osrm-backend/include/util/attributes.hpp

#ifndef OSRM_ATTRIBUTES_HPP_
#define OSRM_ATTRIBUTES_HPP_


// OSRM_ATTR_WARN_UNUSED - caller has to use function's return value
// https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html

#if defined(__GNUC__) && (__GNUC__ >= 4)
  #define OSRM_ATTR_WARN_UNUSED __attribute__ ((warn_unused_result))
#else
  #define OSRM_ATTR_WARN_UNUSED
#endif


#endif
Warn on unused return values in guidance code, resolves #2686. https://github.com/Project-OSRM/osrm-backend/pull/2685/files fixes an issue where we did elongate(fstStep, sndStep); instead of newStep = elongate(fstStep, sndStep); we didn't get any warnings. The only way to trigger a warning here is to use ```cpp __attribute__((warn_unused_result)) ``` This changeset does exactly that: for the new guidance code prone to these kind of issue we add such an attribute to the declaration. 2016-08-02 09:43:29 -04:00			`#ifndef OSRM_ATTRIBUTES_HPP_`
			`#define OSRM_ATTRIBUTES_HPP_`


			`// OSRM_ATTR_WARN_UNUSED - caller has to use function's return value`
			`// https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html`

			`#if defined(__GNUC__) && (__GNUC__ >= 4)`
			`#define OSRM_ATTR_WARN_UNUSED __attribute__ ((warn_unused_result))`
			`#else`
			`#define OSRM_ATTR_WARN_UNUSED`
			`#endif`


			`#endif`