[llvm] Add __attribute__((warn_unused_result)) to LLVMErrorRef (PR #87025)

[Aaron Ballman via llvm-commits]

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@@ -36,4 +36,18 @@
 #define LLVM_C_EXTERN_C_END LLVM_C_STRICT_PROTOTYPES_END
 #endif
 
+#ifndef LLVM_HAS_ATTRIBUTE
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AaronBallman wrote:

Hmm, is this the best place for the code to live given the comment at the top of the file: `This file defines an 'extern "C"' wrapper` ?

Maybe this belongs in `Core.h`? or some new file for compiler-based macro definitions?

https://github.com/llvm/llvm-project/pull/87025