Hi!
Unnamed bitfields are not data members, so we should ignore them when
counting the members or picking up members to initialize from, and
also should ignore them in find_decomp_class_base, they can appear
in various bases etc. and still there could be just one base containing
direct non-static data members.
The patch also fixes an issue I ran into on the testcase, when recursing
from type in which we've found any direct non-static data members, we have
ret set to that type and if the recursion doesn't find anything nor an
error, it returns that ret rather than NULL. So, if t == ret, it just
means it didn't find anything preventing return of ret to the caller.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2018-01-25 Jakub Jelinek <ja...@redhat.com>
PR c++/84031
* decl.c (find_decomp_class_base): Ignore unnamed bitfields. Ignore
recursive calls that return ret.
(cp_finish_decomp): Ignore unnamed bitfields.
* g++.dg/cpp1z/decomp36.C: New test.
--- gcc/cp/decl.c.jj 2018-01-24 17:18:42.376392255 +0100
+++ gcc/cp/decl.c 2018-01-25 10:22:51.267122576 +0100
@@ -7206,7 +7206,9 @@ find_decomp_class_base (location_t loc,
{
bool member_seen = false;
for (tree field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
- if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
+ if (TREE_CODE (field) != FIELD_DECL
+ || DECL_ARTIFICIAL (field)
+ || (DECL_C_BIT_FIELD (field) && !DECL_NAME (field)))
continue;
else if (ret)
return type;
@@ -7245,7 +7247,7 @@ find_decomp_class_base (location_t loc,
tree t = find_decomp_class_base (loc, TREE_TYPE (base_binfo), ret);
if (t == error_mark_node)
return error_mark_node;
- if (t != NULL_TREE)
+ if (t != NULL_TREE && t != ret)
{
if (ret == type)
{
@@ -7256,9 +7258,6 @@ find_decomp_class_base (location_t loc,
}
else if (orig_ret != NULL_TREE)
return t;
- else if (ret == t)
- /* OK, found the same base along another path. We'll complain
- in convert_to_base if it's ambiguous. */;
else if (ret != NULL_TREE)
{
error_at (loc, "cannot decompose class type %qT: its base "
@@ -7645,7 +7644,9 @@ cp_finish_decomp (tree decl, tree first,
goto error_out;
}
for (tree field = TYPE_FIELDS (btype); field; field = TREE_CHAIN (field))
- if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
+ if (TREE_CODE (field) != FIELD_DECL
+ || DECL_ARTIFICIAL (field)
+ || (DECL_C_BIT_FIELD (field) && !DECL_NAME (field)))
continue;
else
eltscnt++;
@@ -7660,7 +7661,9 @@ cp_finish_decomp (tree decl, tree first,
}
unsigned int i = 0;
for (tree field = TYPE_FIELDS (btype); field; field = TREE_CHAIN (field))
- if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
+ if (TREE_CODE (field) != FIELD_DECL
+ || DECL_ARTIFICIAL (field)
+ || (DECL_C_BIT_FIELD (field) && !DECL_NAME (field)))
continue;
else
{
--- gcc/testsuite/g++.dg/cpp1z/decomp36.C.jj 2018-01-25 10:25:23.900154509
+0100
+++ gcc/testsuite/g++.dg/cpp1z/decomp36.C 2018-01-25 10:25:15.996152860
+0100
@@ -0,0 +1,19 @@
+// PR c++/84031
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+struct A { unsigned char : 1, a1 : 1, a2 : 2, : 1, a3 : 3; };
+struct B { unsigned char : 1, : 7; };
+struct C : B { constexpr C () : c1 (1), c2 (2), c3 (3) {} unsigned char : 1,
c1 : 1, c2 : 2, : 1, c3 : 3; };
+struct D : C { constexpr D () {} unsigned char : 1, : 7; };
+
+int
+main ()
+{
+ static constexpr A a { 1, 2, 3 };
+ const auto &[a1, a2, a3] = a; // { dg-warning "only available
with" "" { target c++14_down } }
+ static_assert (a1 == 1 && a2 == 2 && a3 == 3, "");
+ static constexpr D d;
+ const auto &[d1, d2, d3] = d; // { dg-warning "only available
with" "" { target c++14_down } }
+ static_assert (d1 == 1 && d2 == 2 && d3 == 3, "");
+}
Jakub
