Bug 7409 – Overloading with user-defined struct when passing by ref
Status
RESOLVED
Resolution
DUPLICATE
Severity
normal
Priority
P2
Component
dmd
Product
D
Version
D2
Platform
x86
OS
Linux
Creation time
2012-01-31T03:27:00Z
Last change time
2012-01-31T07:46:55Z
Assigned to
nobody
Creator
jens.k.mueller
Comments
Comment #0 by jens.k.mueller — 2012-01-31T03:27:32Z
Overloading does not work with user-defined structs when there are two overloaded functions receiving the struct (one by ref and one by value).
struct MyStruct {}
void fun(ref MyStruct a) {}
void fun(MyStruct a) {}
unittest
{
MyStruct a;
fun(a); // fails both match
}
Tested with DMD32 D Compiler v2.057 which results in the error message:
Error: function struct.fun called with argument types:
((MyStruct))
matches both:
struct.fun(ref MyStruct a)
and:
struct.fun(MyStruct a)
But fun(ref MyStruct a) is more specialized. Thus, it should win.
The overloading protocol is defined in http://dlang.org/function.html section "Function Overloading" and in TDPL Section 5.5 "Overloading". Both description (though different in wording) specify the same behavior.
It works for int. And I assume for other built-in types as well. But I haven't checked.
I believe this issue is important. Because it is often needed (as an optimization to avoid the copy/move) for e.g. operator overloading.
Comment #1 by k.hara.pg — 2012-01-31T07:11:23Z
This issue is a part of bug 5889.
Comment #2 by yebblies — 2012-01-31T07:46:55Z
*** This issue has been marked as a duplicate of issue 4843 ***