[clang] Make PCH's respect any VFS specified. (PR #106577)

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github-actions[bot] wrote:

<!--LLVM CODE FORMAT COMMENT: {clang-format}-->


:warning: C/C++ code formatter, clang-format found issues in your code. :warning:

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git-clang-format --diff 175aa864f33786f3a6a4ee7381cbcafd0758501a e8e06cef736577eb098de57f8dfae201c945d2af --extensions c,cpp -- clang/test/PCH/verify_no_timestamp.c clang/test/VFS/remap-to-fake.c clang/lib/Frontend/FrontendActions.cpp clang/lib/Serialization/ASTWriter.cpp
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View the diff from clang-format here.
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``````````diff
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 94cc1751cd..55cbc46e1c 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -4775,7 +4775,8 @@ bool ASTWriter::PreparePathForOutput(SmallVectorImpl<char> &Path) {
   // If we are generating a normal PCH (EG. not a C++ module).
   if (!WritingModule) {
     // Use the vfs overlay if it exists to translate paths.
-    auto& FileSys = Context->getSourceManager().getFileManager().getVirtualFileSystem();
+    auto &FileSys =
+        Context->getSourceManager().getFileManager().getVirtualFileSystem();
     if (auto *RFS = dyn_cast<llvm::vfs::RedirectingFileSystem>(&FileSys)) {
       if (auto Result = RFS->lookupPath(PathStr)) {
         if (std::optional<StringRef> Redirect = Result->getExternalRedirect()) {

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https://github.com/llvm/llvm-project/pull/106577