[clang] [clang][modules] Reset codegen options. (PR #74006)

[Juergen Ributzka via cfe-commits]

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@@ -4770,9 +4770,20 @@ std::string CompilerInvocation::getModuleHash() const {
 
   // When compiling with -gmodules, also hash -fdebug-prefix-map as it
   // affects the debug info in the PCM.
-  if (getCodeGenOpts().DebugTypeExtRefs)
+  if (getHeaderSearchOpts().ModuleFormat == "obj") {
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ributzka wrote:

CC: @adrian-prantl to confirm my understanding

https://github.com/llvm/llvm-project/pull/74006