[all-commits] [llvm/llvm-project] 92f058: [DebugInfo][CodeView] Resolve forward references t...

[Nerixyz via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 92f058a8b351def1c10cb3f37d05adf813fb9638
      https://github.com/llvm/llvm-project/commit/92f058a8b351def1c10cb3f37d05adf813fb9638
  Author: Nerixyz <nerixdev at outlook.de>
  Date:   2026-06-23 (Tue, 23 Jun 2026)

  Changed paths:
    M llvm/lib/DebugInfo/PDB/Native/TpiStream.cpp
    A llvm/test/tools/llvm-pdbutil/forward-cxx-to-c-odr.test
    A llvm/test/tools/llvm-pdbutil/forward-cxx-to-c.test

  Log Message:
  -----------
  [DebugInfo][CodeView] Resolve forward references to types without unique name (#203781)

In the following code:
```cpp
// header.h
typedef struct lua_State lua_State;
lua_State *getState();

// source.c
#include "header.h"
struct lua_State { int field; };

lua_State *getState() {
    static lua_State state = {.field=42}; // make sure the type is emitted
    return &state;
}

// main.cpp
extern "C" {
    #include "header.h"
}
int main() { return getState() != 0; }
```

We'll get two forward references for `lua_State` when compiling with
clang-cl. One with a unique name (from C++) and one without (from C).
There's one complete definition for the type (from `source.c`). Since
this is from C, it doesn't have a unique name. Before, we could only
resolve the forward reference from C, not from C++.

With this PR, we can resolve both references. I also tested that the VS
debugger resolves the reference correctly.

I'm not sure if this is a clang bug, because when compiling with MSVC,
the C type also has a unique name. Clang omits the unique name, because
C doesn't have ODR like C++.



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