[Bug c++/84972] [6/7/8 Regression] ICE: tree check: expected class 'type', have 'exceptional' (error_mark) in extended_tree, at tree.h:5545

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84972

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Sorry, I already have a patch:

2018-03-20  Marek Polacek  <pola...@redhat.com>

        PR c++/84972
        * c-common.c (complete_array_type): Bail for bogus MAXINDEX.

        * g++.dg/parse/crash68.C: New test.

diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
index e1df1d3b73b..108d5f8f2d8 100644
--- gcc/c-family/c-common.c
+++ gcc/c-family/c-common.c
@@ -6332,6 +6332,11 @@ complete_array_type (tree *ptype, tree initial_value,
bool do_default)
              if ((*v)[0].index)
                maxindex = (*v)[0].index, fold_p = true;

+             /* If we can't do anything useful with the index,
+                signal failure.  */
+             if (maxindex == error_mark_node)
+               return 1;
+
              curindex = maxindex;

              for (cnt = 1; vec_safe_iterate (v, cnt, &ce); cnt++)
diff --git gcc/testsuite/g++.dg/parse/crash68.C
gcc/testsuite/g++.dg/parse/crash68.C
index e69de29bb2d..b8c47ba155c 100644
--- gcc/testsuite/g++.dg/parse/crash68.C
+++ gcc/testsuite/g++.dg/parse/crash68.C
@@ -0,0 +1,4 @@
+// PR c++/84972
+// { dg-additional-options "-w" }
+
+char a[] ({.a = 0}); // { dg-error "" }