CWG DR 5 specifies that in the two-step copy-initialization process, the
temporary object of the target type which is created and then copied
into the target object has cv-unqualified type; this allows volatile
objects to be copy-initialized with the usual copy-constructor signature.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit b99bece161794661520f1e613b67638f5c478dd5
Author: Jason Merrill <ja...@redhat.com>
Date: Thu May 8 17:15:58 2014 -0400
DR 5
PR c++/60019
* call.c (build_user_type_conversion_1): The copy-init temporary
is cv-unqualified.
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index cff7ef3..187fc77 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -3693,11 +3693,20 @@ build_user_type_conversion_1 (tree totype, tree expr, int flags,
return cand;
}
+ tree convtype;
+ if (!DECL_CONSTRUCTOR_P (cand->fn))
+ convtype = non_reference (TREE_TYPE (TREE_TYPE (cand->fn)));
+ else if (cand->second_conv->kind == ck_rvalue)
+ /* DR 5: [in the first step of copy-initialization]...if the function
+ is a constructor, the call initializes a temporary of the
+ cv-unqualified version of the destination type. */
+ convtype = cv_unqualified (totype);
+ else
+ convtype = totype;
/* Build the user conversion sequence. */
conv = build_conv
(ck_user,
- (DECL_CONSTRUCTOR_P (cand->fn)
- ? totype : non_reference (TREE_TYPE (TREE_TYPE (cand->fn)))),
+ convtype,
build_identity_conv (TREE_TYPE (expr), expr));
conv->cand = cand;
if (cand->viable == -1)
diff --git a/gcc/testsuite/g++.dg/init/copy7.C b/gcc/testsuite/g++.dg/init/copy7.C
new file mode 100644
index 0000000..655fae2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/copy7.C
@@ -0,0 +1,9 @@
+// CWG 5
+
+struct C { };
+C c;
+struct A {
+ A(const A&);
+ A(const C&);
+};
+const volatile A a = c; // Okay
