macOS + REDUCE_EXPORTS: Cap'n Proto misidentifies kj::Exception as unknown non-KJ exception #34723

macOS builds with REDUCE_EXPORTS currently cause Cap'n Proto RPC to report:

remote exception: unknown non-KJ exception of type: kj::Exception

instead of expected typed exception messages. Tests currently contain a workaround to accept this behavior.

This issue tracks investigating and fixing the underlying exception type visibility/RTTI problem and removing the workaround.

Related: #34422 (review)

I think I found the root cause and opened #35014 with a fix. CI fails the subtree lint since the change is in type-context.h (libmultiprocess subtree). Should this go through bitcoin-core/libmultiprocess first?

I think I found the root cause and opened #35014 with a fix. CI fails the subtree lint since the change is in type-context.h (libmultiprocess subtree). Should this go through bitcoin-core/libmultiprocess first?

Thanks! It's probably good you opened #35014 first since the macos test passing there helps verify the fix works, but yes the next step should be to open a libmultiprocess PR.

I think I found the root cause and opened #35014 with a fix. CI fails the subtree lint since the change is in type-context.h (libmultiprocess subtree). Should this go through bitcoin-core/libmultiprocess first?

Thanks! It's probably good you opened #35014 first since the macos test passing there helps verify the fix works, but yes the next step should be to open a libmultiprocess PR.

Thanks! opened the libmultiprocess PR: bitcoin-core/libmultiprocess#268