Validate that #[naked] is applied to a function definition

compiler/rustc_passes/src/check_attr.rs

@@ -89,6 +89,8 @@ impl CheckAttrVisitor<'tcx> {
                 self.check_allow_internal_unstable(&attr, span, target, &attrs)
             } else if self.tcx.sess.check_name(attr, sym::rustc_allow_const_fn_unstable) {
                 self.check_rustc_allow_const_fn_unstable(hir_id, &attr, span, target)
+            } else if self.tcx.sess.check_name(attr, sym::naked) {
+                self.check_naked(attr, span, target)
             } else {
                 // lint-only checks
                 if self.tcx.sess.check_name(attr, sym::cold) {
@@ -162,6 +164,25 @@ impl CheckAttrVisitor<'tcx> {
         }
     }
 
+    /// Checks if `#[naked]` is applied to a function definition.
+    fn check_naked(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+        match target {
+            Target::Fn
+            | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
+            _ => {
+                self.tcx
+                    .sess
+                    .struct_span_err(
+                        attr.span,
+                        "attribute should be applied to a function definition",
+                    )
+                    .span_label(*span, "not a function definition")
+                    .emit();
+                false
+            }
+        }
+    }
+
     /// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid.
     fn check_track_caller(
         &self,

src/test/ui/asm/naked-invalid-attr.rs

@@ -0,0 +1,51 @@
+// Checks that #[naked] attribute can be placed on function definitions only.
+//
+// ignore-wasm32 asm unsupported
+#![feature(asm)]
+#![feature(naked_functions)]
+#![naked] //~ ERROR should be applied to a function definition
+
+extern "C" {
+    #[naked] //~ ERROR should be applied to a function definition
+    fn f();
+}
+
+#[naked] //~ ERROR should be applied to a function definition
+#[repr(C)]
+struct S {
+    a: u32,
+    b: u32,
+}
+
+trait Invoke {
+    #[naked] //~ ERROR should be applied to a function definition
+    extern "C" fn invoke(&self);
+}
+
+impl Invoke for S {
+    #[naked]
+    extern "C" fn invoke(&self) {
+        unsafe { asm!("", options(noreturn)) }
+    }
+}
+
+#[naked]
+extern "C" fn ok() {
+    unsafe { asm!("", options(noreturn)) }
+}
+
+impl S {
+    #[naked]
+    extern "C" fn g() {
+        unsafe { asm!("", options(noreturn)) }
+    }
+
+    #[naked]
+    extern "C" fn h(&self) {
+        unsafe { asm!("", options(noreturn)) }
+    }
+}
+
+fn main() {
+    #[naked] || {}; //~ ERROR should be applied to a function definition
+}

src/test/ui/asm/naked-invalid-attr.stderr

@@ -0,0 +1,42 @@
+error: attribute should be applied to a function definition
+  --> $DIR/naked-invalid-attr.rs:9:5
+   |
+LL |     #[naked]
+   |     ^^^^^^^^
+LL |     fn f();
+   |     ------- not a function definition
+
+error: attribute should be applied to a function definition
+  --> $DIR/naked-invalid-attr.rs:13:1
+   |
+LL |   #[naked]
+   |   ^^^^^^^^
+LL |   #[repr(C)]
+LL | / struct S {
+LL | |     a: u32,
+LL | |     b: u32,
+LL | | }
+   | |_- not a function definition
+
+error: attribute should be applied to a function definition
+  --> $DIR/naked-invalid-attr.rs:50:5
+   |
+LL |     #[naked] || {};
+   |     ^^^^^^^^ ----- not a function definition
+
+error: attribute should be applied to a function definition
+  --> $DIR/naked-invalid-attr.rs:21:5
+   |
+LL |     #[naked]
+   |     ^^^^^^^^
+LL |     extern "C" fn invoke(&self);
+   |     ---------------------------- not a function definition
+
+error: attribute should be applied to a function definition
+  --> $DIR/naked-invalid-attr.rs:6:1
+   |
+LL | #![naked]
+   | ^^^^^^^^^
+
+error: aborting due to 5 previous errors
+

src/test/ui/rfc-2091-track-caller/error-with-naked.rs

@@ -12,10 +12,4 @@ impl S {
     fn g() {}
 }
 
-extern "Rust" {
-    #[track_caller] //~ ERROR cannot use `#[track_caller]` with `#[naked]`
-    #[naked]
-    fn h();
-}
-
 fn main() {}

src/test/ui/rfc-2091-track-caller/error-with-naked.stderr

@@ -4,18 +4,12 @@ error[E0736]: cannot use `#[track_caller]` with `#[naked]`
 LL | #[track_caller]
    | ^^^^^^^^^^^^^^^
 
-error[E0736]: cannot use `#[track_caller]` with `#[naked]`
-  --> $DIR/error-with-naked.rs:16:5
-   |
-LL |     #[track_caller]
-   |     ^^^^^^^^^^^^^^^
-
 error[E0736]: cannot use `#[track_caller]` with `#[naked]`
   --> $DIR/error-with-naked.rs:10:5
    |
 LL |     #[track_caller]
    |     ^^^^^^^^^^^^^^^
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0736`.