Fail when using safe/unsafe items inside unadorned extern blocks

rust-lang · May 3, 2024 · b23643b · b23643b
1 parent 3ca0577
commit b23643b
Show file tree

Hide file tree

Showing 5 changed files with 46 additions and 5 deletions.
diff --git a/compiler/rustc_ast_lowering/messages.ftl b/compiler/rustc_ast_lowering/messages.ftl
@@ -104,6 +104,8 @@ ast_lowering_invalid_register =
 ast_lowering_invalid_register_class =
     invalid register class `{$reg_class}`: {$error}
 
+ast_lowering_invalid_safety_on_extern = safety is not expected in unadorned extern blocks
+
 ast_lowering_match_arm_with_no_body =
     `match` arm with no body
     .suggestion = add a body after the pattern

diff --git a/compiler/rustc_ast_lowering/src/errors.rs b/compiler/rustc_ast_lowering/src/errors.rs
@@ -38,6 +38,13 @@ pub struct InvalidAbi {
     pub suggestion: Option<InvalidAbiSuggestion>,
 }
 
+#[derive(Diagnostic)]
+#[diag(ast_lowering_invalid_safety_on_extern)]
+pub struct InvalidSafetyOnExtern {
+    #[primary_span]
+    pub span: Span,
+}
+
 pub struct InvalidAbiReason(pub &'static str);
 
 impl Subdiagnostic for InvalidAbiReason {

diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
@@ -1,4 +1,7 @@
-use super::errors::{InvalidAbi, InvalidAbiReason, InvalidAbiSuggestion, MisplacedRelaxTraitBound};
+use super::errors::{
+    InvalidAbi, InvalidAbiReason, InvalidAbiSuggestion, InvalidSafetyOnExtern,
+    MisplacedRelaxTraitBound,
+};
 use super::ResolverAstLoweringExt;
 use super::{AstOwner, ImplTraitContext, ImplTraitPosition};
 use super::{FnDeclKind, LoweringContext, ParamMode};
@@ -245,9 +248,30 @@ impl<'hir> LoweringContext<'_, 'hir> {
             },
             ItemKind::ForeignMod(fm) => hir::ItemKind::ForeignMod {
                 abi: fm.abi.map_or(abi::Abi::FALLBACK, |abi| self.lower_abi(abi)),
-                items: self
-                    .arena
-                    .alloc_from_iter(fm.items.iter().map(|x| self.lower_foreign_item_ref(x))),
+                items: self.arena.alloc_from_iter(fm.items.iter().map(|x| {
+                    if !span.edition().at_least_rust_2024() && fm.unsafety == Unsafe::No {
+                        match &x.kind {
+                            ForeignItemKind::Static(static_foreign_item)
+                                if matches!(
+                                    static_foreign_item.safety,
+                                    Safety::Safe(_) | Safety::Unsafe(_)
+                                ) =>
+                            {
+                                self.dcx().emit_err(InvalidSafetyOnExtern { span: x.span });
+                            }
+                            ForeignItemKind::Fn(fn_item)
+                                if matches!(
+                                    fn_item.sig.header.safety,
+                                    Safety::Safe(_) | Safety::Unsafe(_)
+                                ) =>
+                            {
+                                self.dcx().emit_err(InvalidSafetyOnExtern { span: x.span });
+                            }
+                            _ => {}
+                        }
+                    }
+                    self.lower_foreign_item_ref(x)
+                })),
             },
             ItemKind::GlobalAsm(asm) => hir::ItemKind::GlobalAsm(self.lower_inline_asm(span, asm)),
             ItemKind::TyAlias(box TyAlias { generics, where_clauses, ty, .. }) => {

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.rs b/tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.rs
@@ -1,7 +1,7 @@
 #[allow(missing_unsafe_on_extern)]
 extern "C" {
     safe fn test1(i: i32);
-    //~^ ERROR
+    //~^ ERROR: safety is not expected in unadorned extern blocks
 }
 
 fn test2(i: i32) {

diff --git a/tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.stderr b/tests/ui/rust-2024/unsafe-extern-blocks/safe-unsafe-on-unadorned-extern-block.stderr
@@ -0,0 +1,8 @@
+error: safety is not expected in unadorned extern blocks
+  --> $DIR/safe-unsafe-on-unadorned-extern-block.rs:3:5
+   |
+LL |     safe fn test1(i: i32);
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+