[PATCH] newlib: switch to autoconf long double wider macro

Now that we require a recent version of autoconf, we can rely on this
macro existing.  It has inverted semantics from the existing test (it
looks for "is wider" instead of "is equal"), so we have to invert the
check when creating our _LDBL_EQ_DBL.
---
 newlib/configure    | 72 +++++++++++++++++++++++++++++----------------
 newlib/configure.ac | 22 ++------------
 newlib/newlib.hin   |  4 +++
 3 files changed, 53 insertions(+), 45 deletions(-)

diff --git a/newlib/configure b/newlib/configure
index 3d9427f6b592..c06805a3ef03 100755
--- a/newlib/configure
+++ b/newlib/configure
@@ -13379,37 +13379,59 @@ else
 fi
 
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether long double equals double" >&5
-$as_echo_n "checking whether long double equals double... " >&6; }
-if ${newlib_cv_ldbl_eq_dbl+:} false; then :
+
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for long double with more range or precision than double" >&5
+$as_echo_n "checking for long double with more range or precision than double... " >&6; }
+if ${ac_cv_type_long_double_wider+:} false; then :
   $as_echo_n "(cached) " >&6
 else
-  cat > conftest.c <<EOF
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
 #include <float.h>
-#if DBL_MANT_DIG == LDBL_MANT_DIG  &&  LDBL_MIN_EXP == DBL_MIN_EXP  && \
-    LDBL_MAX_EXP == DBL_MAX_EXP
-  #define _LDBL_EQ_DBL
- #else
-  #error "LDBL != DBL"
-#endif
-EOF
-if { ac_try='${CC} $CFLAGS $CPPFLAGS -c -o conftest.o conftest.c
-							1>&5'
-  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
-  (eval $ac_try) 2>&5
-  ac_status=$?
-  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
-  test $ac_status = 0; }; }
-then
-  newlib_cv_ldbl_eq_dbl=yes;
+	    long double const a[] =
+	      {
+		 0.0L, DBL_MIN, DBL_MAX, DBL_EPSILON,
+		 LDBL_MIN, LDBL_MAX, LDBL_EPSILON
+	      };
+	    long double
+	    f (long double x)
+	    {
+	       return ((x + (unsigned long int) 10) * (-1 / x) + a[0]
+			+ (x ? f (x) : 'c'));
+	    }
+
+int
+main ()
+{
+static int test_array [1 - 2 * !((0 < ((DBL_MAX_EXP < LDBL_MAX_EXP)
+		   + (DBL_MANT_DIG < LDBL_MANT_DIG)
+		   - (LDBL_MAX_EXP < DBL_MAX_EXP)
+		   - (LDBL_MANT_DIG < DBL_MANT_DIG)))
+	    && (int) LDBL_EPSILON == 0
+	  )];
+test_array [0] = 0;
+return test_array [0];
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_cv_type_long_double_wider=yes
 else
-  newlib_cv_ldbl_eq_dbl=no;
+  ac_cv_type_long_double_wider=no
 fi
-rm -f conftest*
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $newlib_cv_ldbl_eq_dbl" >&5
-$as_echo "$newlib_cv_ldbl_eq_dbl" >&6; }
-if test $newlib_cv_ldbl_eq_dbl = yes; then
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_type_long_double_wider" >&5
+$as_echo "$ac_cv_type_long_double_wider" >&6; }
+  if test $ac_cv_type_long_double_wider = yes; then
+
+$as_echo "#define HAVE_LONG_DOUBLE_WIDER 1" >>confdefs.h
+
+  fi
+
+if test $ac_cv_type_long_double_wider = no; then
 
 $as_echo "#define _LDBL_EQ_DBL 1" >>confdefs.h
 
diff --git a/newlib/configure.ac b/newlib/configure.ac
index 3394e5c89b3c..5760f21844c2 100644
--- a/newlib/configure.ac
+++ b/newlib/configure.ac
@@ -694,26 +694,8 @@ if test $ac_cv_type_long_double = yes; then
 fi
 AM_CONDITIONAL(HAVE_LONG_DOUBLE, test x"$ac_cv_type_long_double" = x"yes")
 
-AC_CACHE_CHECK(whether long double equals double,
-	       newlib_cv_ldbl_eq_dbl, [dnl
-cat > conftest.c <<EOF
-#include <float.h>
-#if DBL_MANT_DIG == LDBL_MANT_DIG  &&  LDBL_MIN_EXP == DBL_MIN_EXP  && \
-    LDBL_MAX_EXP == DBL_MAX_EXP
-  #define _LDBL_EQ_DBL
- #else
-  #error "LDBL != DBL"
-#endif
-EOF
-if AC_TRY_COMMAND([${CC} $CFLAGS $CPPFLAGS -c -o conftest.o conftest.c
-							1>&AS_MESSAGE_LOG_FD])
-then
-  newlib_cv_ldbl_eq_dbl=yes;
-else
-  newlib_cv_ldbl_eq_dbl=no;
-fi
-rm -f conftest*])
-if test $newlib_cv_ldbl_eq_dbl = yes; then
+AC_TYPE_LONG_DOUBLE_WIDER
+if test $ac_cv_type_long_double_wider = no; then
   AC_DEFINE(_LDBL_EQ_DBL, 1, [Define if the platform long double type is equal to double.])
 fi
 
diff --git a/newlib/newlib.hin b/newlib/newlib.hin
index feeb409bbeaf..d2c960dd2a42 100644
--- a/newlib/newlib.hin
+++ b/newlib/newlib.hin
@@ -17,6 +17,10 @@
 /* Define to 1 if the system has the type `long double'. */
 #undef HAVE_LONG_DOUBLE
 
+/* Define to 1 if the type `long double' works and has more range or precision
+   than `double'. */
+#undef HAVE_LONG_DOUBLE_WIDER
+
 /* Define to 1 if you have the <memory.h> header file. */
 #undef HAVE_MEMORY_H
 
-- 
2.34.1