http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55473
Bug #: 55473 Summary: quadmath.h should have extern "C" for C++ users Classification: Unclassified Product: gcc Version: unknown Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: libquadmath AssignedTo: unassig...@gcc.gnu.org ReportedBy: j...@gcc.gnu.org quadmath.h is missing something like: #ifdef __cplusplus extern "C" { #endif /* Content of file */ #ifdef __cplusplus } /* End extern "C". */ #endif As it is, C++ users who wish to use libquadmath have to do this manually before including quadmath.h. E.g. http://gcc.gnu.org/ml/gcc-help/2011-06/msg00148.html or for a more recent example http://stackoverflow.com/questions/13571621/quadruple-precision-in-g-4-6-3-linux-using-quadmath