From 4b8a7f51da224d1a0ad8159935f78ba4e6e16037 Mon Sep 17 00:00:00 2001 From: Serhiy Storchaka Date: Tue, 31 Jul 2018 09:34:30 +0300 Subject: [PATCH] Revert "closes bpo-27494: Fix 2to3 handling of trailing comma after a generator expression (GH-3771)" (#8241) This reverts commit af810b35b494ef1d255d4bf340b92a9dad446995. This is not valid syntax (see bpo-32012). --- Lib/lib2to3/Grammar.txt | 25 +++---------------- Lib/lib2to3/fixer_util.py | 6 ++--- Lib/lib2to3/fixes/fix_dict.py | 2 +- Lib/lib2to3/fixes/fix_paren.py | 4 +-- Lib/lib2to3/fixes/fix_xrange.py | 2 +- Lib/lib2to3/tests/test_parser.py | 7 ------ .../2018-07-11-10-03-21.bpo-27494.04OWkW.rst | 2 ++ 7 files changed, 12 insertions(+), 36 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2018-07-11-10-03-21.bpo-27494.04OWkW.rst diff --git a/Lib/lib2to3/Grammar.txt b/Lib/lib2to3/Grammar.txt index 4905c91e635..a7ddad3cf32 100644 --- a/Lib/lib2to3/Grammar.txt +++ b/Lib/lib2to3/Grammar.txt @@ -111,8 +111,8 @@ atom: ('(' [yield_expr|testlist_gexp] ')' | '{' [dictsetmaker] '}' | '`' testlist1 '`' | NAME | NUMBER | STRING+ | '.' '.' '.') -listmaker: (test|star_expr) ( old_comp_for | (',' (test|star_expr))* [','] ) -testlist_gexp: (test|star_expr) ( old_comp_for | (',' (test|star_expr))* [','] ) +listmaker: (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] ) +testlist_gexp: (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] ) lambdef: 'lambda' [varargslist] ':' test trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME subscriptlist: subscript (',' subscript)* [','] @@ -142,28 +142,9 @@ argument: ( test [comp_for] | star_expr ) comp_iter: comp_for | comp_if -comp_for: [ASYNC] 'for' exprlist 'in' or_test [comp_iter] +comp_for: [ASYNC] 'for' exprlist 'in' testlist_safe [comp_iter] comp_if: 'if' old_test [comp_iter] -# As noted above, testlist_safe extends the syntax allowed in list -# comprehensions and generators. We can't use it indiscriminately in all -# derivations using a comp_for-like pattern because the testlist_safe derivation -# contains comma which clashes with trailing comma in arglist. -# -# This was an issue because the parser would not follow the correct derivation -# when parsing syntactically valid Python code. Since testlist_safe was created -# specifically to handle list comprehensions and generator expressions enclosed -# with parentheses, it's safe to only use it in those. That avoids the issue; we -# can parse code like set(x for x in [],). -# -# The syntax supported by this set of rules is not a valid Python 3 syntax, -# hence the prefix "old". -# -# See https://bugs.python.org/issue27494 -old_comp_iter: old_comp_for | old_comp_if -old_comp_for: [ASYNC] 'for' exprlist 'in' testlist_safe [old_comp_iter] -old_comp_if: 'if' old_test [old_comp_iter] - testlist1: test (',' test)* # not used in grammar, but may appear in "node" passed from Parser to Compiler diff --git a/Lib/lib2to3/fixer_util.py b/Lib/lib2to3/fixer_util.py index 2f9b1c2e766..babe6cb3f66 100644 --- a/Lib/lib2to3/fixer_util.py +++ b/Lib/lib2to3/fixer_util.py @@ -101,8 +101,8 @@ def ListComp(xp, fp, it, test=None): test.prefix = " " if_leaf = Leaf(token.NAME, "if") if_leaf.prefix = " " - inner_args.append(Node(syms.old_comp_if, [if_leaf, test])) - inner = Node(syms.listmaker, [xp, Node(syms.old_comp_for, inner_args)]) + inner_args.append(Node(syms.comp_if, [if_leaf, test])) + inner = Node(syms.listmaker, [xp, Node(syms.comp_for, inner_args)]) return Node(syms.atom, [Leaf(token.LBRACE, "["), inner, @@ -208,7 +208,7 @@ def attr_chain(obj, attr): next = getattr(next, attr) p0 = """for_stmt< 'for' any 'in' node=any ':' any* > - | old_comp_for< 'for' any 'in' node=any any* > + | comp_for< 'for' any 'in' node=any any* > """ p1 = """ power< diff --git a/Lib/lib2to3/fixes/fix_dict.py b/Lib/lib2to3/fixes/fix_dict.py index 55be553baac..d3655c9f1b2 100644 --- a/Lib/lib2to3/fixes/fix_dict.py +++ b/Lib/lib2to3/fixes/fix_dict.py @@ -83,7 +83,7 @@ class FixDict(fixer_base.BaseFix): p1 = patcomp.compile_pattern(P1) P2 = """for_stmt< 'for' any 'in' node=any ':' any* > - | old_comp_for< 'for' any 'in' node=any any* > + | comp_for< 'for' any 'in' node=any any* > """ p2 = patcomp.compile_pattern(P2) diff --git a/Lib/lib2to3/fixes/fix_paren.py b/Lib/lib2to3/fixes/fix_paren.py index de49eef157d..b205aa7e1e9 100644 --- a/Lib/lib2to3/fixes/fix_paren.py +++ b/Lib/lib2to3/fixes/fix_paren.py @@ -15,7 +15,7 @@ class FixParen(fixer_base.BaseFix): PATTERN = """ atom< ('[' | '(') (listmaker< any - old_comp_for< + comp_for< 'for' NAME 'in' target=testlist_safe< any (',' any)+ [','] > @@ -24,7 +24,7 @@ class FixParen(fixer_base.BaseFix): > | testlist_gexp< any - old_comp_for< + comp_for< 'for' NAME 'in' target=testlist_safe< any (',' any)+ [','] > diff --git a/Lib/lib2to3/fixes/fix_xrange.py b/Lib/lib2to3/fixes/fix_xrange.py index f5f06f35435..1e491e166a3 100644 --- a/Lib/lib2to3/fixes/fix_xrange.py +++ b/Lib/lib2to3/fixes/fix_xrange.py @@ -55,7 +55,7 @@ class FixXrange(fixer_base.BaseFix): p1 = patcomp.compile_pattern(P1) P2 = """for_stmt< 'for' any 'in' node=any ':' any* > - | old_comp_for< 'for' any 'in' node=any any* > + | comp_for< 'for' any 'in' node=any any* > | comparison< any 'in' node=any any*> """ p2 = patcomp.compile_pattern(P2) diff --git a/Lib/lib2to3/tests/test_parser.py b/Lib/lib2to3/tests/test_parser.py index 74653ea80fe..7eb9afac46e 100644 --- a/Lib/lib2to3/tests/test_parser.py +++ b/Lib/lib2to3/tests/test_parser.py @@ -612,13 +612,6 @@ class TestLiterals(GrammarTest): self.validate(s) -class TestGeneratorExpressions(GrammarTest): - - def test_trailing_comma_after_generator_expression_argument_works(self): - # BPO issue 27494 - self.validate("set(x for x in [],)") - - def diff_texts(a, b, filename): a = a.splitlines() b = b.splitlines() diff --git a/Misc/NEWS.d/next/Library/2018-07-11-10-03-21.bpo-27494.04OWkW.rst b/Misc/NEWS.d/next/Library/2018-07-11-10-03-21.bpo-27494.04OWkW.rst new file mode 100644 index 00000000000..9ad67c46170 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2018-07-11-10-03-21.bpo-27494.04OWkW.rst @@ -0,0 +1,2 @@ +Reverted :issue:`27494`. 2to3 rejects now a trailing comma in generator +expressions.