After b18cb9c4716, --sysroot no longer applies to C++ system include directory #44268
Description
| Bugzilla Link | 44923 |
| Resolution | FIXED |
| Resolved on | Feb 19, 2020 04:32 |
| Version | trunk |
| OS | All |
| Blocks | #43900 |
| CC | @zmodem,@zygoloid,@sthibaul,@smeenai |
Extended Description
In b50e8c5 the -stdlib++-isystem flag is introduced, for reasons explained in the commit message.
However, the way it is implemented appears to break --sysroot, where such a sysroot points to a directory with correctly populated C and C++ headers. For instance, during the FreeBSD buildworld process, we set up a directory:
/usr/obj/usr/src/amd64.amd64/tmp/usr/include
which has the C headers, and under it also the libc++ headers, in:
/usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1
With clang++ 9.0.1, pointing to such a sysroot with --sysroot, and compiling a simple "hello world" program, the C++ system include directory is correctly appended to the sysroot path, e.g.:
$ clang++-9.0.1 --sysroot=/usr/obj/usr/src/amd64.amd64/tmp -v -c helloworld.cpp
FreeBSD clang version 9.0.1 ([email protected]:llvm/llvm-project.git c1a0a21) (based on LLVM 9.0.1)
Target: x86_64-unknown-freebsd13.0
Thread model: posix
InstalledDir: /usr/bin
"/usr/bin/clang++-9.0.1" -cc1 -triple x86_64-unknown-freebsd13.0 -emit-obj -mrelax-all -disable-free -main-file-name helloworld.cpp -mrelocation-model static -mthread-model posix -mdisable-fp-elim -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -v -coverage-notes-file /tmp/helloworld.gcno -resource-dir /usr/lib/clang/9.0.1 -isysroot /usr/obj/usr/src/amd64.amd64/tmp -internal-isystem /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1 -fdeprecated-macro -fdebug-compilation-dir /tmp -ferror-limit 19 -fmessage-length 160 -fobjc-runtime=gnustep -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -faddrsig -o helloworld.o -x c++ helloworld.cpp
clang -cc1 version 9.0.1 based upon LLVM 9.0.1 default target x86_64-unknown-freebsd13.0
ignoring nonexistent directory "/usr/lib/clang/9.0.1/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1 <--- THIS IS CORRECT
/usr/obj/usr/src/amd64.amd64/tmp/usr/include
End of search list.
With clang++ 10.0.0 (so after b50e8c5), this no longer happens, and it reverts back to the host system's C++ include directory instead:
$ clang++-10.0.0 --sysroot=/usr/obj/usr/src/amd64.amd64/tmp -v -c helloworld.cpp
FreeBSD clang version 10.0.0 ([email protected]:llvm/llvm-project.git 90c7807)
Target: x86_64-unknown-freebsd13.0
Thread model: posix
InstalledDir: /usr/bin
(in-process)
"/usr/bin/clang++-10.0.0" -cc1 -triple x86_64-unknown-freebsd13.0 -emit-obj -mrelax-all -disable-free -main-file-name helloworld.cpp -mrelocation-model static -mthread-model posix -mframe-pointer=all -fno-rounding-math -masm-verbose -mconstructor-aliases -munwind-tables -target-cpu x86-64 -dwarf-column-info -fno-split-dwarf-inlining -debugger-tuning=gdb -v -resource-dir /usr/lib/clang/10.0.0 -isysroot /usr/obj/usr/src/amd64.amd64/tmp -internal-isystem /usr/bin/../include/c++/v1 -fdeprecated-macro -fdebug-compilation-dir /tmp -ferror-limit 19 -fmessage-length 160 -fgnuc-version=4.2.1 -fobjc-runtime=gnustep -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -faddrsig -o helloworld.o -x c++ helloworld.cpp
clang -cc1 version 10.0.0 based upon LLVM 10.0.0git default target x86_64-unknown-freebsd13.0
#include "..." search starts here:
#include <...> search starts here:
/usr/bin/../include/c++/v1 <--- THIS IS WRONG
/usr/lib/clang/10.0.0/include
/usr/obj/usr/src/amd64.amd64/tmp/usr/include
End of search list.