Fix Python 3.8 error issues

parso/python/errors.py

@@ -16,6 +16,7 @@ ALLOWED_FUTURES = (
     'all_feature_names', 'nested_scopes', 'generators', 'division',
     'absolute_import', 'with_statement', 'print_function', 'unicode_literals',
 )
+_COMP_FOR_TYPES = ('comp_for', 'sync_comp_for')
 
 
 def _iter_stmts(scope):
@@ -34,12 +35,12 @@ def _iter_stmts(scope):
 
 def _get_comprehension_type(atom):
     first, second = atom.children[:2]
-    if second.type == 'testlist_comp' and second.children[1].type == 'comp_for':
+    if second.type == 'testlist_comp' and second.children[1].type in _COMP_FOR_TYPES:
         if first == '[':
             return 'list comprehension'
         else:
             return 'generator expression'
-    elif second.type == 'dictorsetmaker' and second.children[-1].type == 'comp_for':
+    elif second.type == 'dictorsetmaker' and second.children[-1].type in _COMP_FOR_TYPES:
         if second.children[1] == ':':
             return 'dict comprehension'
         else:
@@ -460,17 +461,13 @@ class _YieldFromCheck(SyntaxRule):
 @ErrorFinder.register_rule(type='name')
 class _NameChecks(SyntaxRule):
     message = 'cannot assign to __debug__'
-    message_keyword = 'assignment to keyword'
     message_none = 'cannot assign to None'
 
     def is_issue(self, leaf):
         self._normalizer.context.add_name(leaf)
 
         if leaf.value == '__debug__' and leaf.is_definition():
-            if self._normalizer.version < (3, 0):
+            return True
-                return True
-            else:
-                self.add_issue(leaf, message=self.message_keyword)
         if leaf.value == 'None' and self._normalizer.version < (3, 0) \
                 and leaf.is_definition():
             self.add_issue(leaf, message=self.message_none)
@@ -538,7 +535,7 @@ class _StarStarCheck(SyntaxRule):
     def is_issue(self, leaf):
         if leaf.parent.type == 'dictorsetmaker':
             comp_for = leaf.get_next_sibling().get_next_sibling()
-            return comp_for is not None and comp_for.type == 'comp_for'
+            return comp_for is not None and comp_for.type in _COMP_FOR_TYPES
 
 
 @ErrorFinder.register_rule(value='yield')
@@ -637,7 +634,7 @@ class _StarExprRule(SyntaxRule):
             return True
         if node.parent.type == 'testlist_comp':
             # [*[] for a in [1]]
-            if node.parent.children[1].type == 'comp_for':
+            if node.parent.children[1].type in _COMP_FOR_TYPES:
                 self.add_issue(node, message=self.message_iterable_unpacking)
         if self._normalizer.version <= (3, 4):
             n = search_ancestor(node, 'for_stmt', 'expr_stmt')
@@ -730,10 +727,16 @@ class _ArgumentRule(SyntaxRule):
         if node.children[1] == '=' and first.type != 'name':
             if first.type == 'lambdef':
                 # f(lambda: 1=1)
-                message = "lambda cannot contain assignment"
+                if self._normalizer.version < (3, 8):
+                    message = "lambda cannot contain assignment"
+                else:
+                    message = 'expression cannot contain assignment, perhaps you meant "=="?'
             else:
                 # f(+x=1)
-                message = "keyword can't be an expression"
+                if self._normalizer.version < (3, 8):
+                    message = "keyword can't be an expression"
+                else:
+                    message = 'expression cannot contain assignment, perhaps you meant "=="?'
             self.add_issue(first, message=message)
 
 
@@ -757,7 +760,7 @@ class _ArglistRule(SyntaxRule):
     def is_issue(self, node):
         first_arg = node.children[0]
         if first_arg.type == 'argument' \
-                and first_arg.children[1].type in ('comp_for', 'sync_comp_for'):
+                and first_arg.children[1].type in _COMP_FOR_TYPES:
             # e.g. foo(x for x in [], b)
             return len(node.children) >= 2
         else:
@@ -890,7 +893,13 @@ class _CheckAssignmentRule(SyntaxRule):
             error = _get_comprehension_type(node)
             if error is None:
                 if second.type == 'dictorsetmaker':
-                    error = 'literal'
+                    if self._normalizer.version < (3, 8):
+                        error = 'literal'
+                    else:
+                        if second.children[1] == ':':
+                            error = 'dict display'
+                        else:
+                            error = 'set display'
                 elif first in ('(', '['):
                     if second.type == 'yield_expr':
                         error = 'yield expression'
@@ -902,7 +911,10 @@ class _CheckAssignmentRule(SyntaxRule):
                     else:  # Everything handled, must be useless brackets.
                         self._check_assignment(second, is_deletion)
         elif type_ == 'keyword':
-            error = 'keyword'
+            if self._normalizer.version < (3, 8):
+                error = 'keyword'
+            else:
+                error = str(node.value)
         elif type_ == 'operator':
             if node.value == '...':
                 error = 'Ellipsis'
@@ -936,19 +948,23 @@ class _CheckAssignmentRule(SyntaxRule):
             error = 'operator'
 
         if error is not None:
-            message = "can't %s %s" % ("delete" if is_deletion else "assign to", error)
+            cannot = "can't" if self._normalizer.version < (3, 8) else "cannot"
+            message = ' '.join([cannot, "delete" if is_deletion else "assign to", error])
             self.add_issue(node, message=message)
 
 
 @ErrorFinder.register_rule(type='comp_for')
+@ErrorFinder.register_rule(type='sync_comp_for')
 class _CompForRule(_CheckAssignmentRule):
     message = "asynchronous comprehension outside of an asynchronous function"
 
     def is_issue(self, node):
         # Some of the nodes here are already used, so no else if
-        expr_list = node.children[1 + int(node.children[0] == 'async')]
+        if node.type != 'comp_for' or self._normalizer.version < (3, 8):
-        if expr_list.type != 'expr_list':  # Already handled.
+            # comp_for was replaced by sync_comp_for in Python 3.8.
-            self._check_assignment(expr_list)
+            expr_list = node.children[1 + int(node.children[0] == 'async')]
+            if expr_list.type != 'expr_list':  # Already handled.
+                self._check_assignment(expr_list)
 
         return node.children[0] == 'async' \
             and not self._normalizer.context.is_async_funcdef()

test/failing_examples.py

@@ -251,10 +251,6 @@ GLOBAL_NONLOCAL_ERROR = [
 
 if sys.version_info >= (3, 6):
     FAILING_EXAMPLES += GLOBAL_NONLOCAL_ERROR
-    FAILING_EXAMPLES += [
-        # Raises multiple errors in previous versions.
-        'async def foo():\n def nofoo():[x async for x in []]',
-    ]
 if sys.version_info >= (3, 5):
     FAILING_EXAMPLES += [
         # Raises different errors so just ignore them for now.

test/test_python_errors.py

@@ -41,6 +41,29 @@ def test_python_exception_matches(code):
     assert line_nr is None or line_nr == error.start_pos[0]
 
 
+def test_non_async_in_async():
+    """
+    This example doesn't work with FAILING_EXAMPLES, because the line numbers
+    are not always the same / incorrect in Python 3.8.
+    """
+    if sys.version_info[:2] < (3, 5):
+        pytest.skip()
+
+        # Raises multiple errors in previous versions.
+    code = 'async def foo():\n def nofoo():[x async for x in []]'
+    wanted, line_nr = _get_actual_exception(code)
+
+    errors = _get_error_list(code)
+    if errors:
+        error, = errors
+        actual = error.message
+    assert actual in wanted
+    if sys.version_info[:2] < (3, 8):
+        assert line_nr == error.start_pos[0]
+    else:
+        assert line_nr == 0  # For whatever reason this is zero in Python 3.8+
+
+
 @pytest.mark.parametrize(
     ('code', 'positions'), [
         ('1 +', [(1, 3)]),
@@ -103,7 +126,8 @@ def _get_actual_exception(code):
         # The python 3.5+ way, a bit nicer.
         wanted = 'SyntaxError: positional argument follows keyword argument'
     elif wanted == 'SyntaxError: assignment to keyword':
-        return [wanted, "SyntaxError: can't assign to keyword"], line_nr
+        return [wanted, "SyntaxError: can't assign to keyword",
+                'SyntaxError: cannot assign to __debug__'], line_nr
     elif wanted == 'SyntaxError: assignment to None':
         # Python 2.6 does has a slightly different error.
         wanted = 'SyntaxError: cannot assign to None'