In order to drop the final callers to `SourceManager::getBuffer`, change
`FrontendInputFile` to use `Optional<MemoryBufferRef>`. Also updated
the "unowned" version of `SourceManager::createFileID` to take a
`MemoryBufferRef` (it now calls `MemoryBuffer::getMemBuffer`, which
creates a `MemoryBuffer` that does not own the buffer data).
Differential Revision: https://reviews.llvm.org/D89427
Summary:
The MacroExpander allows to expand simple (non-resursive) macro
definitions from a macro identifier token and macro arguments. It
annotates the tokens with a newly introduced MacroContext that keeps
track of the role a token played in expanding the macro in order to
be able to reconstruct the macro expansion from an expanded (formatted)
token stream.
Made Token explicitly copy-able to enable copying tokens from the parsed
macro definition.
Reviewers: sammccall
Subscribers: mgorny, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D83296
Duncan P. N. Exon Smith