Add warning when a value in DB > 255

It will be truncated for being byte.

Author: boriel

src/api/errmsg.py

@@ -186,6 +186,11 @@ def warning_unreachable_code(lineno: int, fname: Optional[str] = None):
 def warning_function_should_return_a_value(lineno: int, func_name: str, fname: Optional[str] = None):
     warning(lineno, f"Function '{func_name}' should return a value", fname=fname)
 
+
+@register_warning('200')
+def warning_value_will_be_truncated(lineno: int, fname: Optional[str] = None):
+    warning(lineno, "Value will be truncated", fname=fname)
+
 # endregion
 
 # region [Syntax Errors]

src/libzxbasm/asmparse.py

@@ -13,21 +13,26 @@
 
 import os
 import re
-from . import asmlex, basic
+
 import src.ply.yacc as yacc
+import src.api.utils
+
+from src import outfmt
+from src.api import errmsg
 
-from .asmlex import tokens  # noqa
-from .asm import AsmInstruction, Error
 from src.ast import Ast
 from src.ast.tree import NotAnAstError
 from src.api.debug import __DEBUG__
 from src.api.config import OPTIONS
 from src.api.errmsg import error
 from src.api.errmsg import warning
 from src.api import global_ as gl
-import src.api.utils
 from src.libzxbpp import zxbpp
-from .. import outfmt
+
+from . import asmlex, basic
+from .asmlex import tokens  # noqa
+from .asm import AsmInstruction, Error
+
 
 LEXER = asmlex.Lexer()
 
@@ -144,6 +149,8 @@ def bytes(self):
                 return tuple([0] * N)  # ??
 
             args = self.argval()
+            if args[1] > 255:
+                errmsg.warning_value_will_be_truncated(self.lineno)
             num = args[1] & 0xFF
             return tuple([num] * args[0])
 
@@ -165,7 +172,10 @@ def argval(self):
             return [None]
 
         if self.asm in ('DEFB', 'DEFS', 'DEFW'):
-            return tuple([x.eval() if isinstance(x, Expr) else x for x in self.arg])
+            result = tuple([x.eval() if isinstance(x, Expr) else x for x in self.arg])
+            if self.asm == 'DEFB' and any(x > 255 for x in result):
+                errmsg.warning_value_will_be_truncated(self.lineno)
+            return result
 
         self.arg = tuple([x if not isinstance(x, Expr) else x.eval() for x in self.arg])
         if gl.has_errors:

tests/functional/db256.asm

@@ -0,0 +1,10 @@
+ORG 32768
+
+DB 0, 1, 2, 256
+DB 1, TEST
+DS 10
+DS 10, 256
+
+TEST:
+
+

tests/functional/db256.bin

@@ -181,6 +181,10 @@ line_err.bas:5: error: Variable 'q' already declared at line_err.bas:1
 >>> process_file('let_expr_type_crash.bas')
 let_expr_type_crash.bas:3: error: Syntax Error. Unexpected token 's' <ID>
 let_expr_type_crash.bas:8: error: Function 'editStringFN' takes 0 parameters, not 3
+>>> process_file('db256.asm')
+db256.asm:3: warning: [W200] Value will be truncated
+db256.asm:4: warning: [W200] Value will be truncated
+db256.asm:6: warning: [W200] Value will be truncated
 
 # Test warning silencing
 >>> process_file('mcleod3.bas', ['-S', '-q', '-O --expect-warnings=2'])