[Issue 12230] New: properties do not bind templates via alias parameter

[d-bugmail at puremagic.com]

https://d.puremagic.com/issues/show_bug.cgi?id=12230

           Summary: properties do not bind templates via alias parameter
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: thecybershadow at gmail.com


--- Comment #0 from Vladimir Panteleev <thecybershadow at gmail.com> 2014-02-23 11:49:08 EET ---
///////////////////// test.d ////////////////////
import std.stdio;

static template T(alias a)
{
    void foo() { writeln(a); }
}

struct S
{
    int i = 1;
    @property int p() { return 2; }

    alias ti = T!i; // OK
    alias tp = T!p; // Error
}
/////////////////////////////////////////////////

The compiler rejects the above code, with the error:
test.d(5,23): Error: need 'this' for 'p' of type '@property int()'

The problem can be worked around by adding an anchor parameter to the template.
This correctly sets the "this" type for the template:

//////////////////// test2.d ////////////////////
static template T(alias a, alias anchor = Object)
{
    void foo() { writeln(a); }
}

struct S
{
    int i = 1;
    @property int p() { return 2; }

    alias ti = T!(i);    // bound to S implicitly
    alias tp = T!(p, i); // bound to S via anchor
}
/////////////////////////////////////////////////

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