Rework mangling of macro expansions in local contexts to not trigger type checking #77999
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
…type checking. The mangling of macro expansions relies on having a type-checked AST for its enclosing context. When that enclosing context is within a local context (say, a local type), mangling would trigger type checking of that local type, which could then involve assigning local discriminators. However, if this happens before type checking of the enclosing function body, we would end up failing to assign closure discriminators to (e.g.) autoclosures within the body. The fundamental problem here is the interaction between discriminator assignment (which can only happen after type checking) and mangling of macro expansion buffers (which can happen during that type checking). Break this cycle by providing a different approach to mangling macro expansions within local contexts as the innermost non-local context + a name-based discriminator within that local context. These manglings are not ABI and are not stable, so we can adjust them later if we come up with a scheme we like better. However, by breaking this cycle, we eliminate assertions and miscompiles that come from missing discriminators in this case. Fixes rdar://139734958.
DougGregor
requested review from
hborla,
slavapestov and
xedin
as code owners
|
@swift-ci please smoke test |
|
@swift-ci please smoke test Windows |
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Outdated suggestions cannot be applied.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.
The mangling of macro expansions relies on having a type-checked AST for its enclosing context. When that enclosing context is within a local context (say, a local type), mangling would trigger type checking of that local type, which could then involve assigning local discriminators. However, if this happens before type checking of the enclosing function body, we would end up failing to assign closure discriminators to (e.g.) autoclosures within the body.
The fundamental problem here is the interaction between discriminator assignment (which can only happen after type checking) and mangling of macro expansion buffers (which can happen during that type checking). Break this cycle by providing a different approach to mangling macro expansions within local contexts as the innermost non-local context + a name-based discriminator within that local context. These manglings are not ABI and are not stable, so we can adjust them later if we come up with a scheme we like better. However, by breaking this cycle, we eliminate assertions and miscompiles that come from missing discriminators in this case.
Fixes rdar://139734958.