Auto merge of #69360 - Mark-Simulacrum:beta-next, r=Mark-Simulacrum

[beta] beta backports

This backports the following PRs:

* Revert "Remove `checked_add` in `Layout::repeat`" #69241
* Do not ICE when encountering `yield` inside `async` block #69175
* Fix MIR typeck soundness holes #69145
* Fix extra subslice lowering #69128
* Correct ICE caused by macros generating invalid spans. #68611
* Make conflicting_repr_hints a deny-by-default c-future-compat lint #68586

src/ci/azure-pipelines/steps/run.yml

@@ -31,6 +31,9 @@ steps:
 - bash: src/ci/scripts/setup-environment.sh
   displayName: Setup environment
 
+- bash: src/ci/scripts/clean-disk.sh
+  displayName: Clean disk
+
 - bash: src/ci/scripts/should-skip-this.sh
   displayName: Decide whether to run this job
 

src/ci/scripts/clean-disk.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+# This script deletes some of the Azure-provided artifacts. We don't use these,
+# and disk space is at a premium on our builders.
+
+set -euo pipefail
+IFS=$'\n\t'
+
+source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
+
+# All the Linux builds happen inside Docker.
+if isLinux; then
+    # 6.7GB
+    sudo rm -rf /opt/ghc
+    # 16GB
+    sudo rm -rf /usr/share/dotnet
+fi

src/libcore/alloc.rs

@@ -241,11 +241,13 @@ impl Layout {
     #[unstable(feature = "alloc_layout_extra", issue = "55724")]
     #[inline]
     pub fn repeat(&self, n: usize) -> Result<(Self, usize), LayoutErr> {
-        // This cannot overflow. Quoting from the invariant of Layout:
-        // > `size`, when rounded up to the nearest multiple of `align`,
-        // > must not overflow (i.e., the rounded value must be less than
-        // > `usize::MAX`)
-        let padded_size = self.size() + self.padding_needed_for(self.align());
+        // Warning, removing the checked_add here led to segfaults in #67174. Further
+        // analysis in #69225 seems to indicate that this is an LTO-related
+        // miscompilation, so #67174 might be able to be reapplied in the future.
+        let padded_size = self
+            .size()
+            .checked_add(self.padding_needed_for(self.align()))
+            .ok_or(LayoutErr { private: () })?;
         let alloc_size = padded_size.checked_mul(n).ok_or(LayoutErr { private: () })?;
 
         unsafe {

src/librustc/hir/check_attr.rs

@@ -14,7 +14,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::DUMMY_HIR_ID;
 use rustc_hir::{self, HirId, Item, ItemKind, TraitItem, TraitItemKind};
-use rustc_session::lint::builtin::UNUSED_ATTRIBUTES;
+use rustc_session::lint::builtin::{CONFLICTING_REPR_HINTS, UNUSED_ATTRIBUTES};
 use rustc_span::symbol::sym;
 use rustc_span::Span;
 use syntax::ast::Attribute;
@@ -196,7 +196,7 @@ impl CheckAttrVisitor<'tcx> {
             self.tcx.codegen_fn_attrs(self.tcx.hir().local_def_id(hir_id));
         }
 
-        self.check_repr(attrs, span, target, item);
+        self.check_repr(attrs, span, target, item, hir_id);
         self.check_used(attrs, target);
     }
 
@@ -357,6 +357,7 @@ impl CheckAttrVisitor<'tcx> {
         span: &Span,
         target: Target,
         item: Option<&Item<'_>>,
+        hir_id: HirId,
     ) {
         // Extract the names of all repr hints, e.g., [foo, bar, align] for:
         // ```
@@ -446,13 +447,15 @@ impl CheckAttrVisitor<'tcx> {
             || (is_simd && is_c)
             || (int_reprs == 1 && is_c && item.map_or(false, |item| is_c_like_enum(item)))
         {
-            struct_span_err!(
-                self.tcx.sess,
-                hint_spans.collect::<Vec<Span>>(),
-                E0566,
-                "conflicting representation hints",
-            )
-            .emit();
+            self.tcx
+                .struct_span_lint_hir(
+                    CONFLICTING_REPR_HINTS,
+                    hir_id,
+                    hint_spans.collect::<Vec<Span>>(),
+                    "conflicting representation hints",
+                )
+                .code(rustc_errors::error_code!(E0566))
+                .emit();
         }
     }
 

src/librustc/hir/map/hir_id_validator.rs

@@ -7,7 +7,7 @@ use rustc_hir::intravisit;
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_hir::{HirId, ItemLocalId};
 
-pub fn check_crate(hir_map: &Map<'_>) {
+pub fn check_crate(hir_map: &Map<'_>, sess: &rustc_session::Session) {
     hir_map.dep_graph.assert_ignored();
 
     let errors = Lock::new(Vec::new());
@@ -24,7 +24,7 @@ pub fn check_crate(hir_map: &Map<'_>) {
 
     if !errors.is_empty() {
         let message = errors.iter().fold(String::new(), |s1, s2| s1 + "\n" + s2);
-        bug!("{}", message);
+        sess.delay_span_bug(rustc_span::DUMMY_SP, &message);
     }
 }
 

src/librustc/hir/map/mod.rs

@@ -1271,7 +1271,7 @@ pub fn map_crate<'hir>(
     };
 
     sess.time("validate_HIR_map", || {
-        hir_id_validator::check_crate(&map);
+        hir_id_validator::check_crate(&map, sess);
     });
 
     map

src/librustc_ast_lowering/pat.rs

@@ -128,6 +128,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let mut slice = None;
         let mut prev_rest_span = None;
 
+        // Lowers `$bm $ident @ ..` to `$bm $ident @ _`.
+        let lower_rest_sub = |this: &mut Self, pat, bm, ident, sub| {
+            let lower_sub = |this: &mut Self| Some(this.pat_wild_with_node_id_of(sub));
+            let node = this.lower_pat_ident(pat, bm, ident, lower_sub);
+            this.pat_with_node_id_of(pat, node)
+        };
+
         let mut iter = pats.iter();
         // Lower all the patterns until the first occurrence of a sub-slice pattern.
         for pat in iter.by_ref() {
@@ -142,9 +149,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 // Record, lower it to `$binding_mode $ident @ _`, and stop here.
                 PatKind::Ident(ref bm, ident, Some(ref sub)) if sub.is_rest() => {
                     prev_rest_span = Some(sub.span);
-                    let lower_sub = |this: &mut Self| Some(this.pat_wild_with_node_id_of(sub));
-                    let node = self.lower_pat_ident(pat, bm, ident, lower_sub);
-                    slice = Some(self.pat_with_node_id_of(pat, node));
+                    slice = Some(lower_rest_sub(self, pat, bm, ident, sub));
                     break;
                 }
                 // It was not a subslice pattern so lower it normally.
@@ -157,9 +162,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             // There was a previous subslice pattern; make sure we don't allow more.
             let rest_span = match pat.kind {
                 PatKind::Rest => Some(pat.span),
-                PatKind::Ident(.., Some(ref sub)) if sub.is_rest() => {
-                    // The `HirValidator` is merciless; add a `_` pattern to avoid ICEs.
-                    after.push(self.pat_wild_with_node_id_of(pat));
+                PatKind::Ident(ref bm, ident, Some(ref sub)) if sub.is_rest() => {
+                    // #69103: Lower into `binding @ _` as above to avoid ICEs.
+                    after.push(lower_rest_sub(self, pat, bm, ident, sub));
                     Some(sub.span)
                 }
                 _ => None,

src/librustc_errors/emitter.rs

@@ -19,6 +19,7 @@ use crate::{
     pluralize, CodeSuggestion, Diagnostic, DiagnosticId, Level, SubDiagnostic, SuggestionStyle,
 };
 
+use log::*;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
 use rustc_span::hygiene::{ExpnKind, MacroKind};
@@ -2108,7 +2109,13 @@ impl<'a> Drop for WritableDst<'a> {
 /// Whether the original and suggested code are visually similar enough to warrant extra wording.
 pub fn is_case_difference(sm: &SourceMap, suggested: &str, sp: Span) -> bool {
     // FIXME: this should probably be extended to also account for `FO0` → `FOO` and unicode.
-    let found = sm.span_to_snippet(sp).unwrap();
+    let found = match sm.span_to_snippet(sp) {
+        Ok(snippet) => snippet,
+        Err(e) => {
+            warn!("Invalid span {:?}. Err={:?}", sp, e);
+            return false;
+        }
+    };
     let ascii_confusables = &['c', 'f', 'i', 'k', 'o', 's', 'u', 'v', 'w', 'x', 'y', 'z'];
     // All the chars that differ in capitalization are confusable (above):
     let confusable = found

src/librustc_mir/borrow_check/type_check/mod.rs

@@ -310,6 +310,7 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
                 );
             }
         } else {
+            let tcx = self.tcx();
             if let ty::ConstKind::Unevaluated(def_id, substs, promoted) = constant.literal.val {
                 if let Some(promoted) = promoted {
                     let check_err = |verifier: &mut TypeVerifier<'a, 'b, 'tcx>,
@@ -359,10 +360,23 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
                         );
                     }
                 }
+            } else if let Some(static_def_id) = constant.check_static_ptr(tcx) {
+                let unnormalized_ty = tcx.type_of(static_def_id);
+                let locations = location.to_locations();
+                let normalized_ty = self.cx.normalize(unnormalized_ty, locations);
+                let literal_ty = constant.literal.ty.builtin_deref(true).unwrap().ty;
+
+                if let Err(terr) = self.cx.eq_types(
+                    normalized_ty,
+                    literal_ty,
+                    locations,
+                    ConstraintCategory::Boring,
+                ) {
+                    span_mirbug!(self, constant, "bad static type {:?} ({:?})", constant, terr);
+                }
             }
-            if let ty::FnDef(def_id, substs) = constant.literal.ty.kind {
-                let tcx = self.tcx();
 
+            if let ty::FnDef(def_id, substs) = constant.literal.ty.kind {
                 let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, substs);
                 self.cx.normalize_and_prove_instantiated_predicates(
                     instantiated_predicates,
@@ -467,33 +481,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
 
         let mut place_ty = PlaceTy::from_ty(self.body.local_decls[place.local].ty);
 
-        if place.projection.is_empty() {
-            if let PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy) = context {
-                let tcx = self.tcx();
-                let trait_ref = ty::TraitRef {
-                    def_id: tcx.lang_items().copy_trait().unwrap(),
-                    substs: tcx.mk_substs_trait(place_ty.ty, &[]),
-                };
-
-                // To have a `Copy` operand, the type `T` of the
-                // value must be `Copy`. Note that we prove that `T: Copy`,
-                // rather than using the `is_copy_modulo_regions`
-                // test. This is important because
-                // `is_copy_modulo_regions` ignores the resulting region
-                // obligations and assumes they pass. This can result in
-                // bounds from `Copy` impls being unsoundly ignored (e.g.,
-                // #29149). Note that we decide to use `Copy` before knowing
-                // whether the bounds fully apply: in effect, the rule is
-                // that if a value of some type could implement `Copy`, then
-                // it must.
-                self.cx.prove_trait_ref(
-                    trait_ref,
-                    location.to_locations(),
-                    ConstraintCategory::CopyBound,
-                );
-            }
-        }
-
         for elem in place.projection.iter() {
             if place_ty.variant_index.is_none() {
                 if place_ty.ty.references_error() {
@@ -504,6 +491,31 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
             place_ty = self.sanitize_projection(place_ty, elem, place, location)
         }
 
+        if let PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy) = context {
+            let tcx = self.tcx();
+            let trait_ref = ty::TraitRef {
+                def_id: tcx.lang_items().copy_trait().unwrap(),
+                substs: tcx.mk_substs_trait(place_ty.ty, &[]),
+            };
+
+            // To have a `Copy` operand, the type `T` of the
+            // value must be `Copy`. Note that we prove that `T: Copy`,
+            // rather than using the `is_copy_modulo_regions`
+            // test. This is important because
+            // `is_copy_modulo_regions` ignores the resulting region
+            // obligations and assumes they pass. This can result in
+            // bounds from `Copy` impls being unsoundly ignored (e.g.,
+            // #29149). Note that we decide to use `Copy` before knowing
+            // whether the bounds fully apply: in effect, the rule is
+            // that if a value of some type could implement `Copy`, then
+            // it must.
+            self.cx.prove_trait_ref(
+                trait_ref,
+                location.to_locations(),
+                ConstraintCategory::CopyBound,
+            );
+        }
+
         place_ty
     }
 

src/librustc_session/lint/builtin.rs

@@ -18,6 +18,16 @@ declare_lint! {
     };
 }
 
+declare_lint! {
+    pub CONFLICTING_REPR_HINTS,
+    Deny,
+    "conflicts between `#[repr(..)]` hints that were previously accepted and used in practice",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #68585 <https://github.com/rust-lang/rust/issues/68585>",
+        edition: None,
+    };
+}
+
 declare_lint! {
     pub META_VARIABLE_MISUSE,
     Allow,
@@ -520,6 +530,7 @@ declare_lint_pass! {
         MACRO_USE_EXTERN_CRATE,
         MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
         ILL_FORMED_ATTRIBUTE_INPUT,
+        CONFLICTING_REPR_HINTS,
         META_VARIABLE_MISUSE,
         DEPRECATED_IN_FUTURE,
         AMBIGUOUS_ASSOCIATED_ITEMS,

src/test/ui/array-slice-vec/issue-69103-extra-binding-subslice.rs

@@ -0,0 +1,18 @@
+// We used to not lower the extra `b @ ..` into `b @ _` which meant that no type
+// was registered for the binding `b` although it passed through resolve.
+// This resulted in an ICE (#69103).
+
+fn main() {
+    let [a @ .., b @ ..] = &mut [1, 2];
+    //~^ ERROR `..` can only be used once per slice pattern
+    b;
+
+    let [.., c @ ..] = [1, 2];
+    //~^ ERROR `..` can only be used once per slice pattern
+    c;
+
+    // This never ICEd, but let's make sure it won't regress either.
+    let (.., d @ ..) = (1, 2);
+    //~^ ERROR `..` patterns are not allowed here
+    d;
+}

src/test/ui/array-slice-vec/issue-69103-extra-binding-subslice.stderr

@@ -0,0 +1,26 @@
+error: `..` can only be used once per slice pattern
+  --> $DIR/issue-69103-extra-binding-subslice.rs:6:22
+   |
+LL |     let [a @ .., b @ ..] = &mut [1, 2];
+   |              --      ^^ can only be used once per slice pattern
+   |              |
+   |              previously used here
+
+error: `..` can only be used once per slice pattern
+  --> $DIR/issue-69103-extra-binding-subslice.rs:10:18
+   |
+LL |     let [.., c @ ..] = [1, 2];
+   |          --      ^^ can only be used once per slice pattern
+   |          |
+   |          previously used here
+
+error: `..` patterns are not allowed here
+  --> $DIR/issue-69103-extra-binding-subslice.rs:15:18
+   |
+LL |     let (.., d @ ..) = (1, 2);
+   |                  ^^
+   |
+   = note: only allowed in tuple, tuple struct, and slice patterns
+
+error: aborting due to 3 previous errors
+

src/test/ui/conflicting-repr-hints.rs

@@ -11,11 +11,13 @@ enum B {
 }
 
 #[repr(C, u64)] //~ ERROR conflicting representation hints
+//~^ WARN this was previously accepted
 enum C {
     C,
 }
 
 #[repr(u32, u64)] //~ ERROR conflicting representation hints
+//~^ WARN this was previously accepted
 enum D {
     D,
 }