From bec8dbdb602688d6da4f49b7fdd74226f0f9f04c Mon Sep 17 00:00:00 2001 From: Michael Howell Date: Mon, 4 Apr 2022 17:37:59 -0700 Subject: [PATCH] diagnostics: give a special note for unsafe fn / Fn/FnOnce/FnMut Fixes #90073 --- .../src/traits/error_reporting/on_unimplemented.rs | 9 +++++++++ library/core/src/ops/function.rs | 12 ++++++++++++ src/test/ui/closures/coerce-unsafe-to-closure.stderr | 1 + .../unboxed-closures-unsafe-extern-fn.stderr | 3 +++ .../unboxed-closures-wrong-arg-type-extern-fn.stderr | 3 +++ 5 files changed, 28 insertions(+) diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs index d2b1fe2e0df9b..31b92d52bebc8 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs @@ -208,6 +208,15 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { flags.push((sym::_Self, Some("&[]".to_owned()))); } + if self_ty.is_fn() { + let fn_sig = self_ty.fn_sig(self.tcx); + let shortname = match fn_sig.unsafety() { + hir::Unsafety::Normal => "fn", + hir::Unsafety::Unsafe => "unsafe fn", + }; + flags.push((sym::_Self, Some(shortname.to_owned()))); + } + if let ty::Array(aty, len) = self_ty.kind() { flags.push((sym::_Self, Some("[]".to_owned()))); flags.push((sym::_Self, Some(format!("[{}]", aty)))); diff --git a/library/core/src/ops/function.rs b/library/core/src/ops/function.rs index e5c4798afcbff..a7b28471bfe12 100644 --- a/library/core/src/ops/function.rs +++ b/library/core/src/ops/function.rs @@ -59,6 +59,10 @@ Args = "()", note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`" ), + on( + _Self = "unsafe fn", + note = "unsafe functions must be wrapped in closures: `|| unsafe {{ /* code */ }}`" + ), message = "expected a `{Fn}<{Args}>` closure, found `{Self}`", label = "expected an `Fn<{Args}>` closure, found `{Self}`" )] @@ -139,6 +143,10 @@ pub trait Fn: FnMut { Args = "()", note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`" ), + on( + _Self = "unsafe fn", + note = "unsafe functions must be wrapped in closures: `|| unsafe {{ /* code */ }}`" + ), message = "expected a `{FnMut}<{Args}>` closure, found `{Self}`", label = "expected an `FnMut<{Args}>` closure, found `{Self}`" )] @@ -211,6 +219,10 @@ pub trait FnMut: FnOnce { Args = "()", note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`" ), + on( + _Self = "unsafe fn", + note = "unsafe functions must be wrapped in closures: `|| unsafe {{ /* code */ }}`" + ), message = "expected a `{FnOnce}<{Args}>` closure, found `{Self}`", label = "expected an `FnOnce<{Args}>` closure, found `{Self}`" )] diff --git a/src/test/ui/closures/coerce-unsafe-to-closure.stderr b/src/test/ui/closures/coerce-unsafe-to-closure.stderr index 883348eb98c70..57043c335c0dd 100644 --- a/src/test/ui/closures/coerce-unsafe-to-closure.stderr +++ b/src/test/ui/closures/coerce-unsafe-to-closure.stderr @@ -7,6 +7,7 @@ LL | let x: Option<&[u8]> = Some("foo").map(std::mem::transmute); | required by a bound introduced by this call | = help: the trait `FnOnce<(&str,)>` is not implemented for `unsafe extern "rust-intrinsic" fn(_) -> _ {transmute::<_, _>}` + = note: unsafe functions must be wrapped in closures: `|| unsafe { /* code */ }` note: required by a bound in `Option::::map` --> $SRC_DIR/core/src/option.rs:LL:COL | diff --git a/src/test/ui/unboxed-closures/unboxed-closures-unsafe-extern-fn.stderr b/src/test/ui/unboxed-closures/unboxed-closures-unsafe-extern-fn.stderr index c9a20232f3508..fcd668c191fdd 100644 --- a/src/test/ui/unboxed-closures/unboxed-closures-unsafe-extern-fn.stderr +++ b/src/test/ui/unboxed-closures/unboxed-closures-unsafe-extern-fn.stderr @@ -7,6 +7,7 @@ LL | let x = call_it(&square, 22); | required by a bound introduced by this call | = help: the trait `for<'r> Fn<(&'r isize,)>` is not implemented for `for<'r> unsafe fn(&'r isize) -> isize {square}` + = note: unsafe functions must be wrapped in closures: `|| unsafe { /* code */ }` note: required by a bound in `call_it` --> $DIR/unboxed-closures-unsafe-extern-fn.rs:9:15 | @@ -22,6 +23,7 @@ LL | let y = call_it_mut(&mut square, 22); | required by a bound introduced by this call | = help: the trait `for<'r> FnMut<(&'r isize,)>` is not implemented for `for<'r> unsafe fn(&'r isize) -> isize {square}` + = note: unsafe functions must be wrapped in closures: `|| unsafe { /* code */ }` note: required by a bound in `call_it_mut` --> $DIR/unboxed-closures-unsafe-extern-fn.rs:12:19 | @@ -37,6 +39,7 @@ LL | let z = call_it_once(square, 22); | required by a bound introduced by this call | = help: the trait `for<'r> FnOnce<(&'r isize,)>` is not implemented for `for<'r> unsafe fn(&'r isize) -> isize {square}` + = note: unsafe functions must be wrapped in closures: `|| unsafe { /* code */ }` note: required by a bound in `call_it_once` --> $DIR/unboxed-closures-unsafe-extern-fn.rs:15:20 | diff --git a/src/test/ui/unboxed-closures/unboxed-closures-wrong-arg-type-extern-fn.stderr b/src/test/ui/unboxed-closures/unboxed-closures-wrong-arg-type-extern-fn.stderr index 64d57773d7081..576806e3956b0 100644 --- a/src/test/ui/unboxed-closures/unboxed-closures-wrong-arg-type-extern-fn.stderr +++ b/src/test/ui/unboxed-closures/unboxed-closures-wrong-arg-type-extern-fn.stderr @@ -7,6 +7,7 @@ LL | let x = call_it(&square, 22); | required by a bound introduced by this call | = help: the trait `for<'r> Fn<(&'r isize,)>` is not implemented for `unsafe fn(isize) -> isize {square}` + = note: unsafe functions must be wrapped in closures: `|| unsafe { /* code */ }` note: required by a bound in `call_it` --> $DIR/unboxed-closures-wrong-arg-type-extern-fn.rs:10:15 | @@ -22,6 +23,7 @@ LL | let y = call_it_mut(&mut square, 22); | required by a bound introduced by this call | = help: the trait `for<'r> FnMut<(&'r isize,)>` is not implemented for `unsafe fn(isize) -> isize {square}` + = note: unsafe functions must be wrapped in closures: `|| unsafe { /* code */ }` note: required by a bound in `call_it_mut` --> $DIR/unboxed-closures-wrong-arg-type-extern-fn.rs:13:19 | @@ -37,6 +39,7 @@ LL | let z = call_it_once(square, 22); | required by a bound introduced by this call | = help: the trait `for<'r> FnOnce<(&'r isize,)>` is not implemented for `unsafe fn(isize) -> isize {square}` + = note: unsafe functions must be wrapped in closures: `|| unsafe { /* code */ }` note: required by a bound in `call_it_once` --> $DIR/unboxed-closures-wrong-arg-type-extern-fn.rs:16:20 |