FunctionSignatureRule with long function name suggest expression body on the same line, when no space available

[jtietema]

Given a long function name (as found in test cases for example) with an expression body and no parameters:

fun `a very long function name as found in a test case`() =
                "some-result"

The function name here exceeds the maxLineLength of the FunctionSignatureRule but not the overal MaxLineLength.

Expected Behavior

To accept this formatting as breaking down into multiline function signature will not fix the problem.

Observed Behavior

Ktlint will assume there are parameters and we will go into multiline mode. Suggesting to put the expression on the same line as the function signature.

Steps to Reproduce

Unit testcase is included in the following PR: #1774

Your Environment

• Version of ktlint used: 0.47.1
• .editorconfig not used
• Name and version (or code for custom task) of integration used (Gradle plugin, Maven plugin, command line, custom Gradle task): detekt formatting plugin 1.22
• Version of Gradle used (if applicable): 7.6
• Operating System and version: Fedora 37 - Linux

[paul-dingemans]

The function signature rule does not have a separate maxLineLength property but uses the same property as the max line length rule.

Test names between backticks may exceed the max line length when property ktlint_ignore_back_ticked_identifier is enabled.

You have specified that you do not use a '.editorconfig' file. What is the exact command that you executed that reproduces problem above?

[jtietema]

I am using the detekt-formatting plugin, so it is executed as part of ./gradlew detekt.
Detekt does have a feature to override the maxLineLength for the rule https://detekt.dev/docs/rules/formatting#functionsignature

I have added a test case in the PR #1774 which demonstrates the issue. If you have a function with:

• a very long name that runs past the maxLineLength
• has no arguments
• has a short expression body
  The ktlint rule will incorrectly calculate the remaining space as it will assume the ) = will be on its own line. Resulting in a remaing space of maxLineLength - ") =".length when in reality it is a single line (as we don't have parameters to wrap) so the remaining space should be 0 (at least, that is what I think it should be 😅).

[paul-dingemans]

This is a regression bug introduced in 0.48.x.