[cfe-users] C/C++ system include dirs when cross-compiling
Hi list, I'm using clang to cross-compile for a sparc-target. Except for the compiler I (seem to) rely entirely on gcc-tools (ld, asm). I doing this by passing the -B - flag to clang. I'm now facing an issue where I would like to have clang use the c++-system-includes of my gcc-installation. When I dump the considered include-dirs with echo | sparc-elf-gcc -nostdlib -xc++ -E -Wp,-v - -fsyntax-only I'm getting a list of all the paths I'm looking for. Doing the same with clang (even with the -B-flag) having the -target-flag set, the list is empty. What is the proper way to let clang now where to find the system-includes in cross-compilation scenarios? I'm now using a script which generates -isystem-arguments which based on a list generated with a call as shown above. Should the list be derived from the -B-argument? best regards, -- Patrick. ___ cfe-users mailing list cfe-users@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
Re: [cfe-users] C/C++ system include dirs when cross-compiling
Hi Arnaud, On Thu, 24 Mar 2016 16:48:30 +0100 Arnaud Allard de Grandmaison wrote: > Hi Patrick, > > This is a common case when cross compiling, so clang knows how to use > a gcc-toolchain installation: you just have to pass it the > "--sysroot=..." and "--toolchain=..." arguments, and it will get the > header files and linker / assembler for your target --- assuming your > gcc-toolchain has a standard layout. It wasn't that straight-forward for me to find information about this "common case" as you call it ;-) . I initially had problems finding the -B option of clang (it is not listed in --help nor in --help-hidden). The --gcc-toolchain-argument does not work with the clang I built: ../../upstream/build/bin/clang++ --gcc-toolchain clang-3.8: error: unsupported option '--gcc-toolchain' clang-3.8: error: no input files But it is listed in --help. Is this a bug or is my build faulty? I tried --sysroot and it made the path appear in the clang-system-include-paths. But my gcc-toolchain does not have the c++-headers in there just the C ones. C++ header files were installed to path/to/toolchain//include/c++/ I generated my gcc-toolchain with crosstool-ng. I haven't found yet the option (if any) to tell ct-ng to install c++-headers in sysroot as well. Thank you for your input. regards, -- Patrick. ___ cfe-users mailing list cfe-users@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
Re: [cfe-users] C/C++ system include dirs when cross-compiling
On Thu, 24 Mar 2016 23:08:40 +0100 Patrick Boettcher via cfe-users wrote: > Hi Arnaud, > > On Thu, 24 Mar 2016 16:48:30 +0100 > Arnaud Allard de Grandmaison wrote: > > > Hi Patrick, > > > > This is a common case when cross compiling, so clang knows how to > > use a gcc-toolchain installation: you just have to pass it the > > "--sysroot=..." and "--toolchain=..." arguments, and it will get the > > header files and linker / assembler for your target --- assuming > > your gcc-toolchain has a standard layout. > > It wasn't that straight-forward for me to find information > about this "common case" as you call it ;-) . > > I initially had problems finding the -B option of clang (it is > not listed in --help nor in --help-hidden). > > The --gcc-toolchain-argument does not work with the clang I built: > > ../../upstream/build/bin/clang++ --gcc-toolchain > clang-3.8: error: unsupported option '--gcc-toolchain' > clang-3.8: error: no input files Stupid me, it is of course --gcc-toolchain=/path/to , I tried --gcc-toolchain /path/to - which gave me the same error. It accepts the argument, but it doesn't seem to use anything of it. I will dig into it. -- Patrick. ___ cfe-users mailing list cfe-users@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
Re: [cfe-users] C/C++ system include dirs when cross-compiling
Hi, On Thu, 24 Mar 2016 16:48:30 +0100 Arnaud Allard de Grandmaison wrote: > Hi Patrick, > > This is a common case when cross compiling, so clang knows how to use > a gcc-toolchain installation: you just have to pass it the > "--sysroot=..." and "--toolchain=..." arguments, and it will get the > header files and linker / assembler for your target --- assuming your > gcc-toolchain has a standard layout. I'm getting back to you after (some vacations and) having compared linaro's latest toolchain to the one I built. Linaro provides a sysroot-package which does not contain c++-header-files. Instead they are located in the gcc-package, as in my package, in /include/c++// I'm unable to convince clang(++) to include this search-dir using any combination of the following options with variations on the path name. --gcc-toolchain= -B --sysroot= sysroot works a little bit, but only for c-include which are located in /usr/include. Using gcc-linaro-5.3-2016.02-x86_64_aarch64-elf I would highly appreciate an example of how to invoke clang++ for cross-compilation with this gcc and its includes? My current try is: TARGET=aarch64-elf \ GCC_ROOT=~/Downloads/gcc-linaro-5.3-2016.02-x86_64_aarch64-elf \ ~/devel/upstream/build/bin/clang++ \ -v \ --target=$TARGET \ --gcc-toolchain=$GCC_ROOT/$TARGET \ --sysroot=$GCC_ROOT/$TARGET/sysroot \ -nostdlib \ -o testCCompiler.cpp.obj -c \ -std=c++11 \ test.cpp test.cpp is empty except #include which it doesn't find. Linaro's gcc has all include paths in its search list. Thanks in advance for any help, -- Patrick. ___ cfe-users mailing list cfe-users@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
Re: [cfe-users] C/C++ system include dirs when cross-compiling
On Thu, 31 Mar 2016 12:18:41 -0400 Jeffrey Walton wrote: > > TARGET=aarch64-elf \ > > GCC_ROOT=~/Downloads/gcc-linaro-5.3-2016.02-x86_64_aarch64-elf \ > > ~/devel/upstream/build/bin/clang++ \ > > -v \ > > --target=$TARGET \ > > --gcc-toolchain=$GCC_ROOT/$TARGET \ > > --sysroot=$GCC_ROOT/$TARGET/sysroot \ > > -nostdlib \ > > -o testCCompiler.cpp.obj -c \ > > -std=c++11 \ > > test.cpp > > > > test.cpp is empty except #include which it doesn't find. > > > > Linaro's gcc has all include paths in its search list. > > > > Thanks in advance for any help, > > We found Ubuntu (perhaps Debian) broke the cross-compile using > --sysroot some time ago. Also see "g++-arm-linux-gnueabi cannot > compile a C++ program with --sysroot", > https://bugs.launchpad.net/ubuntu/+source/gcc-defaults-armel-cross/+bug/1375071. I forgot to mention that I'm using llvm/clang 3.8 which I built myself. > We were working around the broken C++ header includes by specifically > calling them out with -I. See the comment "Fix C++ header paths for > Ubuntu" at > https://github.com/weidai11/cryptopp/blob/master/setenv-embedded.sh#L96. That's what I did as well to work around. > ARM's "GCC ARM Embedded Tools" works as expected. Its maintained by > ARM employees. Also see the PPA at > https://launchpad.net/gcc-arm-embedded. Yeah, but is the problem clang not looking into the right paths or gcc-toolchains having changed their layouts. Comparing older gcc-toolchains I had in my attic it seems that clang is not looking hard enough. -- Patrick. ___ cfe-users mailing list cfe-users@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
Re: [cfe-users] C/C++ system include dirs when cross-compiling
On Thu, 31 Mar 2016 13:56:48 -0400 Jeffrey Walton wrote: > >> We were working around the broken C++ header includes by > >> specifically calling them out with -I. See the comment "Fix C++ > >> header paths for Ubuntu" at > >> https://github.com/weidai11/cryptopp/blob/master/setenv-embedded.sh#L96. > > > > That's what I did as well to work around. > > > >> ARM's "GCC ARM Embedded Tools" works as expected. Its maintained by > >> ARM employees. Also see the PPA at > >> https://launchpad.net/gcc-arm-embedded. > > > > Yeah, but is the problem clang not looking into the right paths or > > gcc-toolchains having changed their layouts. Comparing older > > gcc-toolchains I had in my attic it seems that clang is not looking > > hard enough. > > It sounds like a Clang bug. If you can reduce it to a minimal test > case, consider filing a bug report. After some more investigation I think the non-finding of c++-includes is related to target-name. From it clang derives the OS and it is essentially the OS is the tuple which enables the search of the c++-include-paths. On my host it is Linux::AddClangCXXStdlibIncludeArgs which is doing the job. When cross-compiling I'm with Generic_GCC which doesn't do anything (it is empty). I can regenerate a toolchain which will be called -linux, this might help. Even though it is wrong, I'm on a bare-metal-machine. I just want the (standard-)includes. regards, -- Patrick. ___ cfe-users mailing list cfe-users@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users
