ASTReader: Bypass overridden files when reading PCHs
If contents of a file that is part of a PCM are overridden when reading
it, but weren't overridden when the PCM was being built, the ASTReader
will emit an error. Now it creates a separate FileEntry for recovery,
bypassing the overridden content instead of discarding it. The
pre-existing testcase clang/test/PCH/remap-file-from-pch.cpp confirms
that the new recovery method works correctly.
This resolves a long-standing FIXME to avoid hypothetically invalidating
another precompiled module that's already using the overridden contents.
This also removes ContentCache-related API that would be unsafe to use
across `CompilerInstance`s in an implicit modules build. This helps to
unblock us sinking it from SourceManager into FileManager in the future,
which would allow us to delete `InMemoryModuleCache`.
https://reviews.llvm.org/D66710
llvm-svn: 370546
6 files changed