[Bug c++/84843] [8 Regression] C++ ICE on builtin redefinition since r258391

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84843

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Tue Mar 13 20:32:54 2018
New Revision: 258503

URL: https://gcc.gnu.org/viewcvs?rev=258503&root=gcc&view=rev
Log:
        PR c++/84843
        * decl.c (duplicate_decls): For redefinition of built-in, use error
        and return error_mark_node.  For redeclaration, return error_mark_node
        rather than olddecl if !flag_permissive.

        * g++.dg/ext/pr84843-1.C: New test.
        * g++.dg/ext/pr84843-2.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/ext/pr84843-1.C
    trunk/gcc/testsuite/g++.dg/ext/pr84843-2.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c
    trunk/gcc/testsuite/ChangeLog