check-code: catch Python 'is' comparing number or string literals
The Python 'is' operator compares object identity, so it should
definitely not be applied to string or number literals, which Python
implementations are free to represent with a temporary object.
This should catch the following kinds of bogus expressions (examples):
x is 'foo' x is not 'foo'
x is "bar" x is not "bar"
x is 42 x is not 42
x is -36 x is not -36
As originally proposed by Martin Geisler, amended with catching
negative numbers.
$ cat > correct.py <<EOF
> def toto(arg1, arg2):
> del arg2
> return (5 + 6, 9)
> EOF
$ cat > wrong.py <<EOF
> def toto( arg1, arg2):
> del(arg2)
> return ( 5+6, 9)
> EOF
$ cat > quote.py <<EOF
> # let's use quote in comments
> (''' ( 4x5 )
> but """\\''' and finally''',
> """let's fool checkpatch""", '1+2',
> '"""', 42+1, """and
> ( 4-1 ) """, "( 1+1 )\" and ")
> a, '\\\\\\\\', "\\\\\\" x-2", "c-1"
> EOF
$ cat > non-py24.py <<EOF
> # Using builtins that does not exist in Python 2.4
> if any():
> x = all()
> y = format(x)
>
> # Do not complain about our own definition
> def any(x):
> pass
> EOF
$ check_code="$TESTDIR"/../contrib/check-code.py
$ "$check_code" ./wrong.py ./correct.py ./quote.py ./non-py24.py
./wrong.py:1:
> def toto( arg1, arg2):
gratuitous whitespace in () or []
./wrong.py:2:
> del(arg2)
del isn't a function
./wrong.py:3:
> return ( 5+6, 9)
missing whitespace in expression
gratuitous whitespace in () or []
./quote.py:5:
> '"""', 42+1, """and
missing whitespace in expression
./non-py24.py:2:
> if any():
any/all/format not available in Python 2.4
./non-py24.py:3:
> x = all()
any/all/format not available in Python 2.4
./non-py24.py:4:
> y = format(x)
any/all/format not available in Python 2.4
[1]
$ cat > is-op.py <<EOF
> # is-operator comparing number or string literal
> x = None
> y = x is 'foo'
> y = x is "foo"
> y = x is 5346
> y = x is -6
> y = x is not 'foo'
> y = x is not "foo"
> y = x is not 5346
> y = x is not -6
> EOF
$ "$check_code" ./is-op.py
./is-op.py:3:
> y = x is 'foo'
object comparison with literal
./is-op.py:4:
> y = x is "foo"
object comparison with literal
./is-op.py:5:
> y = x is 5346
object comparison with literal
./is-op.py:6:
> y = x is -6
object comparison with literal
./is-op.py:7:
> y = x is not 'foo'
object comparison with literal
./is-op.py:8:
> y = x is not "foo"
object comparison with literal
./is-op.py:9:
> y = x is not 5346
object comparison with literal
./is-op.py:10:
> y = x is not -6
object comparison with literal
[1]