On Thu, 31 Aug 2006, Sergei Gorelkin wrote:
Thursday, August 31, 2006, 12:35:33 PM, Michael wrote:
MVC> On Thu, 31 Aug 2006, Sergei Gorelkin wrote:
Hello,
While porting some Delphi code, I found the following two
incomatibility issues. Should I report them as bugs?
Sample 1: It compiles both in Delphi and FPC, but FPC executable fails
at runtime. Delphi inserts temporary string variable and conversion
(array of char -> string), but FPC treats the pointer literally.
MVC> Did you check the '@ returns typed pointer' setting in FPC ?
Oops... That was a false alarm - FPC compiler behaves the same way as
Delphi here. They both generate conversion code in {$T+} and do not
generate it in {$T-}.
So my sample appears to be legal only in {$T+}, which isn't a default.
What makes a difference is actually TStrings.SetTextStr implementation.
Delphi accesses the argument as null-terminated string, so it works perfectly
well even without conversion. FPC implementation treats argument as
AnsiString, accesses its Length field and eventually segfaults...
We should check that.
-----
const
TestData: array[0..7] of Char = 'abc'#10'def'#0;
procedure Test1;
var
sl: TStringList;
begin
sl := TStringList.Create;
sl.Text := string(@TestData[0]); // <- fails here
sl.Free;
end;
-----
Sample 2: This one compiles with Delphi (again, it inserts necessary
conversion Wide -> Ansi), but does not compile with FPC, neither in
objfpc nor in Delphi mode.
-----
function Test2: string;
var
buf: array[0..255] of char;
len: Integer;
begin
{ (skipped) I read USB string descriptor into buf. After that,
buf[0] contains length of descriptor in bytes, buf[1] = 3,
and rest is filled with Unicode chars. Now I want to convert it into
ASCII...
}
len := Integer(buf[0]) shr 1;
SetString(result, PWideChar(@buf[2]), len-1);
end;
MVC> What is the error ?
It is 'Incompatible type for arg no.2: Got "PWideChar", expected
"PChar"'.
Seems like a missing overloaded version of SetString()
Michael.
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