Re: "make check" failure when building GNU m4 1.4.13 on Mac OS X Snow Leopard

[Eric Blake]

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According to Leo Davis on 11/5/2009 2:27 PM:
> Hello,
> 
> I tried building GNU m4 1.4.13 on a MacBook running Snow Leopard (10.6.1
> Intel).
> I have Xcode 3.2.1 installed (gcc is i686-apple-darwin10-gcc-4.2.1 (GCC)
> 4.2.1 (Apple Inc. build 5646) (dot 1) according to config.log).
> 
> The "make check" failure I'm seeing is:
> 
> test-strtod.c:647: assertion failed
> test-strtod.c:648: assertion failed
> FAIL: test-strtod

Thanks for the report.  From m4's perspective, this only affects use of
the format builtin, and only if you are trying to print floating point
values, so it's not that bad of a failure.  But if it really bothers you,
you can run 'gl_cv_func_strtod_works=no ./configure' and the failure
should disappear.  From gnulib's perspective, it means our strtod.m4
filter is not strict enough to detect the bugs in darwin's strtod()
implementation.

> 
> this corresponds to the source lines:
> 
>     ASSERT (ptr1 == input + 4);         /* OpenBSD 4.0, HP-UX 11.11,
> IRIX 6.5, OSF/1 5.1, Solaris 2.5.1, mingw */
>     ASSERT (ptr2 == input + 4);         /* OpenBSD 4.0, HP-UX 11.11,
> IRIX 6.5, OSF/1 5.1, Solaris 2.5.1, mingw */
> 
> in a block that starts with:
> 
>     const char input[] = "+nan(";

You may want to report this to Apple, since it is a bug in their libc.
Meanwhile, so I can better characterize the bug, can you tell me what
offset ptr1 and ptr2 are pointing at?  I'm guessing that darwin's strtod
is mistakenly consuming the unbalanced '(', since it did parse a NaN.

But even without understanding the full extent of the bug, I think this
should fix it, so that m4 1.4.14 works out of the box for you.  I'm
applying this:

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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>From 73d863ac524f017ad939fce7d19c35b6feb1246d Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Thu, 5 Nov 2009 20:48:01 -0700
Subject: [PATCH] strtod: detect darwin bug

* m4/strtod.m4 (gl_FUNC_STRTOD): Filter out darwin bug on "nan(".
Reported by Leo Davis.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog    |    6 ++++++
 m4/strtod.m4 |   10 +++++++++-
 2 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 1635de2..e8841d9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2009-11-06  Eric Blake  <address@hidden>
+
+       strtod: detect darwin bug
+       * m4/strtod.m4 (gl_FUNC_STRTOD): Filter out darwin bug on "nan(".
+       Reported by Leo Davis.
+
 2009-11-05  Eric Blake  <address@hidden>

        freopen-safer: new module
diff --git a/m4/strtod.m4 b/m4/strtod.m4
index 9769436..3bc8770 100644
--- a/m4/strtod.m4
+++ b/m4/strtod.m4
@@ -1,4 +1,4 @@
-# strtod.m4 serial 12
+# strtod.m4 serial 13
 dnl Copyright (C) 2002-2003, 2006-2009 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -64,6 +64,14 @@ numeric_equal (double x, double y)
     if (numeric_equal (value, value) || term != (string + 5))
       return 1;
   }
+  {
+    /* darwin 10.6.1 misparses "nan(".  */
+    const char *string = "nan(";
+    char *term;
+    double value = strtod (string, &term);
+    if (numeric_equal (value, value) || term != (string + 3))
+      return 1;
+  }
 ]])],
        [gl_cv_func_strtod_works=yes],
        [gl_cv_func_strtod_works=no],
-- 
1.6.5.rc1