Python 3.6 control flow bug...

Much more is needed, but it's a start

test/simple_source/bug36/10_extended_arg_loop.py

@@ -0,0 +1,49 @@
+# Bug in 3.6 has to do with parsing jumps where
+# the offset is more than 256 bytes so an EXTENDED_ARG
+# instruction is inserted. find_jump_targets() and
+# detect_control_flow need to be able to work in the presence
+# of EXTENDED_ARG.
+
+# This is a problem theoretically in Python before 3.6
+# but since offsets are very large it isn't noticed.
+
+# Code is simplified from trepan2/trepan/cli.py
+import sys
+def main(dbg=None, sys_argv=list(sys.argv)):
+
+    if sys_argv:
+        mainpyfile = None
+    else:
+        mainpyfile = "10"
+        sys.path[0] = "20"
+
+    while True:
+        try:
+            if dbg.program_sys_argv and mainpyfile:
+                normal_termination = dbg.run_script(mainpyfile)
+                if not normal_termination: break
+            else:
+                dbg.core.execution_status = 'No program'
+                dbg.core.processor.process_commands()
+                pass
+
+            dbg.core.execution_status = 'Terminated'
+            dbg.intf[-1].msg("The program finished - quit or restart")
+            dbg.core.processor.process_commands()
+        except IOError:
+            break
+        except RuntimeError:
+            dbg.core.execution_status = 'Restart requested'
+            if dbg.program_sys_argv:
+                sys.argv = list(dbg.program_sys_argv)
+                part1 = ('Restarting %s with arguments:' %
+                         dbg.core.filename(mainpyfile))
+                args  = ' '.join(dbg.program_sys_argv[1:])
+                dbg.intf[-1].msg(args + part1)
+            else: break
+        except SystemExit:
+            break
+        pass
+
+    sys.argv = 5
+    return

uncompyle6/parsers/parse36.py

@@ -32,6 +32,11 @@ class Python36Parser(Python35Parser):
 
         call_function ::= expr expr CALL_FUNCTION_EX
         call_function ::= expr expr expr CALL_FUNCTION_EX_KW_1
+
+        # This might be valid in < 3.6
+        and  ::= expr jmp_false expr
+
+        except_suite ::= c_stmts_opt COME_FROM POP_EXCEPT jump_except COME_FROM
         """
 
     def add_custom_rules(self, tokens, customize):

uncompyle6/scanners/scanner3.py

@@ -213,7 +213,7 @@ class Scanner3(Scanner):
         # Get jump targets
         # Format: {target offset: [jump offsets]}
         jump_targets = self.find_jump_targets(show_asm)
-        ## print("XXX2", jump_targets)
+        # print("XXX2", jump_targets)
         last_op_was_break = False
 
         extended_arg = 0
@@ -797,7 +797,7 @@ class Scanner3(Scanner):
                                      'end': prev_op[target]})
                 return
 
-            # The op offset just before the target jump offset is important
+            # The opcode *two* instructions before the target jump offset is important
             # in making a determination of what we have. Save that.
             pre_rtarget = prev_op[rtarget]
 
@@ -966,8 +966,16 @@ class Scanner3(Scanner):
                     self.not_continue.add(pre_rtarget)
             else:
                 # For now, we'll only tag forward jump.
-                if rtarget > offset:
-                    self.fixed_jumps[offset] = rtarget
+                if self.version >= 3.6:
+                    if target > offset:
+                        self.fixed_jumps[offset] = target
+                        pass
+                else:
+                    # FIXME: This is probably a bug in < 3.6 and we should
+                    # instead use the above code. But until we smoke things
+                    # out we'll stick with it.
+                    if rtarget > offset:
+                        self.fixed_jumps[offset] = rtarget
 
         elif op == self.opc.SETUP_EXCEPT:
             target = self.get_target(offset, extended_arg)