Rollup of 4 pull requests

compiler/rustc_ast_lowering/src/lib.rs

@@ -1619,13 +1619,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 debug!(?hir_bounds);
 
                 let lifetime_mapping = if in_trait {
-                    self.arena.alloc_from_iter(
-                        collected_lifetime_mapping
-                            .iter()
-                            .map(|(lifetime, def_id)| (**lifetime, *def_id)),
+                    Some(
+                        &*self.arena.alloc_from_iter(
+                            collected_lifetime_mapping
+                                .iter()
+                                .map(|(lifetime, def_id)| (**lifetime, *def_id)),
+                        ),
                     )
                 } else {
-                    &mut []
+                    None
                 };
 
                 let opaque_ty_item = hir::OpaqueTy {
@@ -2090,13 +2092,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 debug!("lower_async_fn_ret_ty: generic_params={:#?}", generic_params);
 
                 let lifetime_mapping = if in_trait {
-                    self.arena.alloc_from_iter(
-                        collected_lifetime_mapping
-                            .iter()
-                            .map(|(lifetime, def_id)| (**lifetime, *def_id)),
+                    Some(
+                        &*self.arena.alloc_from_iter(
+                            collected_lifetime_mapping
+                                .iter()
+                                .map(|(lifetime, def_id)| (**lifetime, *def_id)),
+                        ),
                     )
                 } else {
-                    &mut []
+                    None
                 };
 
                 let opaque_ty_item = hir::OpaqueTy {

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -335,6 +335,10 @@ pub fn from_fn_attrs<'ll, 'tcx>(
     to_add.extend(probestack_attr(cx));
     to_add.extend(stackprotector_attr(cx));
 
+    if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NO_BUILTINS) {
+        to_add.push(llvm::CreateAttrString(cx.llcx, "no-builtins"));
+    }
+
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
         to_add.push(AttributeKind::Cold.create_attr(cx.llcx));
     }

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -1,4 +1,4 @@
-use rustc_ast::{ast, MetaItemKind, NestedMetaItem};
+use rustc_ast::{ast, attr, MetaItemKind, NestedMetaItem};
 use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
@@ -60,6 +60,14 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
         codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
     }
 
+    // When `no_builtins` is applied at the crate level, we should add the
+    // `no-builtins` attribute to each function to ensure it takes effect in LTO.
+    let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID);
+    let no_builtins = attr::contains_name(crate_attrs, sym::no_builtins);
+    if no_builtins {
+        codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_BUILTINS;
+    }
+
     let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
 
     let mut inline_span = None;

compiler/rustc_hir/src/hir.rs

@@ -2664,10 +2664,19 @@ pub struct OpaqueTy<'hir> {
     pub generics: &'hir Generics<'hir>,
     pub bounds: GenericBounds<'hir>,
     pub origin: OpaqueTyOrigin,
-    // Opaques have duplicated lifetimes, this mapping connects the original lifetime with the copy
-    // so we can later generate bidirectional outlives predicates to enforce that these lifetimes
-    // stay in sync.
-    pub lifetime_mapping: &'hir [(Lifetime, LocalDefId)],
+    /// Return-position impl traits (and async futures) must "reify" any late-bound
+    /// lifetimes that are captured from the function signature they originate from.
+    ///
+    /// This is done by generating a new early-bound lifetime parameter local to the
+    /// opaque which is substituted in the function signature with the late-bound
+    /// lifetime.
+    ///
+    /// This mapping associated a captured lifetime (first parameter) with the new
+    /// early-bound lifetime that was generated for the opaque.
+    pub lifetime_mapping: Option<&'hir [(Lifetime, LocalDefId)]>,
+    /// Whether the opaque is a return-position impl trait (or async future)
+    /// originating from a trait method. This makes it so that the opaque is
+    /// lowered as an associated type.
     pub in_trait: bool,
 }
 

compiler/rustc_hir_analysis/src/collect/predicates_of.rs

@@ -66,7 +66,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
             let opaque_ty_id = tcx.hir().local_def_id_to_hir_id(opaque_def_id.expect_local());
             let opaque_ty_node = tcx.hir().get(opaque_ty_id);
             let Node::Item(&Item {
-                kind: ItemKind::OpaqueTy(OpaqueTy { lifetime_mapping, .. }),
+                kind: ItemKind::OpaqueTy(OpaqueTy { lifetime_mapping: Some(lifetime_mapping), .. }),
                 ..
             }) = opaque_ty_node
             else {

compiler/rustc_lint/src/context.rs

@@ -956,11 +956,11 @@ pub trait LintContext: Sized {
                     db.span_note(glob_reexport_span, format!("the name `{}` in the {} namespace is supposed to be publicly re-exported here", name, namespace));
                     db.span_note(private_item_span, "but the private item here shadows it".to_owned());
                 }
-                BuiltinLintDiagnostics::UnusedQualifications { path_span, unqualified_path } => {
+                BuiltinLintDiagnostics::UnusedQualifications { removal_span } => {
                     db.span_suggestion_verbose(
-                        path_span,
-                        "replace it with the unqualified path",
-                        unqualified_path,
+                        removal_span,
+                        "remove the unnecessary path segments",
+                        "",
                         Applicability::MachineApplicable
                     );
                 }

compiler/rustc_lint_defs/src/lib.rs

@@ -551,10 +551,8 @@ pub enum BuiltinLintDiagnostics {
         private_item_span: Span,
     },
     UnusedQualifications {
-        /// The span of the unnecessarily-qualified path.
-        path_span: Span,
-        /// The replacement unqualified path.
-        unqualified_path: Ident,
+        /// The span of the unnecessarily-qualified path to remove.
+        removal_span: Span,
     },
 }
 

compiler/rustc_middle/src/middle/codegen_fn_attrs.rs

@@ -100,6 +100,8 @@ bitflags! {
         const REALLOCATOR               = 1 << 18;
         /// `#[rustc_allocator_zeroed]`: a hint to LLVM that the function only allocates zeroed memory.
         const ALLOCATOR_ZEROED          = 1 << 19;
+        /// `#[no_builtins]`: indicates that disable implicit builtin knowledge of functions for the function.
+        const NO_BUILTINS               = 1 << 20;
     }
 }
 

compiler/rustc_resolve/src/late.rs

@@ -3911,8 +3911,9 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             && path[0].ident.name != kw::PathRoot
             && path[0].ident.name != kw::DollarCrate
         {
+            let last_segment = *path.last().unwrap();
             let unqualified_result = {
-                match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
+                match self.resolve_path(&[last_segment], Some(ns), None) {
                     PathResult::NonModule(path_res) => path_res.expect_full_res(),
                     PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
                         module.res().unwrap()
@@ -3928,8 +3929,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                     finalize.path_span,
                     "unnecessary qualification",
                     lint::BuiltinLintDiagnostics::UnusedQualifications {
-                        path_span: finalize.path_span,
-                        unqualified_path: path.last().unwrap().ident
+                        removal_span: finalize.path_span.until(last_segment.ident.span),
                     }
                 )
             }

src/tools/compiletest/src/runtest.rs

@@ -4149,8 +4149,8 @@ impl<'test> TestCx<'test> {
                   # Match paths that don't include spaces.
                   (?:\\[\pL\pN\.\-_']+)+\.\pL+
                 |
-                  # If the path starts with a well-known root, then allow spaces.
-                  \$(?:DIR|SRC_DIR|TEST_BUILD_DIR|BUILD_DIR|LIB_DIR)(?:\\[\pL\pN\.\-_' ]+)+
+                  # If the path starts with a well-known root, then allow spaces and no file extension.
+                  \$(?:DIR|SRC_DIR|TEST_BUILD_DIR|BUILD_DIR|LIB_DIR)(?:\\[\pL\pN\.\-_'\ ]+)+
                 )"#,
             )
             .unwrap()

src/tools/compiletest/src/runtest/tests.rs

@@ -8,8 +8,8 @@ fn normalize_platform_differences() {
         "$BUILD_DIR/../parser.rs"
     );
     assert_eq!(
-        TestCx::normalize_platform_differences(r"$DIR\bar.rs hello\nworld"),
-        r"$DIR/bar.rs hello\nworld"
+        TestCx::normalize_platform_differences(r"$DIR\bar.rs: hello\nworld"),
+        r"$DIR/bar.rs: hello\nworld"
     );
     assert_eq!(
         TestCx::normalize_platform_differences(r"either bar\baz.rs or bar\baz\mod.rs"),
@@ -27,8 +27,8 @@ fn normalize_platform_differences() {
     );
     assert_eq!(TestCx::normalize_platform_differences(r"$DIR\foo.rs:12:11"), "$DIR/foo.rs:12:11",);
     assert_eq!(
-        TestCx::normalize_platform_differences(r"$DIR\path with spaces 'n' quotes"),
-        "$DIR/path with spaces 'n' quotes",
+        TestCx::normalize_platform_differences(r"$DIR\path with\spaces 'n' quotes"),
+        "$DIR/path with/spaces 'n' quotes",
     );
     assert_eq!(
         TestCx::normalize_platform_differences(r"$DIR\file_with\no_extension"),

tests/codegen/no_builtins-at-crate.rs

@@ -0,0 +1,23 @@
+// compile-flags: -C opt-level=1
+
+#![no_builtins]
+#![crate_type = "lib"]
+
+// CHECK: define void @__aeabi_memcpy
+// CHECK-SAME: #0
+#[no_mangle]
+pub unsafe extern "C" fn __aeabi_memcpy(dest: *mut u8, src: *const u8, size: usize) {
+    // CHECK: call
+    // CHECK-SAME: @memcpy(
+    memcpy(dest, src, size);
+}
+
+// CHECK: declare
+// CHECK-SAME: @memcpy
+// CHECK-SAME: #0
+extern "C" {
+    pub fn memcpy(dest: *mut u8, src: *const u8, n: usize) -> *mut u8;
+}
+
+// CHECK: attributes #0
+// CHECK-SAME: "no-builtins"

tests/run-make/no-builtins-attribute/Makefile

@@ -0,0 +1,9 @@
+include ../tools.mk
+
+# We want to check if `no-builtins` is also added to the function declarations in the used crate.
+
+all:
+	$(RUSTC) no_builtins.rs --emit=link
+	$(RUSTC) main.rs --emit=llvm-ir
+
+	cat "$(TMPDIR)"/main.ll | "$(LLVM_FILECHECK)" filecheck.main.txt

tests/run-make/no-builtins-attribute/filecheck.main.txt

@@ -0,0 +1,5 @@
+CHECK: declare void @foo()
+CHECK-SAME: #[[ATTR_3:[0-9]+]]
+
+CHECK: attributes #[[ATTR_3]] 
+CHECK-SAME: no-builtins

tests/run-make/no-builtins-attribute/main.rs

@@ -0,0 +1,10 @@
+extern crate no_builtins;
+
+#[no_mangle]
+fn call_foo() {
+    no_builtins::foo();
+}
+
+fn main() {
+    call_foo();
+}

tests/run-make/no-builtins-attribute/no_builtins.rs

@@ -0,0 +1,5 @@
+#![crate_type = "lib"]
+#![no_builtins]
+
+#[no_mangle]
+pub fn foo() {}

tests/ui/lint/lint-qualification.fixed

@@ -0,0 +1,21 @@
+// run-rustfix
+#![deny(unused_qualifications)]
+#![allow(deprecated)]
+
+mod foo {
+    pub fn bar() {}
+}
+
+fn main() {
+    use foo::bar;
+    bar(); //~ ERROR: unnecessary qualification
+    bar();
+
+    let _ = || -> Result<(), ()> { try!(Ok(())); Ok(()) }; // issue #37345
+
+    macro_rules! m { () => {
+        $crate::foo::bar(); // issue #37357
+        ::foo::bar(); // issue #38682
+    } }
+    m!();
+}

tests/ui/lint/lint-qualification.rs

@@ -1,3 +1,4 @@
+// run-rustfix
 #![deny(unused_qualifications)]
 #![allow(deprecated)]
 

tests/ui/lint/lint-qualification.stderr

@@ -1,18 +1,19 @@
 error: unnecessary qualification
-  --> $DIR/lint-qualification.rs:10:5
+  --> $DIR/lint-qualification.rs:11:5
    |
 LL |     foo::bar();
    |     ^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-qualification.rs:1:9
+  --> $DIR/lint-qualification.rs:2:9
    |
 LL | #![deny(unused_qualifications)]
    |         ^^^^^^^^^^^^^^^^^^^^^
-help: replace it with the unqualified path
+help: remove the unnecessary path segments
+   |
+LL -     foo::bar();
+LL +     bar();
    |
-LL |     bar();
-   |     ~~~
 
 error: aborting due to previous error
 

tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.fixed

@@ -0,0 +1,31 @@
+// run-rustfix
+
+#![deny(unused_qualifications)]
+#![feature(unsized_fn_params)]
+
+#[allow(unused_imports)]
+use std::ops;
+use std::ops::Index;
+
+pub struct A;
+
+impl Index<str> for A {
+    //~^ ERROR unnecessary qualification
+    type Output = ();
+    fn index(&self, _: str) -> &Self::Output {
+        &()
+    }
+}
+
+mod inner {
+    pub trait Trait<T> {}
+}
+
+// the import needs to be here for the lint to show up
+#[allow(unused_imports)]
+use inner::Trait;
+
+impl Trait<u8> for () {}
+//~^ ERROR unnecessary qualification
+
+fn main() {}

tests/ui/resolve/issue-113808-invalid-unused-qualifications-suggestion.rs

@@ -0,0 +1,31 @@
+// run-rustfix
+
+#![deny(unused_qualifications)]
+#![feature(unsized_fn_params)]
+
+#[allow(unused_imports)]
+use std::ops;
+use std::ops::Index;
+
+pub struct A;
+
+impl ops::Index<str> for A {
+    //~^ ERROR unnecessary qualification
+    type Output = ();
+    fn index(&self, _: str) -> &Self::Output {
+        &()
+    }
+}
+
+mod inner {
+    pub trait Trait<T> {}
+}
+
+// the import needs to be here for the lint to show up
+#[allow(unused_imports)]
+use inner::Trait;
+
+impl inner::Trait<u8> for () {}
+//~^ ERROR unnecessary qualification
+
+fn main() {}