fix: crash un undeclared substring assign

Author: boriel

src/api/errmsg.py

@@ -19,6 +19,7 @@
     "register_warning",
     "warning",
     "warning_not_used",
+    "warning_uninitalized_string_var",
 )
 
 
@@ -127,6 +128,12 @@ def warning_implicit_type(lineno: int, id_: str, type_: str = None):
     warning(lineno, "Using default implicit type '%s' for '%s'" % (type_, id_))
 
 
+@register_warning("101")
+def warning_uninitalized_string_var(lineno: int, id_: str):
+    """Warning: Accessing uninitialized string variable"""
+    warning(lineno, f"Accessing uninitialized string variable '{id_}'")
+
+
 @register_warning("110")
 def warning_condition_is_always(lineno: int, cond: bool = False):
     """Warning: Condition is always false/true"""

src/api/symboltable/symboltable.py

@@ -132,7 +132,7 @@ def declare(self, id_: str, lineno: int, entry: symbols.ID | symbols.TYPE) -> No
 
         return entry
 
-    def declare_safe(self, id_: str, lineno: int, entry: symbols.ID):
+    def declare_safe(self, id_: str, lineno: int, entry: symbols.ID) -> symbols.ID | symbols.TYPE:
         """Like declare, but never returns None"""
         result = self.declare(id_, lineno, entry)
         assert result is not None
@@ -204,7 +204,7 @@ def check_is_undeclared(
             )
         return False
 
-    def check_class(self, id_: str, class_: CLASS, lineno: int, scope: Scope = None, show_error=True) -> bool:
+    def check_class(self, id_: str, class_: CLASS, lineno: int, scope: Scope | None = None, show_error=True) -> bool:
         """Check the id is either undefined or defined with
         the given class.
 
@@ -342,7 +342,7 @@ def access_id(
         default_class: CLASS = CLASS.unknown,
         *,
         ignore_explicit_flag=False,
-    ):
+    ) -> symbols.ID | None:
         """Access a symbol by its identifier and checks if it exists.
         If not, it's supposed to be an implicitly declared variable.
 
@@ -442,10 +442,9 @@ def access_func(self, id_: str, lineno: int, scope=None, default_type=None):
 
         return result
 
-    def access_call(self, id_: str, lineno: int, scope=None, type_=None):
+    def access_call(self, id_: str, lineno: int, scope=None, type_=None) -> symbols.ID | None:
         """Creates a func/array/string call. Checks if id is callable or not.
-        An identifier is "callable" if it can be followed by a list of para-
-        meters.
+        An identifier is "callable" if it can be followed by a list of parameters.
         This does not mean the id_ is a function, but that it allows the same
         syntax a function does:
 

src/zxbc/zxbparser.py

@@ -1265,7 +1265,8 @@ def p_substr_assignment_no_let(p):
         return
 
     if entry.class_ == CLASS.unknown:
-        entry.class_ = CLASS.var
+        errmsg.warning_uninitalized_string_var(p.lineno(1), entry.name)
+        entry.to_var()
 
     if p[6].type_ != Type.string:
         errmsg.syntax_error_expected_string(p.lineno(5), p[6].type_)