Use get_inst and self.insts more..

needed more in 3.6 to handle EXTENDED_ARGS before JUMP_xxx

test/simple_source/bug36/09_ext_arg_jump.py

@@ -0,0 +1,37 @@
+# From 3.6 argparse. Bug was in handling EXTENDED_ARGS in a JUMP_FORWARD
+# messing up control flow detection
+def _format_usage(self, usage, actions, groups, prefix):
+    if usage:
+        usage = usage % dict(prog=self._prog)
+
+    elif usage is None:
+        prog = 5
+
+        for action in actions:
+            if action.option_strings:
+                actions.append(action)
+            else:
+                actions.append(action)
+
+        action_usage = format(optionals + positionals, groups)
+
+        text_width = self._width - self._current_indent
+        if len(prefix) + len(usage) > text_width:
+
+            if len(prefix) + len(prog) <= 0.75 * text_width:
+                indent = ' ' * (len(prefix) + len(prog) + 1)
+                if opt_parts:
+                    lines.extend(get_lines(pos_parts, indent))
+                elif pos_parts:
+                    lines = get_lines([prog] + pos_parts, indent, prefix)
+                else:
+                    lines = [prog]
+
+            else:
+                if len(lines) > 1:
+                    lines.extend(get_lines(pos_parts, indent))
+                lines = [prog] + lines
+
+            usage = '\n'.positionals(lines)
+
+    return

uncompyle6/scanner.py

@@ -102,12 +102,15 @@ class Scanner(object):
         That is, it is ether "JUMP_FORWARD" or an absolute jump that
         goes forward.
         """
-        if self.code[offset] == self.opc.JUMP_FORWARD:
+        opname = self.get_inst(offset).opname
+        if opname == 'JUMP_FORWARD':
             return True
-        if self.code[offset] != self.opc.JUMP_ABSOLUTE:
+        if opname != 'JUMP_ABSOLUTE':
             return False
-        # FIXME 0 isn't always correct
-        return offset < self.get_target(offset, 0)
+        return offset < self.get_target(offset)
+
+    def prev_offset(self, offset):
+        return self.insts[self.offset2inst_index[offset]-1].offset
 
     def get_inst(self, offset):
         # Instructions can get moved as a result of EXTENDED_ARGS removal.