Reland "[clang] Delay normalization of `-fmodules-cache-path` (#150123)"

This reverts commit 613caa909c78f707e88960723c6a98364656a926, essentially
reapplying 4a4bddec3571d78c8073fa45b57bbabc8796d13d after moving
`normalizeModuleCachePath` from clangFrontend to clangLex.

This PR is part of an effort to remove file system usage from the
command line parsing code. The reason for that is that it's impossible
to do file system access correctly without a configured VFS, and the VFS
can only be configured after the command line is parsed. I don't want to
intertwine command line parsing and VFS configuration, so I decided to
perform the file system access after the command line is parsed and the
VFS is configured - ideally right before the file system entity is used
for the first time.

This patch delays normalization of the module cache path until
`CompilerInstance` is asked for the cache path in the current
compilation context.

GitOrigin-RevId: 55bef46146f05e1911fcb98715716d914efd518c
8 files changed
tree: f1e33cf64f3ee91a908c569d7afb0674be154352
  1. bindings/
  2. cmake/
  3. docs/
  4. examples/
  5. include/
  6. lib/
  7. runtime/
  8. test/
  9. tools/
  10. unittests/
  11. utils/
  12. www/
  13. .clang-format
  14. .clang-tidy
  15. .gitignore
  16. AreaTeamMembers.txt
  17. CMakeLists.txt
  18. INSTALL.txt
  19. LICENSE.TXT
  20. Maintainers.rst
  21. NOTES.txt
  22. README.md
README.md

C language Family Front-end

Welcome to Clang.

This is a compiler front-end for the C family of languages (C, C++ and Objective-C) which is built as part of the LLVM compiler infrastructure project.

Unlike many other compiler frontends, Clang is useful for a number of things beyond just compiling code: we intend for Clang to be host to a number of different source-level tools. One example of this is the Clang Static Analyzer.

If you're interested in more (including how to build Clang) it is best to read the relevant websites. Here are some pointers: