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gh-103492: Clarify SyntaxWarning with literal comparison #103493

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Merged
hauntsaninja merged 10 commits into from
Apr 24, 2023
Merged

gh-103492: Clarify SyntaxWarning with literal comparison #103493

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5247c04
gh-103492: Clarify SyntaxWarning with literal comparison
hauntsaninja Apr 13, 2023
12ce76c
.
hauntsaninja Apr 13, 2023
bc6d13f
📜🤖 Added by blurb_it.
blurb-it[bot] Apr 13, 2023
d0f2ea3
.
hauntsaninja Apr 13, 2023
9a13700
Update Misc/NEWS.d/next/Core and Builtins/2023-04-13-00-58-55.gh-issu…
hauntsaninja Apr 13, 2023
41c9ad9
Merge branch 'main' into gh-103492
hauntsaninja Apr 13, 2023
30b29bb
single quote types
hauntsaninja Apr 19, 2023
8f16b1a
simplify warning code (tested with and without -W error)
hauntsaninja Apr 20, 2023
b7b4f1a
fix bug irit mentions, add test
hauntsaninja Apr 24, 2023
20d0554
use infer_type
hauntsaninja Apr 24, 2023
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single quote types
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@hauntsaninja
hauntsaninja committed Apr 19, 2023
commit 30b29bb59bdcdb5ca0eba2178a554adf420d3fe5
2 changes: 1 addition & 1 deletion Lib/test/test_codeop.py
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Expand Up @@ -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 str literal', SyntaxWarning),
('"is" with \'str\' literal', SyntaxWarning),
("invalid escape sequence", SyntaxWarning),
) as w:
compile_command(r"'\e' is 0")
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20 changes: 10 additions & 10 deletions Lib/test/test_grammar.py
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Expand Up @@ -1470,16 +1470,16 @@ def test_comparison_is_literal(self):
def check(test, msg):
self.check_syntax_warning(test, msg)

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 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')

with warnings.catch_warnings():
warnings.simplefilter('error', SyntaxWarning)
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4 changes: 2 additions & 2 deletions Python/compile.c
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Expand Up @@ -2285,8 +2285,8 @@ check_compare(struct compiler *c, expr_ty e)
if (op == Is || op == IsNot) {
if (!right || !left) {
const char *msg = (op == Is)
? "\"is\" with %.200s literal. Did you mean \"==\"?"
: "\"is not\" with %.200s literal. Did you mean \"!=\"?";
? "\"is\" with '%.200s' literal. Did you mean \"==\"?"
: "\"is not\" with '%.200s' literal. Did you mean \"!=\"?";
expr_ty literal = !left ? e->v.Compare.left : right_expr;
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@iritkatriel iritkatriel Apr 24, 2023

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left gets updated in each iteration, but e->v.Compare.left is always the same thing. Is this correct?

Should we just check the first item before the loop and then here just look at right_expr?

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@hauntsaninja hauntsaninja Apr 24, 2023

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I might be missing something, but bool left = check_is_arg(e->v.Compare.left); happens once outside the loop and it's only right that is updated in each iteration.

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@iritkatriel iritkatriel Apr 24, 2023

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line 2296?

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@hauntsaninja hauntsaninja Apr 24, 2023

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Ah, of course! Thank you so much, this is buggy. I added the fix and a test case to catch the issue.

I think we can't do the first item check before the loop since all comparators may not be is, e.g. x == 3 is y, but let me know if I'm missing something!

return compiler_warn(
c, LOC(e), msg, Py_TYPE(literal->v.Constant.value)->tp_name
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@iritkatriel iritkatriel Apr 24, 2023

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Suggested change
c, LOC(e), msg, Py_TYPE(literal->v.Constant.value)->tp_name
c, LOC(e), msg, infer_type(literal)->tp_name

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@hauntsaninja hauntsaninja Apr 24, 2023

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I had this originally, but it needed a forward reference / we know it's a Constant_kind so we could skip the switch :-)

I'll add it back!

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@hauntsaninja hauntsaninja Apr 24, 2023

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Addressed, let me know if I should move the function instead

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