Gentoo's Bugzilla –
Attachment 855096 Details for
Bug 898272sci-libs/trilinos-13.4.1 fails to compile (MUSL-CLANG-SYSTEM): trilinos_klu_factor.c:506:19: error: call to undeclared function omp_get_num_threads; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]