I have the following code, and while compiling it with gcc-4.6 I get warning:
warning: variable ‘status’ set but not used [-Wunused-but-set-variable]
#if defined (_DEBUG_)
#define ASSERT assert
#else /* _DEBUG_ */
#define ASSERT( __exp__ )
#endif
static inline void cl_plock(cl_plock_t * const p_lock)
{
status_t status;
ASSERT(p_lock);
ASSERT(p_lock->state == INITIALIZED);
status = pthread_rwlock_unlock(&p_lock->lock);
ASSERT(status == 0);
}
When _DEBUG_ flag isn't set I get the warning. Any ideas how can I workaround this warning?
You can then use -Wunused-variable to turn on that warning specifically, without enabling others. To disable that warning, replace the leading -W with -Wno- , and use it in combination with an option to enable the desired warning level.
The warning is emitted only with --coverage enabled. By default, this warning is enabled and is treated as an error. -Wno-coverage-invalid-line-number can be used to disable the warning or -Wno-error=coverage-invalid-line-number can be used to disable the error.
To answer your question about disabling specific warnings in GCC, you can enable specific warnings in GCC with -Wxxxx and disable them with -Wno-xxxx. From the GCC Warning Options: You can request many specific warnings with options beginning -W , for example -Wimplicit to request warnings on implicit declarations.
You can change your ASSERT
macro to:
#if defined (_DEBUG_)
#define ASSERT assert
#else /* _DEBUG_ */
#define ASSERT( exp ) ((void)(exp))
#endif
If the expression has no sideeffects, then it should still be optimised out, but it should also suppress the warning (if the expression does have side-effects, then you would get different results in debug and non-debug builds, which you don't want either!).
The compiler option to turn off unused variable warnings is -Wno-unused
.
To get the same effect on a more granular level you can use diagnostic pragmas like this:
int main()
{
#pragma GCC diagnostic ignored "-Wunused-variable"
int a;
#pragma GCC diagnostic pop
// -Wunused-variable is on again
return 0;
}
This is, of course, not portable but you can use something similar for VS.
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