my rust fork
https://www.rust-lang.org
3f2f8eee02
Provide structured suggestion to use trait objects in some cases of `if` arm type divergence
```
error[E0308]: `if` and `else` have incompatible types
--> $DIR/suggest-box-on-divergent-if-else-arms.rs:15:9
|
LL | let _ = if true {
| _____________-
LL | | Struct
| | ------ expected because of this
LL | | } else {
LL | | foo()
| | ^^^^^ expected `Struct`, found `Box<dyn Trait>`
LL | | };
| |_____- `if` and `else` have incompatible types
|
= note: expected struct `Struct`
found struct `Box<dyn Trait>`
help: `Struct` implements `Trait` so you can box it to coerce to the trait object `Box<dyn Trait>`
|
LL | Box::new(Struct)
| +++++++++ +
error[E0308]: `if` and `else` have incompatible types
--> $DIR/suggest-box-on-divergent-if-else-arms.rs:20:9
|
LL | let _ = if true {
| _____________-
LL | | foo()
| | ----- expected because of this
LL | | } else {
LL | | Struct
| | ^^^^^^ expected `Box<dyn Trait>`, found `Struct`
LL | | };
| |_____- `if` and `else` have incompatible types
|
= note: expected struct `Box<dyn Trait>`
found struct `Struct`
= note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
help: store this in the heap by calling `Box::new`
|
LL | Box::new(Struct)
| +++++++++ +
error[E0308]: `if` and `else` have incompatible types
--> $DIR/suggest-box-on-divergent-if-else-arms.rs:25:9
|
LL | fn bar() -> impl Trait {
| ---------- the found opaque type
...
LL | let _ = if true {
| _____________-
LL | | Struct
| | ------ expected because of this
LL | | } else {
LL | | bar()
| | ^^^^^ expected `Struct`, found opaque type
LL | | };
| |_____- `if` and `else` have incompatible types
|
= note: expected struct `Struct`
found opaque type `impl Trait`
help: `Struct` implements `Trait` so you can box both arms and coerce to the trait object `Box<dyn Trait>`
|
LL ~ Box::new(Struct) as Box<dyn Trait>
LL | } else {
LL ~ Box::new(bar())
|
error[E0308]: `if` and `else` have incompatible types
--> $DIR/suggest-box-on-divergent-if-else-arms.rs:30:9
|
LL | fn bar() -> impl Trait {
| ---------- the expected opaque type
...
LL | let _ = if true {
| _____________-
LL | | bar()
| | ----- expected because of this
LL | | } else {
LL | | Struct
| | ^^^^^^ expected opaque type, found `Struct`
LL | | };
| |_____- `if` and `else` have incompatible types
|
= note: expected opaque type `impl Trait`
found struct `Struct`
help: `Struct` implements `Trait` so you can box both arms and coerce to the trait object `Box<dyn Trait>`
|
LL ~ Box::new(bar()) as Box<dyn Trait>
LL | } else {
LL ~ Box::new(Struct)
|
```
Partially address #102629.
|
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|---|---|---|
| .github | ||
| .reuse | ||
| compiler | ||
| library | ||
| LICENSES | ||
| src | ||
| tests | ||
| .editorconfig | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .mailmap | ||
| Cargo.lock | ||
| Cargo.toml | ||
| CODE_OF_CONDUCT.md | ||
| config.example.toml | ||
| configure | ||
| CONTRIBUTING.md | ||
| COPYRIGHT | ||
| INSTALL.md | ||
| LICENSE-APACHE | ||
| LICENSE-MIT | ||
| README.md | ||
| RELEASES.md | ||
| rust-bors.toml | ||
| rustfmt.toml | ||
| triagebot.toml | ||
| x | ||
| x.ps1 | ||
| x.py | ||
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