Missing has_include on STM32?

[EternityForest]

I'm getting this error on STM32, but the library seems to compile just fine with the include detection stuff removed and replaced with:

#include <cstddef>
#include <cstdint>

In file included from /home/daniel/Arduino/libraries/SLIPStream/src/SLIPStream.cpp:4:0:
/home/daniel/Arduino/libraries/SLIPStream/src/SLIPStream.h:14:18: error: missing binary operator before token "("
 #if __has_include(<cstddef>)
                  ^
In file included from /home/daniel/Arduino/libraries/SLIPStream/src/SLIPStream.cpp:4:0:
/home/daniel/Arduino/libraries/SLIPStream/src/SLIPStream.h:19:18: error: missing binary operator before token "("
 #if __has_include(<cstdint>)