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Rollup merge of #103283 - nbarrios1337:unsafe-impl-suggestions, r=cjgillot

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Add suggestions for unsafe impl error codes

Adds suggestions for users to add `unsafe` to trait impls that should be `unsafe`, and remove `unsafe` from trait impls that do not require `unsafe`

With the folllowing code:

```rust
struct Foo {}

struct Bar {}

trait Safe {}

unsafe trait Unsafe {}

impl Safe for Foo {} // ok

impl Unsafe for Foo {} // E0200

unsafe impl Safe for Bar {} // E0199

unsafe impl Unsafe for Bar {} // ok

// omitted empty main fn
```

The current rustc output is:
```
error[E0199]: implementing the trait `Safe` is not unsafe
  --> e0200.rs:13:1
   |
13 | unsafe impl Safe for Bar {} // E0199
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0200]: the trait `Unsafe` requires an `unsafe impl` declaration
  --> e0200.rs:11:1
   |
11 | impl Unsafe for Foo {} // E0200
   | ^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0199, E0200.
For more information about an error, try `rustc --explain E0199`.
```

With this PR, the future rustc output would be:
```
error[E0199]: implementing the trait `Safe` is not unsafe
  --> ../../temp/e0200.rs:13:1
   |
13 | unsafe impl Safe for Bar {} // E0199
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
help: remove `unsafe` from this trait implementation
   |
13 - unsafe impl Safe for Bar {} // E0199
13 + impl Safe for Bar {} // E0199
   |

error[E0200]: the trait `Unsafe` requires an `unsafe impl` declaration
  --> ../../temp/e0200.rs:11:1
   |
11 | impl Unsafe for Foo {} // E0200
   | ^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: the trait `Unsafe` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword
help: add `unsafe` to this trait implementation
   |
11 | unsafe impl Unsafe for Foo {} // E0200
   | ++++++

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0199, E0200.
For more information about an error, try `rustc --explain E0199`.
```

``@rustbot`` label +T-compiler +A-diagnostics +A-suggestion-diagnostics
This commit is contained in:
Matthias Krüger 2022-10-28 07:06:42 +02:00 • committed by GitHub
commit 270e0c5357
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7 changed files with 84 additions and 0 deletions
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30
compiler/rustc_hir_analysis/src/coherence/unsafety.rs
View file

@ -26,6 +26,12 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
"implementing the trait `{}` is not unsafe",
trait_ref.print_only_trait_path()
)
.span_suggestion_verbose(
item.span.with_hi(item.span.lo() + rustc_span::BytePos(7)),
"remove `unsafe` from this trait implementation",
"",
rustc_errors::Applicability::MachineApplicable,
)
.emit();
}
@ -37,6 +43,18 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
"the trait `{}` requires an `unsafe impl` declaration",
trait_ref.print_only_trait_path()
)
.note(format!(
"the trait `{}` enforces invariants that the compiler can't check. \
Review the trait documentation and make sure this implementation \
upholds those invariants before adding the `unsafe` keyword",
trait_ref.print_only_trait_path()
))
.span_suggestion_verbose(
item.span.shrink_to_lo(),
"add `unsafe` to this trait implementation",
"unsafe ",
rustc_errors::Applicability::MaybeIncorrect,
)
.emit();
}
@ -48,6 +66,18 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
"requires an `unsafe impl` declaration due to `#[{}]` attribute",
attr_name
)
.note(format!(
"the trait `{}` enforces invariants that the compiler can't check. \
Review the trait documentation and make sure this implementation \
upholds those invariants before adding the `unsafe` keyword",
trait_ref.print_only_trait_path()
))
.span_suggestion_verbose(
item.span.shrink_to_lo(),
"add `unsafe` to this trait implementation",
"unsafe ",
rustc_errors::Applicability::MaybeIncorrect,
)
.emit();
}

12
src/test/ui/coherence/coherence-default-trait-impl.stderr
View file

@ -3,12 +3,24 @@ error[E0199]: implementing the trait `MySafeTrait` is not unsafe
|
LL | unsafe impl MySafeTrait for Foo {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: remove `unsafe` from this trait implementation
|
LL - unsafe impl MySafeTrait for Foo {}
LL + impl MySafeTrait for Foo {}
|
error[E0200]: the trait `MyUnsafeTrait` requires an `unsafe impl` declaration
--> $DIR/coherence-default-trait-impl.rs:13:1
|
LL | impl MyUnsafeTrait for Foo {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: the trait `MyUnsafeTrait` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword
help: add `unsafe` to this trait implementation
|
LL | unsafe impl MyUnsafeTrait for Foo {}
| ++++++
error: aborting due to 2 previous errors

12
src/test/ui/dropck/dropck-eyepatch-implies-unsafe-impl.stderr
View file

@ -8,6 +8,12 @@ LL | | // (unsafe to access self.1 due to #[may_dangle] on A)
LL | | fn drop(&mut self) { println!("drop {} {:?}", self.0, self.2); }
LL | | }
| |_^
|
= note: the trait `Drop` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword
help: add `unsafe` to this trait implementation
|
LL | unsafe impl<#[may_dangle] A, B: fmt::Debug> Drop for Pt<A, B> {
| ++++++
error[E0569]: requires an `unsafe impl` declaration due to `#[may_dangle]` attribute
--> $DIR/dropck-eyepatch-implies-unsafe-impl.rs:27:1
@ -19,6 +25,12 @@ LL | | // (unsafe to access self.1 due to #[may_dangle] on 'a)
LL | | fn drop(&mut self) { println!("drop {} {:?}", self.0, self.2); }
LL | | }
| |_^
|
= note: the trait `Drop` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword
help: add `unsafe` to this trait implementation
|
LL | unsafe impl<#[may_dangle] 'a, 'b, B: fmt::Debug> Drop for Pr<'a, 'b, B> {
| ++++++
error: aborting due to 2 previous errors

6
src/test/ui/error-codes/E0199.stderr
View file

@ -3,6 +3,12 @@ error[E0199]: implementing the trait `Bar` is not unsafe
|
LL | unsafe impl Bar for Foo { }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: remove `unsafe` from this trait implementation
|
LL - unsafe impl Bar for Foo { }
LL + impl Bar for Foo { }
|
error: aborting due to previous error

6
src/test/ui/error-codes/E0200.stderr
View file

@ -3,6 +3,12 @@ error[E0200]: the trait `Bar` requires an `unsafe impl` declaration
|
LL | impl Bar for Foo { }
| ^^^^^^^^^^^^^^^^^^^^
|
= note: the trait `Bar` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword
help: add `unsafe` to this trait implementation
|
LL | unsafe impl Bar for Foo { }
| ++++++
error: aborting due to previous error

6
src/test/ui/traits/safety-trait-impl-cc.stderr
View file

@ -7,6 +7,12 @@ LL | | panic!();
LL | | }
LL | | }
| |_^
|
= note: the trait `Foo` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword
help: add `unsafe` to this trait implementation
|
LL | unsafe impl lib::Foo for Bar {
| ++++++
error: aborting due to previous error

12
src/test/ui/traits/safety-trait-impl.stderr
View file

@ -3,12 +3,24 @@ error[E0200]: the trait `UnsafeTrait` requires an `unsafe impl` declaration
|
LL | impl UnsafeTrait for u16 { }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: the trait `UnsafeTrait` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword
help: add `unsafe` to this trait implementation
|
LL | unsafe impl UnsafeTrait for u16 { }
| ++++++
error[E0199]: implementing the trait `SafeTrait` is not unsafe
--> $DIR/safety-trait-impl.rs:16:1
|
LL | unsafe impl SafeTrait for u32 { }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: remove `unsafe` from this trait implementation
|
LL - unsafe impl SafeTrait for u32 { }
LL + impl SafeTrait for u32 { }
|
error: aborting due to 2 previous errors