Don't lint against named labels in `naked_asm!`

Naked functions are allowed to define global labels, just like
`global_asm!`.

4 files changed, 47 insertions, 31 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 97e07095875..984b280e81b 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -2849,7 +2849,7 @@ impl InlineAsmOperand {
     }
 }
 
-#[derive(Clone, Copy, Encodable, Decodable, Debug, HashStable_Generic, Walkable)]
+#[derive(Clone, Copy, Encodable, Decodable, Debug, HashStable_Generic, Walkable, PartialEq, Eq)]
 pub enum AsmMacro {
     /// The `asm!` macro
     Asm,
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index eb4c3703dbd..bf128b5914f 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -2870,7 +2870,7 @@ impl<'tcx> LateLintPass<'tcx> for AsmLabels {
         if let hir::Expr {
             kind:
                 hir::ExprKind::InlineAsm(hir::InlineAsm {
-                    asm_macro: AsmMacro::Asm | AsmMacro::NakedAsm,
+                    asm_macro: asm_macro @ (AsmMacro::Asm | AsmMacro::NakedAsm),
                     template_strs,
                     options,
                     ..
@@ -2878,6 +2878,15 @@ impl<'tcx> LateLintPass<'tcx> for AsmLabels {
             ..
         } = expr
         {
+            // Non-generic naked functions are allowed to define arbitrary
+            // labels.
+            if *asm_macro == AsmMacro::NakedAsm {
+                let def_id = expr.hir_id.owner.def_id;
+                if !cx.tcx.generics_of(def_id).requires_monomorphization(cx.tcx) {
+                    return;
+                }
+            }
+
             // asm with `options(raw)` does not do replacement with `{` and `}`.
             let raw = options.contains(InlineAsmOptions::RAW);
 
diff --git a/tests/ui/asm/named-asm-labels.rs b/tests/ui/asm/named-asm-labels.rs
index 996fb82a944..e78553fd775 100644
--- a/tests/ui/asm/named-asm-labels.rs
+++ b/tests/ui/asm/named-asm-labels.rs
@@ -171,12 +171,10 @@ fn main() {
     }
 }
 
-// Trigger on naked fns too, even though they can't be inlined, reusing a
-// label or LTO can cause labels to break
+// Don't trigger on naked functions.
 #[unsafe(naked)]
 pub extern "C" fn foo() -> i32 {
     naked_asm!(".Lfoo: mov rax, {}; ret;", "nop", const 1)
-    //~^ ERROR avoid using named labels
 }
 
 // Make sure that non-naked attributes *do* still let the lint happen
@@ -190,7 +188,18 @@ pub extern "C" fn bar() {
 pub extern "C" fn aaa() {
     fn _local() {}
 
-    naked_asm!(".Laaa: nop; ret;") //~ ERROR avoid using named labels
+    naked_asm!(".Laaa: nop; ret;")
+}
+
+#[unsafe(naked)]
+pub extern "C" fn bbb<'a>(a: &'a u32) {
+    naked_asm!(".Lbbb: nop; ret;")
+}
+
+#[unsafe(naked)]
+pub extern "C" fn ccc<T>(a: &T) {
+    naked_asm!(".Lccc: nop; ret;")
+    //~^ ERROR avoid using named labels
 }
 
 pub fn normal() {
@@ -200,7 +209,7 @@ pub fn normal() {
     pub extern "C" fn bbb() {
         fn _very_local() {}
 
-        naked_asm!(".Lbbb: nop; ret;") //~ ERROR avoid using named labels
+        naked_asm!(".Lbbb: nop; ret;")
     }
 
     fn _local2() {}
@@ -230,3 +239,10 @@ fn closures() {
 
 // Don't trigger on global asm
 global_asm!("aaaaaaaa: nop");
+
+trait Foo {
+    #[unsafe(naked)]
+    extern "C" fn bbb<'a>(a: &'a u32) {
+        naked_asm!(".Lbbb: nop; ret;") //~ ERROR avoid using named labels
+    }
+}
diff --git a/tests/ui/asm/named-asm-labels.stderr b/tests/ui/asm/named-asm-labels.stderr
index cd7e7a08c1d..9ba9e14de3a 100644
--- a/tests/ui/asm/named-asm-labels.stderr
+++ b/tests/ui/asm/named-asm-labels.stderr
@@ -475,16 +475,7 @@ LL |         #[warn(named_asm_labels)]
    |                ^^^^^^^^^^^^^^^^
 
 error: avoid using named labels in inline assembly
-  --> $DIR/named-asm-labels.rs:178:17
-   |
-LL |     naked_asm!(".Lfoo: mov rax, {}; ret;", "nop", const 1)
-   |                 ^^^^^
-   |
-   = help: only local labels of the form `<number>:` should be used in inline asm
-   = note: see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
-
-error: avoid using named labels in inline assembly
-  --> $DIR/named-asm-labels.rs:185:20
+  --> $DIR/named-asm-labels.rs:183:20
    |
 LL |     unsafe { asm!(".Lbar: mov rax, {}; ret;", "nop", const 1, options(noreturn)) }
    |                    ^^^^^
@@ -493,49 +484,49 @@ LL |     unsafe { asm!(".Lbar: mov rax, {}; ret;", "nop", const 1, options(noret
    = note: see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
 
 error: avoid using named labels in inline assembly
-  --> $DIR/named-asm-labels.rs:193:17
+  --> $DIR/named-asm-labels.rs:201:17
    |
-LL |     naked_asm!(".Laaa: nop; ret;")
+LL |     naked_asm!(".Lccc: nop; ret;")
    |                 ^^^^^
    |
    = help: only local labels of the form `<number>:` should be used in inline asm
    = note: see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
 
 error: avoid using named labels in inline assembly
-  --> $DIR/named-asm-labels.rs:203:21
+  --> $DIR/named-asm-labels.rs:221:15
    |
-LL |         naked_asm!(".Lbbb: nop; ret;")
-   |                     ^^^^^
+LL |         asm!("closure1: nop");
+   |               ^^^^^^^^
    |
    = help: only local labels of the form `<number>:` should be used in inline asm
    = note: see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
 
 error: avoid using named labels in inline assembly
-  --> $DIR/named-asm-labels.rs:212:15
+  --> $DIR/named-asm-labels.rs:225:15
    |
-LL |         asm!("closure1: nop");
+LL |         asm!("closure2: nop");
    |               ^^^^^^^^
    |
    = help: only local labels of the form `<number>:` should be used in inline asm
    = note: see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
 
 error: avoid using named labels in inline assembly
-  --> $DIR/named-asm-labels.rs:216:15
+  --> $DIR/named-asm-labels.rs:235:19
    |
-LL |         asm!("closure2: nop");
-   |               ^^^^^^^^
+LL |             asm!("closure3: nop");
+   |                   ^^^^^^^^
    |
    = help: only local labels of the form `<number>:` should be used in inline asm
    = note: see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
 
 error: avoid using named labels in inline assembly
-  --> $DIR/named-asm-labels.rs:226:19
+  --> $DIR/named-asm-labels.rs:246:21
    |
-LL |             asm!("closure3: nop");
-   |                   ^^^^^^^^
+LL |         naked_asm!(".Lbbb: nop; ret;")
+   |                     ^^^^^
    |
    = help: only local labels of the form `<number>:` should be used in inline asm
    = note: see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
 
-error: aborting due to 56 previous errors; 1 warning emitted
+error: aborting due to 55 previous errors; 1 warning emitted