[Bug plugins/65226] New: hgcc-plugin.h is unusable when GCC was build with non-system or in-tree GMP

[Bert.Wesarg at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65226

            Bug ID: 65226
           Summary: hgcc-plugin.h is unusable when GCC was build with
                    non-system or in-tree GMP
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: plugins
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Bert.Wesarg at googlemail dot com

Created attachment 34885
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34885&action=edit
file which includes gcc-plugin.h

When building a non-cross GCC with a non-system GMP (i.e., by specifying
--with-gmp or --with-gmp-include) or an in-tree GMP (i.e., having a gmp
directory in the source tree), and no system GMP is avaiable, than the
installed plugin headers are unusable. The following excersices the problem
with an in-tree GMP.

$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/home/wesarg/opt/gcc-4.9.2/libexec/gcc/x86_64-unknown-linux-gnu/4.9.2/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --prefix=/home/wesarg/opt/gcc-4.9.2
--enable-languages=c,c++,fortran --disable-nls --enable-checking=yes
--disable-werror --disable-bootstrap
Thread model: posix
gcc version 4.9.2 (GCC) 

Compiling the attached test file, which just includes the "gcc-plugin.h"
header, results in this error:

$ g++ -save-temps -c -I$(g++ -print-file-name=plugin/include)
include-gcc-plugin.cc 
In file included from
/home/wesarg/opt/gcc-4.9.2/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/plugin/include/gcc-plugin.h:28:0,
                 from include-gcc-plugin.cc:1:
/home/wesarg/opt/gcc-4.9.2/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/plugin/include/system.h:647:17:
fatal error: gmp.h: No such file or directory
 #include <gmp.h>
                 ^
compilation terminated.

This should be unralated to PR 55961, as this handled cross builds, i.e., build
!= host.