diff --git a/Lib/test/test_codeop.py b/Lib/test/test_codeop.py index 6966c2ffd811b8..e3c382266fa058 100644 --- a/Lib/test/test_codeop.py +++ b/Lib/test/test_codeop.py @@ -277,7 +277,7 @@ def test_filename(self): def test_warning(self): # Test that the warning is only returned once. with warnings_helper.check_warnings( - ('"is" with a literal', SyntaxWarning), + ('"is" with \'str\' literal', SyntaxWarning), ("invalid escape sequence", SyntaxWarning), ) as w: compile_command(r"'\e' is 0") diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py index ced9000f75f2e5..ee105a3de17f8a 100644 --- a/Lib/test/test_grammar.py +++ b/Lib/test/test_grammar.py @@ -236,12 +236,9 @@ def check(test, error=False): check(f"[{num}for x in ()]") check(f"{num}spam", error=True) + with self.assertWarnsRegex(SyntaxWarning, r'invalid \w+ literal'): + compile(f"{num}is x", "", "eval") with warnings.catch_warnings(): - warnings.filterwarnings('ignore', '"is" with a literal', - SyntaxWarning) - with self.assertWarnsRegex(SyntaxWarning, - r'invalid \w+ literal'): - compile(f"{num}is x", "", "eval") warnings.simplefilter('error', SyntaxWarning) with self.assertRaisesRegex(SyntaxError, r'invalid \w+ literal'): @@ -1467,14 +1464,22 @@ def test_comparison(self): if 1 < 1 > 1 == 1 >= 1 <= 1 != 1 in 1 not in x is x is not x: pass def test_comparison_is_literal(self): - def check(test, msg='"is" with a literal'): + def check(test, msg): self.check_syntax_warning(test, msg) - check('x is 1') - check('x is "thing"') - check('1 is x') - check('x is y is 1') - check('x is not 1', '"is not" with a literal') + check('x is 1', '"is" with \'int\' literal') + check('x is "thing"', '"is" with \'str\' literal') + check('1 is x', '"is" with \'int\' literal') + check('x is y is 1', '"is" with \'int\' literal') + check('x is not 1', '"is not" with \'int\' literal') + check('x is not (1, 2)', '"is not" with \'tuple\' literal') + check('(1, 2) is not x', '"is not" with \'tuple\' literal') + + check('None is 1', '"is" with \'int\' literal') + check('1 is None', '"is" with \'int\' literal') + + check('x == 3 is y', '"is" with \'int\' literal') + check('x == "thing" is y', '"is" with \'str\' literal') with warnings.catch_warnings(): warnings.simplefilter('error', SyntaxWarning) @@ -1482,6 +1487,10 @@ def check(test, msg='"is" with a literal'): compile('x is False', '', 'exec') compile('x is True', '', 'exec') compile('x is ...', '', 'exec') + compile('None is x', '', 'exec') + compile('False is x', '', 'exec') + compile('True is x', '', 'exec') + compile('... is x', '', 'exec') def test_warn_missed_comma(self): def check(test): diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-04-13-00-58-55.gh-issue-103492.P4k0Ay.rst b/Misc/NEWS.d/next/Core and Builtins/2023-04-13-00-58-55.gh-issue-103492.P4k0Ay.rst new file mode 100644 index 00000000000000..929650968173e7 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2023-04-13-00-58-55.gh-issue-103492.P4k0Ay.rst @@ -0,0 +1 @@ +Clarify :exc:`SyntaxWarning` with literal ``is`` comparison by specifying which literal is problematic, since comparisons using ``is`` with e.g. None and bool literals are idiomatic. diff --git a/Python/compile.c b/Python/compile.c index d6882c31d6437e..ebaad6033edbf9 100644 --- a/Python/compile.c +++ b/Python/compile.c @@ -2269,6 +2269,8 @@ check_is_arg(expr_ty e) || value == Py_Ellipsis); } +static PyTypeObject * infer_type(expr_ty e); + /* Check operands of identity checks ("is" and "is not"). Emit a warning if any operand is a constant except named singletons. */ @@ -2277,19 +2279,25 @@ check_compare(struct compiler *c, expr_ty e) { Py_ssize_t i, n; bool left = check_is_arg(e->v.Compare.left); + expr_ty left_expr = e->v.Compare.left; n = asdl_seq_LEN(e->v.Compare.ops); for (i = 0; i < n; i++) { cmpop_ty op = (cmpop_ty)asdl_seq_GET(e->v.Compare.ops, i); - bool right = check_is_arg((expr_ty)asdl_seq_GET(e->v.Compare.comparators, i)); + expr_ty right_expr = (expr_ty)asdl_seq_GET(e->v.Compare.comparators, i); + bool right = check_is_arg(right_expr); if (op == Is || op == IsNot) { if (!right || !left) { const char *msg = (op == Is) - ? "\"is\" with a literal. Did you mean \"==\"?" - : "\"is not\" with a literal. Did you mean \"!=\"?"; - return compiler_warn(c, LOC(e), msg); + ? "\"is\" with '%.200s' literal. Did you mean \"==\"?" + : "\"is not\" with '%.200s' literal. Did you mean \"!=\"?"; + expr_ty literal = !left ? left_expr : right_expr; + return compiler_warn( + c, LOC(e), msg, infer_type(literal)->tp_name + ); } } left = right; + left_expr = right_expr; } return SUCCESS; }