Re: mdemo ltdl failure

[Charles Wilson]

Ralf Wildenhues wrote:
> * Charles Wilson wrote:
> > This is because the test is just too ugly for words, not to mention 
> > brittle. Trying to tease out malloc issues outside of a dedicated malloc 
> > testsuite is just plain silly.
>
> I think the biggest problem with the previous patch was that it was
> relying so much on undefined behavior, that is not only undefined by any
> relevant standard, but also likely to be explicitly treated in very
> unpredictable ways by different systems/compilers.

Yes, I knew it was, which was why all "error" conditions in the test 
resulted in the test reporting *success*.  I was hoping during 
discussion that somebody would have a better suggestion than "punt and 
use version numbers and explicit OS hacks, even tho that is not the 
Autoconf Way".  But nobody commented on the patch until I raised it in 
private correspondence with BobF.  Now, I just don't think there IS any 
way of actually detecting the error that isn't horrifyingly ugly.

And I felt really dirty after posting the original patch. :-)

> > > (4) linux (whose system argz is OK)
> > >     --detects success, builds using system argz, works.
> > > (5) linux, but with $lt_cv_sys_argz_works=no.
> > >     --doesn't run the test, and builds using libltdl argz. works.
> > > (6) mingw, which doesn't have any system argz facility at all
> > >     --the test is not run
> > >     --builds successfully with libltdl's argz
> > Did not run these tests. configury and sourcecode paths unchanged from 
> > original path so these should obviously still work.  But I'll retest if 
> > desired.
>
> It's a good choice of testing, and should be done again with the final
> patch.  Plus one test on Solaris with its /bin/sh.  (Just noting this,
> I can probably do these tests then.)

will do for linux & mingw, but have no unencumbered access to solaris at 
present.

> Some comments to the patch:
>
> > --- libltdl/m4/argz.m4  25 Mar 2006 11:05:02 -0000      1.3
> > +++ libltdl/m4/argz.m4  17 Mar 2007 06:09:50 -0000
> [...]
> > +            os_ver=$(uname -r | $SED -e 's,^\([[0123456789\.]]*\).*,\1,')
> > +            os_major=${os_ver%%\.*}
> > +            os_micro=${os_ver##*\.}
> > +            os_minor=${os_ver%\.*}
> > +            os_minor=${os_minor##*\.}
>
> You can not use the $(cmd) and the ${var%%pattern} constructs,

address@hidden and I checked to make sure those were fully supported by Posix 
Shell and weren't just convenient bashisms.

> Solaris'
> shell will barf when parsing the code (i.e., even if it's inside a
> conditional branch that is not executed).  Use `cmd` and sed or expr
> instead, see the Autoconf manual's chapter on portable shell.

Geez, solaris sux.  You think they might consider shipping a posix 
compliant /bin/sh sometime this century?

> > +            AS_IF([test "$os_major" -gt "1"],[lt_cv_sys_argz_works=yes],dnl
> > +                 [test "$os_minor" -gt "5"],[lt_cv_sys_argz_works=yes],dnl
> > +                 [test "$os_micro" -gt "24"],[lt_cv_sys_argz_works=yes],dnl
>
> No need for double quoting the literal integers.  And if it can happen
> that $os_micro is the empty string (which I'll consider quite likely),
> then double quoting isn't enough precaution against error output, as 
> "" isn't interpreted by test as a number.

Okay, but actually, all cygwin releases are guaranteed to have non-empty 
major, minor, and micro numbers -- and we're inside a $host_os == cygwin 
block, here.  If I update the os_* variable assignments with protection 
against empty (default to "0"?), I'll move it outside the case block so 
that if any other "bad" systems are discovered they can be added more 
easily -- although I doubt that there are any.

> BTW, what are all the dnl's here for?  If they're necessary in some way,
> that would indicate that AS_IF had a bug.  

Habit. I'll remove 'em all and see what breaks.

> Ahh, that reminds me, AS_IF
> has only been made n-ary in 2.60, and we intend to support 2.59.  Please
> use plain `if..else' or nested AS_IF instead, thanks.

That'll teach me to read the manual. I didn't realize it was n-ary until 
I did so, and thought: Cool!  Never realizing I was reading the 2.61 
manual...

--
Chuck