test-gtx_fast_trigonometry fails on raspberry pi 3, while compiling with clang

[kaomoneus]

clang version 3.8.1-24+rpi (tags/RELEASE_381/final)
Affects glm-0.9.9.3

/home/pi/sync-dest/libglm/glm-0.9.9.3/test/gtx/gtx_component_wise.cpp:81:17: error: comparison of constant -128 with
      expression of type 'const char' is always false [-Werror,-Wtautological-constant-out-of-range-compare]
                        Error += A.y == -128 ? 0 : 1;
                                 ~~~ ^  ~~~~
1 error generated.

Looks like a clang bug (char variable may take a -128 value). And yet better to leave it here.

[epajarre]

I think that C++ "plain" char might be either signed or unsigned, and some docs seem to indicate that on ARM it is unsigned typically.

And at least if GLM_AS_EXTENDED_INTEGER_TYPE is not defined, int8 is typedefed to plain char.

Maybe it should be changed to signed char?

(my glm version might not be the latest, apologies if this is an old version)

[kaomoneus]

Wow! Frankly I'm surprised about unsigned char.
In this case we should take into account CHAR_MIN and CHAR_MAX constants (defined in limits).

[Groovounet]

This issue should be fixed in master branch for GLM 0.9.9.4 release.

Thanks for contributing!