[gnumeric] configure: move warning flags late; verify that cos works.

[Morten Welinder <mortenw src gnome org>]

commit 0525807ca3665f4098a600258aa6f5e7ea669480
Author: Morten Welinder <terra gnome org>
Date:   Fri Aug 19 17:18:03 2016 -0400

    configure: move warning flags late; verify that cos works.
    
    Warning flags need to come after our last use of conftest.c as auto*
    uses pre-ANSI main declaration.
    
    cos doesn't work in glibc 2.23; work around that at the cost of more
    last-bit errors.

 configure.ac |  123 ++++++++++++++++++++++++++++++++++------------------------
 1 files changed, 72 insertions(+), 51 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 93deb25..ccfea49 100644
--- a/configure.ac
+++ b/configure.ac
@@ -270,56 +270,6 @@ AC_SUBST(GLIB_COMPILE_RESOURCES)
 AC_ARG_VAR(GDK_PIXBUF_CSOURCE, [The gdk-pixbuf-csource executable.])
 AC_CHECK_PROG(GDK_PIXBUF_CSOURCE, gdk-pixbuf-csource$ac_exeext, gdk-pixbuf-csource$ac_exeext)
 
-## this should come after `AC_PROG_CC'
-set_more_warnings=yes
-if test "$GCC" = yes -a "x$set_more_warnings" != xno; then
-       dnl Clang needs this option, or else it will appear to support any
-       dnl warning option, only to spew warnings about them later.
-       uwoption="-Werror=unknown-warning-option"
-       SAVE_CFLAGS="$CFLAGS"
-       CFLAGS="$CFLAGS $uwoption"
-       AC_MSG_CHECKING([whether gcc understands $uwoption])
-       AC_COMPILE_IFELSE(
-               [AC_LANG_PROGRAM([], [])],
-               [has_unknown_warning_option=yes],
-               [has_unknown_warning_option=no; uwoption=""])
-       AC_MSG_RESULT($has_unknown_warning_option)
-       CFLAGS="$SAVE_CFLAGS"
-
-       warning_options="-Wall -Werror=init-self -Werror=missing-include-dirs \
-                        -Wsign-compare -Werror=pointer-arith \
-                        -Wchar-subscripts -Wwrite-strings \
-                        -Wdeclaration-after-statement -Wnested-externs \
-                        -Wmissing-noreturn \
-                        -Werror=missing-prototypes -Werror=nested-externs \
-                        -Werror=implicit-function-declaration \
-                        -Wmissing-declarations -Wno-pointer-sign \
-                        -Werror=format-security -Wbitwise -Wcast-to-as \
-                        -Wdefault-bitfield-sign -Wdo-while -Wparen-string \
-                        -Wptr-subtraction-blows -Wreturn-void -Wtypesign \
-                        -Wstrict-prototypes -Wno-error=format-nonliteral "
-       for option in $warning_options ; do
-               SAVE_CFLAGS="$CFLAGS"
-               CFLAGS="$CFLAGS $uwoption $option"
-               AC_MSG_CHECKING([whether gcc understands $option])
-               dnl Include a system header so we ignore Werror=... flags
-               dnl that cause trouble.
-               AC_COMPILE_IFELSE(
-                       [AC_LANG_PROGRAM([[#include <stdio.h>]], [])],
-                       [has_option=yes],
-                       [has_option=no])
-               CFLAGS="$SAVE_CFLAGS"
-               if test $has_option = yes; then
-                       CFLAGS="$CFLAGS $option"
-               fi
-               AC_MSG_RESULT($has_option)
-               unset has_option
-               unset SAVE_CFLAGS
-       done
-       unset option
-fi
-AC_SUBST(WARN_CFLAGS)
-
 AC_ARG_ENABLE(component,
   AS_HELP_STRING([--disable-component], [Do not build the goffice component]),
   [], [enable_component=yes])
@@ -422,6 +372,7 @@ if test $works_without_bsd_source = no ; then
        fi
 fi
 
+
 AC_SUBST(GUILE_LIBS)
 AC_SUBST(GUILE_INCS)
 
@@ -644,7 +595,27 @@ if test $ac_cv_func_lgamma = no; then
        )
 fi
 
-if test "x$with_win32" = "xyes"; then
+cos_works=yes
+AC_MSG_CHECKING([cos is reliable])
+AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM([[
+                       #include <stdlib.h>
+                       #include <math.h>
+               ]],
+               [[
+                       const char *s = "1.5689793435451356";
+                       double x = atof (s);
+                       double c = cos (x);
+                       int ok = (c > 0 && c < 0.05);
+                       return ok ? 0 : 1;
+               ]])],
+       [AC_MSG_RESULT(yes)
+        cos_works=yes],
+       [AC_MSG_RESULT(no)
+        cos_works=no],
+       [AC_MSG_RESULT(assuming it is)])
+
+if test "x$with_win32" = "xyes" -o "x$cos_works" = "xno"; then
    AC_DEFINE(GNM_REDUCES_TRIG_RANGE, 1,
        [Define if Gnumeric reduces the argument range of sin/cos/tan]
        )
@@ -721,6 +692,56 @@ AC_ARG_WITH(long_double,
        fi]
 )
 
+## this should come after `AC_PROG_CC'
+set_more_warnings=yes
+if test "$GCC" = yes -a "x$set_more_warnings" != xno; then
+       dnl Clang needs this option, or else it will appear to support any
+       dnl warning option, only to spew warnings about them later.
+       uwoption="-Werror=unknown-warning-option"
+       SAVE_CFLAGS="$CFLAGS"
+       CFLAGS="$CFLAGS $uwoption"
+       AC_MSG_CHECKING([whether gcc understands $uwoption])
+       AC_COMPILE_IFELSE(
+               [AC_LANG_PROGRAM([], [])],
+               [has_unknown_warning_option=yes],
+               [has_unknown_warning_option=no; uwoption=""])
+       AC_MSG_RESULT($has_unknown_warning_option)
+       CFLAGS="$SAVE_CFLAGS"
+
+       warning_options="-Wall -Werror=init-self -Werror=missing-include-dirs \
+                        -Wsign-compare -Werror=pointer-arith \
+                        -Wchar-subscripts -Wwrite-strings \
+                        -Wdeclaration-after-statement -Wnested-externs \
+                        -Wmissing-noreturn \
+                        -Werror=missing-prototypes -Werror=nested-externs \
+                        -Werror=implicit-function-declaration \
+                        -Wmissing-declarations -Wno-pointer-sign \
+                        -Werror=format-security -Wbitwise -Wcast-to-as \
+                        -Wdefault-bitfield-sign -Wdo-while -Wparen-string \
+                        -Wptr-subtraction-blows -Wreturn-void -Wtypesign \
+                        -Wstrict-prototypes -Wno-error=format-nonliteral "
+       for option in $warning_options ; do
+               SAVE_CFLAGS="$CFLAGS"
+               CFLAGS="$CFLAGS $uwoption $option"
+               AC_MSG_CHECKING([whether gcc understands $option])
+               dnl Include a system header so we ignore Werror=... flags
+               dnl that cause trouble.
+               AC_COMPILE_IFELSE(
+                       [AC_LANG_PROGRAM([[#include <stdio.h>]], [])],
+                       [has_option=yes],
+                       [has_option=no])
+               CFLAGS="$SAVE_CFLAGS"
+               if test $has_option = yes; then
+                       CFLAGS="$CFLAGS $option"
+               fi
+               AC_MSG_RESULT($has_option)
+               unset has_option
+               unset SAVE_CFLAGS
+       done
+       unset option
+fi
+AC_SUBST(WARN_CFLAGS)
+
 dnl **************************************************
 dnl * Check for GSettings
 dnl **************************************************