Re: [fpc-pascal] Non-initialized member access warning
> On Jun 8, 2023, at 6:01 PM, Sven Barth wrote: > > Please report a bug with a complete example. Better late than never :) https://gitlab.com/freepascal.org/fpc/source/-/issues/40321 Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Non-initialized member access warning
Am 07.06.2023 um 10:44 schrieb Hairy Pixels via fpc-pascal: I'm curious, why doesn't the following code give a warning? Shouldn't the compiler know you're assigning to "r" which hasn't been initialized yet? type TMyClass = class x: integer; end; procedure MyProcedure; var r: TMyClass; begin r.x := 1; end; Please report a bug with a complete example. Regards, Sven ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Non-initialized member access warning
> On Jun 8, 2023, at 12:58 AM, Steve Litt via fpc-pascal > wrote: > > I know this isn't a very satisfying answer, but it's the best I can > come up with. Thanks but this is probably a question for the compiler devs. I'm curious if it's intended, a bug or not implemented. Seems like an obvious warning to have but maybe there's a reason... Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Non-initialized member access warning
Hairy Pixels via fpc-pascal said on Wed, 7 Jun 2023 15:44:43 +0700
>I'm curious, why doesn't the following code give a warning? Shouldn't
>the compiler know you're assigning to "r" which hasn't been
>initialized yet?
>
>type
> TMyClass = class
> x: integer;
> end;
>
>procedure MyProcedure;
>var
> r: TMyClass;
>begin
> r.x := 1;
>end;
>
>
>Regards,
> Ryan Joseph
If I had to guess, I'd say it's because you needed to and did declare
{$mode objfpc} or {$mode delphi}, which, my guess would be, don't warn
against using uninitialized variables. The following program contains
your code but includes r := tmyclass.create to allocate RAM to the
object. If that line is commented out, you get a runtime 216, which I
believe is a memory access violation.
{$mode objfpc} {Needed for classes}
{$rangechecks on} {Check for runtime memory tromp}
{$warnings on} {List all warnings}
program junk3;
type
TMyClass = class
x: integer;
end;
procedure show(c: tmyclass);
begin
writeln(c.x);
end;
procedure MyProcedure;
var
r: TMyClass;
begin
{Comment out following line to produce memory error}
r := tmyclass.create; {Allocate ram for object r}
r.x := 1;
show(r);
end;
begin
myprocedure;
writeln('Finished');
end.
I explored {$warn whatever}, and none of the whatevers pertained to
uninitialized varibles, and {$warnings on} didn't bring out a warning.
I've seen uninitialized var warnings in other code, so by process of
elimination I'd imagine this is due to {$mode delphi} and its cousins,
which are necessary to recognize "class" as a reserved word.
I know this isn't a very satisfying answer, but it's the best I can
come up with.
SteveT
Steve Litt
Autumn 2022 featured book: Thriving in Tough Times
http://www.troubleshooters.com/bookstore/thrive.htm
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[fpc-pascal] Non-initialized member access warning
I'm curious, why doesn't the following code give a warning? Shouldn't the compiler know you're assigning to "r" which hasn't been initialized yet? type TMyClass = class x: integer; end; procedure MyProcedure; var r: TMyClass; begin r.x := 1; end; Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
