Method visit_assignment_stmt

mypy/semanal.py:3289–3373

(self, s: AssignmentStmt)

        return True

    def visit_assignment_stmt(self, s: AssignmentStmt) -> None:
        self.statement = s

        # Special case assignment like X = X.
        if self.analyze_identity_global_assignment(s):
            return

        tag = self.track_incomplete_refs()

        # Here we have a chicken and egg problem: at this stage we can't call
        # can_be_type_alias(), because we have not enough information about rvalue.
        # But we can't use a full visit because it may emit extra incomplete refs (namely
        # when analysing any type applications there) thus preventing the further analysis.
        # To break the tie, we first analyse rvalue partially, if it can be a type alias.
        if self.can_possibly_be_type_form(s):
            old_basic_type_applications = self.basic_type_applications
            self.basic_type_applications = True
            with self.allow_unbound_tvars_set():
                s.rvalue.accept(self)
            self.basic_type_applications = old_basic_type_applications
        elif self.can_possibly_be_typevarlike_declaration(s):
            # Allow unbound tvars inside TypeVarLike defaults to be evaluated later
            with self.allow_unbound_tvars_set():
                s.rvalue.accept(self)
        else:
            s.rvalue.accept(self)

        if self.found_incomplete_ref(tag) or self.should_wait_rhs(s.rvalue):
            # Initializer couldn't be fully analyzed. Defer the current node and give up.
            # Make sure that if we skip the definition of some local names, they can't be
            # added later in this scope, since an earlier definition should take precedence.
            for expr in names_modified_by_assignment(s):
                self.mark_incomplete(expr.name, expr)
            return
        if self.can_possibly_be_type_form(s):
            # Now re-visit those rvalues that were we skipped type applications above.
            # This should be safe as generally semantic analyzer is idempotent.
            with self.allow_unbound_tvars_set():
                s.rvalue.accept(self)

        # The r.h.s. is now ready to be classified, first check if it is a special form:
        special_form = False
        # * type alias
        if self.check_and_set_up_type_alias(s):
            s.is_alias_def = True
            special_form = True
        elif isinstance(s.rvalue, CallExpr):
            # * type variable definition
            if self.process_typevar_declaration(s):
                special_form = True
            elif self.process_paramspec_declaration(s):
                special_form = True
            elif self.process_typevartuple_declaration(s):
                special_form = True
            # * type constructors
            elif self.analyze_namedtuple_assign(s):
                special_form = True
            elif self.analyze_typeddict_assign(s):