Add merge symbol logic for MachO symbols

[a-maurice]

Description

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Check for more special symbols when merging dependency symbols into desktop libraries. Some symbols are prefixed with lowercase l, and should be ignored during this logic.

#1920

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Testing

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Type of Change

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• Bug fix. Add the issue # below if applicable.
• New feature. A non-breaking change which adds functionality.
• Other, such as a build process or documentation change.

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Notes

• Bug fixes and feature changes require an update to the Release Notes section of release_build_files/readme.md.
• Read the contribution guidelines CONTRIBUTING.md.
• Changes to the public API require an internal API review. If you'd like to help us make Firebase APIs better, please propose your change in a feature request so that we can discuss it together.

[gemini-code-assist]

Code Review

This pull request addresses a linker issue on macOS (XCode 27) by ignoring Mach-O assembler temporary labels, compiler metadata labels, and Objective-C runtime metadata during library merging. It introduces an is_ignored_symbol helper in merge_libraries.py to filter out these symbols, updates demangling logic to handle linker-private C++ symbols (l__Z), and adds comprehensive unit tests to verify the new behavior. Additionally, it updates the test shell script to conditionally include demumble if it is executable. The review feedback suggests optimizing the condition check in is_ignored_symbol by swapping the order of checks to evaluate not symbol.startswith("_") first, which allows short-circuiting and avoids unnecessary calls to is_cpp_symbol for the majority of symbols.

[github-actions]

✅  Integration test succeeded!

Requested by @a-maurice on commit 25bdab4
Last updated: Wed Oct 7 12:19 PDT 2026
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