[llvm-bugs] [Bug 47923] New: __attribute__((warn_result_unused)) broken for ObjC Methods in Macros

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47923

            Bug ID: 47923
           Summary: __attribute__((warn_result_unused)) broken for ObjC
                    Methods in Macros
           Product: clang
           Version: unspecified
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: dmaclach at gmail.com
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org,
                    neeilans at live.com, richard-llvm at metafoo.co.uk

Overview:

An Objective C call in a macro has its warning about unused results suppressed
which is different than a C function call. I would expect these to be
equivalent in this regard.

```
#import <Foundation/Foundation.h>

__attribute__((warn_unused_result)) static id ReturnSomethingC() { return nil;
}

@interface TestClass : NSObject
+ (id)returnSomething __attribute__((warn_unused_result));
@end

@implementation TestClass
+ (id)returnSomething { return nil; }

@end

#define DOSOMETHING_OBJC [TestClass returnSomething]
#define DOSOMETHING_C ReturnSomethingC()

int main(int argc, const char * argv[]) {
  @autoreleasepool {
    [TestClass returnSomething];  // <-- Here I get the warning
    ReturnSomethingC();  // <-- Here I get the warning
    DOSOMETHING_C;  // <-- Here I get the warning
    DOSOMETHING_OBJC;  // <-- How do I get a warning here?
  }
  return 0;
}
```

it appears that Objc Messages are considered after suppression

https://github.com/llvm/llvm-project/blob/89f7ccea6f6488c443655880229c54db1f180153/clang/lib/Sema/SemaStmt.cpp#L324

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