[llvm-bugs] [Bug 132411] [lld-link] LLD-LINK produces broken forward imports in source DEF

[LLVM Bugs via llvm-bugs]

Issue	132411
Summary	[lld-link] LLD-LINK produces broken forward imports in source DEF
Labels	new issue
Assignees
Reporter	lhmouse

    First let's define an empty DLL that exports `CreateThread`, forwarded from Windows KERNEL32.DLL:

```c
// test.c
int
__stdcall
_DllMainCRTStartup(void* i, unsigned long r, void* p)
{ return 1; }
```

```plaintext
EXPORTS
  CreateThread = kernel32.CreateThread
```

Now build two DLLs, one with Microsoft LINK (good.dll) and one with LLD (bad.dll):

```plaintext
clang test.c -Wl,-DEF:test.def -shared -Wl,-nodefaultlib -Wl,kernel32.lib -o good.dll
clang test.c -Wl,-DEF:test.def -shared -Wl,-nodefaultlib -Wl,kernel32.lib -fuse-ld=lld -o bad.dll
```

The bad DLL will cause failure when it's loaded by another application, saying **\_kernel32.dll** is not found. Now let's open the good DLL with a hex editor:

![Image](https://github.com/user-attachments/assets/5784535f-9f79-4388-baf1-eb673d6c2134)

And this is the bad DLL. The import from `_kernel32.CreateThread` is exactly the issue.

![Image](https://github.com/user-attachments/assets/39ceca71-ee00-4cff-ae38-ea10ac2fed48)

This bug exists only when targeting x86-32.

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