* doc/invoke.texi (-Wabi): Document mangling bug.

	PR c++/8006
	* mangle.c (CLASSTYPE_TEMPLATE_ID_P): Handle instances of template
	template parameters.
	(globals): Add entity and need_abi_warning.
	(decl_is_template_id): Use TYPE_TEMPLATE_INFO, not
	CLASSTYPE_TEMPLATE_INFO.
	(is_std_substitution): Use CLASSTYPE_TI_TEMPLATE, not
	TYPE_TI_TEMPLATE.
	(write_prefix): Handle typename types correctly.
	(write_template_prefix): Handle template template parameters
	correctly.
	(start_mangling): Add entity parameter.
	(finish_mangling): Warn about names whose mangling will change.
	(mangle_decl_string): Adjust.
	(mangle_type_string): Likewise.
	(mangle_special_for_type): Likewise.
	(mangle_ctor_vtbl_for_type): Likewise.
	(mangle_thunk): Likewise.
	(mangle_guard_variable): Likewise.
	(mangle_ref_init_variable): Likewise.

	PR c++/8006
	* g++.dg/abi/mangle9.C: New test.
	* g++.dg/abi/mangle10.C: New test.
	* g++.dg/abi/mangle11.C: New test.
	* g++.dg/abi/mangle12.C: New test.

From-SVN: r57799