Misleading error for mismatch overloaded operator if there are immutable members

[dlangBugzillaToGithub]

Denis Shelomovskii (@denis-sh) reported this on 2013-11-05T05:51:47Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=11443

Description

---
struct S
{
    const int i;
    void opOpAssign(string op : "+")(int) { }
    void opOpAssign(string op : "~")(int) { }
}

void main()
{
    S s;
    s += ""; // Error: cannot modify struct s S with immutable members
    s ~= ""; // Error: cannot modify struct s S with immutable members
}
---