On Sun, 6 Oct 2019 17:03:10 -0400
Ryan Joseph <generic...@gmail.com> wrote:
>[...]
> > 2.
> > DoThis(1,200) gives range check warning instead of error. A warning
> > means there are some rare cases, where this code is correct. Is
> > this a todo or do you see a useful case?
>
> Which test? Please post a sample.
generic procedure DoThis<T>(a:T; b:T);
begin end;
begin
DoThis(1,200); // 1 sets T to shortint, so the 200 gives a warning
end;
> > 3.
> > timpfuncspez2.pp
> > DoThis<T>
> > DoThis<T,U>
> > Delphi gives an error "Ambiguous call to DoThis". FPC silently
> > selects the one with only one param. IMO this is dangerous, it
> > should give an error.
generic function DoThis<T>(a: T): T; overload;
begin end;
generic function DoThis<T,U>(a: T): U; overload;
begin end;
begin
DoThis(3); // both fits, should give an error
end;
>[...]
> > 4.
> > Why does timpfuncspez6 fail?
> > It works in Delphi.
> > The comment has an explanation, which looks wrong to me:
> >
> > generic procedure DoThis<T,U>(msg: T; param1: U; param2: TObject);
> > begin
> > end;
> >
> > begin
> > DoThis('aa', 'aa', TObject.Create);
> > // wil be specialized as DoThis(msg: integer; param1:
> > TObject; param2: TObject)
> > // so we expect an incompatible type error
> > DoThis(1, 1, TObject.Create);
> > end.
>
> That doesn’t make sense to me either so I need to study it. Both
> should fail actually as I designed it (for now).
Why?
> How does Delphi implicitly specialize this?
DoThis(1,1,nil); // T and U become shortint
DoThis('aa','aa',nil); // T and U become string
Mattias
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