[C++ PATCH] Fix ICE in member_vec_dedup (PR c++/83825)

[Jakub Jelinek]

Hi!

As the testcase shows, calls to member_vec_dedup and qsort are just guarded
by the vector being non-NULL, which doesn't mean it must be non-empty,
so we can't do (*member_vec)[0] on it.  Fixed by the second hunk, the
rest is just a small cleanup to use the vec.h methods.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2018-01-15  Jakub Jelinek  <ja...@redhat.com>

        PR c++/83825
        * name-lookup.c (member_vec_dedup): Return early if len is 0.
        (resort_type_member_vec, set_class_bindings,
        insert_late_enum_def_bindings): Use vec qsort method instead of
        calling qsort directly.

        * g++.dg/template/pr83825.C: New test.

--- gcc/cp/name-lookup.c.jj     2018-01-03 13:16:38.537848205 +0100
+++ gcc/cp/name-lookup.c        2018-01-15 14:07:09.494576944 +0100
@@ -1520,8 +1520,7 @@ resort_type_member_vec (void *obj, void
     {
       resort_data.new_value = new_value;
       resort_data.cookie = cookie;
-      qsort (member_vec->address (), member_vec->length (),
-            sizeof (tree), resort_member_name_cmp);
+      member_vec->qsort (resort_member_name_cmp);
     }
 }
 
@@ -1597,6 +1596,9 @@ member_vec_dedup (vec<tree, va_gc> *memb
   unsigned len = member_vec->length ();
   unsigned store = 0;
 
+  if (!len)
+    return;
+
   tree current = (*member_vec)[0], name = OVL_NAME (current);
   tree next = NULL_TREE, next_name = NULL_TREE;
   for (unsigned jx, ix = 0; ix < len;
@@ -1712,8 +1714,7 @@ set_class_bindings (tree klass, unsigned
   if (member_vec)
     {
       CLASSTYPE_MEMBER_VEC (klass) = member_vec;
-      qsort (member_vec->address (), member_vec->length (),
-            sizeof (tree), member_name_cmp);
+      member_vec->qsort (member_name_cmp);
       member_vec_dedup (member_vec);
     }
 }
@@ -1741,8 +1742,7 @@ insert_late_enum_def_bindings (tree klas
       else
        member_vec_append_class_fields (member_vec, klass);
       CLASSTYPE_MEMBER_VEC (klass) = member_vec;
-      qsort (member_vec->address (), member_vec->length (),
-            sizeof (tree), member_name_cmp);
+      member_vec->qsort (member_name_cmp);
       member_vec_dedup (member_vec);
     }
 }
--- gcc/testsuite/g++.dg/template/pr83825.C.jj  2018-01-15 14:16:55.289432205 
+0100
+++ gcc/testsuite/g++.dg/template/pr83825.C     2018-01-15 14:14:03.172490348 
+0100
@@ -0,0 +1,13 @@
+// PR c++/83825
+// { dg-do compile }
+
+template <int A>
+class A {};    // { dg-error "shadows template parameter" }
+
+template <int I>
+class B
+{ 
+  void foo () { A <I> a; }
+};
+
+template void B <0>::foo ();

        Jakub