Error: func(const(A) a) is not callable using argument types (const(A)

[Biotronic via Digitalmars-d-learn]

On Tuesday, 30 May 2017 at 10:09:50 UTC, Andrew Edwards wrote:
> What does that even mean?
>
> Scenario:
>
> bool func(const ImVec2 label_size)
> {
>     return true;
> }
>
> void main()
> {
>     //first attempt:
>     const ImVec2 label_size = CalcTextSize(label.ptr, null, 
> true);
>     //Error: cannot implicitly convert expression 
> (CalcTextSize(cast(immutable(char)*)label, null, true, -1F)) of 
> type ImVec2 to const(ImVec2)
>
>     //second attempt
>     const ImVec2 label_size = 
> cast(const)CalcTextSize(label.ptr, null, true);
>     // Error: cannot implicitly convert expression 
> (CalcTextSize(cast(immutable(char)*)label, null, true, -1F)) of 
> type const(ImVec2) to const(ImVec2)
>
>     //third attempt
>     const auto label_size = CalcTextSize(label.ptr, null, true);
>     //Okay: don't know why the other two didn't work but I can 
> keep going for now
>
>     func(label_size);
>     //Error: function imgui_d.func (const(ImVec2) label_size) 
> is not callable using argument types (const(ImVec2))
> }

My immediate thought is 'is that the same ImVec2?' Do you have 
two definitions of ImVec2 laying about?

What's the output of this code, if you insert it somewhere in the 
above?

import std.traits;

pragma(msg, fqn!ImVec2);
pragma(msg, fqn!(typeof(CalcTextSize(label.ptr, null,
> true))));

--
   Biotronic