Hi!
ARRAY_REF is a handled component, so when a virtual call is on an array
element (or some component thereof), the loop to look through handled
components will look through the ARRAY_REFs too and then TREE_TYPE (obj)
might be an ARRAY_TYPE. The code wants to look at the class type instead
though.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2018-09-25 Jakub Jelinek <ja...@redhat.com>
PR c++/87398
* constexpr.c (cxx_eval_constant_expression) <case OBJ_TYPE_REF>: Use
strip_array_types before checking TYPE_BINFO.
* g++.dg/other/pr87398.C: New test.
* g++.dg/cpp2a/constexpr-virtual10.C: New test.
--- gcc/cp/constexpr.c.jj 2018-09-24 10:36:53.687031261 +0200
+++ gcc/cp/constexpr.c 2018-09-24 11:01:34.035268597 +0200
@@ -4814,7 +4814,7 @@ cxx_eval_constant_expression (const cons
obj = TREE_OPERAND (obj, 0);
while (handled_component_p (obj))
obj = TREE_OPERAND (obj, 0);
- tree objtype = TREE_TYPE (obj);
+ tree objtype = strip_array_types (TREE_TYPE (obj));
/* Find the function decl in the virtual functions list. TOKEN is
the DECL_VINDEX that says which function we're looking for. */
tree virtuals = BINFO_VIRTUALS (TYPE_BINFO (objtype));
--- gcc/testsuite/g++.dg/other/pr87398.C.jj 2018-09-24 10:53:41.605170048
+0200
+++ gcc/testsuite/g++.dg/other/pr87398.C 2018-09-24 10:53:14.642621001
+0200
@@ -0,0 +1,12 @@
+// PR c++/87398
+// { dg-do compile }
+
+struct A { virtual int foo (); };
+
+int
+bar (int x)
+{
+ A e[5][2];
+ int f = e[4][x].foo ();
+ return f;
+}
--- gcc/testsuite/g++.dg/cpp2a/constexpr-virtual10.C.jj 2018-09-24
10:56:15.604594387 +0200
+++ gcc/testsuite/g++.dg/cpp2a/constexpr-virtual10.C 2018-09-24
10:56:54.882937453 +0200
@@ -0,0 +1,18 @@
+// P1064R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+struct X
+{
+ constexpr virtual int f() const { return 1; };
+};
+
+struct Y : public X
+{
+ constexpr virtual int f() const { return 2; };
+};
+
+constexpr X a[2][1][3];
+constexpr Y b[3][12];
+static_assert (a[1][0][1].f() == 1);
+static_assert (b[2][11].f() == 2);
Jakub
