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Make #[target_feature] Fn trait error message less confusing

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This commit is contained in:
Caleb Zulawski 2020-06-30 18:42:55 -04:00
parent 8e899b1cbe
commit 51858dae1e
2 changed files with 21 additions and 22 deletions
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31
src/librustc_trait_selection/traits/error_reporting/mod.rs
View file

@ -286,18 +286,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
.starts_with("std::convert::From<");
let is_unsize =
{ Some(trait_ref.def_id()) == self.tcx.lang_items().unsize_trait() };
let is_fn_trait = [
self.tcx.lang_items().fn_trait(),
self.tcx.lang_items().fn_mut_trait(),
self.tcx.lang_items().fn_once_trait(),
]
.contains(&Some(trait_ref.def_id()));
let is_target_feature_fn =
if let ty::FnDef(def_id, _) = trait_ref.skip_binder().self_ty().kind {
!self.tcx.codegen_fn_attrs(def_id).target_features.is_empty()
} else {
false
};
let (message, note) = if is_try && is_from {
(
Some(format!(
@ -439,11 +427,22 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
);
}
let is_fn_trait = [
self.tcx.lang_items().fn_trait(),
self.tcx.lang_items().fn_mut_trait(),
self.tcx.lang_items().fn_once_trait(),
]
.contains(&Some(trait_ref.def_id()));
let is_target_feature_fn =
if let ty::FnDef(def_id, _) = trait_ref.skip_binder().self_ty().kind {
!self.tcx.codegen_fn_attrs(def_id).target_features.is_empty()
} else {
false
};
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(),
));
err.note(
"`#[target_feature]` functions do not implement the `Fn` traits",
);
}
// Try to report a help message

12
src/test/ui/rfcs/rfc-2396-target_feature-11/fn-traits.stderr
View file

@ -9,7 +9,7 @@ LL | call(foo);
|
= help: the trait `std::ops::Fn<()>` is not implemented for `fn() {foo}`
= note: wrap the `fn() {foo}` in a closure with no arguments: `|| { /* code */ }
= note: `fn() {foo}` has `#[target_feature]` and is unsafe to call
= note: `#[target_feature]` functions do not implement the `Fn` traits
error[E0277]: expected a `std::ops::FnMut<()>` closure, found `fn() {foo}`
--> $DIR/fn-traits.rs:25:14
@ -22,7 +22,7 @@ LL | call_mut(foo);
|
= help: the trait `std::ops::FnMut<()>` is not implemented for `fn() {foo}`
= note: wrap the `fn() {foo}` in a closure with no arguments: `|| { /* code */ }
= note: `fn() {foo}` has `#[target_feature]` and is unsafe to call
= note: `#[target_feature]` functions do not implement the `Fn` traits
error[E0277]: expected a `std::ops::FnOnce<()>` closure, found `fn() {foo}`
--> $DIR/fn-traits.rs:26:15
@ -35,7 +35,7 @@ LL | call_once(foo);
|
= help: the trait `std::ops::FnOnce<()>` is not implemented for `fn() {foo}`
= note: wrap the `fn() {foo}` in a closure with no arguments: `|| { /* code */ }
= note: `fn() {foo}` has `#[target_feature]` and is unsafe to call
= note: `#[target_feature]` functions do not implement the `Fn` traits
error[E0277]: expected a `std::ops::Fn<()>` closure, found `unsafe fn() {foo_unsafe}`
--> $DIR/fn-traits.rs:28:10
@ -48,7 +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
= note: `#[target_feature]` functions do not implement the `Fn` traits
error[E0277]: expected a `std::ops::FnMut<()>` closure, found `unsafe fn() {foo_unsafe}`
--> $DIR/fn-traits.rs:30:14
@ -61,7 +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
= note: `#[target_feature]` functions do not implement the `Fn` traits
error[E0277]: expected a `std::ops::FnOnce<()>` closure, found `unsafe fn() {foo_unsafe}`
--> $DIR/fn-traits.rs:32:15
@ -74,7 +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
= note: `#[target_feature]` functions do not implement the `Fn` traits
error: aborting due to 6 previous errors