fixing argument offset logic

Author: samuelcolvin

devtools/debug.py

@@ -125,11 +125,12 @@ def _process_args(self, func_ast, code_lines, args, kwargs) -> Generator[DebugAr
                 yield self.output_class.arg_class(arg, name=ast_node.id)
             elif isinstance(ast_node, self.complex_nodes):
                 # TODO replace this hack with astor when it get's round to a new release
-                start_line, start_col = ast_node.lineno - 1, ast_node.col_offset
-                end_line, end_col = len(code_lines) - 1, None
+                start_line, start_col = arg_offsets[i]
 
-                if i < len(arg_offsets) - 1:
+                if i + 1 < len(arg_offsets):
                     end_line, end_col = arg_offsets[i + 1]
+                else:
+                    end_line, end_col = len(code_lines) - 1, None
 
                 name_lines = []
                 for l in range(start_line, end_line + 1):
@@ -193,7 +194,12 @@ def _parse_code(self, call_frame, func_regex, filename) -> Tuple[Optional[ast.AS
     @classmethod
     def _get_offsets(cls, func_ast):
         for arg in func_ast.args:
-            yield arg.lineno - 1, arg.col_offset
+            start_line, start_col = arg.lineno - 1, arg.col_offset
+
+            # horrible hack for http://bugs.python.org/issue31241
+            if isinstance(arg, (ast.ListComp, ast.GeneratorExp)):
+                start_col -= 1
+            yield start_line, start_col
         for kw in func_ast.keywords:
             yield kw.value.lineno - 1, kw.value.col_offset - len(kw.arg) - 1
 

tests/test_expr_render.py

@@ -45,11 +45,11 @@ def test_exotic_types():
         '  1 < 2 = True (bool)\n'
         '  1 << 2 = 4 (int)\n'
         '  \'t\' if True else \'f\' = "t" (str) len=1\n'
-        '  1 or 2, [ = 1 (int)\n'
-        '  a for a in aa] = [1, 2, 3] (list)\n'
+        '  1 or 2 = 1 (int)\n'
+        '  [a for a in aa] = [1, 2, 3] (list)\n'
         '  {a for a in aa} = {1, 2, 3} (set)\n'
-        '  {a: a + 1 for a in aa}, ( = {1: 2, 2: 3, 3: 4} (dict)\n'
-        '  a for a in aa) = <generator object test_exotic_types.<locals>.<genexpr> at 0x<hash>> (generator)'
+        '  {a: a + 1 for a in aa} = {1: 2, 2: 3, 3: 4} (dict)\n'
+        '  (a for a in aa) = <generator object test_exotic_types.<locals>.<genexpr> at 0x<hash>> (generator)'
     ) == s