[llvm] [DebugInfo] Make DISubprogram's hashing always produce the same result (PR #90770)

[Augusto Noronha via llvm-commits]

================
@@ -1184,4 +1186,52 @@ TEST(MetadataTest, DbgVariableRecordConversionRoutines) {
   UseNewDbgInfoFormat = false;
 }
 
+// Test that the hashing function for DISubprograms produce the same result
+// after replacing the temporary scope.
+TEST(DIBuilder, HashingDISubprogram) {
+  LLVMContext Ctx;
+  std::unique_ptr<Module> M = std::make_unique<Module>("MyModule", Ctx);
+  DIBuilder DIB(*M);
+
+  DIFile *F = DIB.createFile("main.c", "/");
+  DICompileUnit *CU =
+      DIB.createCompileUnit(dwarf::DW_LANG_C, F, "Test", false, "", 0);
+
+  llvm::TempDIType ForwardDeclaredType =
+      llvm::TempDIType(DIB.createReplaceableCompositeType(
+          llvm::dwarf::DW_TAG_structure_type, "MyType", CU, F, 0, 0, 8, 8, {},
+          "UniqueIdentifier"));
+
----------------
augusto2112 wrote:

There's already a comment above the test with an explanation of why we need the type. Do you think I should add some clarification to it?

```
// Test that the hashing function for DISubprograms produce the same result
// after replacing the temporary scope.
```

https://github.com/llvm/llvm-project/pull/90770