#include_next not working in g++-8

[jeroen]

As a temporary workaround for #450 I was able to build a --static-gcc toolchain using --no-extras. The basic C stuff works well I was able to build my application.

However for C++ I keep getting errors about #include_next in headers:

In file included from libjson/Source/JSONMemory.h:4,
                 from libjson/Source/JSONChildren.h:6,
                 from JSONChildren.cpp:1:
C:/gcc8/mingw32/i686-w64-mingw32/include/c++/cstdlib:75:15: fatal error: stdlib.h: No such file or directory
 #include_next <stdlib.h>
               ^~~~~~~~~~

and

In file included from ../inst/include/Rcpp/platform/compiler.h:100,
                 from ../inst/include/Rcpp/r/headers.h:48,
                 from ../inst/include/RcppCommon.h:38,
                 from ../inst/include/Rcpp.h:27,
                 from Date.cpp:31:
C:/gcc8/mingw32/i686-w64-mingw32/include/c++/cmath:45:15: fatal error: math.h: No such file or directory
 #include_next <math.h>
               ^~~~~~~~

I confirmed that stdlib.h and math.h are definitly installed. Is this perhaps a problem in mingw-w64 or an upstream gcc regression? @mingwandroid

[niXman]

I think this is a gcc regression...

Try to rebuild with commented out this line: https://github.com/niXman/mingw-builds/blob/develop/scripts/gcc-trunk.sh#L73

[jeroen]

Yes that fixed it! Thank you!

Filed upstream bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85145

[jeroen]

GCC 8 has been released. Maybe we should comment that out by default?

[niXman]

Please explain, what is the relationship between this bug and the release of gcc-8.1?

[jeroen]

As I understand it, the bug still persists in gcc 8.1 release.