Gentoo's Bugzilla –
Attachment 842877 Details for
Bug 886137sci-electronics/gsmc-1.1-r2 fails to compile (CLANG-STRICTER-SYSTEM): autotune.c:82:7: error: call to undeclared function recalc; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]