[flukus]

> You shouldn't hard-code gcc.

You should unless you've committed to writing portable code. If you're using GCC specific features then using CC would imply a false level of compatibility.

In this case they are using gcc specific features "-MMD -MP -MT".

[hoytech]

I just tested and this Makefile works fine with clang, except that -flto should be added to LDFLAGS.

In fact I believe it should be there for gcc too, according to https://gcc.gnu.org/wiki/LinkTimeOptimization so perhaps this is a bug in the Makefile?

Flushing out issues like this is another reason to commit to writing portable code (and build systems), as you put it.