptr::null(), 0, libc::STATX_BASIC_STATS | libc::STATX_BTIME, ptr::null_mut()))
                 .err()
                 .and_then(|e| e.raw_os_error());
             if err2 == Some(libc::EFAULT) {
@@ -910,7 +910,7 @@ impl DirEntry {
                 fd,
                 name,
                 libc::AT_SYMLINK_NOFOLLOW | libc::AT_STATX_SYNC_AS_STAT,
-                libc::STATX_ALL,
+                libc::STATX_BASIC_STATS | libc::STATX_BTIME,
             ) } {
                 return ret;
             }
@@ -1194,7 +1194,7 @@ impl File {
                 fd,
                 c"".as_ptr() as *const c_char,
                 libc::AT_EMPTY_PATH | libc::AT_STATX_SYNC_AS_STAT,
-                libc::STATX_ALL,
+                libc::STATX_BASIC_STATS | libc::STATX_BTIME,
             ) } {
                 return ret;
             }
@@ -1767,7 +1767,7 @@ pub fn stat(p: &Path) -> io::Result<FileAttr> {
                 libc::AT_FDCWD,
                 p.as_ptr(),
                 libc::AT_STATX_SYNC_AS_STAT,
-                libc::STATX_ALL,
+                libc::STATX_BASIC_STATS | libc::STATX_BTIME,
             ) } {
                 return ret;
             }
@@ -1786,7 +1786,7 @@ pub fn lstat(p: &Path) -> io::Result<FileAttr> {
                 libc::AT_FDCWD,
                 p.as_ptr(),
                 libc::AT_SYMLINK_NOFOLLOW | libc::AT_STATX_SYNC_AS_STAT,
-                libc::STATX_ALL,
+                libc::STATX_BASIC_STATS | libc::STATX_BTIME,
             ) } {
                 return ret;
             }

src/bootstrap/src/core/build_steps/test.rs

@@ -1834,6 +1834,9 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         if builder.config.cmd.only_modified() {
             cmd.arg("--only-modified");
         }
+        if let Some(compiletest_diff_tool) = &builder.config.compiletest_diff_tool {
+            cmd.arg("--compiletest-diff-tool").arg(compiletest_diff_tool);
+        }
 
         let mut flags = if is_rustdoc { Vec::new() } else { vec!["-Crpath".to_string()] };
         flags.push(format!("-Cdebuginfo={}", builder.config.rust_debuginfo_level_tests));

src/bootstrap/src/core/config/config.rs

@@ -368,6 +368,9 @@ pub struct Config {
     /// The paths to work with. For example: with `./x check foo bar` we get
     /// `paths=["foo", "bar"]`.
     pub paths: Vec<PathBuf>,
+
+    /// Command for visual diff display, e.g. `diff-tool --color=always`.
+    pub compiletest_diff_tool: Option<String>,
 }
 
 #[derive(Clone, Debug, Default)]
@@ -891,6 +894,7 @@ define_config! {
         metrics: Option<bool> = "metrics",
         android_ndk: Option<PathBuf> = "android-ndk",
         optimized_compiler_builtins: Option<bool> = "optimized-compiler-builtins",
+        compiletest_diff_tool: Option<String> = "compiletest-diff-tool",
     }
 }
 
@@ -1511,6 +1515,7 @@ impl Config {
             metrics: _,
             android_ndk,
             optimized_compiler_builtins,
+            compiletest_diff_tool,
         } = toml.build.unwrap_or_default();
 
         if let Some(file_build) = build {
@@ -2155,6 +2160,7 @@ impl Config {
         config.rust_debuginfo_level_tests = debuginfo_level_tests.unwrap_or(DebuginfoLevel::None);
         config.optimized_compiler_builtins =
             optimized_compiler_builtins.unwrap_or(config.channel != "dev");
+        config.compiletest_diff_tool = compiletest_diff_tool;
 
         let download_rustc = config.download_rustc_commit.is_some();
         // See https://github.com/rust-lang/compiler-team/issues/326

src/bootstrap/src/utils/change_tracker.rs

@@ -275,4 +275,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "New option `./x setup editor` added, replacing `./x setup vscode` and adding support for vim, emacs and helix.",
     },
+    ChangeInfo {
+        change_id: 131181,
+        severity: ChangeSeverity::Info,
+        summary: "New option `build.compiletest-diff-tool` that adds support for a custom differ for compiletest",
+    },
 ];

src/tools/compiletest/src/common.rs

@@ -387,6 +387,9 @@ pub struct Config {
     /// True if the profiler runtime is enabled for this target.
     /// Used by the "needs-profiler-runtime" directive in test files.
     pub profiler_runtime: bool,
+
+    /// Command for visual diff display, e.g. `diff-tool --color=always`.
+    pub diff_command: Option<String>,
 }
 
 impl Config {