[clang] [clang][modules] Timestamp PCM files when writing (PR #112452)

[Chuanqi Xu via cfe-commits]

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@@ -4905,6 +4905,10 @@ ASTFileSignature ASTWriter::WriteAST(Sema &SemaRef, StringRef OutputFile,
   this->BaseDirectory.clear();
 
   WritingAST = false;
+
+  if (WritingModule)
+    updateModuleTimestamp(OutputFile);
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ChuanqiXu9 wrote:

Yeah, I'd like to make such changes doesn't affect C++20 modules if possible.

https://github.com/llvm/llvm-project/pull/112452