[libc-commits] [libc] [llvm] [libc] Allow each function can have extra attributes by defining LLVM_LIBC_FUNCTION_ATTR_func macro. (PR #116160)

[Nick Desaulniers via libc-commits]

================
@@ -21,9 +21,25 @@
 #define LLVM_LIBC_FUNCTION_ATTR
 #endif
 
+// Allow each function `func` to have extra attributes specified by defining:
+// `LLVM_LIBC_FUNCTION_ATTR_func` macro, which should always start with
+// "LLVM_LIBC_EMPTY, "
+//
+// For examples:
+// #define LLVM_LIBC_FUNCTION_ATTR_memcpy LLVM_LIBC_EMPTY, [[gnu::weak]]
+// #define LLVM_LIBC_FUNCTION_ATTR_memchr LLVM_LIBC_EMPTY, [[gnu::weak]]       \
+//                                        [[gnu::visibility("default")]]
+#define LLVM_LIBC_EMPTY
+
+#define GET_SECOND(first, second, ...) second
+#define EXPAND_THEN_SECOND(name) GET_SECOND(name, LLVM_LIBC_EMPTY, )
----------------
nickdesaulniers wrote:

I think this still works: https://godbolt.org/z/dT4xTYqoY
```suggestion
#define EXPAND_THEN_SECOND(name) GET_SECOND(name, LLVM_LIBC_EMPTY)
```

https://github.com/llvm/llvm-project/pull/116160