A string that's been split across several lines that needn't be has " " in the middle

[fpdotmonkey]

Describe the style change

Given a split string that is now too short to need to be split, black will combine the string with an implicit concatenation (with " " in the middle) instead of just extending the string. This is ugly, unnecessary, and fails common linters.

Examples in the current Black style

some_variable = (
    "this string needn't be split "
    "because it's too short"
)

# output

some_variable = "this string needn't be split " "because it's too short"

Desired style

some_variable = (
    "this string needn't be split "
    "because it's too short"
)

# output

some_variable = "this string needn't be split because it's too short"

Version information

$ python3 -m black --version
__main__.py, version 20.8b1
$ python3 --version
Python 3.6.9

[JelleZijlstra]

The --experimental-string-processing option will do this. We'll enable it by default once it's sufficiently stable.

[felix-hilden]

A ref to the issue that will make it the default: #2188