Formatter Bug: All values for parentheses_positions_in_method_declaration are ignored, while ...invocation works #4237

Problem

There appears to be a persistent bug in the Java formatter where the setting org.eclipse.jdt.core.formatter.parentheses_positions_in_method_declaration is completely ignored.

It seems that all possible values for this setting (e.g., separate_lines, preserve_positions, etc.) have no effect on formatting method declarations.

This is especially problematic for the separate_lines_if_wrapped value, which is a common and useful setting for code readability. Even when parameters are wrapped onto new lines, the closing parenthesis ) is still incorrectly forced onto the same line as the last parameter, directly violating the ...if_wrapped rule.

Key Evidence of Bug: Inconsistency with ...invocation

The strongest evidence of this bug is the clear inconsistency with its parallel setting, which works perfectly.

• Works: org.eclipse.jdt.core.formatter.parentheses_positions_in_method_invocation

  • This setting correctly applies all its values (like separate_lines_if_wrapped) to method calls.

• Fails: org.eclipse.jdt.core.formatter.parentheses_positions_in_method_declaration

  • This setting fails to apply the exact same logic to method declarations.

This inconsistency proves the bug is isolated specifically to the ..._in_method_declaration implementation.

Related Anomaly (Workaround Glitch)

We also observed a related anomaly that further highlights the bug:

If a user manually inserts a blank line (two newlines) before the closing parenthesis in a method declaration (e.g., ...status, \n \n ) {), the formatter preserves this structure.

This shows the formatter is not applying its own rules consistently. It fails to enforce the parentheses_positions... rule, but it can be "tricked" into the correct layout by this manual formatting glitch (likely due to join_wrapped_lines="false" behavior).

Conclusion

This is a bug in the Red Hat Java extension's formatter. The configuration settings for method declarations and invocations should behave identically, but they do not.