extend.texi (gnu_inline funtion attribute): Document C++ behavior.

extend.texi (gnu_inline funtion attribute): Document C++ behavior.

gcc/ChangeLog:
* doc/extend.texi (gnu_inline funtion attribute): Document C++
behavior.
gcc/cp/ChangeLog:
* decl.c (GNU_INLINE_P): New.
(duplicate_decls): Handle gnu_inline.  Merge attributes and
some flags in overriding definitions.
(redeclaration_error_message): Handle gnu_inline.
(start_preparsed_function): Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/ext/gnu-inline-common.h: New.
* g++.dg/ext/gnu-inline-global-reject.C: New.
* g++.dg/ext/gnu-inline-global.C: New.
* g++.dg/ext/gnu-inline-namespace.C: New.
* g++.dg/ext/gnu-inline-anon-namespace.C: New.
* g++.dg/ext/gnu-inline-class.C: New.
* g++.dg/ext/gnu-inline-class-static.C: New.
* g++.dg/ext/gnu-inline-template-class.C: New.
* g++.dg/ext/gnu-inline-template-func.C: New.

From-SVN: r127839