Can someone point to any detailed information about how these flags work? I have a custom-compiled version of GCC on Linux and I'm trying to build Clang 4.0.0 for this system as well. I would like it to use libstdc++ from my custom-compiled GCC installation to allow linking of other libraries built with libstdc++.
I also have a sysroot that I use with GCC so it compiles against a known set of system headers and libraries (based on Red Hat 6.3 in this case). This sysroot is directly extracted from a Red Hat system (technically, it's extracted from the RPMs) so the layout is straightforward and using the --sysroot for GCC locates it without any problems. However, I can't get clang to work with either of these environments no matter what options I provide it. For --sysroot for example, I have this: /my/sysroot/lib /my/sysroot/lib64 /my/sysroot/usr/include /my/sysroot/usr/lib /my/sysroot/usr/lib64 /my/sysroot/usr/libexec If I use "gcc --sysroot=/my/sysroot" all works fine. If I use "clang --syroot=mysysroot" no system headers are found. I used strace on the clang binary to try to figure out what it's looking for and it searches for all of these things in my sysroot directory: /my/sysroot/usr/local/cuda /my/sysroot/usr/local/cuda-8.0 /my/sysroot/usr/local/cuda-7.5 /my/sysroot/usr/local/cuda-7.0 /my/sysroot/lib/x86_64-linux-gnu /my/sysroot/lib/x86_64-generic-linux-gnu > /my/sysroot/lib/../lib64 /my/sysroot/usr/lib/x86_64-generic-linux-gnu > /my/sysroot/usr/lib/../lib64 /my/sysroot/usr/lib/x86_64-generic-linux-gnu/../../lib64 > /my/sysroot/lib > /my/sysroot/usr/lib Of these only the four marked exist in my sysroot. But the big thing here is that at no time does clang look for /my/sysroot/usr/include, and indeed when the preprocessor tries to find headers it doesn't look there, and none of my system header files are found! Do I have to add these myself with -isystem even when I specify --sysroot and the header directory is right there? Is --sysroot not intended to be used to locate header files? For --gcc-toolchain the situation is similar although clang looks in MANY more places to try to locate the GCC toolchain. However, I build GCC myself and I have a completely standard installation: what you get when you run make / make install after a configure --prefix. My GCC installation looks like: /my/gcc/bin /my/gcc/lib/gcc/x86_64-generic-linux-gnu/7.1.0/include /my/gcc/lib64 /my/gcc/libexec/gcc/x86_64-generic-linux-gnu/7.1.0 /my/gcc/x86_64-generic-linux-gnu/bin /my/gcc/x86_64-generic-linux-gnu/include/c++/7.1.0/... /my/gcc/x86_64-generic-linux-gnu/include/c++/7.1.0/x86_64-generic-linux-gnu/... /my/gcc/x86_64-generic-linux-gnu/lib /my/gcc/x86_64-generic-linux-gnu/lib64 (I have a GCC 6.2 install too and the layout is basically identical.) When I use --gcc-toolchain with clang it looks in about 50 different directories but doesn't seem to be able to locate this: a standard unmodified installation of GCC. I've tried numerous different values for --gcc-toolchain but none seem to work. Am I doing something wrong here? Or is this just not going to work and I'll have to figure out all the include directories, etc. I need by hand and add them via -isystem etc. myself? Thanks for any help you can provide! _______________________________________________ cfe-users mailing list cfe-users@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
