Fix not checking for spacing around binary operators inside unary expression

[cflee]

Description

Fixes #2652

For the operator spacing standard rule, instead of checking for whether any ancestor element is a KtPrefixExpression, check whether the closest ancestor that is a KtOperationExpression is a KtPrefixExpression.

This change will identify the case where the operator is inside a binary expression inside a prefix expression as not being a unary operator, and hence subject to the operator spacing checks.

• PREFIX_EXPRESSION
  • PARENTHESIZED
  • BINARY_EXPRESSION
    • OPERATION_REFERENCE
    • PsiElement(ELVIS)

The closest ancestor of KtPrefixExpression and KtBinaryExpression seems to be KtOperationExpression, so I've opted to use that as the predicate when searching through the ancestors. KtExpressionImpl seems to cover a lot more expression types. Alternatively, it might be possible to specifically search for the closest parent that is either KtPrefixExpression or KtBinaryExpression?

• abstract class KtExpressionImpl : KtElementImpl(node), KtExpression
• interface KtOperationExpression extends KtExpression
  • abstract class KtUnaryExpression extends KtExpressionImpl implements KtOperationExpression
  • class KtPrefixExpression extends KtUnaryExpression
  • class KtPostfixExpression extends KtUnaryExpression
  • class KtBinaryExpression extends KtExpressionImpl implements KtOperationExpression
  • class KtIsExpression extends KtExpressionImpl implements KtOperationExpression

Checklist

Before submitting the PR, please check following (checks which are not relevant may be ignored):

• [x] Commit message are well written. In addition to a short title, the commit message also explain why a change is made.
• [x] At least one commit message contains a reference Closes #<xxx> or Fixes #<xxx> (replace<xxx> with issue number)
• [x] Tests are added
• [x] KtLint format has been applied on source code itself and violations are fixed
• [ ] PR title is short and clear (it is used as description in the release changelog)
• [x] PR description added (background information)

Documentation is updated. See difference between snapshot and release documentation

• [ ] Snapshot documentation in case documentation is to be released together with a code change
• [ ] Release documentation in case documentation is related to a released version of ktlint and has to be published as soon as the change is merged to master

[paul-dingemans]

Tnx for your contribution. I really liked the way you documented the issue, and of course that you implemented the fix. Except for the commit message (it is better to explain the why instead of what you changed) I have no remarks. I have fix the commit message during merge.