NetWkstaGetInfo ACCESS_VIOLATION under WIN64 - delphi

Question

I'm have code, which works fine during many years under WIN32. But yesterday, after compiling under WIN64 I'm got strange ACCESS_VIOLATION error when trying get wki100_langroup field. Where wrong this code? (Computer not in domain and in Delphi 11 debug window I can see, that this field is empty)
const
NERR_SUCCESS = 0;
type
WKSTA_INFO_100 = record
wki100_platform_id: DWORD;
wki100_computername: LPWSTR;
wki100_langroup: LPWSTR;
wki100_ver_major: DWORD;
wki100_ver_minor: DWORD;
end;
LPWKSTA_INFO_100 = ^WKSTA_INFO_100;
function NetWkstaGetInfo(ServerName: LPWSTR; Level: DWORD; var BufPtr: Pointer): DWORD; stdcall;
external 'netapi32.dll' Name 'NetWkstaGetInfo';
function GetDomain: string;
var
PBuf: Pointer;
Res: Integer;
begin
Result := '';
Res := NetWkstaGetInfo(nil, 100, PBuf);
if (Res = NERR_Success) then begin
Result := LPWKSTA_INFO_100(PBuf)^.wki100_langroup; // ACCESS_VIOLATION here
if Assigned(PBuf) then
NetApiBufferFree(PBuf);
end;
end;
Update:
After changing Pointer to PByte I have the same exception
function NetWkstaGetInfo(ServerName: LPWSTR; Level: DWORD; BufPtr: PByte): DWORD; stdcall;
external 'netapi32.dll' Name 'NetWkstaGetInfo';
function GetDomain: string;
var
PBuf: PByte;
Res: Integer;
begin
Result := '';
Res := NetWkstaGetInfo(nil, 100, #PBuf);
if (Res = NERR_Success) then begin
Result := LPWKSTA_INFO_100(PBuf)^.wki100_langroup; // ACCESS_VIOLATION here
if Assigned(PBuf) then
NetApiBufferFree(PBuf);
end;
end;
Screenshots from Win32:
and Win64 breakpoints:

Answer 1

The symptoms suggest that some other code changed default record alignment for WKSTA_INFO_100 record type.
Under 32-bit compiler that wouldn't have an impact because all values in the record are also 32-bit therefore they will be correctly aligned even if other alignment size is specified.
Under 64-bit compiler DWORD is 32-bit, while LPWSTR is 64-bit. With default 8 byte alignment that means there will be 4 padding bytes inserted after wki100_platform_id. If some other alignment is used following fields will not be at correct positions.
To correct this you need to specify 8 byte alignment {$A8} before type declaration.
type
{$A8}
WKSTA_INFO_100 = record
wki100_platform_id: DWORD;
wki100_computername: LPWSTR;
wki100_langroup: LPWSTR;
wki100_ver_major: DWORD;
wki100_ver_minor: DWORD;
end;