[fpc-devel] Impossible CONST generic constraints in forward declarations...?

[Martin Frb]

On 25/11/2025 20:41, Martin Frb via fpc-devel wrote:
> According to
> https://forum.lazarus.freepascal.org/index.php/topic,52157.msg383991.html#msg383991 
>
>
> 2) Constraints in a "forward" declaration in the implementation (or a 
> program?) must be kept.

Actually, that does not seem to be true either...

The below only compiles when they are NOT kept (same if converted to 
mode delphi)

unit Unit1;{$mode ObjFPC}
interface
implementation
generic procedure Foo3<A: TObject;B>(p1: A); forward;

generic procedure Foo3<A; B>(p1: A); begin end;

end.


However,
in a program, they must be dropped.
(it will not compile, if the :TObject is kept)

program Project1;
generic procedure Foo3<A: TObject;B>(p1: A); forward;

generic procedure Foo3<A; B>(p1: A);
begin  end;

begin end.



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More, it seems that many checks are performed only on the FIRST gen param.
Changes in the rest of them seems to be ignored, at least sometimes...