nes-pascal

Semantic diagnostics

Semantic-analysis diagnostics use the E3000-E3999 range.

E3001 - Missing nes.run

• Category: Semantic Analysis
• Explanation: A valid program must finish with exactly one nes.run statement.

• Trigger:

  begin
      nes.set_background_color($21);
  end.
  

• Expected compiler output:

  E3001 demo.nsp:4:1
  
  The program must end with nes.run.
  

• Suggested fix: Add nes.run; as the final statement.

E3002 - Statement after nes.run

• Category: Semantic Analysis
• Explanation: nes.run transfers control to the stable main loop, so no later statement can execute.

• Trigger:

  nes.run;
  Counter := $01;
  

• Expected compiler output:

  E3002 demo.nsp:2:1
  
  No statement may appear after nes.run.
  

• Suggested fix: Move nes.run; to the end of the block.

E3003 - Invalid background-color call count

• Category: Semantic Analysis
• Explanation: A valid program requires exactly one call to nes.set_background_color.

• Trigger:

  begin
      nes.run;
  end.
  

• Expected compiler output:

  E3003 demo.nsp:3:1
  
  The program must set the background color exactly once.
  

• Suggested fix: Add one nes.set_background_color(value); call before nes.run.

E3004 - Duplicate symbol

• Category: Semantic Analysis
• Explanation: Constants, variables, and procedures share a case-insensitive namespace. Parameter names are case-insensitive within a procedure and cannot shadow a global symbol.

• Trigger:

  var
      Color: byte;
      COLOR: byte;
  

• Expected compiler output:

  E3004 demo.nsp:3:5
  
  Symbol COLOR is already declared.
  

• Suggested fix: Use a unique name in the current scope. Rename a parameter if it duplicates another parameter or a global symbol.

E3005 - Unknown identifier

• Category: Semantic Analysis
• Explanation: A value expression references a name that has not been declared.

• Trigger:

  Counter := Missing;
  

• Expected compiler output:

  E3005 demo.nsp:1:12
  
  Unknown identifier: Missing.
  

• Suggested fix: Declare the referenced constant or variable before use.

E3006 - Assignment to constant

• Category: Semantic Analysis
• Explanation: Constants cannot be modified after declaration.

• Trigger:

  Maximum := $10;
  

• Expected compiler output:

  E3006 demo.nsp:1:1
  
  Cannot assign to constant Maximum.
  

• Suggested fix: Assign the value to a variable instead.

E3007 - Unknown assignment target

• Category: Semantic Analysis
• Explanation: The left side of an assignment is not a declared variable.

• Trigger:

  Missing := $01;
  

• Expected compiler output:

  E3007 demo.nsp:1:1
  
  Unknown variable: Missing.
  

• Suggested fix: Declare the target in the var section.

E3008 - Variable read before assignment

• Category: Semantic Analysis
• Explanation: A variable value is read before an earlier statement assigns it, or a procedure is called before the globals it requires have been assigned.

• Trigger:

  var
      BackgroundColor: nes_color;
  begin
      nes.set_background_color(BackgroundColor);
  

• Expected compiler output:

  E3008 demo.nsp:4:30
  
  Variable BackgroundColor is read before it is assigned.
  
      nes.set_background_color(BackgroundColor);
                               ^^^^^^^^^^^^^^^
  

• Suggested fix: Assign the variable before reading it or before calling a procedure that requires it.

E3009 - Runtime command inside conditional

• Category: Semantic Analysis
• Explanation: NES initialization commands must execute exactly once in the top-level program block. nes.set_background_color and nes.run cannot be placed on a conditional execution path.

• Trigger:

  if Enabled then
      nes.run;
  

• Expected compiler output:

  E3009 demo.nsp:2:5
  
  nes.run cannot appear inside a conditional branch.
  

• Suggested fix: Move the NES runtime command out of the conditional and place it in the top-level program block.

E3010 - Loop control outside loop

• Category: Semantic Analysis
• Explanation: break and continue require an enclosing while, repeat, or for loop that provides their control-flow target.

• Trigger:

  begin
      break;
  end.
  

• Expected compiler output:

  E3010 demo.nsp:2:5
  
  break can appear only inside a loop.
  

• Suggested fix: Move the statement inside a loop or remove it.

E3011 - Runtime command inside loop

• Category: Semantic Analysis
• Explanation: NES initialization commands must execute exactly once. nes.set_background_color and nes.run cannot be repeated by a loop.

• Trigger:

  while Running do
      nes.run;
  

• Expected compiler output:

  E3011 demo.nsp:2:5
  
  nes.run cannot appear inside a loop body.
  

• Suggested fix: Move the NES runtime command out of the loop and into the top-level program block.

E3012 - For control variable modification

• Category: Semantic Analysis
• Explanation: A for loop owns its control variable while its body is executing. Assigning it, updating it with inc or dec, or reusing it as the control variable of a nested for would make loop termination unpredictable.

• Trigger:

  for Index := $00 to $03 do
      Index := $01;
  

• Expected compiler output:

  E3012 demo.nsp:2:5
  
  For control variable Index cannot be modified inside its loop body.
  

• Suggested fix: Remove the modification, use a different variable in the body, or update the control variable after the loop.

E3013 - Unknown procedure

• Category: Semantic Analysis
• Explanation: A bare procedure call must resolve to a declared procedure. All procedure declarations appear before the main program block, but their relative order does not restrict calls.

• Trigger:

  begin
      Missing;
  end.
  

• Expected compiler output:

  E3013 demo.nsp:2:5
  
  Unknown procedure: Missing.
  

• Suggested fix: Declare the procedure before the main program block or correct the call’s spelling.

E3014 - Recursive procedure call

• Category: Semantic Analysis
• Explanation: The calling convention supports nested acyclic calls but does not support direct or indirect recursion.

• Trigger:

  procedure Again;
  begin
      Again;
  end;
  

• Expected compiler output:

  E3014 demo.nsp:4:5
  
  Recursive procedure call involving Again is not supported.
  

• Suggested fix: Remove the recursive call cycle and express the repeated work with a supported loop.

E3015 - Runtime command inside procedure

• Category: Semantic Analysis
• Explanation: nes.set_background_color and nes.run belong to the main initialization sequence and must execute exactly once. They cannot be hidden behind a procedure call.

• Trigger:

  procedure StartRuntime;
  begin
      nes.run;
  end;
  

• Expected compiler output:

  E3015 demo.nsp:4:5
  
  nes.run cannot appear inside a procedure.
  

• Suggested fix: Move the runtime command to the main program block.

E3016 - Incorrect procedure argument count

• Category: Semantic Analysis
• Explanation: Every procedure call must provide exactly one argument for each declared value parameter. Parameterless procedures continue to use a bare call without parentheses.

• Trigger:

  procedure Initialize(Value: byte);
  begin
  end;
  
  begin
      Initialize;
  end.
  

• Expected compiler output:

  E3016 demo.nsp:7:5
  
  Procedure Initialize expects 1 argument(s), but 0 were provided.
  

• Suggested fix: Pass exactly the declared number of arguments, in the same order as the parameters.