[Bug c++/95728] [11 Regression] tree check: expected tree_list, have error_mark in tsubst_copy_and_build, at cp/pt.c:19594

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95728

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:81caacc273399c91ae3182021ad87bc2ba786039

commit r11-1507-g81caacc273399c91ae3182021ad87bc2ba786039
Author: Marek Polacek <polacek@redhat.com>
Date:   Wed Jun 17 19:23:10 2020 -0400

    c++: Fix tsubst ICE with invalid static_cast [PR95728]

    Since r11-423 tsubst_copy_and_build/TREE_LIST uses tsubst_tree_list
    instead of open coding it.  While the latter could return an error
    node wrapped in a TREE_LIST, the former can return a naked error node.

    That broke in tsubst_copy_and_build/NEW_EXPR:
      tree placement = RECUR (TREE_OPERAND (t, 0));
      // placement is now error_mark_node, so...
      for (; placement != NULL_TREE; placement = TREE_CHAIN (placement))
      // ... this crashes

    If we just return, we avoid the ICE and improve the diagnostic a bit.

    gcc/cp/ChangeLog:

            PR c++/95728
            * pt.c (tsubst_copy_and_build) <case NEW_EXPR>: Return
error_mark_node
            if placement is erroneous.

    gcc/testsuite/ChangeLog:

            PR c++/95728
            * g++.dg/template/cast6.C: New test.