s0 := s1 + s2; => Pointer issue.

[paule32]

I have the following Code Snippet:

var
  s1, s2: String;
begin
  s1 := 'mufoLo';
  s2 := 'Hello World' + s1;
end;

But with my Custom RTL, I get Error during Compilation on Line: s2
=> Error: Call by var for arg no. 1 has to match exactly: Got "AnsiString" expected "Pointer"

Is there a CompilerProc available or how can I implement this ?

[Thaddy]

look in system.fpd

[marcov]

Yeah probably something in sstrings.inc or astrings.inc

[Thaddy]

Dead giveaway 2:
AnsiStrings have a refcount and a length stored at negative offset of ansistring[1] and all ansistrings must add an extra termination zero. (Because of casting to Pchars).
Apart from that you will have to implement refcount.

If I were you I would forget about Ansi and use shortstring, which is much easier to implement.

[paule32]

I am successfully implement the "Assign", and "Concatenate" CompilerProc:

Code: Pascal  [Select][+][-]

1. procedure fpc_ansistr_assign(var DestS: Pointer; S2: Pointer); [public, alias: 'FPC_ANSISTR_ASSIGN']; compilerproc;
2. var
3.     SLen: SIZE_T;
4. begin
5.     SLen  := strlen( LPCSTR( S2 ) );
6.     DestS := VirtualAlloc( nil, SLen, MEM_COMMIT or MEM_RESERVE, PAGE_READWRITE );
7.    
8.     if (not (DestS = nil)) then
9.     begin
10.         FillChar( DestS^, SLen, #0 );
11.         move( S2^, DestS^, SLen );
12.     end else
13.     begin
14.         MessageBox( 0, 'Error: fpc_AnsiStr_Assign memory allocation fail.', 'Error', 0 );
15.         ExitProcess( 1 );
16.     end;
17.  
18.     // TODO: add delete
19.     //VirtualFree( DestS, 0, MEM_RELEASE );
20. end;
21. procedure fpc_ansistr_concat(var dst: String; const S1,S2 : String; cp: DWORD); compilerproc;
22. Var
23.     S1Len, S2Len, S3Len: SIZE_T;
24.     DestS: Pointer;
25. begin
26.     S1Len := strlen( LPCSTR( S1 ) );
27.     S2Len := strlen( LPCSTR( S2 ) );
28.    
29.     S3Len := S1Len + S2Len + 1;
30.     DestS := VirtualAlloc( nil, S3Len, MEM_COMMIT or MEM_RESERVE, PAGE_READWRITE );
31.    
32.     if (not (DestS = nil)) then
33.     begin
34.         FillChar( DestS^, S3Len, #0 );
35.  
36.         move( PChar( S1 )^,        DestS^ , S1Len );
37.         move( PChar( S2 )^, (PChar(DestS) + S1Len)^, S2Len );
38.        
39.         dst := String( DestS );
40.     end else
41.     begin
42.         MessageBox( 0, 'Error: fpc_AnsiStr_Concat memory allocation fail.', 'Error', 0 );
43.         ExitProcess( 1 );
44.     end;
45. end;
46.  

This is not simply portable, because I use win32api Windows 10 API Funktion's.
But for me it is okay - I have tiny .ExE - Goal reached so far.

Okay. This could be a nogo for productive System's - I am not a professional Programmer/Developer.
But for me it is enough.

Thanks for your patient, and Hints.