remobjects/pascalscript

Dynamic array result types cause Access Violation in FPC

dezlov opened this issue · 1 comments

dezlov commented

Functions which use dynamic array types as results produce Access Violation when array is being accessed.

Consider registering the following type and function:

type
  TTestArrayType = Array of String;

function TestReturn: TTestArrayType;
begin
  SetLength(Result, 1); // <<<--- ACCESS VIOLATION !!!
  Result[0] := 'TestReturn';
end;

Then, simply call TestReturn in a script to get Access Violation in fpc_dynarray_setlength at assembler line cmpl $0x0,(%eax).

It is worth noting that using dynamic array types as parameters, or changing the calling convention to cdecl works fine.

Tested with FPC 3.0.4 on Windows 7 and 10 64-bit.

dezlov commented

Could it be due to some changes in FPC calling convention related to how dynamic arrays are passed to functions, i.e. registers vs stack?

May be related to FPC issue: https://bugs.freepascal.org/view.php?id=29230

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