re PR c++/28736 (ICE with friend of invalid template class)
PR c++/28736
PR c++/28737
PR c++/28738
* pt.c (process_template_parm): Store invalid template
parameters as a TREE_LIST with a TREE_VALUE of error_mark_node.
(push_inline_template_parms_recursive): Check for template
parameters having a TREE_VALUE of error_mark_node rather than
check the parameter itself.
(mangle_class_name_for_template): Likewise.
(comp_template_parms): When comparing the individual template
parameters, return 1 if either is error_mark_node.
(current_template_args): Robustify.
(redeclare_class_template): Likewise.
* g++.dg/template/void10.C: New test.
* g++.dg/template/void8.C: New test.
* g++.dg/template/void9.C: New test.
* g++.dg/template/void3.C: Adjust error markers.
* g++.dg/template/void4.C: Likewise.
* g++.dg/template/crash55.C: Likewise.
* g++.dg/template/void7.C: Likewise.
From-SVN: r116473