Rollup of 6 pull requests

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1415,7 +1415,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     if !self.is_tilde_const_allowed {
                         self.err_handler()
                             .struct_span_err(bound.span(), "`~const` is not allowed here")
-                            .note("only allowed on bounds on traits' associated types and functions, const fns, const impls and its associated functions")
+                            .note("only allowed on bounds on functions, traits' associated types and functions, const impls and its associated functions")
                             .emit();
                     }
                 }
@@ -1523,9 +1523,8 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
             });
         }
 
-        let tilde_const_allowed =
-            matches!(fk.header(), Some(FnHeader { constness: Const::Yes(_), .. }))
-                || matches!(fk.ctxt(), Some(FnCtxt::Assoc(_)));
+        let tilde_const_allowed = matches!(fk.header(), Some(FnHeader { .. }))
+            || matches!(fk.ctxt(), Some(FnCtxt::Assoc(_)));
 
         self.with_tilde_const(tilde_const_allowed, |this| visit::walk_fn(this, fk));
     }

compiler/rustc_error_messages/locales/en-US/parser.ftl

@@ -158,3 +158,6 @@ parser_remove_let = expected pattern, found `let`
 
 parser_use_eq_instead = unexpected `==`
     .suggestion = try using `=` instead
+
+parser_use_empty_block_not_semi = expected { "`{}`" }, found `;`
+    .suggestion = try using { "`{}`" } instead

compiler/rustc_mir_build/src/build/block.rs

@@ -221,27 +221,37 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                     let init = &this.thir[*initializer];
                     let initializer_span = init.span;
-                    this.declare_bindings(
-                        visibility_scope,
-                        remainder_span,
-                        pattern,
-                        ArmHasGuard(false),
-                        Some((None, initializer_span)),
-                    );
-                    this.visit_primary_bindings(
-                        pattern,
-                        UserTypeProjections::none(),
-                        &mut |this, _, _, _, node, span, _, _| {
-                            this.storage_live_binding(block, node, span, OutsideGuard, true);
-                            this.schedule_drop_for_binding(node, span, OutsideGuard);
-                        },
-                    );
                     let failure = unpack!(
                         block = this.in_opt_scope(
                             opt_destruction_scope.map(|de| (de, source_info)),
                             |this| {
                                 let scope = (*init_scope, source_info);
                                 this.in_scope(scope, *lint_level, |this| {
+                                    this.declare_bindings(
+                                        visibility_scope,
+                                        remainder_span,
+                                        pattern,
+                                        ArmHasGuard(false),
+                                        Some((None, initializer_span)),
+                                    );
+                                    this.visit_primary_bindings(
+                                        pattern,
+                                        UserTypeProjections::none(),
+                                        &mut |this, _, _, _, node, span, _, _| {
+                                            this.storage_live_binding(
+                                                block,
+                                                node,
+                                                span,
+                                                OutsideGuard,
+                                                true,
+                                            );
+                                            this.schedule_drop_for_binding(
+                                                node,
+                                                span,
+                                                OutsideGuard,
+                                            );
+                                        },
+                                    );
                                     this.ast_let_else(
                                         block,
                                         init,
@@ -306,7 +316,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                                             ArmHasGuard(false),
                                             Some((None, initializer_span)),
                                         );
-                                        this.expr_into_pattern(block, &pattern, init) // irrefutable pattern
+                                        this.expr_into_pattern(block, &pattern, init)
+                                        // irrefutable pattern
                                     })
                                 },
                             )

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -745,6 +745,14 @@ pub(crate) struct UseEqInstead {
     pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(parser::use_empty_block_not_semi)]
+pub(crate) struct UseEmptyBlockNotSemi {
+    #[primary_span]
+    #[suggestion_hidden(applicability = "machine-applicable", code = "{{}}")]
+    pub span: Span,
+}
+
 // SnapshotParser is used to create a snapshot of the parser
 // without causing duplicate errors being emitted when the `Parser`
 // is dropped.

compiler/rustc_parse/src/parser/item.rs

@@ -1,4 +1,4 @@
-use super::diagnostics::{dummy_arg, ConsumeClosingDelim, Error};
+use super::diagnostics::{dummy_arg, ConsumeClosingDelim, Error, UseEmptyBlockNotSemi};
 use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
 use super::{AttrWrapper, FollowedByType, ForceCollect, Parser, PathStyle, TrailingToken};
 
@@ -664,6 +664,14 @@ impl<'a> Parser<'a> {
         mut parse_item: impl FnMut(&mut Parser<'a>) -> PResult<'a, Option<Option<T>>>,
     ) -> PResult<'a, Vec<T>> {
         let open_brace_span = self.token.span;
+
+        // Recover `impl Ty;` instead of `impl Ty {}`
+        if self.token == TokenKind::Semi {
+            self.sess.emit_err(UseEmptyBlockNotSemi { span: self.token.span });
+            self.bump();
+            return Ok(vec![]);
+        }
+
         self.expect(&token::OpenDelim(Delimiter::Brace))?;
         attrs.extend(self.parse_inner_attributes()?);
 
@@ -1305,12 +1313,19 @@ impl<'a> Parser<'a> {
         let mut generics = self.parse_generics()?;
         generics.where_clause = self.parse_where_clause()?;
 
-        let (variants, _) = self
-            .parse_delim_comma_seq(Delimiter::Brace, |p| p.parse_enum_variant())
-            .map_err(|e| {
-                self.recover_stmt();
-                e
-            })?;
+        // Possibly recover `enum Foo;` instead of `enum Foo {}`
+        let (variants, _) = if self.token == TokenKind::Semi {
+            self.sess.emit_err(UseEmptyBlockNotSemi { span: self.token.span });
+            self.bump();
+            (vec![], false)
+        } else {
+            self.parse_delim_comma_seq(Delimiter::Brace, |p| p.parse_enum_variant()).map_err(
+                |e| {
+                    self.recover_stmt();
+                    e
+                },
+            )?
+        };
 
         let enum_definition = EnumDef { variants: variants.into_iter().flatten().collect() };
         Ok((id, ItemKind::Enum(enum_definition, generics)))

compiler/rustc_typeck/src/coherence/builtin.rs

@@ -70,23 +70,21 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
     let self_type = tcx.type_of(impl_did);
     debug!("visit_implementation_of_copy: self_type={:?} (bound)", self_type);
 
-    let span = tcx.hir().span(impl_hir_id);
     let param_env = tcx.param_env(impl_did);
     assert!(!self_type.has_escaping_bound_vars());
 
     debug!("visit_implementation_of_copy: self_type={:?} (free)", self_type);
 
+    let span = match tcx.hir().expect_item(impl_did).kind {
+        ItemKind::Impl(hir::Impl { polarity: hir::ImplPolarity::Negative(_), .. }) => return,
+        ItemKind::Impl(impl_) => impl_.self_ty.span,
+        _ => bug!("expected Copy impl item"),
+    };
+
     let cause = traits::ObligationCause::misc(span, impl_hir_id);
     match can_type_implement_copy(tcx, param_env, self_type, cause) {
         Ok(()) => {}
         Err(CopyImplementationError::InfrigingFields(fields)) => {
-            let item = tcx.hir().expect_item(impl_did);
-            let span = if let ItemKind::Impl(hir::Impl { of_trait: Some(ref tr), .. }) = item.kind {
-                tr.path.span
-            } else {
-                span
-            };
-
             let mut err = struct_span_err!(
                 tcx.sess,
                 span,
@@ -166,10 +164,6 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
             err.emit();
         }
         Err(CopyImplementationError::NotAnAdt) => {
-            let item = tcx.hir().expect_item(impl_did);
-            let span =
-                if let ItemKind::Impl(ref impl_) = item.kind { impl_.self_ty.span } else { span };
-
             tcx.sess.emit_err(CopyImplOnNonAdt { span });
         }
         Err(CopyImplementationError::HasDestructor) => {

config.toml.example

@@ -291,6 +291,10 @@ changelog-seen = 2
 # on this runtime, such as `-C profile-generate` or `-C instrument-coverage`).
 #profiler = false
 
+# Use the optimized LLVM C intrinsics for `compiler_builtins`, rather than Rust intrinsics.
+# Requires the LLVM submodule to be managed by bootstrap (i.e. not external).
+#optimized-compiler-builtins = false
+
 # Indicates whether the native libraries linked into Cargo will be statically
 # linked or not.
 #cargo-native-static = false

src/bootstrap/compile.rs

@@ -299,9 +299,7 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
 
     // Determine if we're going to compile in optimized C intrinsics to
     // the `compiler-builtins` crate. These intrinsics live in LLVM's
-    // `compiler-rt` repository, but our `src/llvm-project` submodule isn't
-    // always checked out, so we need to conditionally look for this. (e.g. if
-    // an external LLVM is used we skip the LLVM submodule checkout).
+    // `compiler-rt` repository.
     //
     // Note that this shouldn't affect the correctness of `compiler-builtins`,
     // but only its speed. Some intrinsics in C haven't been translated to Rust
@@ -312,8 +310,15 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
     // If `compiler-rt` is available ensure that the `c` feature of the
     // `compiler-builtins` crate is enabled and it's configured to learn where
     // `compiler-rt` is located.
-    let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
-    let compiler_builtins_c_feature = if compiler_builtins_root.exists() {
+    let compiler_builtins_c_feature = if builder.config.optimized_compiler_builtins {
+        if !builder.is_rust_llvm(target) {
+            panic!(
+                "need a managed LLVM submodule for optimized intrinsics support; unset `llvm-config` or `optimized-compiler-builtins`"
+            );
+        }
+
+        builder.update_submodule(&Path::new("src").join("llvm-project"));
+        let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
         // Note that `libprofiler_builtins/build.rs` also computes this so if
         // you're changing something here please also change that.
         cargo.env("RUST_COMPILER_RT_ROOT", &compiler_builtins_root);

src/bootstrap/config.rs

@@ -73,6 +73,8 @@ pub struct Config {
     pub color: Color,
     pub patch_binaries_for_nix: bool,
     pub stage0_metadata: Stage0Metadata,
+    /// Whether to use the `c` feature of the `compiler_builtins` crate.
+    pub optimized_compiler_builtins: bool,
 
     pub on_fail: Option<String>,
     pub stage: u32,
@@ -597,6 +599,7 @@ define_config! {
         bench_stage: Option<u32> = "bench-stage",
         patch_binaries_for_nix: Option<bool> = "patch-binaries-for-nix",
         metrics: Option<bool> = "metrics",
+        optimized_compiler_builtins: Option<bool> = "optimized-compiler-builtins",
     }
 }
 
@@ -966,6 +969,7 @@ impl Config {
         set(&mut config.print_step_timings, build.print_step_timings);
         set(&mut config.print_step_rusage, build.print_step_rusage);
         set(&mut config.patch_binaries_for_nix, build.patch_binaries_for_nix);
+        set(&mut config.optimized_compiler_builtins, build.optimized_compiler_builtins);
 
         config.verbose = cmp::max(config.verbose, flags.verbose);
 

src/bootstrap/dist.rs

@@ -1844,23 +1844,21 @@ fn add_env(builder: &Builder<'_>, cmd: &mut Command, target: TargetSelection) {
 ///
 /// Returns whether the files were actually copied.
 fn maybe_install_llvm(builder: &Builder<'_>, target: TargetSelection, dst_libdir: &Path) -> bool {
-    if let Some(config) = builder.config.target_config.get(&target) {
-        if config.llvm_config.is_some() && !builder.config.llvm_from_ci {
-            // If the LLVM was externally provided, then we don't currently copy
-            // artifacts into the sysroot. This is not necessarily the right
-            // choice (in particular, it will require the LLVM dylib to be in
-            // the linker's load path at runtime), but the common use case for
-            // external LLVMs is distribution provided LLVMs, and in that case
-            // they're usually in the standard search path (e.g., /usr/lib) and
-            // copying them here is going to cause problems as we may end up
-            // with the wrong files and isn't what distributions want.
-            //
-            // This behavior may be revisited in the future though.
-            //
-            // If the LLVM is coming from ourselves (just from CI) though, we
-            // still want to install it, as it otherwise won't be available.
-            return false;
-        }
+    if builder.is_rust_llvm(target) {
+        // If the LLVM was externally provided, then we don't currently copy
+        // artifacts into the sysroot. This is not necessarily the right
+        // choice (in particular, it will require the LLVM dylib to be in
+        // the linker's load path at runtime), but the common use case for
+        // external LLVMs is distribution provided LLVMs, and in that case
+        // they're usually in the standard search path (e.g., /usr/lib) and
+        // copying them here is going to cause problems as we may end up
+        // with the wrong files and isn't what distributions want.
+        //
+        // This behavior may be revisited in the future though.
+        //
+        // If the LLVM is coming from ourselves (just from CI) though, we
+        // still want to install it, as it otherwise won't be available.
+        return false;
     }
 
     // On macOS, rustc (and LLVM tools) link to an unversioned libLLVM.dylib

src/ci/docker/host-x86_64/disabled/dist-x86_64-haiku/Dockerfile

@@ -47,4 +47,6 @@ ENV RUST_CONFIGURE_ARGS --disable-jemalloc \
   --set=$TARGET.cc=x86_64-unknown-haiku-gcc \
   --set=$TARGET.cxx=x86_64-unknown-haiku-g++ \
   --set=$TARGET.llvm-config=/bin/llvm-config-haiku
+ENV EXTERNAL_LLVM 1
+
 ENV SCRIPT python3 ../x.py dist --host=$HOST --target=$HOST

src/ci/docker/host-x86_64/dist-various-2/Dockerfile

@@ -129,4 +129,6 @@ ENV RUST_CONFIGURE_ARGS --enable-extended --enable-lld --disable-docs \
   --set target.wasm32-wasi.wasi-root=/wasm32-wasi \
   --musl-root-armv7=/musl-armv7
 
+ENV EXTERNAL_LLVM 1
+
 ENV SCRIPT python3 ../x.py dist --host='' --target $TARGETS

src/ci/docker/host-x86_64/x86_64-gnu-llvm-13-stage1/Dockerfile

@@ -29,6 +29,7 @@ RUN sh /scripts/sccache.sh
 # We are disabling CI LLVM since this builder is intentionally using a host
 # LLVM, rather than the typical src/llvm-project LLVM.
 ENV NO_DOWNLOAD_CI_LLVM 1
+ENV EXTERNAL_LLVM 1
 
 # Using llvm-link-shared due to libffi issues -- see #34486
 ENV RUST_CONFIGURE_ARGS \

src/ci/docker/host-x86_64/x86_64-gnu-llvm-13/Dockerfile

@@ -40,6 +40,7 @@ RUN sh /scripts/sccache.sh
 # We are disabling CI LLVM since this builder is intentionally using a host
 # LLVM, rather than the typical src/llvm-project LLVM.
 ENV NO_DOWNLOAD_CI_LLVM 1
+ENV EXTERNAL_LLVM 1
 
 # Using llvm-link-shared due to libffi issues -- see #34486
 ENV RUST_CONFIGURE_ARGS \

src/ci/run.sh

@@ -69,6 +69,11 @@ RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.codegen-units-std=1"
 # space required for CI artifacts.
 RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --dist-compression-formats=xz"
 
+# Enable the `c` feature for compiler_builtins, but only when the `compiler-rt` source is available.
+if [ "$EXTERNAL_LLVM" = "" ]; then
+  RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set build.optimized-compiler-builtins"
+fi
+
 if [ "$DIST_SRC" = "" ]; then
   RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --disable-dist-src"
 fi

src/test/ui/coherence/coherence-negative-impls-copy-bad.rs

@@ -0,0 +1,11 @@
+#![feature(negative_impls)]
+#![crate_type = "lib"]
+
+impl !Copy for str {}
+//~^ ERROR only traits defined in the current crate can be implemented
+
+impl !Copy for fn() {}
+//~^ ERROR only traits defined in the current crate can be implemented
+
+impl !Copy for () {}
+//~^ ERROR only traits defined in the current crate can be implemented

src/test/ui/coherence/coherence-negative-impls-copy-bad.stderr

@@ -0,0 +1,36 @@
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+  --> $DIR/coherence-negative-impls-copy-bad.rs:4:1
+   |
+LL | impl !Copy for str {}
+   | ^^^^^^^^^^^^^^^---
+   | |              |
+   | |              `str` is not defined in the current crate
+   | impl doesn't use only types from inside the current crate
+   |
+   = note: define and implement a trait or new type instead
+
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+  --> $DIR/coherence-negative-impls-copy-bad.rs:7:1
+   |
+LL | impl !Copy for fn() {}
+   | ^^^^^^^^^^^^^^^----
+   | |              |
+   | |              `fn()` is not defined in the current crate
+   | impl doesn't use only types from inside the current crate
+   |
+   = note: define and implement a trait or new type instead
+
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+  --> $DIR/coherence-negative-impls-copy-bad.rs:10:1
+   |
+LL | impl !Copy for () {}
+   | ^^^^^^^^^^^^^^^--
+   | |              |
+   | |              this is not defined in the current crate because tuples are always foreign
+   | impl doesn't use only types from inside the current crate
+   |
+   = note: define and implement a trait or new type instead
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0117`.