Reland #156511 after fixing a build failure not caught by clang. The
default implementation of `parseRecord` is currently unused. Apparently,
clang doesn't type check uninstantiated methods in class templates. To
avoid this footgun, we `= delete` the impl for now.
Original message:
In preparation of larger changes to the bitstream remark format,
refactor the error handling code in the BitstreamRemarkParser.
Main change: move the various static helper methods into the parser
helper classes, so we don't need to pass around as many args. Calling
`error(...)` inside the helper classes now automatically prepends the
current block being parsed to the error message.
NFCI (except for error messages on invalid bitstream files).
Pull Request: https://github.com/llvm/llvm-project/pull/158667
45f1440d9a