Add some temporary autoconf checks to try to figure out why test_math is

failing on Debian/alpha.  (log(9.88e-324) gives an unexpected ValueError
on that platform).  These checks will be removed again once the source
of the problem is identified.

I hope this is a reasonable way to approach the Debian/alpha buildbot
failures; if there's a better way of debugging buildbot test failures
then please let me know.

1 files changed, 135 insertions, 0 deletions

diff --git a/configure.in b/configure.in
index 43d6ae0..ea04b76 100644
--- a/configure.in
+++ b/configure.in
@@ -2980,6 +2980,141 @@ fi],
 # ************************************
 LIBS_SAVE=$LIBS
 LIBS="$LIBS $LIBM"
+
+# temporary checks to try to track down what's going wrong
+# with test_math on Debian/alpha.  These checks will be
+# removed later.
+
+case $ac_sys_machine in
+alpha*)
+
+    AC_MSG_CHECKING(whether 9.88e-324 compares unequal to 0.0)
+    AC_TRY_RUN([
+    #include <stdlib.h>
+    int main() {
+        double x = 9.88e-324;
+        if (x != 0.0)
+            exit(0);
+        else
+            exit(1);
+    }
+    ],
+    ac_cv_subnormal_nonzero=yes,
+    ac_cv_subnormal_nonzero=no,
+    ac_cv_subnormal_nonzero=no)
+    AC_MSG_RESULT($ac_cv_subnormal_nonzero)
+
+    AC_MSG_CHECKING(whether log(9.88e-324) succeeds)
+    AC_TRY_RUN([
+    #include <math.h>
+    #include <stdlib.h>
+    int main() {
+        double x = 9.88e-324;
+        x = log(x);
+        exit(0);
+    }
+    ],
+    ac_cv_log_subnormal_succeeds=yes,
+    ac_cv_log_subnormal_succeeds=no,
+    ac_cv_log_subnormal_succeeds=no)
+    AC_MSG_RESULT($ac_cv_log_subnormal_succeeds)
+
+    AC_MSG_CHECKING(whether log(9.88e-324) returns correct result)
+    AC_TRY_RUN([
+    #include <math.h>
+    #include <stdlib.h>
+    int main() {
+        double x = 9.88e-324;
+        x = log(x);
+        if (-744. < x && x < -743.)
+            exit(0);
+        else
+            exit(1);
+    }
+    ],
+    ac_cv_log_subnormal_returns_correct_result=yes,
+    ac_cv_log_subnormal_returns_correct_result=no,
+    ac_cv_log_subnormal_returns_correct_result=no)
+    AC_MSG_RESULT($ac_cv_log_subnormal_returns_correct_result)
+
+    AC_MSG_CHECKING(whether log(9.88e-324) sets errno)
+    AC_TRY_RUN([
+    #include <math.h>
+    #include <stdlib.h>
+    #include <errno.h>
+    int main() {
+        double x = 9.88e-324;
+        errno = 0;
+        x = log(x);
+        if (errno != 0)
+            exit(0);
+        else
+            exit(1);
+    }
+    ],
+    ac_cv_log_subnormal_sets_errno=yes,
+    ac_cv_log_subnormal_sets_errno=no,
+    ac_cv_log_subnormal_sets_errno=no)
+    AC_MSG_RESULT($ac_cv_log_subnormal_sets_errno)
+
+    AC_MSG_CHECKING(whether log(9.88e-324) sets errno = EDOM)
+    AC_TRY_RUN([
+    #include <math.h>
+    #include <stdlib.h>
+    #include <errno.h>
+    int main() {
+        double x = 9.88e-324;
+        errno = 0;
+        x = log(x);
+        if (errno == EDOM)
+            exit(0);
+        else
+            exit(1);
+    }
+    ],
+    ac_cv_log_subnormal_sets_errno_to_EDOM=yes,
+    ac_cv_log_subnormal_sets_errno_to_EDOM=no,
+    ac_cv_log_subnormal_sets_errno_to_EDOM=no)
+    AC_MSG_RESULT($ac_cv_log_subnormal_sets_errno_to_EDOM)
+
+    AC_MSG_CHECKING(whether log(9.88e-324) is infinite)
+    AC_TRY_RUN([
+    #include <math.h>
+    #include <stdlib.h>
+    int main() {
+        double x = 9.88e-324;
+        x = log(x);
+        if ((x > 1. || x < -1.) && x/2. == x)
+            exit(0);
+        else
+            exit(1);
+    }
+    ],
+    ac_cv_log_subnormal_is_infinite=yes,
+    ac_cv_log_subnormal_is_infinite=no,
+    ac_cv_log_subnormal_is_infinite=no)
+    AC_MSG_RESULT($ac_cv_log_subnormal_is_infinite)
+
+    AC_MSG_CHECKING(whether log(9.88e-324) is a nan)
+    AC_TRY_RUN([
+    #include <math.h>
+    #include <stdlib.h>
+    int main() {
+        double x = 9.88e-324;
+        x = log(x);
+        if (x != x)
+            exit(0);
+        else
+            exit(1);
+    }
+    ],
+    ac_cv_log_subnormal_is_nan=yes,
+    ac_cv_log_subnormal_is_nan=no,
+    ac_cv_log_subnormal_is_nan=no)
+    AC_MSG_RESULT($ac_cv_log_subnormal_is_nan)
+;;
+esac
+
 AC_REPLACE_FUNCS(hypot)
 
 AC_CHECK_FUNCS(acosh asinh atanh copysign expm1 finite isinf isnan log1p)