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According to Jim Meyering on 3/30/2008 8:49 AM:
|
| In my copy of test-strtod.c, they're all comparing sign bits:
|
| ASSERT (signbit (result1) != signbit (result2));
The default value of NaN (both sign bit and other bits) are enough of a
portability mess on different hardware that I'm willing to just skip those
tests. I think a good implementation of strtod should be able to
distinguish between "nan" and "-nan", but as either result will still be
NaN, I'm happy to disable those tests, as in the patch below:
|
| This sort of mix-up is a good argument for not changing
| line numbers when we add the two prefix lines:
|
| /* -*- buffer-read-only: t -*- vi: set ro: */
| /* DO NOT EDIT! GENERATED AUTOMATICALLY! */
Ahh. That makes sense - I was going off the line numbers in gnulib, not
in my bootstrapped copy of coreutils. Maybe the same bootstrap process
that adds those two lines should add a third line?
#line 1
| When I run the tests on a 32-bit system with ubuntu's
| 2.7-9ubuntu2, I get even more failures:
|
| PASS: test-string
| test-strtod.c:285: assertion failed
| test-strtod.c:371: assertion failed
Parsing "-0" as 0.0 rather than -0.0 - definite bug. The buildbot is
showing the same failure. But the buildbot also shows:
checking whether strtod obeys C99... no
-e 's|@''REPLACE_STRTOD''@|1|g' \
So, just to be clear, are we seeing any platforms that return positive 0
on "-0" but which are not using the replacement function? However, I
thought strtod.m4 already caught that.
Yet, when I tested the replacement function (in both mingw, where
strtod.m4 selects it, and on cygwin, by using gl_cv_func_strtod_works=no,
but in both cases with gcc -g without optimization), I didn't see this
failure. I'm wondering if it is a gcc -O2 bug? I'm not quite sure what
to do here, without access to a machine with those failures. Can you step
through the replacement function with a debugger?
And just now, I tested cygwin with -O2, and got:
../../m4/tests/test-strtod.c:149: assertion failed
../../m4/tests/test-strtod.c:221: assertion failed
which looks like rounding errors in computing 0.1. On further thought,
that particular failure is due to x86 registers having more precision than
memory, such that .1 (register) != .1 (memory). So I've also changed the
test to use .5 instead of .1.
| test-strtod.c:480: assertion failed
Returning positive zero for negative underflow - glibc bug:
http://sources.redhat.com/bugzilla/show_bug.cgi?id=5995
This is a QoI issue, and not a POSIX-compliance bug, so I'm disabling it
for now. On the other hand, if this was a case of the replacement
function not returning -0, then it could be the same as the other bugs on
this platform.
| test-strtod.c:544: assertion failed
| test-strtod.c:592: assertion failed
| test-strtod.c:635: assertion failed
disabled per above; sign bits on NaN are quite difficult.
| test-strtod.c:816: assertion failed
Another case of not returning -0.
|>
|> This shows some different failures, such as on not leaving errno unchanged
|> for "-0". Also something I should add to strtod.m4.
Well, now that we've straightened out the line number issue, errno is just
fine. Rather, the problem is that the result has the wrong sign.
- --
Don't work too hard, make some time for fun as well!
Eric Blake [EMAIL PROTECTED]
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>From 35029b9098fbe10eeb3ba5833ee5f01b77c5d883 Mon Sep 17 00:00:00 2001
From: Eric Blake <[EMAIL PROTECTED]>
Date: Sun, 30 Mar 2008 15:57:54 -0600
Subject: [PATCH] More strtod touchups.
* tests/test-strtod.c (main): Ignore tests for signbit on NaN, and
sign of negative underflow, for now. Use .5, not .1.
* doc/posix-functions/strtod.texi (strtod): Mention these
limitations.
Reported by Jim Meyering.
Signed-off-by: Eric Blake <[EMAIL PROTECTED]>
---
ChangeLog | 9 +++++++++
doc/posix-functions/strtod.texi | 7 ++++++-
tests/test-strtod.c | 30 ++++++++++++++++++++++++------
3 files changed, 39 insertions(+), 7 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 5df9267..117ff3d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -19,6 +19,15 @@
2008-03-30 Eric Blake <[EMAIL PROTECTED]>
+ More strtod touchups.
+ * tests/test-strtod.c (main): Ignore tests for signbit on NaN, and
+ sign of negative underflow, for now. Use .5, not .1.
+ * doc/posix-functions/strtod.texi (strtod): Mention these
+ limitations.
+ Reported by Jim Meyering.
+
+2008-03-30 Eric Blake <[EMAIL PROTECTED]>
+
strtod touchups.
* lib/strtod.c (strtod): Avoid compiler warnings.
Reported by Jim Meyering.
diff --git a/doc/posix-functions/strtod.texi b/doc/posix-functions/strtod.texi
index fecade3..6e137dd 100644
--- a/doc/posix-functions/strtod.texi
+++ b/doc/posix-functions/strtod.texi
@@ -52,7 +52,12 @@ Portability problems not fixed by Gnulib:
@item
This function returns a positive value for negative underflow on some
platforms:
-glibc 2.4, Mingw, Cygwin.
+glibc 2.7, Mingw, Cygwin.
+
[EMAIL PROTECTED]
+This function cannot distinguish between ``nan'' and ``-nan'' on some
+platforms:
+glibc 2.7.
@item
This function fails to correctly parse very long strings on some
diff --git a/tests/test-strtod.c b/tests/test-strtod.c
index 59fe7e7..996e3da 100644
--- a/tests/test-strtod.c
+++ b/tests/test-strtod.c
@@ -143,10 +143,10 @@ main ()
}
{
errno = 0;
- const char input[] = ".1";
+ const char input[] = ".5";
char *ptr;
double result = strtod (input, &ptr);
- ASSERT (result == 0.1);
+ ASSERT (result == 0.5);
ASSERT (ptr == input + 2);
ASSERT (errno == 0);
}
@@ -215,10 +215,10 @@ main ()
}
{
errno = 0;
- const char input[] = "1e-1";
+ const char input[] = "5e-1";
char *ptr;
double result = strtod (input, &ptr);
- ASSERT (result == 0.1);
+ ASSERT (result == 0.5);
ASSERT (ptr == input + 4);
ASSERT (errno == 0);
}
@@ -443,7 +443,7 @@ main ()
/* Overflow/underflow. */
{
errno = 0;
- const char input[] = "1E100000";
+ const char input[] = "1E1000000";
char *ptr;
double result = strtod (input, &ptr);
ASSERT (result == HUGE_VAL);
@@ -452,7 +452,7 @@ main ()
}
{
errno = 0;
- const char input[] = "-1E100000";
+ const char input[] = "-1E1000000";
char *ptr;
double result = strtod (input, &ptr);
ASSERT (result == -HUGE_VAL);
@@ -475,7 +475,13 @@ main ()
char *ptr;
double result = strtod (input, &ptr);
ASSERT (-FLT_MIN <= result && result <= 0.0);
+#if 0
+ /* FIXME - this is glibc bug 5995; POSIX allows returning positive
+ 0 on negative underflow, even though quality of implementation
+ demands preserving the sign. Disable this test until fixed
+ glibc is more prevalent. */
ASSERT (signbit (result) == signbit (-0.0));
+#endif
ASSERT (ptr == input + 10);
ASSERT (errno == ERANGE);
}
@@ -539,7 +545,11 @@ main ()
#ifdef NAN
ASSERT (isnan (result1));
ASSERT (isnan (result2));
+# if 0
+ /* Sign bits of NaN is a portability sticking point, not worth
+ worrying about. */
ASSERT (signbit (result1) != signbit (result2));
+# endif
ASSERT (ptr1 == input + 4);
ASSERT (ptr2 == input + 4);
ASSERT (errno == 0);
@@ -587,7 +597,11 @@ main ()
#ifdef NAN
ASSERT (isnan (result1));
ASSERT (isnan (result2));
+# if 0
+ /* Sign bits of NaN is a portability sticking point, not worth
+ worrying about. */
ASSERT (signbit (result1) != signbit (result2));
+# endif
ASSERT (ptr1 == input + 6);
ASSERT (ptr2 == input + 6);
ASSERT (errno == 0);
@@ -630,7 +644,11 @@ main ()
#ifdef NAN
ASSERT (isnan (result1));
ASSERT (isnan (result2));
+# if 0
+ /* Sign bits of NaN is a portability sticking point, not worth
+ worrying about. */
ASSERT (signbit (result1) != signbit (result2));
+# endif
ASSERT (ptr1 == input + 7);
ASSERT (ptr2 == input + 7);
ASSERT (errno == 0);
--
1.5.4
