Hello everybody,

I am new to this list and to libcurl but I've found it a really cool and
very useful library.

But I believe to have found a bug in libcurl.m4 provided on the libcurl
website.

When configuring my GNU autotools project, which optionally
(default=yes) uses libcurl on a system without a (usable) libcurl
installation, but not specifying `--without-libcurl', configure
determines correctly that no libcurl is available, however, the LIBCURL
variable gets expanded to `LIBCURL = -lcurl' in the resulting
Makefiles.

I figured this is because of the test whether libcurl is available
through a user-supplied link line:

Quoting from libcurl.m4:

# we didn't find curl-config, so let's see if the user-supplied
# link line (or failing that, "-lcurl") is enough.
LIBCURL=${LIBCURL-"$_libcurl_ldflags -lcurl"}

Here the LIBCURL variable get set to `-lcurl' and is never reset again,
thus making it's way into the resulting Makefile. Although I don't
really see how this happens since when libcurl is detected to be
unusable no calls to AC_SUBST(LIBCURL) are made, as far as I could see.
NB: I am quite new to developing with GNU autotools and m4 has always
been a bit of black magic to me so I please forgive me if I am wrong
here.

Compiling the project with such a Makefile naturally results in an error
where the linker complains that it cannot find `-lcurl'.

Please find attached a small patch I created that fixed this bug for me,
at least on the systems I configure my autotools project on. The patch
also contains the definition of an AM_CONDITIONAL called `USE_LIBCURL'
to be used in a Makefile.am to be able to determine whether to include
certain source files in the build process or not, depending on the
availability of libcurl.

If I am wrong and this is not a bug but an error on my side please tell
me where I went wrong and how to avoid this problem. And disregard the
patch of course :) (although the conditional would certainly be useful
to others as well I guess?)

Thanks,

kind regards

Andreas

-- 
Andreas "daff" Ntaflos 
daff AT dword DOT org
Vienna, Austria 
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