On 2019-1-10 16:25 , Eric A. Borisch wrote: > As discussed here [1] on GitHub, 'curl-config --libs' is returning > results like this: > > -L/opt/local/lib -lcurl -lidn2 -lpsl -lssl -lcrypto -lssl -lcrypto -lz > > while 'pkg-config --libs libcurl' gives this: > > -L/opt/local/lib -lcurl > > The curl-config version results in lots of unnecessary libraries being > linked against by the resulting binary. As a result, executables > depending on libcurl (but not the underling lib API calls directly) can > break (unnecessarily) if they use the curl-config --libs output when the > underlying dependencies (like libidn2) change.
Libtool seems to overlink by design -- see our code to remove dependency_libs in .la files after destrooting. I guess it's sort of convenient from a certain point of view? Like "hey why are these zlib symbols I'm using not found, I'm linking with libpng which depends on zlib!" It gets a lot less convenient when you have to maintain a distro. > It looks like FreeBSD takes the approach (linked in the GitHub comments) > of modifying libtool's libtool.mk <http://libtool.mk> to change its > link_all_deplibs behavior (to "no") for a number of ports (any with > 'using libtool'.) > > Ubuntu does something similar to end up with a crow-barred clause of 'if > test "Xno" = "Xyes"; then' in curl-config such that --libs returns > '-lcurl' alone; I haven't tracked down their actual build scripts for this. > > RedHat 6 (I haven't checked 7) changes curl-config --libs to just call > 'pkg-config --libs libcurl' directly. > > Any thoughts on how to resolve this? Take the FreeBSD/Ubuntu approach of > patching libtool.mk <http://libtool.mk> at some point (for all ports? > for just curl?) to say link_all_deplibs="no"? Every OS on upstream GNU > libtool returns "yes" or "unknown" (="yes"), and you can google for > link_all_deplibs Debian to see some discussions of the pros and cons of > "no". It doesn't help that libtool's documentation gives this unhelpfully ambiguous definition of what link_all_deplibs means: "Whether libtool must link a program against all its dependency libraries." OK, sure, but what about whether it must link against all the dependencies' dependencies as well? Curl can be fixed with a simple patch to the configure script. I'm not sure if we should try to do something about libtool in general; it's no good fixing things there if we have to autoreconf the whole world to actually have the fix used. And we'll be fighting upstream's apparent design philosophy as well. - Josh
