Developer insists there is a bug in GCC6 that prevents this from compiling right. Not sure I see evidence of that, but at the moment this isn't ready to be included.

Different tar: https://github.com/stepmania/stepmania/archive/v5.1.0a3.tar.gz

I'm not sure if the new tar specifically builds in GCC6, but according to the Arch package on AUR, the stable/old 5.0 version of StepMania has issues with compiling on GCC6 and the maintainer forces it to use GCC5. I can compile StepMania 5.1 from git on GCC6.

The tar above specifically is the latest one listed on the GitHub page, but it's tagged as pre-release.

Good to know it will be fixed in 5.1.0. Now we wait.

This compiles successfully, but won't run. I don't think it's related to GCC, because it compiles and runs fine on openSUSE Tumbleweed using GCC 6.3.1

I couldn’t get this to run in Solus using GCC 5.4.0, 6.3.0, or 7.1.0