- AC_CHECK_DECLS([_snprintf], , , [#include <stdio.h>])
+ AC_CHECK_DECLS([_snprintf], , , [[#include <stdio.h>]])
+ dnl Knowing DBL_EXPBIT0_WORD and DBL_EXPBIT0_BIT enables an optimization
+ dnl in the code for NEED_PRINTF_LONG_DOUBLE || NEED_PRINTF_DOUBLE.
+ AC_REQUIRE([gl_DOUBLE_EXPONENT_LOCATION])