On Fri, 17 Dec 2021 13:35:04 GMT, Erik Joelsson <er...@openjdk.org> wrote:
>> When running `configure`, using `--with-devkit=` to point to a typical linux >> devkit along with `--with-toolchain-path=` and `--with-toolchain-type=clang` >> to point to a clang-based toolchain results in: >> >> configure:75064: checking whether the C compiler works >> configure:75086: /dl/tools/clang -m64 -isysroot >> /dl/x86_64-linux-gnu-to-x86_64-linux-gnu/x86_64-linux-gnu/sysroot -isysroot >> /dl/x86_64-linux-gnu-to-x86_64-linux-gnu/x86_64-linux-gnu/sysroot -m64 >> -isysroot /dl/x86_64-linux-gnu-to-x86_64-linux-gnu/x86_64-linux-gnu/sysroot >> conftest.c >&5 >> d.lld: error: cannot open crt1.o: No such file or directory >> ld.lld: error: cannot open crti.o: No such file or directory >> ld.lld: error: cannot open crtbegin.o: No such file or directory >> ld.lld: error: unable to find library -lgcc >> ld.lld: error: unable to find library -lgcc_s >> ld.lld: error: unable to find library -lc >> ld.lld: error: unable to find library -lgcc >> ld.lld: error: unable to find library -lgcc_s >> ld.lld: error: cannot open crtend.o: No such file or directory >> ld.lld: error: cannot open crtn.o: No such file or directory >> clang-12: error: linker command failed with exit code 1 (use -v to see >> invocation) >> ``` >> This is because clang is unable to locate the gcc installation from the >> devkit. >> The gcc toolchain is not in the location clang expects in the sysroot >> (that's not how our devkits are structured). >> Note that it might go unnoticed on machines that have gcc installed because >> clang will fallback to system-global locations. >> >> We can help clang by letting it now about the gcc location in the devkit >> with `--gcc-toolchain=`. >> However that's not enough and we then get: >> >> ld.lld: error: cannot open crt1.o: No such file or directory >> ld.lld: error: cannot open crti.o: No such file or directory >> ld.lld: error: unable to find library -lc >> ld.lld: error: cannot open crtn.o: No such file or directory >> >> clang was able to locate the gcc support libraries but is not able to locate >> required system libraries. >> That's because `-isysroot` is not intended for libraries (only headers) but >> also because `-isysroot` has no effect for clang on linux (see >> [llvm#11503](https://bugs.llvm.org/show_bug.cgi?id=11503)). >> Using `--sysroot=` in this case (clang on linux) resolves this issue. > > Marked as reviewed by erikj (Reviewer). Thanks for the prompt review @erikj79! ------------- PR: https://git.openjdk.java.net/jdk/pull/6880
