[clang] [llvm] Disentangle DISubprogram ODR type method uniquing from metadata uniquing (PR #217042)

[Jeremy Morse via cfe-commits]

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@@ -1440,4 +1440,84 @@ TEST_F(CloneModule, GlobalWithBlockAddressesInitializer) {
   ASSERT_NE(OriginalBa->getBasicBlock(), ClonedBa->getBasicBlock());
 }
 
+TEST_F(CloneModule, ODRUniqueTypeMethodVerifier) {
+  // Test that the following IR, reduced from a self-host clang-22 compile,
+  // doesn't trip the verifier after cloning.
+  //
+  // The focus of the test is "operator!=" which is a DISubprogram that is:
+  //   * a declaration (therefore not distinct),
+  //   * has uniqued metadata fields used for ODR-type-method uniquing
+  //     (linkage name, scope, template params),
+  //   * and has other distinct metadata fields (type).
+  //
+  // The issue can be reproduced from C++ from this less-reduced C++:
+  // ```
+  // template <typename e> class BaseIt {
+  // public:
+  //   [[gnu::nodebug]] BaseIt();
+  //   bool operator!=(e);
+  // };
+  //
+  // template <typename TLambda> class It : public BaseIt<It<TLambda>> {
+  // public:
+  //   It() {}
+  //   [[gnu::nodebug]] It end();
+  //   [[gnu::nodebug]] It begin();
+  //   [[gnu::nodebug]] int *operator++();
+  //   [[gnu::nodebug]] int operator*();
+  // };
+  //
+  // template <typename TLambda > [[gnu::nodebug]]  It<TLambda> i(TLambda) {
+  //   return {};
+  // }
+  //
+  // class ar {
+  // public:
+  //   static auto lol() {
+  //     return i([] {});
+  //   }
+  // };
+  //
+  // [[gnu::nodebug]] ar au;
+  //
+  // bool func() {
+  //   for ([[gnu::nodebug]] auto av : au.lol())
+  //     ;
+  // }
+  // ```
+
+  StringRef IR = R"(
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jmorse wrote:

SGTM, and thanks.

https://github.com/llvm/llvm-project/pull/217042