[clang] [PATCH] [clang][modules] Fix serialization and de-serialization of PCH module file refs (#105994) (PR #132802)

[Chuanqi Xu via cfe-commits]

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@@ -9615,7 +9615,7 @@ ModuleFile *ASTReader::getLocalModuleFile(ModuleFile &M, unsigned ID) const {
     // It's a prefix (preamble, PCH, ...). Look it up by index.
     unsigned IndexFromEnd = ID >> 1;
     assert(IndexFromEnd && "got reference to unknown module file");
-    return getModuleManager().pch_modules().end()[-IndexFromEnd];
+    return getModuleManager().pch_modules().end()[-static_cast<int>(IndexFromEnd)];
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ChuanqiXu9 wrote:

Why is this needed?

https://github.com/llvm/llvm-project/pull/132802