Account for type alias projections in E0308 "expected/found" shortening logic#159189
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Account for type alias projections in E0308 "expected/found" shortening logic#159189estebank wants to merge 2 commits into
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…ng logic
When encountering a E0308 error involving `ty::Projection`s, highlight only the sub-parts that are actually relevant:
```
error[E0308]: mismatched types
--> tests/ui/associated-types/long-type-E0308.rs:19:5
|
16 | fn foo<'a, T: FooBar>(value: T) -> <<<T::Wrapper<T> as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<<T::Assoc as FooBar>::Assoc> {
| ----------------------------------------------------------------------------------------------------- expected `<<<... as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<...>` because of return type
...
19 | value.assoc().assoc().assoc().wrap(value.assoc().assoc())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `really_really_really_long_module::FooBar::Wrapper`, found `really_really_really_long_module::FooBar::Assoc`
|
= note: expected associated type `<<<<_ as FooBar>::Wrapper<T> as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<_>`
found associated type `<<<<_ as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<_>`
= note: an associated type was expected, but a different one was found
= note: the full name for the type has been written to 'long-type-E0308.long-type-5396540309891820670.txt'
= note: consider using `--verbose` to print the full type name to the console
```
Deduplicate param highlighting logic.
Account for type param difference in trait in E0308 highlighting.
Collaborator
|
This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
chenyukang
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Jul 18, 2026
chenyukang
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Jul 18, 2026
Member
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No other issues except two trivial one. |
…e highlighted string instead
Introduce a mechanism to textually trim highlighted strings, so that we can print out "expected/found" note with shorter output while still keeping the highlighted inner parts.
```
error[E0308]: mismatched types
--> $DIR/long-type-E0308.rs:30:5
|
LL | ) -> <
| ______-
LL | | <
LL | | <T::Wrapper<T> as FooBar>::Assoc as FooBar
LL | | >::Assoc as FooBar
LL | | >::Wrapper<<T::Assoc as FooBar>::Assoc>
| |_______________________________________- expected `<_ as FooBar>::Wrapper<_>` because of return type
...
LL | value...oc())
| ^^^^^...^^^^^ expected `really_really_really_long_module::FooBar::Wrapper`, found `really_really_really_long_module::FooBar::Assoc`
|
= note: expected associated type `<<<<_ as FooBar>::Wrapper<_> as...pper<_>`
found associated type `<<<<_ as FooBar>::Assoc as Fo...pper<_>`
= note: an associated type was expected, but a different one was found
= note: the full name for the type has been written to '$TEST_BUILD_DIR/long-type-E0308.long-type-$LONG_TYPE_HASH.txt'
= note: consider using `--verbose` to print the full type name to the console
```
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@bors r=chenyukang |
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Jul 18, 2026
Account for type alias projections in E0308 "expected/found" shortening logic
When encountering a E0308 error involving `ty::Projection`s, highlight only the sub-parts that are actually relevant:
```
error[E0308]: mismatched types
--> tests/ui/associated-types/long-type-E0308.rs:19:5
|
16 | fn foo<'a, T: FooBar>(value: T) -> <<<T::Wrapper<T> as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<<T::Assoc as FooBar>::Assoc> {
| ----------------------------------------------------------------------------------------------------- expected `<<<... as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<...>` because of return type
...
19 | value.assoc().assoc().assoc().wrap(value.assoc().assoc())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `really_really_really_long_module::FooBar::Wrapper`, found `really_really_really_long_module::FooBar::Assoc`
|
= note: expected associated type `<<<<_ as FooBar>::Wrapper<T> as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<_>`
found associated type `<<<<_ as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<_>`
= note: an associated type was expected, but a different one was found
= note: the full name for the type has been written to 'long-type-E0308.long-type-5396540309891820670.txt'
= note: consider using `--verbose` to print the full type name to the console
```
Fix rust-lang#159043, by including a textual type shortening logic that operates on the highlighted text on really narrow terminals:
```
error[E0308]: mismatched types
--> $DIR/long-type-E0308.rs:30:5
|
LL | ) -> <
| ______-
LL | | <
LL | | <T::Wrapper<T> as FooBar>::Assoc as FooBar
LL | | >::Assoc as FooBar
LL | | >::Wrapper<<T::Assoc as FooBar>::Assoc>
| |_______________________________________- expected `<_ as FooBar>::Wrapper<_>` because of return type
...
LL | value...oc())
| ^^^^^...^^^^^ expected `really_really_really_long_module::FooBar::Wrapper`, found `really_really_really_long_module::FooBar::Assoc`
|
= note: expected associated type `<<<<_ as FooBar>::Wrapper<_> as...pper<_>`
found associated type `<<<<_ as FooBar>::Assoc as Fo...pper<_>`
= note: an associated type was expected, but a different one was found
= note: the full name for the type has been written to '$TEST_BUILD_DIR/long-type-E0308.long-type-$LONG_TYPE_HASH.txt'
= note: consider using `--verbose` to print the full type name to the console
```
r? @chenyukang
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…uwer Rollup of 5 pull requests Successful merges: - #159189 (Account for type alias projections in E0308 "expected/found" shortening logic) - #158545 (Move `std::io::read_to_string` to `alloc::io`) - #159328 (tests/assembly-llvm: pin frame pointer in issue-141649 aarch64 test) - #159470 (Fix string indexing in diagnostic format strings) - #159500 (Move compiletest CLI parsing to `cli.rs`)
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Jul 18, 2026
Account for type alias projections in E0308 "expected/found" shortening logic
When encountering a E0308 error involving `ty::Projection`s, highlight only the sub-parts that are actually relevant:
```
error[E0308]: mismatched types
--> tests/ui/associated-types/long-type-E0308.rs:19:5
|
16 | fn foo<'a, T: FooBar>(value: T) -> <<<T::Wrapper<T> as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<<T::Assoc as FooBar>::Assoc> {
| ----------------------------------------------------------------------------------------------------- expected `<<<... as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<...>` because of return type
...
19 | value.assoc().assoc().assoc().wrap(value.assoc().assoc())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `really_really_really_long_module::FooBar::Wrapper`, found `really_really_really_long_module::FooBar::Assoc`
|
= note: expected associated type `<<<<_ as FooBar>::Wrapper<T> as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<_>`
found associated type `<<<<_ as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Assoc as FooBar>::Wrapper<_>`
= note: an associated type was expected, but a different one was found
= note: the full name for the type has been written to 'long-type-E0308.long-type-5396540309891820670.txt'
= note: consider using `--verbose` to print the full type name to the console
```
Fix #159043, by including a textual type shortening logic that operates on the highlighted text on really narrow terminals:
```
error[E0308]: mismatched types
--> $DIR/long-type-E0308.rs:30:5
|
LL | ) -> <
| ______-
LL | | <
LL | | <T::Wrapper<T> as FooBar>::Assoc as FooBar
LL | | >::Assoc as FooBar
LL | | >::Wrapper<<T::Assoc as FooBar>::Assoc>
| |_______________________________________- expected `<_ as FooBar>::Wrapper<_>` because of return type
...
LL | value...oc())
| ^^^^^...^^^^^ expected `really_really_really_long_module::FooBar::Wrapper`, found `really_really_really_long_module::FooBar::Assoc`
|
= note: expected associated type `<<<<_ as FooBar>::Wrapper<_> as...pper<_>`
found associated type `<<<<_ as FooBar>::Assoc as Fo...pper<_>`
= note: an associated type was expected, but a different one was found
= note: the full name for the type has been written to '$TEST_BUILD_DIR/long-type-E0308.long-type-$LONG_TYPE_HASH.txt'
= note: consider using `--verbose` to print the full type name to the console
```
r? @chenyukang
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|
The job Click to see the possible cause of the failure (guessed by this bot) |
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💔 Test for b356d7c failed: CI. Failed job:
|
Contributor
|
💔 I suspect this PR failed tests as part of a rollup After fixing the problem, consider running a try job for the failed job before re-approving. Link to failure: #159501 (comment) |
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Contributor
|
This PR was contained in a rollup (#159501), which was unapproved. |
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When encountering a E0308 error involving
ty::Projections, highlight only the sub-parts that are actually relevant:Fix #159043, by including a textual type shortening logic that operates on the highlighted text on really narrow terminals:
r? @chenyukang