From 1f188e40b270229ad4c81243dddee5e11752c3c6 Mon Sep 17 00:00:00 2001 From: Lysandros Nikolaou Date: Mon, 16 Nov 2020 19:52:55 +0200 Subject: [PATCH 1/3] bpo-42374: Allow unparenthesized walrus in genexps This fixes a regression that was introduced by the new parser. --- Grammar/python.gram | 2 +- Lib/test/test_named_expressions.py | 10 ++++++++++ Parser/parser.c | 12 ++++++------ 3 files changed, 17 insertions(+), 7 deletions(-) diff --git a/Grammar/python.gram b/Grammar/python.gram index ae5e4b5d4ca64d..91ce520be1ce76 100644 --- a/Grammar/python.gram +++ b/Grammar/python.gram @@ -517,7 +517,7 @@ group[expr_ty]: | '(' a=(yield_expr | named_expression) ')' { a } | invalid_group genexp[expr_ty]: - | '(' a=expression ~ b=for_if_clauses ')' { _Py_GeneratorExp(a, b, EXTRA) } + | '(' a=named_expression ~ b=for_if_clauses ')' { _Py_GeneratorExp(a, b, EXTRA) } | invalid_comprehension set[expr_ty]: '{' a=expressions_list '}' { _Py_Set(a, EXTRA) } setcomp[expr_ty]: diff --git a/Lib/test/test_named_expressions.py b/Lib/test/test_named_expressions.py index c813830ce6d3cf..46a2bbc0bd111e 100644 --- a/Lib/test/test_named_expressions.py +++ b/Lib/test/test_named_expressions.py @@ -513,6 +513,16 @@ def g(): self.assertEqual(nonlocal_var, None) f() + def test_named_expression_scope_in_genexp(self): + a = 1 + b = [1, 2, 3, 4] + genexp = (c := i + a for i in b) + + with self.assertRaises(NameError): + print(c) # c is not bound here + for idx, elem in enumerate(genexp): + self.assertEqual(elem, b[idx] + a) + if __name__ == "__main__": unittest.main() diff --git a/Parser/parser.c b/Parser/parser.c index 48ebfe65aedafa..94e265881984c5 100644 --- a/Parser/parser.c +++ b/Parser/parser.c @@ -11357,7 +11357,7 @@ group_rule(Parser *p) return _res; } -// genexp: '(' expression ~ for_if_clauses ')' | invalid_comprehension +// genexp: '(' named_expression ~ for_if_clauses ')' | invalid_comprehension static expr_ty genexp_rule(Parser *p) { @@ -11377,12 +11377,12 @@ genexp_rule(Parser *p) UNUSED(_start_lineno); // Only used by EXTRA macro int _start_col_offset = p->tokens[_mark]->col_offset; UNUSED(_start_col_offset); // Only used by EXTRA macro - { // '(' expression ~ for_if_clauses ')' + { // '(' named_expression ~ for_if_clauses ')' if (p->error_indicator) { D(p->level--); return NULL; } - D(fprintf(stderr, "%*c> genexp[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "'(' expression ~ for_if_clauses ')'")); + D(fprintf(stderr, "%*c> genexp[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "'(' named_expression ~ for_if_clauses ')'")); int _cut_var = 0; Token * _literal; Token * _literal_1; @@ -11391,7 +11391,7 @@ genexp_rule(Parser *p) if ( (_literal = _PyPegen_expect_token(p, 7)) // token='(' && - (a = expression_rule(p)) // expression + (a = named_expression_rule(p)) // named_expression && (_cut_var = 1) && @@ -11400,7 +11400,7 @@ genexp_rule(Parser *p) (_literal_1 = _PyPegen_expect_token(p, 8)) // token=')' ) { - D(fprintf(stderr, "%*c+ genexp[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "'(' expression ~ for_if_clauses ')'")); + D(fprintf(stderr, "%*c+ genexp[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "'(' named_expression ~ for_if_clauses ')'")); Token *_token = _PyPegen_get_last_nonnwhitespace_token(p); if (_token == NULL) { D(p->level--); @@ -11420,7 +11420,7 @@ genexp_rule(Parser *p) } p->mark = _mark; D(fprintf(stderr, "%*c%s genexp[%d-%d]: %s failed!\n", p->level, ' ', - p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "'(' expression ~ for_if_clauses ')'")); + p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "'(' named_expression ~ for_if_clauses ')'")); if (_cut_var) { D(p->level--); return NULL; From 344502273482e8e0cc6a78e267e6e1a287d59047 Mon Sep 17 00:00:00 2001 From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com> Date: Mon, 16 Nov 2020 17:57:12 +0000 Subject: [PATCH 2/3] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?= =?UTF-8?q?rb=5Fit.?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../Core and Builtins/2020-11-16-17-57-09.bpo-42374.t7np1E.rst | 2 ++ 1 file changed, 2 insertions(+) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2020-11-16-17-57-09.bpo-42374.t7np1E.rst diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-11-16-17-57-09.bpo-42374.t7np1E.rst b/Misc/NEWS.d/next/Core and Builtins/2020-11-16-17-57-09.bpo-42374.t7np1E.rst new file mode 100644 index 00000000000000..d86d038c8425c5 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2020-11-16-17-57-09.bpo-42374.t7np1E.rst @@ -0,0 +1,2 @@ +Fix a regression introduced by the new parser, where an unparenthesized walrus operator +was not allowed within generator expressions. \ No newline at end of file From 49d61d58b55bc5adc9cf6b60471bd4e275d038dd Mon Sep 17 00:00:00 2001 From: Lysandros Nikolaou Date: Tue, 17 Nov 2020 00:46:32 +0200 Subject: [PATCH 3/3] Change assertion --- Lib/test/test_named_expressions.py | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/Lib/test/test_named_expressions.py b/Lib/test/test_named_expressions.py index 46a2bbc0bd111e..d614f3267fad37 100644 --- a/Lib/test/test_named_expressions.py +++ b/Lib/test/test_named_expressions.py @@ -518,8 +518,7 @@ def test_named_expression_scope_in_genexp(self): b = [1, 2, 3, 4] genexp = (c := i + a for i in b) - with self.assertRaises(NameError): - print(c) # c is not bound here + self.assertNotIn("c", locals()) for idx, elem in enumerate(genexp): self.assertEqual(elem, b[idx] + a)