[fpc-pascal] overloading function

[Sven Barth]

On 02.05.2014 07:45, LacaK wrote:
> Hi,
> I am trying understand how FPC determines which version of overloaded
> function to call.
> Take as example these 2 functions (from SysUtils):
> 1. function StrPLCopy(Dest: PChar; Source: string; MaxLen: SizeUInt):
> PChar; overload;
> 2. function StrPLCopy(Dest: PWideChar; const Source: UnicodeString;
> MaxLen: SizeInt): PWideChar; overload;
>
> And in program I use:
> var p: pointer;
>       s: string;
> begin
>    StrPLCopy(p, s, 10);
> end;
>
> It seems, that 2nd "unicode" version of StrPLCopy is called. But why?
> I am thinking as:
> 1st parameter is untyped pointer, so no one of function can be prefered
> 2nd parameter is "string" which exactly match 1st function signature
> 3rd parameter is "integer constant" which mach both signatures
>
> So it seems to me, that 1st version of function signature matches
> better, because of exact match of 2nd parameter ... why is then called
> 2nd version?

I don't have a explanation for now, but it *might* be important to note 
whether you are using 2.6.x or 2.7.1.

Regards,
Sven