Hide all ICU public C++ Symbols #34
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
jmschonfeld
reviewed
Jul 24, 2024
I didn't bother because we are gonna upgrade ICU very soon anyways. We just won't apply that diff anymore |
iCharlesHu
force-pushed
the
charles/hide-cxx-apis
branch
from
528ad42 to
85d92d8
Compare
|
Added comments. |
jmschonfeld
approved these changes
Jul 24, 2024
There was a problem hiding this comment.
Left two small nits on the wording in the comment that I think might help clarify what we found in our investigation, but otherwise this looks good to me thanks!
Should we run a full toolchain build before merging to ensure we don't break the toolchain with this change just in case something goes wrong?
**Rationale:** When FoundationInternationalization tests are executed, we effectively load two ICU instances into memory: 1) The system ICU loaded by XCTest via system Foundation; 2) The package ICU SwiftFoundation utilizes. These two ICUs cause symbol collisions for dyld due to the fact that all public C++ symbols share a global namespace and coalesce across all loaded dylibs. Consequently, we encounter sporadic test failures in SwiftFoundation as dyld arbitrarily selects ICU symbols and occasionally chooses the system one. To address this issue, we resolved to hide all C++ APIs, ensuring they are not weakly referenced and potentially bound to the system ICU implementation. This solution proves effective for SwiftFoundation, as it does not actually utilize the C++ APIs.
iCharlesHu
force-pushed
the
charles/hide-cxx-apis
branch
from
85d92d8 to
ff7d419
Compare
|
Toolchain build test: swiftlang/swift#75452 |
|
Looks like this caused toolchain build failures that we'll need to resolve: |
|
Building new toolchain now... |
Merged
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.
Rationale: When FoundationInternationalization tests are executed, we effectively load two ICU instances into memory: 1) The system ICU loaded by XCTest via system Foundation; 2) The package ICU SwiftFoundation utilizes.
These two ICUs cause symbol collisions for dyld due to the fact that all public C++ symbols have their own namespaces and coalesce across all loaded dylibs. Consequently, we encounter sporadic test failures in SwiftFoundation as dyld arbitrarily selects ICU symbols and occasionally chooses the system one.
To address this issue, we resolved to hide all C++ APIs, ensuring they are not in the same namespace as the system ICU. This solution proves effective for SwiftFoundation, as it does not actually utilize the C++ APIs.