Remote debugging with XE2 - display of strings
StringDelphiDebuggingDelphi Xe2Remote DebuggingString Problem Overview
I'm remote debugging a large app between DElphi XE2 (update #4) and a Windows XP target. PAServer is running on the target and the application works fine and stops at breakpoints (you would NOT believe how hard just that achievement was - hint - delete your DPROJ and start again if it has been through any IDE prior to XE).
I notice that the display of local variables and watches show my strings in a strange format compared to the usual display of the 'some string' format that one sees when debugging locally. I see:
Can anyone tell me why the strings are displayed this way? I also get quite a bit of { NULL } and garbage between {}'s on output variables that are not yet assigned. Thanks.
The displayed local string variables:
Note the truncated 'Hello'. It would seem that XE2 has a problem with remote unicode strings at times. My PaServer is version 1.0.2. Can anyone check that this is the latest? 'Twas taken from Update #4...
String Solutions
Solution 1 - String
I'm not entirely sure why you have the {} around the string values, - my hunch is that it is to demonstrate that the values are coming from a remote execution - but I know for a fact that S
is being truncated due to optimization...
{$O-} // Disable Optimization
var
S: AnsiString;
S2: UnicodeString;
begin
S := 'Hello';
S2 := 'Hello2';
ShowMessage(S2);
end;
{$O+} // Enable Optimization
You'll now note that the value 'Hello' (of variable S
) remains intact when debugging. Likewise if you make use of the value assigned to S
:
var
S: AnsiString;
S2: UnicodeString;
begin
S := 'Hello';
S2 := 'Hello2';
ShowMessage(S + S2);
end;
Delphi's optimization now identifies that S
is being used within its valid scope, and so the value is preserved.
So, what you're calling a "bug" is in fact a "compiler feature" exactly as Borland/Inprise/Codegear/Embarcadero intended.
Solution 2 - String
(I am copying code from @Dave)
var
S1: AnsiString;
S2: UnicodeString;
begin
S1 := 'Foo';
S2 := 'Bar';
ShowMessage(Format('%s!', S2));
end;
I am guessing local var S1 here is optimized because it is not used anywhere, so the value is not relvant anymore.
Try run this on a local machine, can you see S1?
Solution 3 - String
I am not sure if it pertains, but I am aware of System.AnsiStrings containing specialized commands such as "Format", etc... Using something like the following may resolve your issue:
var
S1: AnsiString;
S2: UnicodeString;
begin
S1 := 'Foo';
S2 := 'Bar';
ShowMessage(Format('%s!', S2));
end;
Also there are a few open bugs, just to rule out any of those, what specific versions of the os and tools are you using i.e. Win7 x64 Ultimate etc.?
Solution 4 - String
Project -> Options -> Delphi Compiler -> Linking -> Include remote debug symbols = true