http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54419
--- Comment #43 from Jack Howarth <howarth at nitro dot med.uc.edu> 2012-09-06 14:31:53 UTC --- (In reply to comment #42) > Sorry if I'm saying something naive - I didn't follow the whole discussion - > but I don't understand why - assuming indeed we want to do something at > configure time - are being attached patches directly touching > libstdc++-v3/configure* files, instead of acinclude.m4 (to be processed by > autoreconf), which is the normal way we write this kind of code in the > libraries. Probably because... AC_TRY_COMPILE(, [ #if !defined __LONG_DOUBLE_128__ || (defined(__sparc__) && defined(__arch64__)) #error no need for long double compatibility #endif ], [ac_ldbl_compat=yes], [ac_ldbl_compat=no]) if test "$ac_ldbl_compat" = yes; then AC_DEFINE([_GLIBCXX_LONG_DOUBLE_COMPAT],1, [Define if compatibility should be provided for -mlong-double-64.]) port_specific_symbol_files="\$(top_srcdir)/config/os/gnu-linux/ldbl-extra.ver" fi already existed immediately above the new test in configure.ac.