On borrow return type, suggest borrowing from arg or owned return type #117914
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☔ The latest upstream changes (presumably #117683) made this pull request unmergeable. Please resolve the merge conflicts. |
When we encounter a function with a return type that has an anonymous
lifetime with no argument to borrow from, besides suggesting the
`'static` lifetime we now also suggest changing the arguments to be
borrows or changing the return type to be an owned type.
```
error[E0106]: missing lifetime specifier
--> $DIR/variadic-ffi-6.rs:7:6
|
LL | ) -> &usize {
| ^ expected named lifetime parameter
|
= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`
|
LL | ) -> &'static usize {
| +++++++
help: instead, you are more likely to want to change one of the arguments to be borrowed...
|
LL | x: &usize,
| +
help: ...or alternatively, to want to return an owned value
|
LL - ) -> &usize {
LL + ) -> usize {
|
```
Fix rust-lang#85843.
When encountering
```rust
fn g(mut x: impl Iterator<Item = &()>) -> Option<&()> { /* */ }
```
Suggest
```rust
fn g<'a>(mut x: impl Iterator<Item = &'a ()>) -> Option<&'a ()> { /* */ }
```
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| ", but this is uncommon unless you're returning a borrowed value from a \ | ||
| `const` or a `static`{owned}", |
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Should we make these messages translatable?
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We should, but I didn't want to make the PR too big to review.
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Dec 12, 2023
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#116740 (dont ICE when ConstKind::Expr for is_const_evaluatable) - rust-lang#117914 (On borrow return type, suggest borrowing from arg or owned return type) - rust-lang#117927 (Clarify how to choose a FutureIncompatibilityReason variant.) - rust-lang#118855 (Improve an error involving attribute values.) - rust-lang#118856 (rustdoc-search: clean up parser) - rust-lang#118865 (rustc_codegen_llvm: Enforce `rustc::potential_query_instability` lint) - rust-lang#118866 (llvm-wrapper: adapt for LLVM API change) - rust-lang#118868 (Correctly gate the parsing of match arms without body) - rust-lang#118877 (tests: CGU tests require build-pass, not check-pass (remove FIXME)) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#117914 - estebank:issue-85843, r=wesleywiser On borrow return type, suggest borrowing from arg or owned return type When we encounter a function with a return type that has an anonymous lifetime with no argument to borrow from, besides suggesting the `'static` lifetime we now also suggest changing the arguments to be borrows or changing the return type to be an owned type. ``` error[E0106]: missing lifetime specifier --> $DIR/variadic-ffi-6.rs:7:6 | LL | ) -> &usize { | ^ expected named lifetime parameter | = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static` | LL | ) -> &'static usize { | +++++++ help: instead, you are more likely to want to change one of the arguments to be borrowed... | LL | x: &usize, | + help: ...or alternatively, to want to return an owned value | LL - ) -> &usize { LL + ) -> usize { | ``` Fix rust-lang#85843.
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When we encounter a function with a return type that has an anonymous lifetime with no argument to borrow from, besides suggesting the
'staticlifetime we now also suggest changing the arguments to be borrows or changing the return type to be an owned type.Fix #85843.