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digitalmars.D.learn - Error: template cannot deduce function from argument types.

reply "Damian Day" <damianroyday gmail.com> writes:
Hi, I've been trying to reduce a bug in the containers (8824).

 From the example below it seems the dup method is passing the 
constructor
an array of dchars and the template is failing.

Is this a compiler bug, or ?

import std.range, std.traits;

struct Array2(T)
{
     private T[] _payload;

     size_t insertAt(R)(size_t index, R rng)
         if (isInputRange!R && 
isImplicitlyConvertible!(ElementType!R, T))
     {
         return 0;
     }

     this(U)(U[] values...)
         if (isImplicitlyConvertible!(U, T))
     {
         insertAt(0, values);
     }

      property Array2 dup()
     {
         return Array2(_payload);
     }
}

unittest
{
     Array2!int a; //passes
     Array2!char a; //fails
}
Aug 23 2014
next sibling parent "anonymous" <anonymous example.com> writes:
On Sunday, 24 August 2014 at 02:53:41 UTC, Damian Day wrote:

 Hi, I've been trying to reduce a bug in the containers (8824).

 From the example below it seems the dup method is passing the 
 constructor
 an array of dchars and the template is failing.

 Is this a compiler bug, or ?

 import std.range, std.traits;

 struct Array2(T)
 {
     private T[] _payload;

     size_t insertAt(R)(size_t index, R rng)
         if (isInputRange!R && 
 isImplicitlyConvertible!(ElementType!R, T))
     {
         return 0;
     }

     this(U)(U[] values...)
         if (isImplicitlyConvertible!(U, T))
     {
         insertAt(0, values);
     }

      property Array2 dup()
     {
         return Array2(_payload);
     }
 }

 unittest
 {
     Array2!int a; //passes
     Array2!char a; //fails
 }


Not a compiler bug. char[] (and wchar[]) as ranges auto-decode to
dchars. I.e. ElementType!(char[]) is dchar. And dchar isn't
implicitly convertible to char. So the instantiation of insertAt
fails.
Aug 24 2014
prev sibling parent "sigod" <sigod.mail gmail.com> writes:
On Sunday, 24 August 2014 at 02:53:41 UTC, Damian Day wrote:

 isImplicitlyConvertible!(ElementType!R, T))


Try [ElementEncodingType][0].

[0]: http://dlang.org/phobos/std_range.html#ElementEncodingType
Aug 24 2014