[Bug libstdc++/70129] New: [6 Regression] stdlib.h: No such file or directory when using -isystem /usr/include

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70129

            Bug ID: 70129
           Summary: [6 Regression]  stdlib.h: No such file or directory
                    when using -isystem /usr/include
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
  Target Milestone: ---

markus@x4 tmp % echo "#include<algorithm>" | g++ -x c++ -isystem /usr/include -
In file included from
/usr/lib/gcc/x86_64-pc-linux-gnu/6.0.0/include/g++-v6/bits/stl_algo.h:59:0,
                 from
/usr/lib/gcc/x86_64-pc-linux-gnu/6.0.0/include/g++-v6/algorithm:62,
                 from <stdin>:1:
/usr/lib/gcc/x86_64-pc-linux-gnu/6.0.0/include/g++-v6/cstdlib:75:25: fatal
error: stdlib.h: No such file or directory
 #include_next <stdlib.h>
                         ^
compilation terminated.

gcc-5 and older is fine.