This area of the standard is in flux, but what we were doing was
definitely wrong. The proposed resolution for issue 1402 says that if a
move constructor would call a non-trivial non-move constructor for a
subobject, it is not implicitly declared. We might end up dropping that
provision entirely, but in any case we should allow moving via template
constructor as well as non-template.
Tested x86_64-pc-linux-gnu, applying to trunk and 4.7 (since it only
affects C++11 mode).
commit 37c8977bb82c984645795a9992fe6658841e2d35
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Sep 10 09:22:37 2012 -0400
PR c++/54506
* decl.c (move_signature_fn_p): Split out from move_fn_p.
* method.c (process_subob_fn): Use it.
* cp-tree.h: Declare it.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 3e0fc3f..3c55ba4 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -5066,6 +5066,7 @@ extern tree build_ptrmem_type (tree, tree);
extern tree build_this_parm (tree, cp_cv_quals);
extern int copy_fn_p (const_tree);
extern bool move_fn_p (const_tree);
+extern bool move_signature_fn_p (const_tree);
extern tree get_scope_of_declarator (const cp_declarator *);
extern void grok_special_member_properties (tree);
extern int grok_ctor_properties (const_tree, const_tree);
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 7655f78..e34092d 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -10859,10 +10859,6 @@ copy_fn_p (const_tree d)
bool
move_fn_p (const_tree d)
{
- tree args;
- tree arg_type;
- bool result = false;
-
gcc_assert (DECL_FUNCTION_MEMBER_P (d));
if (cxx_dialect == cxx98)
@@ -10872,12 +10868,29 @@ move_fn_p (const_tree d)
if (TREE_CODE (d) == TEMPLATE_DECL
|| (DECL_TEMPLATE_INFO (d)
&& DECL_MEMBER_TEMPLATE_P (DECL_TI_TEMPLATE (d))))
- /* Instantiations of template member functions are never copy
+ /* Instantiations of template member functions are never move
functions. Note that member functions of templated classes are
represented as template functions internally, and we must
- accept those as copy functions. */
+ accept those as move functions. */
return 0;
+ return move_signature_fn_p (d);
+}
+
+/* D is a constructor or overloaded `operator='.
+
+ Then, this function returns true when D has the same signature as a move
+ constructor or move assignment operator (because either it is such a
+ ctor/op= or it is a template specialization with the same signature),
+ false otherwise. */
+
+bool
+move_signature_fn_p (const_tree d)
+{
+ tree args;
+ tree arg_type;
+ bool result = false;
+
args = FUNCTION_FIRST_USER_PARMTYPE (d);
if (!args)
return 0;
diff --git a/gcc/cp/method.c b/gcc/cp/method.c
index c21ae15..a42ed60 100644
--- a/gcc/cp/method.c
+++ b/gcc/cp/method.c
@@ -947,9 +947,10 @@ process_subob_fn (tree fn, bool move_p, tree *spec_p, bool *trivial_p,
}
}
- /* Core 1402: A non-trivial copy op suppresses the implicit
+ /* Core 1402: A non-trivial non-move ctor suppresses the implicit
declaration of the move ctor/op=. */
- if (no_implicit_p && move_p && !move_fn_p (fn) && !trivial_fn_p (fn))
+ if (no_implicit_p && move_p && !move_signature_fn_p (fn)
+ && !trivial_fn_p (fn))
*no_implicit_p = true;
if (constexpr_p && !DECL_DECLARED_CONSTEXPR_P (fn))
diff --git a/gcc/testsuite/g++.dg/cpp0x/implicit14.C b/gcc/testsuite/g++.dg/cpp0x/implicit14.C
new file mode 100644
index 0000000..8a56244
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/implicit14.C
@@ -0,0 +1,26 @@
+// PR c++/54506
+// { dg-do compile { target c++11 } }
+
+template <class T>
+struct A
+{
+ A() {}
+
+ A(A const volatile &&) = delete;
+ A &operator =(A const volatile &&) = delete;
+
+ template <class U> A(A<U> &&) {}
+ template <class U> A &operator =(A<U> &&) { return *this; }
+};
+
+struct B
+{
+ A<int> a;
+ B() = default;
+};
+
+int main()
+{
+ B b = B();
+ b = B();
+}
