[GRASS5] CVS version of grass5 failing to compile nviz & r.in.gdal because of -ldl flag
Scott W Mitchell
smitch at eos.geog.utoronto.ca
Tue, 19 Nov 2002 13:42:56 -0500
OK, sorry to be answering my own post for the second time, but I found
the answer, so here it is to make sure it's in the archives for the
next person... at least I learned and hopefully nobody else (i.e. Glynn
- thanks for all the help !) will expend effort on this before seeing
that I have an answer.
Took a break and with a fresh mind, finally paid attention to the fact
that I only had the .dylib version of libdl, and investigated that
further. Turned out that at some point the fink dlcompat package got
broken into 3 sub-packages, and I didn't have the -dev package that is
needed to install the .a version of the library, AND it installs a
"versionless" softlink to libdl.0.dylib, taking care of the version
number that I worked around in my previous post.
So the answer is that Mac OS X users will need the dlcompat-dev package
installed if they are using fink - there are also other ways to install
the dlcompat package, but no matter how they do it, they need those
bits - you want all three libdl files available:
[fats:GMSL/NVIZ2.2/src] smitch% fink list apropos dlcompat
Information about 1752 packages read in 3 seconds.
i dlcompat 20021117-1 Dynamic loading compatibility library
i dlcompat-dev 20021117-1 headers and static libraries for
i dlcompat-shlibs 20021117-1 shared libraries for dlcompat
[fats:GMSL/NVIZ2.2/src] smitch% ls -l /sw/lib/libdl*
-rw-r--r-- 1 root unknown 20852 Nov 18 11:28 /sw/lib/libdl.0.dylib
-rw-r--r-- 1 root unknown 15964 Nov 18 11:28 /sw/lib/libdl.a
lrwxr-xr-x 1 smitch unknown 13 Nov 19 13:28 /sw/lib/libdl.dylib
On Tuesday, November 19, 2002, at 12:23 PM, Scott W Mitchell wrote:
> A slight update, since it looks like it may explain what's happening;
> a random brain electron just fired, and I tried changing -ldl to
> -ldl.0 (i.e. added a "zero" version number since I have
> /sw/lib/libdl.0.dylib in my system) in a call to gcc, and it compiled
> the output file despite some TclTk symbol warnings. So I'm not sure
> what this means in terms of a portable solution as opposed to Darwin
> weirdness, but it gets around the error without taking away the DLLIB
>> On Monday, November 18, 2002, at 11:53 PM, Glynn Clements wrote:
>>> Scott W Mitchell wrote:
>>>> Digging deeper, the error was the same in both cases - when it
>>>> tries to
>>>> link everything together there's a lib flag for the DL library
>>>> and libdl isn't found. IF I understand correctly (and that's a big
>>>> if), libopen() etc are provided by dlcompat in this OS so there is
>>>> such DL library.
>>>> So... I tracked down the -ldl call to the head file, and just made
>>>> DLLIB variable empty in my copy of head.powerpc-apple-darwin6.1 -
>>>> then tried to compile NVIZ and it does so without an error.
>>> 1. The use of $(DLLIB) by NVIZ is gratuitous; the NVWISH2.2 binary
>>> doesn't directly call dlopen() etc.
>>> It's possible that one of the libraries against which NVIZ is linked
>>> may require libdl on some platforms; however, that should be handled
>>> by configure when detecting the library in question (libtcl and libGL
>>> are both candidates; configure *does* check for $DLLIB when checking
>>> 2. r.in.gdal *does* use dlopen() unless you use the --with-gdal
>>> configure switch. However, this is handled by configure, which adds
>>> $DLLIB to GDAL_LIBS where appropriate (i.e. when you aren't using
>>> 3. However, neither of the above should really matter, because DLLIB
>>> should be empty unless configure actually finds dlsym() in libdl.
>>> Specifically, configure:
>>> a) checks whether dlsym() is available without any additional
>>> switches; if it is, then DLLIB is set to empty.
>>> b) otherwise, it checks whether dlsym() is available when linking
>>> against the "dl" library (i.e. with "-ldl"); if it is, then DLLIB is
>>> set to "-ldl".
>>> c) otherwise, DLLIB is set to empty.
>>> The resulting value of DLLIB is used in the rest of the configure
>>> script, and is substituted when converting src/CMD/head/head.in into
>>> src/CMD/head/head (which is later renamed to e.g.
>>> So, I'm curious as to why configure decided to set DLLIB to "-ldl" if
>>> you don't have a library with that name.
>>> Glynn Clements <email@example.com>
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