When transpiling Pascal to C++, one challenge is managing platform-specific headers without creating conflicts. For example, if you want to call Windows API functions like MessageBoxW, you need <windows.h> on the C++ side. But including Windows headers globally causes conflicts with cross-platform libraries like raylib (due to functions like CloseWindow and DrawText).

The Solution: {$INCLUDE_HEADER}

Just added a simple directive that lets you specify which C/C++ headers to include directly from your Pascal code:

{$APPTYPE GUI}
{$INCLUDE_HEADER 'windows.h'}
program ProgramMessageBox;
function MessageBoxW(hWnd: Cardinal; lpText: PChar; 
 lpCaption: PChar; uType: Cardinal): Integer; 
 stdcall; external 'user32.dll';
begin
 MessageBoxW(0, 'Hello from NitroPascal!', 'Test', 0);
end.

How it works:

• Headers are emitted at the top of the generated .h file (after pragma guards)
• No global header pollution - only include what you need
• Supports both system headers (<header.h>) and local headers ("header.h")
• Works with conditional compilation for cross-platform code

Platform-Specific Headers:

{$IFDEF MSWINDOWS}
 {$INCLUDE_HEADER 'windows.h'}
{$ENDIF}
{$IFDEF POSIX}
 {$INCLUDE_HEADER 'unistd.h'}
{$ENDIF}

Clean, simple, and solves the header conflict problem elegantly! 💪