Since power operators almost always have the highest binding power in expressions, it's often more readable to hug it with its operands. The main exception to this is when its operands are non-trivial in which case the power operator will not hug, the rule for this is the following:
> For power ops, an operand is considered "simple" if it's only a NAME, numeric CONSTANT, or attribute access (chained attribute access is allowed), with or without a preceding unary operator.
Fixes GH-538.
Closes GH-2095.
diff-shades results: https://gist.github.com/ichard26/ca6c6ad4bd1de5152d95418c8645354b
Co-authored-by: Diego <dpalma@evernote.com>
Co-authored-by: Felix Hildén <felix.hilden@gmail.com>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
* Fix incorrect space before colon in if/while stmts
Previously Black would format this code
```
if (foo := True):
print(foo)
```
as
```
if (foo := True) :
print(foo)
```
adding an incorrect space after the RPAR. Buggy code in the
normalize_invisible_parens function caused the colon to be wrapped in
invisible parentheses. The LPAR of that pair was then prefixed with a
single space at the request of the whitespace function.
This commit fixes the accidental skipping of a pre-condition check
which must return True before parenthesis normalization of a specific
child Leaf or Node can happen. The pre-condition check being skipped
was why the colon was wrapped in invisible parentheses.
* Add an entry in CHANGES.md
* Parse `:=` properly
* never unwrap parenthesis around `:=`
* When checking for AST-equivalence, use `ast` instead of `typed-ast` when running on python >=3.8
* Assume code that uses `:=` is at least 3.8
