Improve the diagnostics for a bad exit test capture. #1146
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This PR improves the diagnostics presented at compile time when an exit test captures an unsupported value. For example, given the following (bad) exit test:
```swift
struct NonCodableValue {}
let x = NonCodableValue()
await #expect(processExitsWith: .success) { [x = x as NonCodableValue] in
_ = x
}
```
We currently get diagnostics of the form:
> 🛑 Global function '__checkClosureCall(identifiedBy:encodingCapturedValues:processExitsWith:observing:performing:expression:comments:isRequired:isolation:sourceLocation:)' requires that 'ExitTestTests.NonCodableValue' conform to 'Decodable'
> 🛑 Global function '__checkClosureCall(identifiedBy:encodingCapturedValues:processExitsWith:observing:performing:expression:comments:isRequired:isolation:sourceLocation:)' requires that 'ExitTestTests.NonCodableValue' conform to 'Encodable'
> ⚠️ No 'async' operations occur within 'await' expression
None of which actually tell the developer (clearly) what's wrong. With this PR, we instead get:
> 🛑 Type of captured value 'x' must conform to 'Sendable' and 'Codable' (from macro '__capturedValue')
Much better! The diagnostic is attributed to the temporary file containing the expansion of `#expect()` rather than to the original source file, but I've opened [an issue](swiftlang/swift-syntax#3085) against swift-syntax with a fix in mind. Even with the misattribution, this diagnostic is still an improvement, yeah?
> [!NOTE]
> Exit test value capture remains an experimental feature.
grynspan
requested review from
stmontgomery,
briancroom and
suzannaratcliff
as code owners
grynspan
added
enhancement
|
@swift-ci test |
|
@swift-ci test |
|
@swift-ci test |
briancroom
reviewed
Jun 12, 2025
briancroom
approved these changes
Jun 12, 2025
2 tasks
grynspan
added a commit
that referenced
this pull request
Jun 13, 2025
…t test. (#1130) This PR adds the ability to infer the type of a parameter of a function or closure that encloses an exit test. For example, `x` here: ```swift func f(x: Int) async { await #expect(processExitsWith: .failure) { [x] in ... } } ``` This inference still fails if a parameter is shadowed by a variable with an incompatible type; we still need something like `decltype()` to solve for such cases. We emit a custom diagnostic of the form "🛑 Type of captured value 'x' is ambiguous" if the inferred type of the captured value doesn't match what the compiler thinks it is (see #1146). Still, being able to capture `@Test` function arguments with minimal ceremony is helpful: ```swift @test(arguments: 0 ..< 100) func f(i: Int) async { await #expect(exitsWith: .failure) { [i] in ... } } ``` Also type inference for literals because "why not?" > [!NOTE] > Exit test value capture remains an experimental feature. ### Checklist: - [x] Code and documentation should follow the style of the [Style Guide](https://github.com/apple/swift-testing/blob/main/Documentation/StyleGuide.md). - [x] If public symbols are renamed or modified, DocC references should be updated.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This PR improves the diagnostics presented at compile time when an exit test captures an unsupported value. For example, given the following (bad) exit test:
We currently get diagnostics of the form:
None of which actually tell the developer (clearly) what's wrong. With this PR, we instead get:
Much better! The diagnostic is attributed to the temporary file containing the expansion of
#expect()rather than to the original source file, but I've opened an issue against swift-syntax with a fix in mind. Even with the misattribution, this diagnostic is still an improvement, yeah?Note
Exit test value capture remains an experimental feature.
Checklist: