acl: allow cross-compilation to Gentoo

[gnulib.git] / m4 / log10l.m4

diff --git a/m4/log10l.m4 b/m4/log10l.m4
index c124f89..ca4a331 100644 (file)
--- a/m4/log10l.m4
+++ b/m4/log10l.m4
@@ -1,5 +1,5 @@
-# log10l.m4 serial 2
-dnl Copyright (C) 2011-2012 Free Software Foundation, Inc.
+# log10l.m4 serial 3
+dnl Copyright (C) 2011-2013 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -24,14 +24,75 @@ AC_DEFUN([gl_FUNC_LOG10L],
   LIBS="$save_LIBS"
   if test $ac_cv_func_log10l = yes; then
     LOG10L_LIBM="$LOG10_LIBM"
+
+    save_LIBS="$LIBS"
+    LIBS="$LIBS $LOG10L_LIBM"
+    gl_FUNC_LOG10L_WORKS
+    LIBS="$save_LIBS"
+    case "$gl_cv_func_log10l_works" in
+      *yes) ;;
+      *) REPLACE_LOG10L=1 ;;
+    esac
   else
     HAVE_LOG10L=0
+  fi
+  if test $HAVE_LOG10L = 0 || test $REPLACE_LOG10L = 1; then
     if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
       LOG10L_LIBM="$LOG10_LIBM"
     else
-      AC_REQUIRE([gl_FUNC_LOGL])
-      LOG10L_LIBM="$LOGL_LIBM"
+      if test $HAVE_LOG10L = 0; then
+        AC_REQUIRE([gl_FUNC_LOGL])
+        LOG10L_LIBM="$LOGL_LIBM"
+      fi
     fi
   fi
   AC_SUBST([LOG10L_LIBM])
 ])
+
+dnl Test whether log10l() works.
+dnl On OSF/1 5.1, log10l(-0.0L) is NaN.
+dnl On IRIX 6.5, log10l(-0.0L) is an unnormalized negative infinity
+dnl 0xFFF00000000000007FF0000000000000, should be
+dnl 0xFFF00000000000000000000000000000.
+dnl On AIX 5.1, log10l(-0.0L) is finite if it's not the first log10l call
+dnl in the program.
+AC_DEFUN([gl_FUNC_LOG10L_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether log10l works], [gl_cv_func_log10l_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <math.h>
+#ifndef log10l /* for AIX */
+extern
+#ifdef __cplusplus
+"C"
+#endif
+long double log10l (long double);
+#endif
+volatile long double x;
+long double y;
+int main ()
+{
+  /* Dummy call, to trigger the AIX 5.1 bug.  */
+  x = 0.6L;
+  y = log10l (x);
+  /* This test fails on AIX 5.1, IRIX 6.5, OSF/1 5.1.  */
+  x = -0.0L;
+  y = log10l (x);
+  if (!(y + y == y))
+    return 1;
+  return 0;
+}
+]])],
+        [gl_cv_func_log10l_works=yes],
+        [gl_cv_func_log10l_works=no],
+        [case "$host_os" in
+           aix* | irix* | osf*) gl_cv_func_log10l_works="guessing no";;
+           *)                   gl_cv_func_log10l_works="guessing yes";;
+         esac
+        ])
+    ])
+])