rint: Determine RINT_LIBM correctly on AIX 7.

[gnulib.git] / m4 / rint.m4

diff --git a/m4/rint.m4 b/m4/rint.m4
index 5d9e832..2a09136 100644 (file)
--- a/m4/rint.m4
+++ b/m4/rint.m4
@@ -1,4 +1,4 @@
-# rint.m4 serial 2
+# rint.m4 serial 3
 dnl Copyright (C) 2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -9,7 +9,11 @@ AC_DEFUN([gl_FUNC_RINT],
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
 
   dnl Determine RINT_LIBM.
-  gl_MATHFUNC([rint], [double], [(double)])
+  dnl The reason for the extra code is:
+  dnl In AIX 7.1 with gcc 4.2, when optimization is turned on, calls to
+  dnl rint() with simple arguments are turned into rintf() calls by the
+  dnl compiler. But while rint() is resides in libc, rintf() is in libm.
+  gl_MATHFUNC([rint], [double], [(double)], [y += rint (2.0);])
   if test $gl_cv_func_rint_no_libm = no \
      && test $gl_cv_func_rint_in_libm = no; then
     HAVE_RINT=0