value() has undesired exception checking semantics and calls
__throw_bad_optional_access in libc++. Moreover, the API is unavailable without
_LIBCPP_NO_EXCEPTIONS on older Mach-O platforms (see
_LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS).
This fixes check-llvm.
Now that TableGen no longer relies on global Record state, we can allow
for the client to own the RecordKeeper and SourceMgr. Given that TableGen
internally still relies on the global llvm::SrcMgr, this method unfortunately
still isn't thread-safe.
Differential Revision: https://reviews.llvm.org/D125277
This commit adds a new `TableGenParseFile` entry point for tablegen
that parses an input buffer and invokes a callback function with
a record keeper (notably without an output buffer). This kind of entry
point is very useful for tablegen consuming tools that don't create
output, and want invoke tablegen multiple times. The current way
that we interact with tablegen is via relative includes to
TGParser(not great).
Differential Revision: https://reviews.llvm.org/D119899
