Bitstream reader: Fix undefined behavior seen after rL364464
After rL364464 the following tests started to fail when
running the clang-doc tests with an ubsan instrumented
build of clang-doc:
Clang Tools :: clang-doc/single-file-public.cpp Extra Tools Unit Tests :: clang-doc/./ClangDocTests/BitcodeTest.emitEnumInfoBitcode Extra Tools Unit Tests :: clang-doc/./ClangDocTests/BitcodeTest.emitMethodInfoBitcode Extra Tools Unit Tests :: clang-doc/./ClangDocTests/BitcodeTest.emitRecordInfoBitcode Extra Tools Unit Tests :: clang-doc/./ClangDocTests/SerializeTest.emitInfoWithCommentBitcode
We need to check that the read value is in range for being
casted to the llvm::bitc::FixedAbbrevIDs enum, before the
cast in ClangDocBitcodeReader::skipUntilRecordOrBlock.
SerializedDiagnosticReader::skipUntilRecordOrBlock was updated
in the same way.
Reviewed By: jfb
Subscribers: Bigcheese, vsapsai, bruno, ilya-biryukov, dexonsmith, kadircet, cfe-commits
Differential Revision: https://reviews.llvm.org/D64262