[fpc-pascal] Why does nested function get corrupted?
Curious more than anything, if is nested captures state in a record and passes it as an hidden self param, why does returning the variable and calling from outside the calling stack frame corrupt the data? It seems like it technically should be there. == type TProc = procedure is nested; function TestNested: TProc; var data: integer; begin data := 100; result := procedure begin writeln(data); end; end; var proc: TProc; begin proc := TestNested; proc(); end. Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Get TMethod from function reference
> On Sep 8, 2022, at 11:14 AM, Michael Van Canneyt via fpc-pascal > wrote: > > It must keep this information somewhere, but this does not mean you can > typecast it to a TMethod. Indeed. I wonder if this information could be exposed by some method in the interface? It would be useful to introspect the target class like you can do with “of object”. Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Get TMethod from function reference
On Thu, 8 Sep 2022, Hairy Pixels via fpc-pascal wrote: On Sep 8, 2022, at 9:09 AM, Michael Van Canneyt wrote: To me it seems logical that you cannot do this, since a function reference is actually an interface, and there is no actual object to back it up. Your function reference could also be a regular procedure (no data at all) or even a local procedure. I thought it keeps the method data in the interface so it could dispatch it later. How would it work otherwise? It must keep this information somewhere, but this does not mean you can typecast it to a TMethod. Michael. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Get TMethod from function reference
> On Sep 8, 2022, at 9:09 AM, Michael Van Canneyt > wrote: > > To me it seems logical that you cannot do this, since a function reference is > actually an > interface, and there is no actual object to back it up. > > Your function reference could also be a regular procedure (no data at all) or > even a local > procedure. I thought it keeps the method data in the interface so it could dispatch it later. How would it work otherwise? Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Get TMethod from function reference
On Thu, 8 Sep 2022, Hairy Pixels via fpc-pascal wrote: A function reference can call a class method but can you get the TMethod data from function references? It was possible with “is object” to cast to TMethod but that doesn’t seem to be possible with references. = type TMyClass = class constructor Create; procedure DoThis; end; constructor TMyClass.Create; var proc: reference to procedure; begin proc := @DoThis; writeln(Assigned(PMethod(proc)^.data)); // FALSE end; To me it seems logical that you cannot do this, since a function reference is actually an interface, and there is no actual object to back it up. Your function reference could also be a regular procedure (no data at all) or even a local procedure. Michael.___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
[fpc-pascal] Get TMethod from function reference
A function reference can call a class method but can you get the TMethod data from function references? It was possible with “is object” to cast to TMethod but that doesn’t seem to be possible with references. = type TMyClass = class constructor Create; procedure DoThis; end; constructor TMyClass.Create; var proc: reference to procedure; begin proc := @DoThis; writeln(Assigned(PMethod(proc)^.data)); // FALSE end; Regards, Ryan Joseph ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Access Violation When SetLength(DynArray, Value)
> curious minds want to know: what was the fix? In a separate part of the pool table initialization, I was precalculating the midpoints and normals for bumper rails. I had carelessly written this code: for I := 0 to Length(Rails) do RailInit(Rails[I], I); ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Access Violation When SetLength(DynArray, Value)
On 9/8/22 9:54 AM, Anthony Walter via fpc-pascal wrote: Please ignore this post. I fixed the issue. curious minds want to know: what was the fix? -- NOTE: No off-list assistance is given without prior approval. *Please keep mailing list traffic on the list where it belongs!* ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Access Violation When SetLength(DynArray, Value)
Please ignore this post. I fixed the issue. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Access Violation When SetLength(DynArray, Value)
I suggest trying without optimisations and/or using cmem, to see if that changes the outcome. Also, if the array is corrupted prior to the setlength, then iterating the array with a trivial with... Writeln(Color) or whatever, should trigger an exception. That could then be used at various parts of the program to identify the point of corruption, which might seem unrelated to array in question if the heap is getting messed up somehow. Cheers, Peter P.S. I had a strange (possible) heap corruption issue with a large program a year ago that broke stringlists. I never found the cause, and after many minor code changes, the problem just dissappeared. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Access Violation When SetLength(DynArray, Value)
On 2022-09-08 09:30, Anthony Walter via fpc-pascal wrote: Is there a known edge case issue connected to setting the length of dynamic arrays? No, and the location where you're getting the crash suggests an issue in your program that has corrupted the heap manager state. Jonas ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
[fpc-pascal] Access Violation When SetLength(DynArray, Value)
Is there a known edge case issue connected to setting the length of dynamic arrays? I have a program that simulates a billiards game, and during the rerack balls method of TPoolTable the number of pool balls on the table varies based on the rerack option used. Currently, I am having a problem where an exception is thrown if I try to SetLenth(Balls, 10) or greater than 10. Values less than 10 work fine, but at 10 balls and above an exception is thrown right at the SetLength call. External: SIGSEGV 0041DCA4 eb12 jmp0x41dcb8 0041DCA6 4c89f0 mov%r14,%rax 0041DCA9 488b5008 mov0x8(%rax),%rdx 0041DCAD 488b4018 mov0x18(%rax),%rax 0041DCB1 488982a800 mov%rax,0xa8(%rdx) ^ instruction pointer is at this line ^ I tried compiler both FPC 3.3.1 from trunk source and 3.2.2 from the official Sourceforge binary. The same error occurs when building with both compilers. My platform is x86_64 Linux. For reference here is the type of Balls: TVec2 = record X, Y: Single; end; TPoolBall = record Pos: TVec2; Dir: TVec2; Speed: Double; Color: LongWord; Touched: Boolean; Sinking: Single; SinkPocket: Integer; SinkPos: TVec2; Pocketed: Boolean; Index: Integer; end; TPoolBalls = array of TPoolBall; ... later inside TPoolTable ... Balls: TPoolBalls; ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
