Compiler warning in src/opentime/timeRange.h when compiling in shared lib mode

[jfpanisset]

On Linux, when building OTIO 0.18.1 with OTIO_SHARED_LIBS, gcc 14 in C++ 20 mode, you get the following warning for almost every C++ file:

src/opentime/timeRange.h:19:31: warning: 'visibility' attribute ignored [-Wattributes]
19 | OPENTIME_API constexpr double DEFAULT_EPSILON_s = 1.0 / (2 * 192000.0);

The definition of DEFAULT_EPSILON is:

OPENTIME_API constexpr double DEFAULT_EPSILON_s = 1.0 / (2 * 192000.0);

and when OPENTIME_EXPORT is defined, in src/opentime/export.h:

...
#elif defined(__GNUC__) && __GNUC__ >= 4 || defined(__clang__)
#    define OPENTIMELINEIO_EXPORT __attribute__((visibility("default")))
...
define OPENTIME_API OPENTIMELINEIO_EXPORT

I believe const objects automatically have internal linkage unless you make them extern, so the visibility attribute does not apply to DEFAULT_EPSILON, hence the warning.

[darbyjohnston]

Thanks for catching this; I think replacing the export with inline will also work, and also lets us keep the constexpr.