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

[Juergen Ributzka via cfe-commits]

================
@@ -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") {
----------------
ributzka wrote:

There was a test case that only passed the module format, but not DebugTypeExtRefs. DebugTypeExtRefs was used as a proxy for `-gmodules`, but that doesn't always work. From my understanding the driving factor should be the ModuleFormat, because that decides if debug options make a difference in the PCM.

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