Merging in recent 3.7 and 3.8 improvements from decompyle6

This rebases 3.7, 3.8 ...decompilation off of 3.7ish rather than a 3.4
base.

Add more 3.7 and 3.8 tests

pytest/test_grammar.py

@@ -20,8 +20,12 @@ def test_grammar():
     (lhs, rhs, tokens, right_recursive, dup_rhs) = p.check_sets()
 
     # We have custom rules that create the below
-    expect_lhs = set(["pos_arg", "attribute"])
+    expect_lhs = set(["pos_arg"])
+
     if PYTHON_VERSION < 3.8:
+        if PYTHON_VERSION < 3.7:
+            expect_lhs.add("attribute")
+
         expect_lhs.add("get_iter")
     else:
         expect_lhs.add("async_with_as_stmt")
@@ -31,7 +35,7 @@ def test_grammar():
 
     expect_right_recursive = set([("designList", ("store", "DUP_TOP", "designList"))])
 
-    if PYTHON_VERSION < 3.7:
+    if PYTHON_VERSION <= 3.7:
         unused_rhs.add("call")
 
     if PYTHON_VERSION > 2.6:
@@ -50,9 +54,11 @@ def test_grammar():
             )
         )
         if PYTHON_VERSION >= 3.0:
+            if PYTHON_VERSION < 3.7:
                 expect_lhs.add("annotate_arg")
                 expect_lhs.add("annotate_tuple")
                 unused_rhs.add("mkfunc_annotate")
+
             unused_rhs.add("dict_comp")
             unused_rhs.add("classdefdeco1")
             unused_rhs.add("tryelsestmtl")

test/simple_source/bug37/03_ifelse_chained_for.py

@@ -0,0 +1,24 @@
+# From decompyle3/semantics/customize3.py
+# The bug is handling "for" loop inside the
+# chained compare ifelse
+def n_classdef3(a, b, c, l):
+    r = 1
+    if 3.0 <= a <= 3.2:
+        for n in l:
+            if b:
+                break
+            elif c:
+                r = 2
+            pass
+        pass
+    else:
+        r = 3
+        pass
+    return r
+
+assert n_classdef3(10, True, True, []) == 3
+assert n_classdef3(0, False, True, []) == 3
+assert n_classdef3(3.1, True, True, []) == 1
+assert n_classdef3(3.1, True, False, [1]) == 1
+assert n_classdef3(3.1, True, True, [2]) == 1
+assert n_classdef3(3.1, False, True, [3]) == 2

test/simple_source/bug38/01_named_expr.py

@@ -0,0 +1,5 @@
+(x, y) = "foo", 0
+if x := __name__:
+    y = 1
+assert x == "__main__", "Walrus operator changes value"
+assert y == 1, "Walrus operator branch taken"

test/simple_source/bug38/04_for_no_jump_back.py

@@ -0,0 +1,17 @@
+# from mult_by_const/instruction.py
+# Bug in 3.8 was handling no JUMP_BACK in "for" loop. It is
+# in the "if" instead
+def instruction_sequence_value(instrs, a, b):
+    for instr in instrs:
+        if a:
+            a = 6
+        elif b:
+            return 0
+        pass
+
+    return a
+
+assert instruction_sequence_value([], True, True) == 1
+assert instruction_sequence_value([1], True, True) == 6
+assert instruction_sequence_value([1], False, True) == 0
+assert instruction_sequence_value([1], False, False) == False

test/simple_source/expression/14_mixed_expressions.py

@@ -0,0 +1,53 @@
+# Covers a large number of operators
+#
+# This code is RUNNABLE!
+
+import sys
+PYTHON_VERSION = sys.version_info[0] + (sys.version_info[1] / 10.0)
+
+assert PYTHON_VERSION >= 3.7
+
+# some floats (from 01_float.py)
+
+x = 1e300
+assert 0.0 == x * 0
+assert x * 1e300 == float("inf")
+assert str(float("inf") * 0.0) == "nan"
+assert str(float("-inf") * 0.0) == "nan"
+assert -1e300 * 1e300 == float("-inf")
+
+# Complex (adapted from 02_complex.py)
+y = 5j
+assert y ** 2 == -25
+y **= 3
+assert y == (-0-125j)
+
+
+# Tests BINARY_TRUE_DIVIDE and INPLACE_TRUE_DIVIDE (from 02_try_divide.py)
+x = 2
+assert 4 / x == 2
+
+x = 5
+assert x / 2 == 2.5
+x = 3
+x /= 2
+assert x == 1.5
+
+x = 2
+assert 4 // x == 2
+x = 7
+x //= 2
+assert x == 3
+
+x = 3
+assert x % 2 == 1
+x %= 2
+assert x == 1
+
+assert x << 2 == 4
+x <<= 3
+assert x == 8
+
+assert x >> 1 == 4
+x >>= 1
+assert x == 4

uncompyle6/parsers/parse38.py

@@ -22,6 +22,12 @@ from spark_parser import DEFAULT_DEBUG as PARSER_DEFAULT_DEBUG
 from uncompyle6.parsers.parse37 import Python37Parser
 
 class Python38Parser(Python37Parser):
+    def p_38walrus(self, args):
+        """
+        # named_expr is also known as the "walrus op" :=
+        expr              ::= named_expr
+        named_expr        ::= expr DUP_TOP store
+        """
 
     def p_38misc(self, args):
         """
@@ -38,6 +44,12 @@ class Python38Parser(Python37Parser):
         stmt               ::= whilestmt38
         stmt               ::= whileTruestmt38
         stmt               ::= call
+        stmt               ::= ifstmtl
+
+        break ::= POP_BLOCK BREAK_LOOP
+        break ::= POP_BLOCK POP_TOP BREAK_LOOP
+        break ::= POP_TOP BREAK_LOOP
+        break ::= POP_EXCEPT BREAK_LOOP
 
         # FIXME: this should be restricted to being inside a try block
         stmt               ::= except_ret38
@@ -89,27 +101,39 @@ class Python38Parser(Python37Parser):
 
         return             ::= ret_expr ROT_TWO POP_TOP RETURN_VALUE
 
+        # 3.8 can push a looping JUMP_BACK into into a JUMP_ from a statement that jumps to it
+        lastl_stmt         ::= ifpoplaststmtl
+        ifpoplaststmtl     ::= testexpr POP_TOP c_stmts_opt JUMP_BACK
+        ifelsestmtl        ::= testexpr c_stmts_opt jb_cfs else_suitel JUMP_BACK come_froms
+
+        _ifstmts_jumpl     ::= c_stmts JUMP_BACK
+        _ifstmts_jumpl     ::= _ifstmts_jump
+        ifstmtl            ::= testexpr _ifstmts_jumpl
+
         for38              ::= expr get_iter store for_block JUMP_BACK
-        for38              ::= expr for_iter store for_block JUMP_BACK
-        for38              ::= expr for_iter store for_block JUMP_BACK POP_BLOCK
-        for38              ::= expr for_iter store for_block
+        for38              ::= expr get_for_iter store for_block JUMP_BACK
+        for38              ::= expr get_for_iter store for_block JUMP_BACK POP_BLOCK
+        for38              ::= expr get_for_iter store for_block
 
-        forelsestmt38      ::= expr for_iter store for_block POP_BLOCK else_suite
-        forelselaststmt38  ::= expr for_iter store for_block POP_BLOCK else_suitec
-        forelselaststmtl38 ::= expr for_iter store for_block POP_BLOCK else_suitel
+        forelsestmt38      ::= expr get_for_iter store for_block POP_BLOCK else_suite
+        forelselaststmt38  ::= expr get_for_iter store for_block POP_BLOCK else_suitec
+        forelselaststmtl38 ::= expr get_for_iter store for_block POP_BLOCK else_suitel
 
-        whilestmt38        ::= testexpr l_stmts_opt COME_FROM JUMP_BACK POP_BLOCK
-        whilestmt38        ::= testexpr l_stmts_opt JUMP_BACK POP_BLOCK
-        whilestmt38        ::= testexpr returns               POP_BLOCK
-        whilestmt38        ::= testexpr l_stmts     JUMP_BACK
+        whilestmt38        ::= _come_froms testexpr l_stmts_opt COME_FROM JUMP_BACK POP_BLOCK
+        whilestmt38        ::= _come_froms testexpr l_stmts_opt JUMP_BACK POP_BLOCK
+        whilestmt38        ::= _come_froms testexpr l_stmts_opt JUMP_BACK come_froms
+        whilestmt38        ::= _come_froms testexpr returns               POP_BLOCK
+        whilestmt38        ::= _come_froms testexpr l_stmts     JUMP_BACK
+        whilestmt38        ::= _come_froms testexpr l_stmts     come_froms
 
         # while1elsestmt   ::=          l_stmts     JUMP_BACK
-        whileTruestmt      ::= l_stmts              JUMP_BACK POP_BLOCK
-        while1stmt         ::= l_stmts COME_FROM_LOOP
-        while1stmt         ::= l_stmts COME_FROM JUMP_BACK COME_FROM_LOOP
-        whileTruestmt38    ::= l_stmts JUMP_BACK
+        whileTruestmt      ::= _come_froms l_stmts              JUMP_BACK POP_BLOCK
+        while1stmt         ::= _come_froms l_stmts COME_FROM_LOOP
+        while1stmt         ::= _come_froms l_stmts COME_FROM JUMP_BACK COME_FROM_LOOP
+        whileTruestmt38    ::= _come_froms l_stmts JUMP_BACK
+        whileTruestmt38    ::= _come_froms l_stmts JUMP_BACK COME_FROM_EXCEPT_CLAUSE
 
-        for_block          ::= l_stmts_opt _come_from_loops JUMP_BACK
+        for_block          ::= _come_froms l_stmts_opt _come_from_loops JUMP_BACK
 
         except_cond1       ::= DUP_TOP expr COMPARE_OP jmp_false
                                POP_TOP POP_TOP POP_TOP
@@ -134,7 +158,8 @@ class Python38Parser(Python37Parser):
         except_ret38a      ::= COME_FROM_FINALLY POP_TOP POP_TOP POP_TOP
                                expr ROT_FOUR
                                POP_EXCEPT RETURN_VALUE END_FINALLY
-        except_handler38   ::= JUMP_FORWARD COME_FROM_FINALLY
+
+        except_handler38   ::= _jump COME_FROM_FINALLY
                                except_stmts END_FINALLY opt_come_from_except
         except_handler38a  ::= COME_FROM_FINALLY POP_TOP POP_TOP POP_TOP
                                POP_EXCEPT POP_TOP stmts END_FINALLY
@@ -160,13 +185,15 @@ class Python38Parser(Python37Parser):
         self.customized = {}
 
     def remove_rules_38(self):
-        self.remove_rules("""
+        self.remove_rules(
+            """
            stmt               ::= async_for_stmt37
            stmt               ::= for
            stmt               ::= forelsestmt
            stmt               ::= try_except36
+           stmt               ::= async_forelse_stmt
 
-           async_for_stmt     ::= SETUP_LOOP expr
+           async_for_stmt     ::= setup_loop expr
                                   GET_AITER
                                   SETUP_EXCEPT GET_ANEXT LOAD_CONST
                                   YIELD_FROM
@@ -178,7 +205,7 @@ class Python38Parser(Python37Parser):
                                   COME_FROM
                                   POP_TOP POP_TOP POP_TOP POP_EXCEPT POP_TOP POP_BLOCK
                                   COME_FROM_LOOP
-           async_for_stmt37   ::= SETUP_LOOP expr
+           async_for_stmt37   ::= setup_loop expr
                                   GET_AITER
                                   SETUP_EXCEPT GET_ANEXT
                                   LOAD_CONST YIELD_FROM
@@ -190,7 +217,7 @@ class Python38Parser(Python37Parser):
                                   POP_TOP POP_BLOCK
                                   COME_FROM_LOOP
 
-          async_forelse_stmt ::= SETUP_LOOP expr
+          async_forelse_stmt ::= setup_loop expr
                                  GET_AITER
                                  SETUP_EXCEPT GET_ANEXT LOAD_CONST
                                  YIELD_FROM
@@ -203,13 +230,13 @@ class Python38Parser(Python37Parser):
                                  POP_TOP POP_TOP POP_TOP POP_EXCEPT POP_TOP POP_BLOCK
                                  else_suite COME_FROM_LOOP
 
-           for                ::= SETUP_LOOP expr for_iter store for_block POP_BLOCK
-           for                ::= SETUP_LOOP expr for_iter store for_block POP_BLOCK NOP
+           for                ::= setup_loop expr get_for_iter store for_block POP_BLOCK
+           for                ::= setup_loop expr get_for_iter store for_block POP_BLOCK NOP
 
            for_block          ::= l_stmts_opt COME_FROM_LOOP JUMP_BACK
-           forelsestmt        ::= SETUP_LOOP expr for_iter store for_block POP_BLOCK else_suite
-           forelselaststmt    ::= SETUP_LOOP expr for_iter store for_block POP_BLOCK else_suitec
-           forelselaststmtl   ::= SETUP_LOOP expr for_iter store for_block POP_BLOCK else_suitel
+           forelsestmt        ::= setup_loop expr get_for_iter store for_block POP_BLOCK else_suite
+           forelselaststmt    ::= setup_loop expr get_for_iter store for_block POP_BLOCK else_suitec
+           forelselaststmtl   ::= setup_loop expr get_for_iter store for_block POP_BLOCK else_suitel
 
            tryelsestmtl3      ::= SETUP_EXCEPT suite_stmts_opt POP_BLOCK
                                   except_handler COME_FROM else_suitel
@@ -223,15 +250,16 @@ class Python38Parser(Python37Parser):
                                   COME_FROM_FINALLY suite_stmts_opt END_FINALLY
            tryfinally_return_stmt ::= SETUP_FINALLY suite_stmts_opt POP_BLOCK
                                       LOAD_CONST COME_FROM_FINALLY
-
-
-        """)
+        """
+        )
 
     def customize_grammar_rules(self, tokens, customize):
         super(Python37Parser, self).customize_grammar_rules(tokens, customize)
         self.remove_rules_38()
-        self.check_reduce['ifstmt'] = 'tokens'
-        self.check_reduce['whileTruestmt38'] = 'tokens'
+        self.check_reduce["ifstmt"] = "tokens"
+        self.check_reduce["whileTruestmt38"] = "tokens"
+        self.check_reduce["whilestmt38"] = "tokens"
+        self.check_reduce["ifstmtl"] = "tokens"
 
     def reduce_is_invalid(self, rule, ast, tokens, first, last):
         invalid = super(Python38Parser,
@@ -240,34 +268,47 @@ class Python38Parser(Python37Parser):
         self.remove_rules_38()
         if invalid:
             return invalid
-        if rule[0] == 'ifstmt':
+        lhs = rule[0]
+        if lhs == "ifstmt":
             # Make sure jumps don't extend beyond the end of the if statement.
             l = last
             if l == len(tokens):
                 l -= 1
             if isinstance(tokens[l].offset, str):
-                last_offset = int(tokens[l].offset.split('_')[0], 10)
+                last_offset = int(tokens[l].offset.split("_")[0], 10)
             else:
                 last_offset = tokens[l].offset
             for i in range(first, l):
                 t = tokens[i]
-                if t.kind == 'POP_JUMP_IF_FALSE':
+                if t.kind == "POP_JUMP_IF_FALSE":
                     if t.attr > last_offset:
                         return True
                     pass
                 pass
             pass
-        elif rule[0] == 'whileTruestmt38':
-            t = tokens[last-1]
-            if t.kind == 'JUMP_BACK':
-                return t.attr != tokens[first].offset
+        elif lhs == "ifstmtl":
+            if last == len(tokens):
+                last -= 1
+            if (tokens[last].attr and isinstance(tokens[last].attr, int)):
+                return tokens[first].offset < tokens[last].attr
+            pass
+        elif lhs in ("whileTruestmt38", "whilestmt38"):
+            jb_index = last - 1
+            while jb_index > 0 and tokens[jb_index].kind.startswith("COME_FROM"):
+                jb_index -= 1
+            t = tokens[jb_index]
+            if t.kind != "JUMP_BACK":
+                return True
+            return t.attr != tokens[first].off2int()
             pass
 
         return False
 
+
 class Python38ParserSingle(Python38Parser, PythonParserSingle):
     pass
 
+
 if __name__ == "__main__":
     # Check grammar
     # FIXME: DRY this with other parseXX.py routines
@@ -286,7 +327,9 @@ if __name__ == "__main__":
                 """JUMP_BACK CONTINUE RETURN_END_IF COME_FROM
                LOAD_GENEXPR LOAD_ASSERT LOAD_SETCOMP LOAD_DICTCOMP LOAD_CLASSNAME
                LAMBDA_MARKER RETURN_LAST
-            """.split()))
+            """.split()
+            )
+        )
         remain_tokens = set(tokens) - opcode_set
         import re
 

uncompyle6/scanners/scanner37.py

@@ -22,24 +22,50 @@ This sets up opcodes Python's 3.7 and calls a generalized
 scanner routine for Python 3.
 """
 
-from uncompyle6.scanners.scanner36 import Scanner36
-from uncompyle6.scanners.scanner3 import Scanner3
+from uncompyle6.scanners.scanner37base import Scanner37Base
 
 # bytecode verification, verify(), uses JUMP_OPs from here
 from xdis.opcodes import opcode_37 as opc
+
+# bytecode verification, verify(), uses JUMP_OPS from here
 JUMP_OPs = opc.JUMP_OPS
 
-class Scanner37(Scanner36):
 
+class Scanner37(Scanner37Base):
     def __init__(self, show_asm=None):
-        Scanner3.__init__(self, 3.7, show_asm)
+        Scanner37Base.__init__(self, 3.7, show_asm)
         return
+
     pass
 
+    def ingest(self, co, classname=None, code_objects={}, show_asm=None):
+        tokens, customize = Scanner37Base.ingest(self, co, classname, code_objects, show_asm)
+        for t in tokens:
+            # The lowest bit of flags indicates whether the
+            # var-keyword argument is placed at the top of the stack
+            if t.op == self.opc.CALL_FUNCTION_EX and t.attr & 1:
+                t.kind = "CALL_FUNCTION_EX_KW"
+                pass
+            elif t.op == self.opc.BUILD_STRING:
+                t.kind = "BUILD_STRING_%s" % t.attr
+            elif t.op == self.opc.CALL_FUNCTION_KW:
+                t.kind = "CALL_FUNCTION_KW_%s" % t.attr
+            elif t.op == self.opc.FORMAT_VALUE:
+                if t.attr & 0x4:
+                    t.kind = "FORMAT_VALUE_ATTR"
+                    pass
+            elif t.op == self.opc.BUILD_MAP_UNPACK_WITH_CALL:
+                t.kind = "BUILD_MAP_UNPACK_WITH_CALL_%d" % t.attr
+            elif t.op == self.opc.BUILD_TUPLE_UNPACK_WITH_CALL:
+                t.kind = "BUILD_TUPLE_UNPACK_WITH_CALL_%d" % t.attr
+            pass
+        return tokens, customize
+
 if __name__ == "__main__":
     from uncompyle6 import PYTHON_VERSION
     if PYTHON_VERSION == 3.7:
         import inspect
+
         co = inspect.currentframe().f_code
         tokens, customize = Scanner37().ingest(co)
         for t in tokens:

uncompyle6/scanners/scanner38.py

@@ -23,23 +23,63 @@ scanner routine for Python 3.
 """
 
 from uncompyle6.scanners.scanner37 import Scanner37
-from uncompyle6.scanners.scanner3 import Scanner3
+from uncompyle6.scanners.scanner37base import Scanner37Base
 
 # bytecode verification, verify(), uses JUMP_OPs from here
 from xdis.opcodes import opcode_38 as opc
+
+# bytecode verification, verify(), uses JUMP_OPS from here
 JUMP_OPs = opc.JUMP_OPS
 
-class Scanner38(Scanner37):
 
+class Scanner38(Scanner37):
     def __init__(self, show_asm=None):
-        Scanner3.__init__(self, 3.8, show_asm)
+        Scanner37Base.__init__(self, 3.8, show_asm)
         return
+
     pass
 
+    def ingest(self, co, classname=None, code_objects={}, show_asm=None):
+        tokens, customize = super(Scanner38, self).ingest(
+            co, classname, code_objects, show_asm
+        )
+        for i, token in enumerate(tokens):
+            opname = token.kind
+            if opname in ("JUMP_FORWARD", "JUMP_ABSOLUTE"):
+                # Turn JUMPs into BREAK_LOOP
+                jump_target = token.attr
+
+                if opname == "JUMP_ABSOLUTE" and token.offset >= jump_target:
+                    # Not a forward jump, so continue
+                    # FIXME: Do we need "continue" detection?
+                    continue
+                if i + 1 < len(tokens) and tokens[i + 1] == "JUMP_BACK":
+                    # Sometimes the jump back is *after* the break...
+                    jump_back_index = i + 1
+                else:
+                    # and sometimes it is *before* where we jumped to.
+                    jump_back_index = self.offset2tok_index[jump_target] - 1
+                    while tokens[jump_back_index].kind.startswith("COME_FROM_"):
+                        jump_back_index -= 1
+                        pass
+                    pass
+                jump_back_token = tokens[jump_back_index]
+                if (
+                    jump_back_token == "JUMP_BACK"
+                    and jump_back_token.attr < token.offset
+                ):
+                    token.kind = "BREAK_LOOP"
+                pass
+            pass
+        return tokens, customize
+
+
 if __name__ == "__main__":
-    from uncompyle6 import PYTHON_VERSION
+    from decompyle3 import PYTHON_VERSION
+
     if PYTHON_VERSION == 3.8:
         import inspect
+
         co = inspect.currentframe().f_code
         tokens, customize = Scanner38().ingest(co)
         for t in tokens:

uncompyle6/scanners/tok.py

@@ -159,5 +159,12 @@ class Token:
     def __getitem__(self, i):
         raise IndexError
 
+    def off2int(self):
+        if isinstance(self.offset, int):
+            return self.offset
+        else:
+            assert isinstance(self.offset, str)
+            return(int(self.offset.split("_")[0]))
+
 
 NoneToken = Token("LOAD_CONST", offset=-1, attr=None, pattr=None)

uncompyle6/semantics/consts.py

@@ -344,7 +344,11 @@ TABLE_DIRECT = {
 #    'return':	        ( '%|return %c\n', 0),
     'return_if_stmt':	( 'return %c\n', 0),
 
-    'ifstmt':		    ( '%|if %c:\n%+%c%-', 0, 1 ),
+    'ifstmt':		( '%|if %c:\n%+%c%-',
+                            0, # "testexpr" or "testexpr_then"
+                            1, # "_ifstmts_jump" or "return_stmts"
+                        ),
+
     'iflaststmt':	( '%|if %c:\n%+%c%-', 0, 1 ),
     'iflaststmtl':		( '%|if %c:\n%+%c%-', 0, 1 ),
     'testtrue':         ( 'not %p',
@@ -359,18 +363,18 @@ TABLE_DIRECT = {
     'ifelsestmt':	( '%|if %c:\n%+%c%-%|else:\n%+%c%-', 0, 1, 3 ),
     'ifelsestmtc':	( '%|if %c:\n%+%c%-%|else:\n%+%c%-', 0, 1, 3 ),
     'ifelsestmtl':	( '%|if %c:\n%+%c%-%|else:\n%+%c%-', 0, 1, 3 ),
-    'ifelsestmtr':	( '%|if %c:\n%+%c%-%|else:\n%+%c%-', 0, 1, 2 ),
-    'ifelsestmtr2':	( '%|if %c:\n%+%c%-%|else:\n%+%c%-\n\n', 0, 1, 3 ), # has COME_FROM in position 2
 
-
-    # "elif" forms are not generated by the parser but are created through tree
-    # transformations. See "n_ifelsestmt".
-    'ifelifstmt':	( '%|if %c:\n%+%c%-%c', 0, 1, 3 ),
+    #  These are created only via transformation
+    'ifelifstmt':	( '%|if %c:\n%+%c%-%c',
+                          0, # "testexpr" or "testexpr_then"
+                          1, 3 ),
     'elifelifstmt':	( '%|elif %c:\n%+%c%-%c', 0, 1, 3 ),
     'elifstmt':		( '%|elif %c:\n%+%c%-', 0, 1 ),
     'elifelsestmt':	( '%|elif %c:\n%+%c%-%|else:\n%+%c%-', 0, 1, 3 ),
+    'ifelsestmtr':	( '%|if %c:\n%+%c%-%|else:\n%+%c%-', 0, 1, 2 ),
+    'ifelsestmtr2':	( '%|if %c:\n%+%c%-%|else:\n%+%c%-\n\n', 0, 1, 3 ), # has COME_FROM
     'elifelsestmtr':	( '%|elif %c:\n%+%c%-%|else:\n%+%c%-\n\n', 0, 1, 2 ),
-    'elifelsestmtr2':	( '%|elif %c:\n%+%c%-%|else:\n%+%c%-\n\n', 0, 1, 3 ), # has COME_FROM in position 2
+    'elifelsestmtr2':	( '%|elif %c:\n%+%c%-%|else:\n%+%c%-\n\n', 0, 1, 3 ), # has COME_FROM
 
     'whileTruestmt':	( '%|while True:\n%+%c%-\n\n', 1 ),
     'whilestmt':	    ( '%|while %c:\n%+%c%-\n\n', 1, 2 ),
@@ -414,10 +418,11 @@ TABLE_DIRECT = {
                           (1, 'expr'), (5, 'store') ),
     'except_suite':     ( '%+%c%-%C', 0, (1, maxint, '') ),
 
-    # In Python 3.6, this is more complicated in the presence of "returns"
+    # In Python 3.6+, this is more complicated in the presence of "returns"
     'except_suite_finalize':     ( '%+%c%-%C', 1, (3, maxint, '') ),
 
     'pass':	            ( '%|pass\n', ),
+    'STORE_FAST':	    ( '%{pattr}', ),
     'kv':		    ( '%c: %c', 3, 1 ),
     'kv2':		    ( '%c: %c', 1, 2 ),
     'import':               ( '%|import %c\n', 2),

uncompyle6/semantics/customize3.py

@@ -37,6 +37,7 @@ def customize_for_version3(self, version):
                 (0, "expr"),
                 (4, "expr"),
             ),
+            "except_cond2": ("%|except %c as %c:\n", (1, "expr"), (5, "store")),
             "function_def_annotate": ("\n\n%|def %c%c\n", -1, 0),
             # When a generator is a single parameter of a function,
             # it doesn't need the surrounding parenethesis.
@@ -331,7 +332,8 @@ def customize_for_version3(self, version):
                 (1, "suite_stmts_opt"),
                 (3, "except_handler"),
                 (5, "else_suitel"),
-            )
+            ),
+            "LOAD_CLASSDEREF": ("%{pattr}",),
         }
     )
     if version >= 3.4:

uncompyle6/semantics/customize38.py

@@ -12,7 +12,7 @@
 #
 #  You should have received a copy of the GNU General Public License
 #  along with this program.  If not, see <http://www.gnu.org/licenses/>.
-"""Isolate Python 3.6 version-specific semantic actions here.
+"""Isolate Python 3.8 version-specific semantic actions here.
 """
 
 ########################
@@ -80,10 +80,18 @@ def customize_for_version38(self, version):
             (0, 'expr'),
             (3, 'for_block'), -2 ),
 
+        'ifpoplaststmtl': ( '%|if %c:\n%+%c%-',
+                            (0, "testexpr"),
+                            (2, "c_stmts" ) ),
+
+        'ifstmtl':	  ( '%|if %c:\n%+%c%-',
+                            (0, "testexpr"),
+                            (1, "_ifstmts_jumpl") ),
+
         'whilestmt38': ( '%|while %c:\n%+%c%-\n\n',
-                         (0, 'testexpr'), (1, 'l_stmts') ),
+                         (1, 'testexpr'), (2, 'l_stmts') ),
         'whileTruestmt38': ( '%|while True:\n%+%c%-\n\n',
-                         (0, 'l_stmts') ),
+                         (1, 'l_stmts') ),
         'try_elsestmtl38': (
             '%|try:\n%+%c%-%c%|else:\n%+%c%-',
             (1, 'suite_stmts_opt'),
@@ -98,4 +106,7 @@ def customize_for_version38(self, version):
         'tryfinally38': (
             '%|try:\n%+%c%-%|finally:\n%+%c%-\n\n',
                    (3, 'returns'), 6 ),
+        "named_expr": ( # AKA "walrus operatotr"
+            "%c := %c", (2, "store"), (0, "expr")
+            )
     })

uncompyle6/semantics/pysource.py

@@ -1130,11 +1130,15 @@ class SourceWalker(GenericASTTraversal, object):
 
     def n_generator_exp(self, node):
         self.write("(")
+        iter_index = 3
         if self.version > 3.2:
             code_index = -6
+            if self.version > 3.6:
+                # Python 3.7+ adds optional "come_froms" at node[0]
+                iter_index = 4
         else:
             code_index = -5
-        self.comprehension_walk(node, iter_index=3, code_index=code_index)
+        self.comprehension_walk(node, iter_index=iter_index, code_index=code_index)
         self.write(")")
         self.prune()
 
@@ -2015,8 +2019,13 @@ class SourceWalker(GenericASTTraversal, object):
         self.default(node)
 
     def n_except_cond2(self, node):
-        if node[-2][0] == "unpack":
-            node[-2][0].kind = "unpack_w_parens"
+        if node[-1] == "come_from_opt":
+            unpack_node = -3
+        else:
+            unpack_node = -2
+
+        if node[unpack_node][0] == "unpack":
+            node[unpack_node][0].kind = "unpack_w_parens"
         self.default(node)
 
     def template_engine(self, entry, startnode):

uncompyle6/semantics/transform.py

@@ -181,6 +181,7 @@ class TreeTransform(GenericASTTraversal, object):
 
         n = else_suite[0]
         old_stmts = None
+        else_suite_index = 1
 
         if len(n) == 1 == len(n[0]) and n[0] == "stmt":
             n = n[0][0]
@@ -192,9 +193,12 @@ class TreeTransform(GenericASTTraversal, object):
                 "iflaststmtl",
                 "ifelsestmtl",
                 "ifelsestmtc",
+                "ifpoplaststmtl",
             ):
-                # This seems needed for Python 2.5-2.7
                 n = n[0]
+                if n.kind == "ifpoplaststmtl":
+                    old_stmts = n[2]
+                    else_suite_index = 2
                 pass
             pass
         elif len(n) > 1 and 1 == len(n[0]) and n[0] == "stmt" and n[1].kind == "stmt":
@@ -206,7 +210,7 @@ class TreeTransform(GenericASTTraversal, object):
         else:
             return node
 
-        if n.kind in ("ifstmt", "iflaststmt", "iflaststmtl"):
+        if n.kind in ("ifstmt", "iflaststmt", "iflaststmtl", "ifpoplaststmtl"):
             node.kind = "ifelifstmt"
             n.kind = "elifstmt"
         elif n.kind in ("ifelsestmtr",):
@@ -223,17 +227,24 @@ class TreeTransform(GenericASTTraversal, object):
             if old_stmts:
                 if n.kind == "elifstmt":
                     trailing_else = SyntaxTree("stmts", old_stmts[1:])
+                    if len(trailing_else):
                         # We use elifelsestmtr because it has 3 nodes
                         elifelse_stmt = SyntaxTree(
-                        "elifelsestmtr", [n[0], n[1], trailing_else]
+                            "elifelsestmtr", [n[0], n[else_suite_index], trailing_else]
                         )
                         node[3] = elifelse_stmt
+                    else:
+                        elif_stmt = SyntaxTree(
+                            "elifstmt", [n[0], n[else_suite_index]]
+                        )
+                        node[3] = elif_stmt
+
+                    node.transformed_by = "n_ifelsestmt"
                     pass
                 else:
                     # Other cases for n.kind may happen here
                     pass
                 pass
-            node.transformed_by = "n_ifelsestmt"
             return node
 
     n_ifelsestmtc = n_ifelsestmtl = n_ifelsestmt