On the above platform, functions in C++ header files that are found by g++ via
the CPLUS_INCLUDE_PATH, are treated as C functions. This leads to function
declaration conflict errors when that header defines multiple overloaded
versions of a function.

This problem only occurs on solaris, with gcc 3.x. Everything works fine on
linux, or with solaris and gcc 2.95.

If the header file can be found on standard system paths, or  is in the current
directory, or its directory is specified explicitly with a -I flag to the
compiler, then everything works fine. The problem only happens when the header
is found via CPLUS_INCLUDE_PATH.

The example given below uses these two files:

foo.h:
-----------------------------------------
// Dummy overloaded prototypes

void foo(int x);
void foo(double x);
-----------------------------------------


and foo.cc:
-----------------------------------------
#include "foo.h"

int main() {
  main();
}
-----------------------------------------

Simply compiling foo.cc causes errors on gcc 3.x on solaris, if foo.h is found
via the CPLUS_INCLUDE_PATH.

This PR seems similar to 4662, but there was no resolution to that one that I
could see. A search on the web seems to turn up a number of people reporting
similar problems in other places.

Release:
gcc-3.0.3

Environment:
sparc-sun-solaris2.8

How-To-Repeat:
Using bash:

cerrogrande[tmp] tar xvf foo.tar
foo/
foo/bar/
foo/bar/foo.cc
foo/foo.h
cerrogrande[tmp] cd foo/bar
cerrogrande[bar] export CPLUS_INCLUDE_PATH=..
cerrogrande[bar] g++ foo.cc -c
In file included from foo.cc:1:
../foo.h:4: declaration of C function `void foo(double)' conflicts with
../foo.h:3: previous declaration `void foo(int)' here
cerrogrande[bar] 



Or in more detail:

cerrogrande[bar] g++ foo.cc -c -v
Reading specs from /usr/local/lib/gcc-lib/sparc-sun-solaris2.8/3.0.3/specs
Configured with: ../configure --with-as=/usr/local/bin/as
--with-ld=/usr/local/bin/ld --enable-libgcj
Thread model: posix
gcc version 3.0.3
 /usr/local/lib/gcc-lib/sparc-sun-solaris2.8/3.0.3/cc1plus -v -D__GNUC__=3
-D__GNUC_MINOR__=0 -D__GNUC_PATCHLEVEL__=3 -Dsparc -Dsun -Dunix -D__svr4__
-D__SVR4 -D__sparc__ -D__sun__ -D__unix__ -D__svr4__ -D__SVR4 -D__sparc -D__sun
-D__unix -Asystem=unix -Asystem=svr4 -D__NO_INLINE__ -D__STDC_HOSTED__=1
-D_XOPEN_SOURCE=500 -D_LARGEFILE_SOURCE=1 -D_LARGEFILE64_SOURCE=1
-D__EXTENSIONS__ -D__GCC_NEW_VARARGS__ -Acpu=sparc -Amachine=sparc foo.cc
-D__GNUG__=3 -D__GXX_DEPRECATED -D__EXCEPTIONS -D__GXX_ABI_VERSION=100 -quiet
-dumpbase foo.cc -version -o /var/tmp/ccutpIcL.s
GNU CPP version 3.0.3 (cpplib) (sparc)
GNU C++ version 3.0.3 (sparc-sun-solaris2.8)
        compiled by GNU C version 3.0.3.
ignoring nonexistent directory "/usr/local/sparc-sun-solaris2.8/include"
#include "..." search starts here:
#include <...> search starts here:
 ..
 /usr/local/include/g++-v3
 /usr/local/include/g++-v3/sparc-sun-solaris2.8
 /usr/local/include/g++-v3/backward
 /usr/local/include
 /usr/local/lib/gcc-lib/sparc-sun-solaris2.8/3.0.3/include
 /usr/include
End of search list.
In file included from foo.cc:1:
../foo.h:4: declaration of C function `void foo(double)' conflicts with
../foo.h:3: previous declaration `void foo(int)' here
cerrogrande[bar] 


But on the other hand:

cerrogrande[bar] g++ foo.cc -c -I..
cerrogrande[bar] 

works fine...