hanchenye-llvm-project/llvm/autoconf/m4/c_printf_a.m4

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#
# Determine if the printf() functions have the %a format character.
# This is modified from:
# http://www.gnu.org/software/ac-archive/htmldoc/ac_cxx_have_ext_slist.html
AC_DEFUN([AC_C_PRINTF_A],
[
AC_MSG_CHECKING([for printf %a format specifier])
AC_LANG_SAVE
AC_LANG_C
AC_RUN_IFELSE(
AC_LANG_PROGRAM([#include <stdio.h>
#include <stdlib.h>],
[[[
volatile double A, B;
char Buffer[100];
A = 1;
A /= 10.0;
sprintf(Buffer, "%a", A);
B = atof(Buffer);
if (A != B)
return (1);
if (A != 0x1.999999999999ap-4)
return (1);
return (0);]]]),
ac_c_printf_a=yes,ac_c_printf_a=no)
AC_LANG_RESTORE
AC_MSG_RESULT($ac_c_printf_a)
if test "$ac_c_printf_a" = "yes"; then
AC_DEFINE([HAVE_PRINTF_A],[1],[Define to have the %a format string])
fi
])