Merge upstream stable #4798
Merged
Merge upstream stable #4798
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
Commit c1ace63 fixes some cases of lambdas having unstable symbol names between compilation units by using `generateIdWithLoc` to generate stable lambda names, however since LOC doesn't uniquely identify a lambda instance (because templates, mixins, static foreach and foreach unrolling), `generateIdWithLoc` adds a counter, so there is still some instability going on. `generateIdWithLoc` makes the name uniq per file+loc, by adding adding a numeric suffix. But the order of instantiations might be different across compilation units, so with this counting scheme we are back to unstable names, so one module might have `t!0.__lambda_LOC` and `t!1.__lambda_LOC_1` while another one has `t!1.__lambda_LOC` This is not a critical problem, but at very least the code gets duplicated for no reason. I also have an example where it leads to linking error, but since it's not a small one and fails to minimize further, I suspect it's a result of interaction with some other bug. The thing is we don't even need uniqueness for those lambdas inside templates/mixins: their final names will have the instantiation prefix anyway. But we can't also just disable this uniqueness check completely: `static foreach` as well as unrollings of the normal `foreach` with lambdas in the loop body will have several copies of a single lambda with the same file+loc. So here we do want to keep making them unique. Fortunately, I don't think a `foreach` could be iterated in different order in different compilation units, so hopefully if we limit the counting to this case only, it won't make symbols unstable. To implement this idea, I've added an extra `parent` argument to `generateIdWithLoc`: it works like using `parent ~ prefix` prefix, but without adding `parent` to the final output. Fixes since last review: 1. Changed `fromStringz` to `toDString` 2. Added a test to showcase the problem
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
2 participants
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.
No description provided.