https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=213217
Dimitry Andric <[email protected]> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |[email protected] Status|New |Closed Resolution|--- |Rejected --- Comment #2 from Dimitry Andric <[email protected]> --- Short answer: Don't use -isystem /usr/include. If you do so for C++ programs, you mess up the include search path order. If you must do it for some reason, you must also add -isystem entries for the C++ include directories, and at the front of the list. For example, a C++ program will use the following search path by default (where x.y.z is the clang version): #include "..." search starts here: #include <...> search starts here: /usr/include/c++/v1 /usr/bin/../lib/clang/x.y.z/include /usr/include End of search list. >From libc++ 3.8.0 onwards, if you include a C standard header, such as <cstddef>, you will get libc++'s wrapper header first. This header sets up a few things, then does #include_next<stddef.h>, and with the above search path, this finds /usr/include/stddef.h. (We don't install clang's internal stddef.h, since it is not compatible with our system headers yet.) However, if you add -isystem /usr/include, you force /usr/include to be the first in the list, e.g. the search path will become: ignoring duplicate directory "/usr/include" #include "..." search starts here: #include <...> search starts here: /usr/include /usr/include/c++/v1 /usr/bin/../lib/clang/x.y.z/include End of search list. If you now include <cstddef>, and it eventually does #include_next<stddef.h>, it will attempt to search the paths *after* /usr/include/c++/v1, and will not be able to find the header. Summary: If for some reason you must completely rebuild the header search path from scratch, you need to add -isystem /usr/include/c++/v1 *before* -isystem /usr/include. But it is better not to do this at all. :) -- You are receiving this mail because: You are the assignee for the bug. _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain To unsubscribe, send any mail to "[email protected]"
