nes-pascal

Type-system diagnostics

Type-system diagnostics use the E4000-E4999 range.

E4001 - Unknown type

• Category: Type System
• Explanation: A declaration names a type not provided by the implemented language.

• Trigger:

  Counter: word;
  

• Expected compiler output:

  E4001 demo.nsp:1:10
  
  Unknown type: word.
  

• Suggested fix: Use nes_color, byte, or boolean.

E4002 - Invalid nes_color value

• Category: Type System
• Explanation: nes_color values are limited to the NES palette range $00..$3F.

• Trigger:

  BackgroundColor := $80;
  

• Expected compiler output:

  E4002 demo.nsp:1:20
  
  Value $80 is not valid for type nes_color.
  
  Allowed range: $00..$3F.
  

• Suggested fix: Use a hexadecimal value from $00 through $3F.

E4003 - Invalid byte value

• Category: Type System
• Explanation: A byte occupies one byte and cannot represent values above $FF.

• Trigger:

  Counter := $100;
  

• Expected compiler output:

  E4003 demo.nsp:1:12
  
  Value $100 is not valid for type byte.
  
  Allowed range: $00..$FF.
  

• Suggested fix: Use a hexadecimal value from $00 through $FF.

E4004 - Incompatible types

• Category: Type System
• Explanation: Assignments and intrinsic arguments require exact type matches. Numeric-to-boolean and other implicit conversions are forbidden. Arithmetic expressions and their operands must have type byte. Comparison operands must follow the comparison operator’s type rules, and Boolean operators require boolean operands. Increment/decrement targets and amounts, plus for control variables and bounds, must have type byte. Procedure arguments must exactly match their corresponding byte or boolean parameter types.

• Trigger:

  Counter := Active;
  

• Expected compiler output:

  E4004 demo.nsp:1:12
  
  Cannot assign a value of type boolean to variable Counter of type byte.
  
  The source and target types must match.
  

• Suggested fix: Use a source value with exactly the target type. Use true or false for a boolean literal, and use arithmetic only with byte values. Compare matching types, and use not, and, and or only with boolean values.

E4005 - Unsupported parameter type

• Category: Type System
• Explanation: The current value-parameter calling convention supports only byte and boolean. Although nes_color remains a valid type for constants and global variables, it cannot be used for a parameter yet.

• Trigger:

  procedure SetColor(Color: nes_color);
  begin
  end;
  

• Expected compiler output:

  E4005 demo.nsp:1:27
  
  Type nes_color is not supported for procedure parameters.
  

• Suggested fix: Declare the value parameter as byte or boolean, or keep an nes_color value in global state.