[llvm-commits] [llvm] r116920 - /llvm/trunk/include/llvm/Support/Compiler.h

[Bill Wendling]

On Oct 20, 2010, at 1:44 AM, Chandler Carruth wrote:

> Author: chandlerc
> Date: Wed Oct 20 03:44:27 2010
> New Revision: 116920
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=116920&view=rev
> Log:
> Add a comment about ATTRIBUTE_UNUSED to avoid further confusion over when to
> use it.
> 
There's no reason not to use this for variables. And it avoids the void-casting hack.

-bw

> Modified:
>    llvm/trunk/include/llvm/Support/Compiler.h
> 
> Modified: llvm/trunk/include/llvm/Support/Compiler.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Compiler.h?rev=116920&r1=116919&r2=116920&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Support/Compiler.h (original)
> +++ llvm/trunk/include/llvm/Support/Compiler.h Wed Oct 20 03:44:27 2010
> @@ -31,6 +31,14 @@
> #define ATTRIBUTE_USED
> #endif
> 
> +// Some compilers warn about unused functions. When a function is sometimes
> +// used or not depending on build settings (e.g. a function only called from
> +// within "assert"), this attribute can be used to suppress such warnings.
> +//
> +// However, it shouldn't be used for unused *variables*, as those have a much
> +// more portable solution:
> +//   (void)unused_var_name;
> +// Prefer cast-to-void wherever it is sufficient.
> #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
> #define ATTRIBUTE_UNUSED __attribute__((__unused__))
> #else
> 
> 
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