protobuf 3.20.1

[owine]

Created by brew bump

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Created with brew bump-formula-pr.

[github-actions]

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[chenrui333]

protobuf changed the version scheme, here is the doc for it

Versioning
We changed our versioning scheme to enable more-nimble updates to language-specific parts of Protocol Buffers. In the new scheme, each language has its own major version that can be incremented independently of other languages, as covered later in this topic with the Python release. The minor and patch versions, however, will remain coupled. This allows us to introduce breaking changes into some languages without requiring a bump of the major version in languages that do not experience a breaking change.

The first instance of this new versioning scheme is the new version of the Python API, 4.21.0, which follows the preceding version, 3.20.1. Other language APIs will be released as 3.21.0.

it might be good shipping this release before bumping to 21.1

[owine]

Sorry, all - I have taken this one as far as I am capable. I would appreciate an assist in keeping this one moving or I can close in favor of another attempt.

[cho-m]

For error:

Undefined symbols for architecture arm64:
    "google::protobuf::internal::InternalMetadata::~InternalMetadata()", referenced from:

The issue is that destructor should be defined in header when using NDEBUG https://github.com/protocolbuffers/protobuf/blob/v3.20.1/src/google/protobuf/metadata_lite.h#L73-L81

#if defined(NDEBUG) || defined(_MSC_VER)
  ~InternalMetadata() {
    if (HasMessageOwnedArenaTag()) {
      delete reinterpret_cast<Arena*>(ptr_ - kMessageOwnedArenaTagMask);
    }
  }
#else
  ~InternalMetadata();
#endif

However, this information isn't propagated to dependent builds, so they end up trying to use #else (assuming they don't set NDEBUG) and this fails since Homebrew's protobuf was compiled with NDEBUG.

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One possibility is to get upstream to add flag as part of pkgconfig file https://github.com/protocolbuffers/protobuf/blob/v3.20.1/protobuf.pc.in when library is built with it.

This would then propagate the -DNDEBUG to all dependents that use pkg-config.

EDIT: though not sure how this may impact projects also uses (N)DEBUG and user wants to compile with DEBUG but gets NDEBUG due to pkg-config flags. In this case, protobuf would need a more specific solution to avoid impact of commonly used build variables.

The workarounds available is to manually append -DNDEBUG to CXXFLAGS for every dependent that is hitting this issue.

[SMillerDev]

Closing in favor of #105712

[carlocab]

@owine, don't delete your branch yet. It seems like we might still want this update, as #105712 is blocked.

[pitrou]

@cho-m For the record, the ABI issue should be fixed in protobuf 21.3: protocolbuffers/protobuf#10273

[carlocab]

Thanks for the fix @pitrou!