[tests] Solve issues with the incorrect use of mpfr_sgn, and make sure

that this cannot happen again without being detected: on zero, +1 or -1
was sometimes expected to check the sign of zero, but mpfr_sgn actually
returned 0, so that the check always succeeded whatever the sign of the
null result.
  * mpfr-test.h: define a new mpfr_sgn macro that fails when used on NaN
    or zero (whose sign is not +1 or -1), except when MPFR_TESTS_TSGN is
    defined.
  * tacos.c, tasin.c, tasinh.c, tatanh.c, tcbrt.c, tdim.c, terf.c,
    texp.c, texp10.c, texp2.c, texpm1.c, tset.c, tset_str.c: replaced
    the incorrect use of mpfr_sgn; some other related improvements.
    Note: in tset.c, a "mpfr_sgn (x) < 0" test had to be replaced by
    "MPFR_IS_POS (x)" since we really want to test whether the sign
    is positive (not negative).
  * tdiv.c, tmul.c, tui_div.c: simplified some tests, in particular to
    avoid a failure with the new mpfr_sgn macro for the tests; here,
    the use of mpfr_sgn was correct, but one could do simpler.
  * tgmpop.c: replaced "mpfr_sgn (z)" by "(mpfr_sgn) (z)" to avoid the
    new mpfr_sgn macro (here, we really want the mathematical sign).
  * tsgn.c: define MPFR_TESTS_TSGN as the goal of this program is to
    test mpfr_sgn itself (both the function and the macro in mpfr.h).

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@11755 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/mpfr-test.h b/tests/mpfr-test.h
index f4d452f39..7bcc15f37 100644
--- a/tests/mpfr-test.h
+++ b/tests/mpfr-test.h
@@ -85,6 +85,25 @@ extern "C" {
 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
 #define ABS(x) (((x)>0) ? (x) : -(x))
 
+/* In the tests, mpfr_sgn was sometimes used incorrectly, for instance:
+ *
+ *   if (mpfr_cmp_ui (y, 0) || mpfr_sgn (y) < 0)
+ *
+ * to check that y is +0. This does not make sense since on 0, mpfr_sgn
+ * yields 0, so that -0 would not be detected as an error. To make sure
+ * that mpfr_sgn is not used incorrectly, we choose to fail when this
+ * macro is used on a datum whose mathematical sign is not +1 or -1.
+ * This feature is disabled when MPFR_TESTS_TSGN is defined, typically
+ * in tsgn (to test mpfr_sgn itself).
+ */
+#ifndef MPFR_TESTS_TSGN
+# undef mpfr_sgn
+# define mpfr_sgn(x)                   \
+  (MPFR_ASSERTN (! MPFR_IS_NAN (x)),   \
+   MPFR_ASSERTN (! MPFR_IS_ZERO (x)),  \
+   MPFR_SIGN (x))
+#endif
+
 #define FLIST mpfr_ptr, mpfr_srcptr, mpfr_rnd_t
 
 int test_version (void);