Don't implement Fn* for unsafe #[target_feature] functions

Author: calebzulawski

src/librustc_trait_selection/traits/error_reporting/mod.rs

@@ -292,11 +292,9 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                             self.tcx.lang_items().fn_once_trait(),
                         ]
                         .contains(&Some(trait_ref.def_id()));
-                        let is_safe_target_feature_fn =
+                        let is_target_feature_fn =
                             if let ty::FnDef(def_id, _) = trait_ref.skip_binder().self_ty().kind {
-                                trait_ref.skip_binder().self_ty().fn_sig(self.tcx).unsafety()
-                                    == hir::Unsafety::Normal
-                                    && !self.tcx.codegen_fn_attrs(def_id).target_features.is_empty()
+                                !self.tcx.codegen_fn_attrs(def_id).target_features.is_empty()
                             } else {
                                 false
                             };
@@ -441,7 +439,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                             );
                         }
 
-                        if is_fn_trait && is_safe_target_feature_fn {
+                        if is_fn_trait && is_target_feature_fn {
                             err.note(&format!(
                                 "`{}` has `#[target_feature]` and is unsafe to call",
                                 trait_ref.skip_binder().self_ty(),

src/test/ui/rfcs/rfc-2396-target_feature-11/fn-traits.stderr

@@ -48,6 +48,7 @@ LL |     call(foo_unsafe);
    |
    = help: the trait `std::ops::Fn<()>` is not implemented for `unsafe fn() {foo_unsafe}`
    = note: wrap the `unsafe fn() {foo_unsafe}` in a closure with no arguments: `|| { /* code */ }
+   = note: `unsafe fn() {foo_unsafe}` has `#[target_feature]` and is unsafe to call
 
 error[E0277]: expected a `std::ops::FnMut<()>` closure, found `unsafe fn() {foo_unsafe}`
   --> $DIR/fn-traits.rs:30:14
@@ -60,6 +61,7 @@ LL |     call_mut(foo_unsafe);
    |
    = help: the trait `std::ops::FnMut<()>` is not implemented for `unsafe fn() {foo_unsafe}`
    = note: wrap the `unsafe fn() {foo_unsafe}` in a closure with no arguments: `|| { /* code */ }
+   = note: `unsafe fn() {foo_unsafe}` has `#[target_feature]` and is unsafe to call
 
 error[E0277]: expected a `std::ops::FnOnce<()>` closure, found `unsafe fn() {foo_unsafe}`
   --> $DIR/fn-traits.rs:32:15
@@ -72,6 +74,7 @@ LL |     call_once(foo_unsafe);
    |
    = help: the trait `std::ops::FnOnce<()>` is not implemented for `unsafe fn() {foo_unsafe}`
    = note: wrap the `unsafe fn() {foo_unsafe}` in a closure with no arguments: `|| { /* code */ }
+   = note: `unsafe fn() {foo_unsafe}` has `#[target_feature]` and is unsafe to call
 
 error: aborting due to 6 previous errors