Trailing Comma misformats `when` expression

[pschichtel]

Expected Behavior

enum class Test {
    TEST_1,
    TEST_2,
    TEST_3,
}

fun bla(value: Test) = when (value) {
    Test.TEST_1,
    Test.TEST_2 -> {
        println("1, 2")
    }
    Test.TEST_3 -> {
        println("3")
    }
}

gets formatted to (omitting the enum):

fun bla(value: Test) = when (value) {
    Test.TEST_1,
    Test.TEST_2,
-> {
        println("1, 2")
    }
    Test.TEST_3 -> {
        println("3")
    }
}

intellij does not modify it.

when the function initially looks like this:

fun bla(value: Test) = when (value) {
    Test.TEST_1,
    Test.TEST_2, -> {
        println("1, 2")
    }
    Test.TEST_3 -> {
        println("3")
    }
}

then ktlint doesn't change it, but intellij changes it to:

fun bla(value: Test) = when (value) {
    Test.TEST_1,
    Test.TEST_2,
    -> {
        println("1, 2")
    }
    Test.TEST_3 -> {
        println("3")
    }
}

when the function initially looks like this:

fun bla(value: Test) = when (value) {
    Test.TEST_1,
    Test.TEST_2
    -> {
        println("1, 2")
    }
    Test.TEST_3 -> {
        println("3")
    }
}

then ktlint changes it to:

fun bla(value: Test) = when (value) {
    Test.TEST_1,
    Test.TEST_2,
    -> {
        println("1, 2")
    }
    Test.TEST_3 -> {
        println("3")
    }
}

intellij however does not change it.

Your Environment

• Version of ktlint used: 0.46.1
• Relevant parts of the .editorconfig settings

  [{*.gradle.kts,*.kt,*.kts,*.main.kts,*.space.kts}]
  max_line_length = 9999
  ij_continuation_indent_size = 4
  ij_kotlin_align_in_columns_case_branch = false
  ij_kotlin_align_multiline_binary_operation = false
  ij_kotlin_align_multiline_extends_list = false
  ij_kotlin_align_multiline_method_parentheses = false
  ij_kotlin_align_multiline_parameters = false
  ij_kotlin_align_multiline_parameters_in_calls = false
  ij_kotlin_allow_trailing_comma = true
  ij_kotlin_allow_trailing_comma_on_call_site = true
  ij_kotlin_assignment_wrap = normal
  ij_kotlin_blank_lines_after_class_header = 0
  ij_kotlin_blank_lines_around_block_when_branches = 0
  ij_kotlin_blank_lines_before_declaration_with_comment_or_annotation_on_separate_line = 1
  ij_kotlin_block_comment_at_first_column = true
  ij_kotlin_call_parameters_new_line_after_left_paren = true
  ij_kotlin_call_parameters_right_paren_on_new_line = true
  ij_kotlin_call_parameters_wrap = on_every_item
  ij_kotlin_catch_on_new_line = false
  ij_kotlin_class_annotation_wrap = split_into_lines
  ij_kotlin_code_style_defaults = KOTLIN_OFFICIAL
  ij_kotlin_continuation_indent_for_chained_calls = false
  ij_kotlin_continuation_indent_for_expression_bodies = false
  ij_kotlin_continuation_indent_in_argument_lists = false
  ij_kotlin_continuation_indent_in_elvis = false
  ij_kotlin_continuation_indent_in_if_conditions = false
  ij_kotlin_continuation_indent_in_parameter_lists = false
  ij_kotlin_continuation_indent_in_supertype_lists = false
  ij_kotlin_else_on_new_line = false
  ij_kotlin_enum_constants_wrap = off
  ij_kotlin_extends_list_wrap = normal
  ij_kotlin_field_annotation_wrap = split_into_lines
  ij_kotlin_finally_on_new_line = false
  ij_kotlin_if_rparen_on_new_line = true
  ij_kotlin_import_nested_classes = false
  ij_kotlin_insert_whitespaces_in_simple_one_line_method = true
  ij_kotlin_keep_blank_lines_before_right_brace = 0
  ij_kotlin_keep_blank_lines_in_code = 1
  ij_kotlin_keep_blank_lines_in_declarations = 1
  ij_kotlin_keep_first_column_comment = true
  ij_kotlin_keep_indents_on_empty_lines = false
  ij_kotlin_keep_line_breaks = true
  ij_kotlin_lbrace_on_next_line = false
  ij_kotlin_line_comment_add_space = true
  ij_kotlin_line_comment_at_first_column = false
  ij_kotlin_method_annotation_wrap = split_into_lines
  ij_kotlin_method_call_chain_wrap = normal
  ij_kotlin_method_parameters_new_line_after_left_paren = true
  ij_kotlin_method_parameters_right_paren_on_new_line = true
  ij_kotlin_method_parameters_wrap = on_every_item
  ij_kotlin_name_count_to_use_star_import = 2147483647
  ij_kotlin_name_count_to_use_star_import_for_members = 2147483647
  ij_kotlin_parameter_annotation_wrap = off
  ij_kotlin_space_after_comma = true
  ij_kotlin_space_after_extend_colon = true
  ij_kotlin_space_after_type_colon = true
  ij_kotlin_space_before_catch_parentheses = true
  ij_kotlin_space_before_comma = false
  ij_kotlin_space_before_extend_colon = true
  ij_kotlin_space_before_for_parentheses = true
  ij_kotlin_space_before_if_parentheses = true
  ij_kotlin_space_before_lambda_arrow = true
  ij_kotlin_space_before_type_colon = false
  ij_kotlin_space_before_when_parentheses = true
  ij_kotlin_space_before_while_parentheses = true
  ij_kotlin_spaces_around_additive_operators = true
  ij_kotlin_spaces_around_assignment_operators = true
  ij_kotlin_spaces_around_equality_operators = true
  ij_kotlin_spaces_around_function_type_arrow = true
  ij_kotlin_spaces_around_logical_operators = true
  ij_kotlin_spaces_around_multiplicative_operators = true
  ij_kotlin_spaces_around_range = false
  ij_kotlin_spaces_around_relational_operators = true
  ij_kotlin_spaces_around_unary_operator = false
  ij_kotlin_spaces_around_when_arrow = true
  ij_kotlin_variable_annotation_wrap = off
  ij_kotlin_while_on_new_line = false
  ij_kotlin_wrap_elvis_expressions = 1
  ij_kotlin_wrap_expression_body_functions = 1
  ij_kotlin_wrap_first_method_in_call_chain = false
  disabled_rules = no-wildcard-imports

• Operating System and version: Archlinux

[paul-dingemans]

Thx for clear examples.

fun bla(value: Test) = when (value) {
Test.TEST_1,
Test.TEST_2 -> {
println("1, 2")
}
Test.TEST_3 -> {
println("3")
}
}

#1576 fixes the formatting to be same as IntelliJ IDEA default formatting.

fun bla(value: Test) = when (value) {
    Test.TEST_1,
    Test.TEST_2, -> {
        println("1, 2")
    }
    Test.TEST_3 -> {
        println("3")
    }
}

#1576 fixes the formatting to be same as IntelliJ IDEA default formatting.

fun bla(value: Test) = when (value) {
    Test.TEST_1,
    Test.TEST_2
    -> {
        println("1, 2")
    }
    Test.TEST_3 -> {
        println("3")
    }
}

Formatting of ktlint will not be changed. In ktlint the trailing comma is enforced instead of just allowed to improve the consistency in the codebase which is formatted by ktlint.