Rollup merge of #131550 - compiler-errors:extern-diags, r=spastorino

Make some tweaks to extern block diagnostics

Self-explanatory. See the diagnostic changes; I hope they make them a bit more descriptive.

r? spastorino

compiler/rustc_ast_passes/messages.ftl

@@ -62,12 +62,12 @@ ast_passes_equality_in_where = equality constraints are not yet supported in `wh
 
 ast_passes_extern_block_suggestion = if you meant to declare an externally defined function, use an `extern` block
 
-ast_passes_extern_fn_qualifiers = functions in `extern` blocks cannot have qualifiers
+ast_passes_extern_fn_qualifiers = functions in `extern` blocks cannot have `{$kw}` qualifier
     .label = in this `extern` block
-    .suggestion = remove this qualifier
+    .suggestion = remove the `{$kw}` qualifier
 
-ast_passes_extern_invalid_safety = items in unadorned `extern` blocks cannot have safety qualifiers
-    .suggestion = add unsafe to this `extern` block
+ast_passes_extern_invalid_safety = items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
+    .suggestion = add `unsafe` to this `extern` block
 
 ast_passes_extern_item_ascii = items in `extern` blocks cannot use non-ascii identifiers
     .label = in this `extern` block

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -524,21 +524,24 @@ impl<'a> AstValidator<'a> {
         // Deconstruct to ensure exhaustiveness
         FnHeader { safety: _, coroutine_kind, constness, ext }: FnHeader,
     ) {
-        let report_err = |span| {
-            self.dcx()
-                .emit_err(errors::FnQualifierInExtern { span, block: self.current_extern_span() });
+        let report_err = |span, kw| {
+            self.dcx().emit_err(errors::FnQualifierInExtern {
+                span,
+                kw,
+                block: self.current_extern_span(),
+            });
         };
         match coroutine_kind {
-            Some(knd) => report_err(knd.span()),
+            Some(kind) => report_err(kind.span(), kind.as_str()),
             None => (),
         }
         match constness {
-            Const::Yes(span) => report_err(span),
+            Const::Yes(span) => report_err(span, "const"),
             Const::No => (),
         }
         match ext {
             Extern::None => (),
-            Extern::Implicit(span) | Extern::Explicit(_, span) => report_err(span),
+            Extern::Implicit(span) | Extern::Explicit(_, span) => report_err(span, "extern"),
         }
     }
 

compiler/rustc_ast_passes/src/errors.rs

@@ -295,6 +295,7 @@ pub(crate) struct FnQualifierInExtern {
     pub span: Span,
     #[label]
     pub block: Span,
+    pub kw: &'static str,
 }
 
 #[derive(Diagnostic)]

tests/rustdoc-json/fns/extern_safe.rs

@@ -2,7 +2,7 @@ extern "C" {
     //@ is "$.index[*][?(@.name=='f1')].inner.function.header.is_unsafe" true
     pub fn f1();
 
-    // items in unadorned `extern` blocks cannot have safety qualifiers
+    // items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
 }
 
 unsafe extern "C" {

tests/ui/extern/issue-95829.rs

@@ -2,7 +2,7 @@
 
 extern {
     async fn L() { //~ ERROR: incorrect function inside `extern` block
-        //~^ ERROR: functions in `extern` blocks cannot have qualifiers
+        //~^ ERROR: functions in `extern` blocks cannot have `async` qualifier
         async fn M() {}
     }
 }

tests/ui/extern/issue-95829.stderr

@@ -15,13 +15,13 @@ LL | |     }
    = help: you might have meant to write a function accessible through FFI, which can be done by writing `extern fn` outside of the `extern` block
    = note: for more information, visit https://doc.rust-lang.org/std/keyword.extern.html
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `async` qualifier
   --> $DIR/issue-95829.rs:4:5
    |
 LL | extern {
    | ------ in this `extern` block
 LL |     async fn L() {
-   |     ^^^^^ help: remove this qualifier
+   |     ^^^^^ help: remove the `async` qualifier
 
 error: aborting due to 2 previous errors
 

tests/ui/parser/fn-header-semantic-fail.rs

@@ -41,15 +41,15 @@ fn main() {
     }
 
     extern "C" {
-        async fn fe1(); //~ ERROR functions in `extern` blocks cannot have qualifiers
-        unsafe fn fe2(); //~ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
-        const fn fe3(); //~ ERROR functions in `extern` blocks cannot have qualifiers
-        extern "C" fn fe4(); //~ ERROR functions in `extern` blocks cannot have qualifiers
+        async fn fe1(); //~ ERROR functions in `extern` blocks cannot
+        unsafe fn fe2(); //~ ERROR items in `extern` blocks without an `unsafe` qualifier cannot
+        const fn fe3(); //~ ERROR functions in `extern` blocks cannot
+        extern "C" fn fe4(); //~ ERROR functions in `extern` blocks cannot
         const async unsafe extern "C" fn fe5();
         //~^ ERROR functions in `extern` blocks
         //~| ERROR functions in `extern` blocks
         //~| ERROR functions in `extern` blocks
         //~| ERROR functions cannot be both `const` and `async`
-        //~| ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+        //~| ERROR items in `extern` blocks without an `unsafe` qualifier cannot have
     }
 }

tests/ui/parser/fn-header-semantic-fail.stderr

@@ -70,77 +70,77 @@ LL |         const async unsafe extern "C" fn fi5() {}
    |         |     `async` because of this
    |         `const` because of this
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `async` qualifier
   --> $DIR/fn-header-semantic-fail.rs:44:9
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 LL |         async fn fe1();
-   |         ^^^^^ help: remove this qualifier
+   |         ^^^^^ help: remove the `async` qualifier
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/fn-header-semantic-fail.rs:45:9
    |
 LL |         unsafe fn fe2();
    |         ^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL |     unsafe extern "C" {
    |     ++++++
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `const` qualifier
   --> $DIR/fn-header-semantic-fail.rs:46:9
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         const fn fe3();
-   |         ^^^^^ help: remove this qualifier
+   |         ^^^^^ help: remove the `const` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `extern` qualifier
   --> $DIR/fn-header-semantic-fail.rs:47:9
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         extern "C" fn fe4();
-   |         ^^^^^^^^^^ help: remove this qualifier
+   |         ^^^^^^^^^^ help: remove the `extern` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `async` qualifier
   --> $DIR/fn-header-semantic-fail.rs:48:15
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         const async unsafe extern "C" fn fe5();
-   |               ^^^^^ help: remove this qualifier
+   |               ^^^^^ help: remove the `async` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `const` qualifier
   --> $DIR/fn-header-semantic-fail.rs:48:9
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         const async unsafe extern "C" fn fe5();
-   |         ^^^^^ help: remove this qualifier
+   |         ^^^^^ help: remove the `const` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `extern` qualifier
   --> $DIR/fn-header-semantic-fail.rs:48:28
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
 ...
 LL |         const async unsafe extern "C" fn fe5();
-   |                            ^^^^^^^^^^ help: remove this qualifier
+   |                            ^^^^^^^^^^ help: remove the `extern` qualifier
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/fn-header-semantic-fail.rs:48:9
    |
 LL |         const async unsafe extern "C" fn fe5();
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL |     unsafe extern "C" {
    |     ++++++

tests/ui/parser/no-const-fn-in-extern-block.rs

@@ -1,9 +1,9 @@
 extern "C" {
     const fn foo();
-    //~^ ERROR functions in `extern` blocks cannot have qualifiers
+    //~^ ERROR functions in `extern` blocks cannot
     const unsafe fn bar();
-    //~^ ERROR functions in `extern` blocks cannot have qualifiers
-    //~| ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    //~^ ERROR functions in `extern` blocks cannot
+    //~| ERROR items in `extern` blocks without an `unsafe` qualifier cannot
 }
 
 fn main() {}

tests/ui/parser/no-const-fn-in-extern-block.stderr

@@ -1,27 +1,27 @@
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `const` qualifier
   --> $DIR/no-const-fn-in-extern-block.rs:2:5
    |
 LL | extern "C" {
    | ---------- in this `extern` block
 LL |     const fn foo();
-   |     ^^^^^ help: remove this qualifier
+   |     ^^^^^ help: remove the `const` qualifier
 
-error: functions in `extern` blocks cannot have qualifiers
+error: functions in `extern` blocks cannot have `const` qualifier
   --> $DIR/no-const-fn-in-extern-block.rs:4:5
    |
 LL | extern "C" {
    | ---------- in this `extern` block
 ...
 LL |     const unsafe fn bar();
-   |     ^^^^^ help: remove this qualifier
+   |     ^^^^^ help: remove the `const` qualifier
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/no-const-fn-in-extern-block.rs:4:5
    |
 LL |     const unsafe fn bar();
    |     ^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++

tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.edition2021.stderr

@@ -1,21 +1,21 @@
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:8:5
    |
 LL |     safe static TEST1: i32;
    |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:10:5
    |
 LL |     safe fn test1(i: i32);
    |     ^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++

tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.edition2024.stderr

@@ -10,24 +10,24 @@ LL | |
 LL | | }
    | |_^
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:8:5
    |
 LL |     safe static TEST1: i32;
    |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++
 
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:10:5
    |
 LL |     safe fn test1(i: i32);
    |     ^^^^^^^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++

tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.rs

@@ -6,9 +6,9 @@
 extern "C" {
     //[edition2024]~^ ERROR extern blocks must be unsafe
     safe static TEST1: i32;
-    //~^ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    //~^ ERROR items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
     safe fn test1(i: i32);
-    //~^ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    //~^ ERROR items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
 }
 
 fn test2() {

tests/ui/rust-2024/unsafe-extern-blocks/unsafe-on-extern-block-issue-126756.fixed

@@ -3,7 +3,7 @@
 #![allow(dead_code)]
 
 unsafe extern "C" {
-    unsafe fn foo(); //~ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    unsafe fn foo(); //~ ERROR items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
 }
 
 fn main() {}

tests/ui/rust-2024/unsafe-extern-blocks/unsafe-on-extern-block-issue-126756.rs

@@ -3,7 +3,7 @@
 #![allow(dead_code)]
 
 extern "C" {
-    unsafe fn foo(); //~ ERROR items in unadorned `extern` blocks cannot have safety qualifiers
+    unsafe fn foo(); //~ ERROR items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
 }
 
 fn main() {}

tests/ui/rust-2024/unsafe-extern-blocks/unsafe-on-extern-block-issue-126756.stderr

@@ -1,10 +1,10 @@
-error: items in unadorned `extern` blocks cannot have safety qualifiers
+error: items in `extern` blocks without an `unsafe` qualifier cannot have safety qualifiers
   --> $DIR/unsafe-on-extern-block-issue-126756.rs:6:5
    |
 LL |     unsafe fn foo();
    |     ^^^^^^^^^^^^^^^^
    |
-help: add unsafe to this `extern` block
+help: add `unsafe` to this `extern` block
    |
 LL | unsafe extern "C" {
    | ++++++