(Unreplicable) Internal error 200109092 when accessing enum-range-specified array

Original Reporter info from Mantis: etrusco

• Reporter name: Flávio Etrusco

Description:

I'm reporting this bug just in case there's any interest in fixing it. It's very obscure and AFAICS from the code the 200109092 is very generic...

I found it while making a change in Lazarus, but that I can't replicate in a smaller test-case, and it doesn't even occur when compiling from the command-line! (I'd guess it must be caused by a compiler flag, but the package - LCLBase - doesn't use any special flag, just -O1, and the test-case doesn't trigger the error no matter what flags I use)

Running inside Lazarus I get:
(...)\lcl\controls.pp(3122,18) Error: range check error while evaluating constants
(...)\lcl\controls.pp(3122,33) Error: range check error while evaluating constants
(...)\lcl\controls.pp(3122,11) Fatal: Internal error 200109092

The problem occurs in the following code:

function TControlBorderSpacing.IsEqual(Spacing: TControlBorderSpacing
  ): boolean;
begin
  Result:=(FAround=Spacing.Around)
      and (FSides[akLeft]=Spacing.FSides[akLeft])
      and (FSides[akTop]=Spacing.FSides[akTop])
      and (FSides[akBottom]=Spacing.FSides[akBottom])
      and (FSides[akRight]=Spacing.FSides[akRight]);
end;

The types:
  TSpacingSize = 0..MaxInt;
  (...)
  TControlBorderSpacing = class(TPersistent)
  (...)
    FSides: array [akLeft..akBottom] of TSpacingSize;
  (...)
  end;

If I declare FSides using TAnchorKind instead of the range (akLeft..akBottom) the error is gone.

BorderSpacing-refactor-r32343.patch is a working change needed to apply the buggy patch.
BorderSpacing-refactor-bug-r32343.patch contains only the TAnchorKind -> akLeft..akBottom changes that trigger the bug.
FWIW I'll attach the starting test project (that doesn't trigger the bug).

Mantis conversion info:

• Mantis ID: 20251
• OS: win32
• OS Build: Windows 7 32-bit
• Platform: i386
• Version: 2.4.4