[clang][lex] Use FileManager to make prebuilt module paths absolute

[jansvoboda11]

This PR switches from using llvm::sys::fs::make_absolute() to FileManager::makeAbsolutePath() so that FileSystemOptions (i.e. the -working-directory option) and the VFS's CWD have a say in how the prebuilt module paths are resolved. This matches how the rest of the compiler treats input files.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Jan Svoboda (jansvoboda11)

Changes

This PR switches from using llvm::sys::fs::make_absolute() to FileManager::makeAbsolutePath() so that FileSystemOptions (i.e. the -working-directory option) and the VFS's CWD have a say in how the prebuilt module paths are resolved. This matches how the rest of the compiler treats input files.

---

Full diff: https://github.com/llvm/llvm-project/pull/165347.diff

1 Files Affected:

• (modified) clang/lib/Lex/HeaderSearch.cpp (+2-2)

diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 65c324c10ca5d..f05c28fd7a123 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -221,7 +221,7 @@ std::string HeaderSearch::getPrebuiltModuleFileName(StringRef ModuleName,
   // file.
   for (const std::string &Dir : HSOpts.PrebuiltModulePaths) {
     SmallString<256> Result(Dir);
-    llvm::sys::fs::make_absolute(Result);
+    FileMgr.makeAbsolutePath(Result);
     if (ModuleName.contains(':'))
       // The separator of C++20 modules partitions (':') is not good for file
       // systems, here clang and gcc choose '-' by default since it is not a
@@ -246,7 +246,7 @@ std::string HeaderSearch::getPrebuiltImplicitModuleFileName(Module *Module) {
   StringRef ModuleCacheHash = HSOpts.DisableModuleHash ? "" : getModuleHash();
   for (const std::string &Dir : HSOpts.PrebuiltModulePaths) {
     SmallString<256> CachePath(Dir);
-    llvm::sys::fs::make_absolute(CachePath);
+    FileMgr.makeAbsolutePath(CachePath);
     llvm::sys::path::append(CachePath, ModuleCacheHash);
     std::string FileName =
         getCachedModuleFileNameImpl(ModuleName, ModuleMapPath, CachePath);

[cachemeifyoucan]

LGTM