Off-by-one error in TConnectorFastReadExpr.GetDataPtr

[Anders Melander]

The line EvalAsVariant(exec, resultData[1]); causes a Range Check error.

unit dwsConnectorExprs;
...
procedure TConnectorFastReadExpr.GetDataPtr(exec : TdwsExecution; var result : IDataContext);
var
   resultData : TData;
begin
   SetLength(resultData, 1);
   EvalAsVariant(exec, resultData[1]);
   exec.DataContext_Create(resultData, 0, result);
end;

[Eric Grange]

Fixed Issue #40

→ <<cset f475993ff9fb>>

[Eric Grange]

This appears to be dead code, did you hit the code at runtime or found the bug by looking at the code? (might make the method as abstract in that case)

[Anders Melander]

I encountered it at runtime assigning a JSONVariant member to a Variant.

    ProjectProperties.Values['customer.name'] := Customer.name;

TProjectProperties.Values[] is a Variant.
Customer is a JSONVariant.
Customer.name is a string.

Call stack:

dwsConnectorExprs.TConnectorFastReadExpr.GetDataPtr($F67F0F0,nil)
dwsExprs.TPushOperator.ExecuteAddr($F67F0F0)
dwsExprs.TFuncExpr.DoEvalCall($F67F0F0,$D2B3590)
dwsMethodExprs.TMethodExpr.EvalAsVariant($F67F0F0,Unassigned)
dwsMethodExprs.TMethodStaticExpr.EvalAsVariant($F67F0F0,Unassigned) dwsSymbols.TExprBase.EvalNoResult($F67F0F0)

[Eric Grange]

What is the underltying method behind "TProjectProperties.Values[]" ?

I could reproduce it with a method with a const parameter like "SetValues(const arg : Variant)"

[Anders Melander]

TProjectProperties is declared in a TdwsUnit and implemented Delphi side.

The declaration looks something like:

TProjectProperties
  procedure SetValue(const Name: string; const Value: Variant);
  property Values[const Name: string]: Variant read GetValue write SetValue;

and this is the implementation of TProjectProperties.SetValue:

  TSigmaProjectPropertySet(ExtObject).Items[Info.ParamAsString[0]] := Info.ParamAsVariant[1];

[Eric Grange]

Ok, should be covered by the test case.

FWIW const parameters are currently executed slowly for simple datatypes (cf. Issue #42)