CODEWITHSUNDEEP
iosobjective-cxcodemacrosclang
AAV
AAV

Reputation: 3803

Unused parameter warning

I am getting "unused parameter 'testString'" warning from following code. But I am using testString to log. So how come it is unused ? 

- (void)getString:(NSString *)testString {
          ICELogInfo(@"%@", testString);
}

ICELogInfo is a macro for NSLog.

#define ICELogInfo(fmt, ...) LOG_FORMAT(fmt, @"INFO", ##__VA_ARGS__)
#define LOG_FORMAT(fmt, lvl, ...) LOG_FORMAT_NO_LOCATION(fmt, lvl, ##__VA_ARGS__)
#define LOG_FORMAT_NO_LOCATION(fmt, lvl, ...) NSLog((@"%@ " fmt), lvl, ##__VA_ARGS__)

What I am doing wrong ?

Upvotes: 7

Views: 1791

Answers (3)

Alex Curylo
Alex Curylo

Reputation: 4772

What version of Xcode are you using? This looks like a lambda capture bug in LLVM from over a year ago now:

[LLVMbugs] [Bug 12153] New: Incorrect warning about unused parameter when using capturing variadic parameter in lambda

as the VA_ARGS in those macros can be expected to work out to the same problem described in that bug report; but it should be resolved in recent Xcodes. Definitely is in Xcode 5 DP 3 that I'm running right now, your code gives me no warnings.

Upvotes: 1

gsach
gsach

Reputation: 5775

You aren't doing something wrong. This is a common problem when using macros.

As a workaround if you want to get rid of the warning, you can use this code:

- (void)getString:(NSSTring*) __unused testString {
          ICELogInfo(@"%@", testString);
}

Upvotes: 6

Groot
Groot

Reputation: 14251

I've run into the same "problem" before. Solved it by using the unused flag as e.g.

- (void)getString:(NSString *)testString {
    ICELogInfo(@"%@", testString);
    #pragma unused (testString)
}

Upvotes: 2

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