On 5 July 2012 15:53, Vincent Lefevre wrote: > On 2012-07-05 13:37:11 +0100, Jonathan Wakely wrote: >> On 5 July 2012 13:21, Vincent Lefevre wrote: >> > On 2012-07-05 15:07:53 +0300, Kai Ruottu wrote: >> >> The '--with-*' options only advice the compile time linker to find >> >> the right libraries but don't do anything for the runtime >> >> situation... >> > >> > Ah, OK. Why isn't this fixed, e.g. by adding --with-* paths to >> > the runpath of the generated executables needed for the build? >> >> The --with-xxx options only affect -I and -L >> >> GCC never adds runpaths to executables by default. This is also a FAQ: >> http://gcc.gnu.org/faq.html#rpath > > No, this FAQ covers the executables that are generated for the user > by the build (e.g. when the user runs the gcc command), not those > used for the build. The GCC build system doesn't set an RPATH in GCC for the same reason GCC doesn't set an RPATH in the executables it produces. It's a GCC policy. When bootstrapping GCC is built by GCC, so an answer explaining why GCC doesn't set RPATH in executables produced by GCC is entirely relevant. > For instance, to build MPFR when using --with-gmp=GMP_DIR, setting > LD_LIBRARY_PATH is not necessary for the build and "make check". > But after installing MPFR, if the user wants to use it and that > GMP can be found in GMP_DIR, the user may need to set up > LD_LIBRARY_PATH. GCC is different. Feel free to suggest changing that, but until that happens the docs reflect reality. >> > I'd say that the goal of the --with-* options is to provide the >> > paths when they are not in the default environment (including >> > the runtime linker). >> >> What if the location of those libs during bootstrap is not the same as >> the location will be when the installed compiler is used? > > Doesn't LD_LIBRARY_PATH have the precedence? There are several ways to tell the runtime loader how to find the libraries, users can decide which to use. If they use the DT_RPATH section then that has precedence over LD_LIBRARY_PATH. If they use LD_LIBRARY_PATH then it has precedence over DT_RUNPATH or ldconfig. The --with-xxx options don't use any method. You can use LD_RUN_PATH or LD_LIBRARY_PATH during the build to control it if you want to. I consider it much simpler to install the support libs in standard locations or to build them in-tree, and the problem simply doesn't exist, which is the best option for at least 90% of people building GCC. > Or if the locations > of the libraries have definitely changed, can't the user update > the rpath with a utility like chrpath? That's not widely available. You asked where the problem came from, so I pointed you to the relevant documentation which answers the question and says how to avoid the problem. Now you're arguing about whether it should be that way, which is a different discussion and not one I'm interested in right now.
