[Issue 8015] New: std.typecons.Tuple does not support struct with alias method this

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=8015

           Summary: std.typecons.Tuple does not support struct with alias
                    method this
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody at puremagic.com
        ReportedBy: robert at octarineparrot.com


--- Comment #0 from Robert Clipsham <robert at octarineparrot.com> 2012-05-02 15:17:09 BST ---
The following code:
----
import std.typecons;

struct MyStruct {
    string str;
    string toStr() {
        return str;
    }
    alias toStr this;
}

void main() {
    Tuple!(MyStruct) t;
}
----
Gives the following errors:
----
std/utf.d(558): Error: undefined identifier 'length'
std/utf.d(566): Error: no [] operator overload for type const(MyStruct)
std/utf.d(567): Error: no [] operator overload for type const(MyStruct)
std/utf.d(569): Error: undefined identifier 'ptr', did you mean 'template
put(R,E)'?
std/utf.d(569): Error: undefined identifier 'length'
std/utf.d(569): Error: function std.utf.decodeImpl (const(char)* pstr, ulong
length, ref ulong index) is not callable using argument types
(_error_,_error_,ulong)
std/utf.d(569): Error: expected 2 arguments, not 3 for non-variadic function
type pure @safe dchar(const(dchar[]) str, ref ulong index)
std/format.d(1935): Error: template instance std.utf.decode!(MyStruct) error
instantiating
std/typecons.d(515):        instantiated from here:
formatElement!(Appender!(string),MyStruct,char)
test.d(12):        instantiated from here: Tuple!(MyStruct)
std/typecons.d(515): Error: template instance
std.format.formatElement!(Appender!(string),MyStruct,char) error instantiating
test.d(12):        instantiated from here: Tuple!(MyStruct)
test.d(12): Error: template instance std.typecons.Tuple!(MyStruct) error
instantiating
----
When compiling with dmd 2.059. If the alias this is changed to use str instead
of toStr this works without error.

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