libstdc++-v3/acinclude.m4 tests if sys_nerr is in errno.h. On mingw32, it is declared in stdlib.h, so autoconf test fails. Judging from comment in libiberty/strerror.c, sys_nerr is declared in stdio.h on BSD.
-- Summary: sys_nerr declaration assumed to be in errno.h Product: gcc Version: 4.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: dannysmith at users dot sourceforge dot net GCC build triplet: i686-pc-mingw32 GCC host triplet: i686-pc-mingw32 GCC target triplet: i686-pc-mingw32 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33328