diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index 48694bac3bc..c1a5c63c6e2 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -1361,57 +1361,117 @@ fn suggest_remove_reference( err: &mut Diagnostic, trait_pred: ty::PolyTraitPredicate<'tcx>, ) -> bool { - let span = obligation.cause.span; + let mut span = obligation.cause.span; + let mut trait_pred = trait_pred; + let mut code = obligation.cause.code(); + while let Some((c, Some(parent_trait_pred))) = code.parent() { + // We want the root obligation, in order to detect properly handle + // `for _ in &mut &mut vec![] {}`. + code = c; + trait_pred = parent_trait_pred; + } + while span.desugaring_kind().is_some() { + // Remove all the hir desugaring contexts while maintaining the macro contexts. + span.remove_mark(); + } + let mut expr_finder = super::FindExprBySpan::new(span); + let Some(hir::Node::Expr(body)) = self.tcx.hir().find(obligation.cause.body_id) else { + return false; + }; + expr_finder.visit_expr(&body); + let mut maybe_suggest = |suggested_ty, count, suggestions| { + // Remapping bound vars here + let trait_pred_and_suggested_ty = + trait_pred.map_bound(|trait_pred| (trait_pred, suggested_ty)); - let mut suggested = false; - if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) { - let refs_number = - snippet.chars().filter(|c| !c.is_whitespace()).take_while(|c| *c == '&').count(); - if let Some('\'') = snippet.chars().filter(|c| !c.is_whitespace()).nth(refs_number) { - // Do not suggest removal of borrow from type arguments. - return false; + let new_obligation = self.mk_trait_obligation_with_new_self_ty( + obligation.param_env, + trait_pred_and_suggested_ty, + ); + + if self.predicate_may_hold(&new_obligation) { + let msg = if count == 1 { + "consider removing the leading `&`-reference".to_string() + } else { + format!("consider removing {count} leading `&`-references") + }; + + err.multipart_suggestion_verbose( + &msg, + suggestions, + Applicability::MachineApplicable, + ); + true + } else { + false } + }; - // Skipping binder here, remapping below - let mut suggested_ty = trait_pred.self_ty().skip_binder(); + // Maybe suggest removal of borrows from types in type parameters, like in + // `src/test/ui/not-panic/not-panic-safe.rs`. + let mut count = 0; + let mut suggestions = vec![]; + // Skipping binder here, remapping below + let mut suggested_ty = trait_pred.self_ty().skip_binder(); + if let Some(mut hir_ty) = expr_finder.ty_result { + while let hir::TyKind::Ref(_, mut_ty) = &hir_ty.kind { + count += 1; + let span = hir_ty.span.until(mut_ty.ty.span); + suggestions.push((span, String::new())); - for refs_remaining in 0..refs_number { let ty::Ref(_, inner_ty, _) = suggested_ty.kind() else { break; }; suggested_ty = *inner_ty; - // Remapping bound vars here - let trait_pred_and_suggested_ty = - trait_pred.map_bound(|trait_pred| (trait_pred, suggested_ty)); + hir_ty = mut_ty.ty; - let new_obligation = self.mk_trait_obligation_with_new_self_ty( - obligation.param_env, - trait_pred_and_suggested_ty, - ); - - if self.predicate_may_hold(&new_obligation) { - let sp = self - .tcx - .sess - .source_map() - .span_take_while(span, |c| c.is_whitespace() || *c == '&'); - - let remove_refs = refs_remaining + 1; - - let msg = if remove_refs == 1 { - "consider removing the leading `&`-reference".to_string() - } else { - format!("consider removing {} leading `&`-references", remove_refs) - }; - - err.span_suggestion_short(sp, &msg, "", Applicability::MachineApplicable); - suggested = true; - break; + if maybe_suggest(suggested_ty, count, suggestions.clone()) { + return true; } } } - suggested + + // Maybe suggest removal of borrows from expressions, like in `for i in &&&foo {}`. + let Some(mut expr) = expr_finder.result else { return false; }; + let mut count = 0; + let mut suggestions = vec![]; + // Skipping binder here, remapping below + let mut suggested_ty = trait_pred.self_ty().skip_binder(); + 'outer: loop { + while let hir::ExprKind::AddrOf(_, _, borrowed) = expr.kind { + count += 1; + let span = if expr.span.eq_ctxt(borrowed.span) { + expr.span.until(borrowed.span) + } else { + expr.span.with_hi(expr.span.lo() + BytePos(1)) + }; + suggestions.push((span, String::new())); + + let ty::Ref(_, inner_ty, _) = suggested_ty.kind() else { + break 'outer; + }; + suggested_ty = *inner_ty; + + expr = borrowed; + + if maybe_suggest(suggested_ty, count, suggestions.clone()) { + return true; + } + } + if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind + && let hir::def::Res::Local(hir_id) = path.res + && let Some(hir::Node::Pat(binding)) = self.tcx.hir().find(hir_id) + && let Some(hir::Node::Local(local)) = self.tcx.hir().find_parent(binding.hir_id) + && let None = local.ty + && let Some(binding_expr) = local.init + { + expr = binding_expr; + } else { + break 'outer; + } + } + false } fn suggest_remove_await(&self, obligation: &PredicateObligation<'tcx>, err: &mut Diagnostic) { diff --git a/tests/ui/auto-traits/typeck-default-trait-impl-precedence.stderr b/tests/ui/auto-traits/typeck-default-trait-impl-precedence.stderr index 9aae9013d1b..bd7aaf6fb6d 100644 --- a/tests/ui/auto-traits/typeck-default-trait-impl-precedence.stderr +++ b/tests/ui/auto-traits/typeck-default-trait-impl-precedence.stderr @@ -4,7 +4,6 @@ error[E0277]: the trait bound `u32: Signed` is not satisfied LL | is_defaulted::<&'static u32>(); | ^^^^^^^^^^^^ the trait `Signed` is not implemented for `u32` | - = help: the trait `Signed` is implemented for `i32` note: required for `&'static u32` to implement `Defaulted` --> $DIR/typeck-default-trait-impl-precedence.rs:10:19 | @@ -17,6 +16,11 @@ note: required by a bound in `is_defaulted` | LL | fn is_defaulted() { } | ^^^^^^^^^ required by this bound in `is_defaulted` +help: consider removing the leading `&`-reference + | +LL - is_defaulted::<&'static u32>(); +LL + is_defaulted::(); + | error: aborting due to previous error diff --git a/tests/ui/impl-trait/in-trait/issue-102140.stderr b/tests/ui/impl-trait/in-trait/issue-102140.stderr index 08602185f50..18bb63745d7 100644 --- a/tests/ui/impl-trait/in-trait/issue-102140.stderr +++ b/tests/ui/impl-trait/in-trait/issue-102140.stderr @@ -2,11 +2,15 @@ error[E0277]: the trait bound `&dyn MyTrait: MyTrait` is not satisfied --> $DIR/issue-102140.rs:23:22 | LL | MyTrait::foo(&self) - | ------------ -^^^^ - | | | - | | the trait `MyTrait` is not implemented for `&dyn MyTrait` - | | help: consider removing the leading `&`-reference + | ------------ ^^^^^ the trait `MyTrait` is not implemented for `&dyn MyTrait` + | | | required by a bound introduced by this call + | +help: consider removing the leading `&`-reference + | +LL - MyTrait::foo(&self) +LL + MyTrait::foo(self) + | error[E0277]: the trait bound `&dyn MyTrait: MyTrait` is not satisfied --> $DIR/issue-102140.rs:23:9 diff --git a/tests/ui/kindck/kindck-copy.stderr b/tests/ui/kindck/kindck-copy.stderr index 9af89159a8c..aee2aa98a60 100644 --- a/tests/ui/kindck/kindck-copy.stderr +++ b/tests/ui/kindck/kindck-copy.stderr @@ -4,12 +4,16 @@ error[E0277]: the trait bound `&'static mut isize: Copy` is not satisfied LL | assert_copy::<&'static mut isize>(); | ^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `&'static mut isize` | - = help: the trait `Copy` is implemented for `isize` note: required by a bound in `assert_copy` --> $DIR/kindck-copy.rs:5:18 | LL | fn assert_copy() { } | ^^^^ required by this bound in `assert_copy` +help: consider removing the leading `&`-reference + | +LL - assert_copy::<&'static mut isize>(); +LL + assert_copy::(); + | error[E0277]: the trait bound `&'a mut isize: Copy` is not satisfied --> $DIR/kindck-copy.rs:28:19 @@ -17,12 +21,16 @@ error[E0277]: the trait bound `&'a mut isize: Copy` is not satisfied LL | assert_copy::<&'a mut isize>(); | ^^^^^^^^^^^^^ the trait `Copy` is not implemented for `&'a mut isize` | - = help: the trait `Copy` is implemented for `isize` note: required by a bound in `assert_copy` --> $DIR/kindck-copy.rs:5:18 | LL | fn assert_copy() { } | ^^^^ required by this bound in `assert_copy` +help: consider removing the leading `&`-reference + | +LL - assert_copy::<&'a mut isize>(); +LL + assert_copy::(); + | error[E0277]: the trait bound `Box: Copy` is not satisfied --> $DIR/kindck-copy.rs:31:19 diff --git a/tests/ui/not-panic/not-panic-safe-4.stderr b/tests/ui/not-panic/not-panic-safe-4.stderr index fc1c594d0d4..9428c125651 100644 --- a/tests/ui/not-panic/not-panic-safe-4.stderr +++ b/tests/ui/not-panic/not-panic-safe-4.stderr @@ -12,6 +12,11 @@ note: required by a bound in `assert` | LL | fn assert() {} | ^^^^^^^^^^ required by this bound in `assert` +help: consider removing the leading `&`-reference + | +LL - assert::<&RefCell>(); +LL + assert::>(); + | error[E0277]: the type `UnsafeCell` may contain interior mutability and a reference may not be safely transferrable across a catch_unwind boundary --> $DIR/not-panic-safe-4.rs:9:14 @@ -28,6 +33,11 @@ note: required by a bound in `assert` | LL | fn assert() {} | ^^^^^^^^^^ required by this bound in `assert` +help: consider removing the leading `&`-reference + | +LL - assert::<&RefCell>(); +LL + assert::>(); + | error: aborting due to 2 previous errors diff --git a/tests/ui/not-panic/not-panic-safe.rs b/tests/ui/not-panic/not-panic-safe.rs index 4165c5dc13a..1b3c6482ce9 100644 --- a/tests/ui/not-panic/not-panic-safe.rs +++ b/tests/ui/not-panic/not-panic-safe.rs @@ -5,6 +5,6 @@ fn assert() {} fn main() { - assert::<&mut i32>(); - //~^ ERROR the type `&mut i32` may not be safely transferred across an unwind boundary + assert::<&mut &mut &i32>(); + //~^ ERROR the type `&mut &mut &i32` may not be safely transferred across an unwind boundary } diff --git a/tests/ui/not-panic/not-panic-safe.stderr b/tests/ui/not-panic/not-panic-safe.stderr index 2cd51a43998..37a6aee3906 100644 --- a/tests/ui/not-panic/not-panic-safe.stderr +++ b/tests/ui/not-panic/not-panic-safe.stderr @@ -1,19 +1,21 @@ -error[E0277]: the type `&mut i32` may not be safely transferred across an unwind boundary +error[E0277]: the type `&mut &mut &i32` may not be safely transferred across an unwind boundary --> $DIR/not-panic-safe.rs:8:14 | -LL | assert::<&mut i32>(); - | -^^^^^^^ - | | - | `&mut i32` may not be safely transferred across an unwind boundary - | help: consider removing the leading `&`-reference +LL | assert::<&mut &mut &i32>(); + | ^^^^^^^^^^^^^^ `&mut &mut &i32` may not be safely transferred across an unwind boundary | - = help: the trait `UnwindSafe` is not implemented for `&mut i32` - = note: `UnwindSafe` is implemented for `&i32`, but not for `&mut i32` + = help: the trait `UnwindSafe` is not implemented for `&mut &mut &i32` + = note: `UnwindSafe` is implemented for `&&mut &i32`, but not for `&mut &mut &i32` note: required by a bound in `assert` --> $DIR/not-panic-safe.rs:5:14 | LL | fn assert() {} | ^^^^^^^^^^ required by this bound in `assert` +help: consider removing 2 leading `&`-references + | +LL - assert::<&mut &mut &i32>(); +LL + assert::<&i32>(); + | error: aborting due to previous error diff --git a/tests/ui/suggestions/suggest-remove-refs-1.stderr b/tests/ui/suggestions/suggest-remove-refs-1.stderr index 1a843f3f509..387770535f6 100644 --- a/tests/ui/suggestions/suggest-remove-refs-1.stderr +++ b/tests/ui/suggestions/suggest-remove-refs-1.stderr @@ -2,13 +2,15 @@ error[E0277]: `&Enumerate>` is not an iterator --> $DIR/suggest-remove-refs-1.rs:6:19 | LL | for (i, _) in &v.iter().enumerate() { - | -^^^^^^^^^^^^^^^^^^^^ - | | - | `&Enumerate>` is not an iterator - | help: consider removing the leading `&`-reference + | ^^^^^^^^^^^^^^^^^^^^^ `&Enumerate>` is not an iterator | = help: the trait `Iterator` is not implemented for `&Enumerate>` = note: required for `&Enumerate>` to implement `IntoIterator` +help: consider removing the leading `&`-reference + | +LL - for (i, _) in &v.iter().enumerate() { +LL + for (i, _) in v.iter().enumerate() { + | error: aborting due to previous error diff --git a/tests/ui/suggestions/suggest-remove-refs-2.stderr b/tests/ui/suggestions/suggest-remove-refs-2.stderr index f39361d529f..1632b2abb2f 100644 --- a/tests/ui/suggestions/suggest-remove-refs-2.stderr +++ b/tests/ui/suggestions/suggest-remove-refs-2.stderr @@ -2,13 +2,15 @@ error[E0277]: `&&&&&Enumerate>` is not an iterat --> $DIR/suggest-remove-refs-2.rs:6:19 | LL | for (i, _) in & & & & &v.iter().enumerate() { - | ---------^^^^^^^^^^^^^^^^^^^^ - | | - | `&&&&&Enumerate>` is not an iterator - | help: consider removing 5 leading `&`-references + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `&&&&&Enumerate>` is not an iterator | = help: the trait `Iterator` is not implemented for `&&&&&Enumerate>` = note: required for `&&&&&Enumerate>` to implement `IntoIterator` +help: consider removing 5 leading `&`-references + | +LL - for (i, _) in & & & & &v.iter().enumerate() { +LL + for (i, _) in v.iter().enumerate() { + | error: aborting due to previous error diff --git a/tests/ui/suggestions/suggest-remove-refs-3.stderr b/tests/ui/suggestions/suggest-remove-refs-3.stderr index 31cca323d0e..7bf421a7729 100644 --- a/tests/ui/suggestions/suggest-remove-refs-3.stderr +++ b/tests/ui/suggestions/suggest-remove-refs-3.stderr @@ -1,18 +1,20 @@ error[E0277]: `&&&&&Enumerate>` is not an iterator --> $DIR/suggest-remove-refs-3.rs:6:19 | -LL | for (i, _) in & & & - | ____________________^ - | | ___________________| - | || -LL | || & &v - | ||___________- help: consider removing 5 leading `&`-references -LL | | .iter() -LL | | .enumerate() { - | |_____________________^ `&&&&&Enumerate>` is not an iterator +LL | for (i, _) in & & & + | ___________________^ +LL | | & &v +LL | | .iter() +LL | | .enumerate() { + | |____________________^ `&&&&&Enumerate>` is not an iterator | = help: the trait `Iterator` is not implemented for `&&&&&Enumerate>` = note: required for `&&&&&Enumerate>` to implement `IntoIterator` +help: consider removing 5 leading `&`-references + | +LL - for (i, _) in & & & +LL + for (i, _) in v + | error: aborting due to previous error diff --git a/tests/ui/suggestions/suggest-remove-refs-4.fixed b/tests/ui/suggestions/suggest-remove-refs-4.fixed new file mode 100644 index 00000000000..dd63d215972 --- /dev/null +++ b/tests/ui/suggestions/suggest-remove-refs-4.fixed @@ -0,0 +1,5 @@ +// run-rustfix +fn main() { + let foo = [1,2,3].iter(); + for _i in foo {} //~ ERROR E0277 +} diff --git a/tests/ui/suggestions/suggest-remove-refs-4.rs b/tests/ui/suggestions/suggest-remove-refs-4.rs new file mode 100644 index 00000000000..3c3d9b1b3f9 --- /dev/null +++ b/tests/ui/suggestions/suggest-remove-refs-4.rs @@ -0,0 +1,5 @@ +// run-rustfix +fn main() { + let foo = &[1,2,3].iter(); + for _i in &foo {} //~ ERROR E0277 +} diff --git a/tests/ui/suggestions/suggest-remove-refs-4.stderr b/tests/ui/suggestions/suggest-remove-refs-4.stderr new file mode 100644 index 00000000000..e4ad17e0671 --- /dev/null +++ b/tests/ui/suggestions/suggest-remove-refs-4.stderr @@ -0,0 +1,17 @@ +error[E0277]: `&&std::slice::Iter<'_, {integer}>` is not an iterator + --> $DIR/suggest-remove-refs-4.rs:4:15 + | +LL | for _i in &foo {} + | ^^^^ `&&std::slice::Iter<'_, {integer}>` is not an iterator + | + = help: the trait `Iterator` is not implemented for `&&std::slice::Iter<'_, {integer}>` + = note: required for `&&std::slice::Iter<'_, {integer}>` to implement `IntoIterator` +help: consider removing 2 leading `&`-references + | +LL ~ let foo = [1,2,3].iter(); +LL ~ for _i in foo {} + | + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/suggestions/suggest-remove-refs-5.fixed b/tests/ui/suggestions/suggest-remove-refs-5.fixed new file mode 100644 index 00000000000..9f59f9c199a --- /dev/null +++ b/tests/ui/suggestions/suggest-remove-refs-5.fixed @@ -0,0 +1,8 @@ +// run-rustfix +fn main() { + let v = &mut Vec::::new(); + for _ in v {} //~ ERROR E0277 + + let v = &mut [1u8]; + for _ in v {} //~ ERROR E0277 +} diff --git a/tests/ui/suggestions/suggest-remove-refs-5.rs b/tests/ui/suggestions/suggest-remove-refs-5.rs new file mode 100644 index 00000000000..d56aa0c9ca4 --- /dev/null +++ b/tests/ui/suggestions/suggest-remove-refs-5.rs @@ -0,0 +1,8 @@ +// run-rustfix +fn main() { + let v = &mut &mut Vec::::new(); + for _ in &mut &mut v {} //~ ERROR E0277 + + let v = &mut &mut [1u8]; + for _ in &mut v {} //~ ERROR E0277 +} diff --git a/tests/ui/suggestions/suggest-remove-refs-5.stderr b/tests/ui/suggestions/suggest-remove-refs-5.stderr new file mode 100644 index 00000000000..7de84d6122b --- /dev/null +++ b/tests/ui/suggestions/suggest-remove-refs-5.stderr @@ -0,0 +1,37 @@ +error[E0277]: `Vec` is not an iterator + --> $DIR/suggest-remove-refs-5.rs:4:14 + | +LL | for _ in &mut &mut v {} + | ^^^^^^^^^^^ `Vec` is not an iterator; try calling `.into_iter()` or `.iter()` + | + = help: the trait `Iterator` is not implemented for `Vec` + = note: required for `&mut Vec` to implement `Iterator` + = note: 3 redundant requirements hidden + = note: required for `&mut &mut &mut &mut Vec` to implement `Iterator` + = note: required for `&mut &mut &mut &mut Vec` to implement `IntoIterator` +help: consider removing 3 leading `&`-references + | +LL ~ let v = &mut Vec::::new(); +LL ~ for _ in v {} + | + +error[E0277]: `[u8; 1]` is not an iterator + --> $DIR/suggest-remove-refs-5.rs:7:14 + | +LL | for _ in &mut v {} + | ^^^^^^ `[u8; 1]` is not an iterator; try calling `.into_iter()` or `.iter()` + | + = help: the trait `Iterator` is not implemented for `[u8; 1]` + = note: required for `&mut [u8; 1]` to implement `Iterator` + = note: 2 redundant requirements hidden + = note: required for `&mut &mut &mut [u8; 1]` to implement `Iterator` + = note: required for `&mut &mut &mut [u8; 1]` to implement `IntoIterator` +help: consider removing 2 leading `&`-references + | +LL ~ let v = &mut [1u8]; +LL ~ for _ in v {} + | + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/typeck/issue-57404.stderr b/tests/ui/typeck/issue-57404.stderr index 5065ac32ad2..a631dbb39fb 100644 --- a/tests/ui/typeck/issue-57404.stderr +++ b/tests/ui/typeck/issue-57404.stderr @@ -2,14 +2,17 @@ error[E0277]: `&mut ()` is not a tuple --> $DIR/issue-57404.rs:6:41 | LL | handlers.unwrap().as_mut().call_mut(&mut ()); - | -------- -^^^^^^ - | | | - | | the trait `Tuple` is not implemented for `&mut ()` - | | help: consider removing the leading `&`-reference + | -------- ^^^^^^^ the trait `Tuple` is not implemented for `&mut ()` + | | | required by a bound introduced by this call | note: required by a bound in `call_mut` --> $SRC_DIR/core/src/ops/function.rs:LL:COL +help: consider removing the leading `&`-reference + | +LL - handlers.unwrap().as_mut().call_mut(&mut ()); +LL + handlers.unwrap().as_mut().call_mut(()); + | error: aborting due to previous error