implicit-str-concat / W1404

Message emitted:

Implicit string concatenation found in %s

Description:

String literals are implicitly concatenated in a literal iterable definition : maybe a comma is missing ?

Problematic code:

list.py:

x = ["a" "b"]  # [implicit-str-concat]

open.py:

with open("hello.txt" "r") as f:  # [implicit-str-concat]
    print(f.read())

Correct code:

list.py:

x = ["a", "b"]

open.py:

with open("hello.txt", "r") as f:
    print(f.read())

Additional details:

By default, detection of implicit string concatenation of line jumps is disabled. Hence the following code will not trigger this rule:

SEQ = ('a', 'b'
            'c')

In order to detect this case, you must enable check-str-concat-over-line-jumps:

[STRING_CONSTANT]
check-str-concat-over-line-jumps = true

However, the drawback of this setting is that it will trigger false positive for string parameters passed on multiple lines in function calls:

warnings.warn(
    "rotate() is deprecated and will be removed in a future release. "
    "Use the rotation() context manager instead.",
    DeprecationWarning,
    stacklevel=3,
)

No message will be emitted, though, if you clarify the wanted concatenation with parentheses:

warnings.warn(
    (
        "rotate() is deprecated and will be removed in a future release. "
        "Use the rotation() context manager instead."
    ),
    DeprecationWarning,
    stacklevel=3,
)

Created by the string checker.