From 4a7e9d7867a4000cbba65735490aa55ecf0a2a8b Mon Sep 17 00:00:00 2001
From: Paul Dingemans <paul-dingemans@users.noreply.github.com>
Date: Mon, 14 Oct 2024 17:17:54 +0200
Subject: [PATCH] Fix wrapping of expression body when `max_line_length` not
 set (#2833)

This fixes the wrapping of the expression for code style `intellij_idea` which does not set the `max_line_length` property by default. But it also fixes the wrapping in case the `max_line_length` property contains value `unset` for any of the code styles.

Closes #2827
---
 .../standard/rules/FunctionSignatureRule.kt   |  1 +
 .../rules/FunctionSignatureRuleTest.kt        | 36 ++++++++++++++-----
 2 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionSignatureRule.kt b/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionSignatureRule.kt
index 5417905292..b56b62e85f 100644
--- a/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionSignatureRule.kt
+++ b/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionSignatureRule.kt
@@ -240,6 +240,7 @@ public class FunctionSignatureRule :
             } else {
                 fixWhiteSpacesInValueParameterList(node, emit, multiline = true, dryRun = false)
             }
+            fixFunctionBodyExpression(node, emit, MAX_LINE_LENGTH_PROPERTY_OFF)
         }
     }
 
diff --git a/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionSignatureRuleTest.kt b/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionSignatureRuleTest.kt
index 0deeadb929..3ab138c6bd 100644
--- a/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionSignatureRuleTest.kt
+++ b/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionSignatureRuleTest.kt
@@ -8,6 +8,7 @@ import com.pinterest.ktlint.ruleset.standard.StandardRuleSetProvider
 import com.pinterest.ktlint.ruleset.standard.rules.FunctionSignatureRule.Companion.FORCE_MULTILINE_WHEN_PARAMETER_COUNT_GREATER_OR_EQUAL_THAN_PROPERTY
 import com.pinterest.ktlint.ruleset.standard.rules.FunctionSignatureRule.Companion.FUNCTION_BODY_EXPRESSION_WRAPPING_PROPERTY
 import com.pinterest.ktlint.ruleset.standard.rules.FunctionSignatureRule.FunctionBodyExpressionWrapping
+import com.pinterest.ktlint.ruleset.standard.rules.FunctionSignatureRule.FunctionBodyExpressionWrapping.always
 import com.pinterest.ktlint.ruleset.standard.rules.FunctionSignatureRule.FunctionBodyExpressionWrapping.default
 import com.pinterest.ktlint.test.KtLintAssertThat.Companion.EOL_CHAR
 import com.pinterest.ktlint.test.KtLintAssertThat.Companion.MAX_LINE_LENGTH_MARKER
@@ -743,14 +744,8 @@ class FunctionSignatureRuleTest {
                 .hasNoLintViolations()
         }
 
-        @ParameterizedTest(name = "bodyExpressionWrapping: {0}")
-        @EnumSource(
-            value = FunctionBodyExpressionWrapping::class,
-            names = ["always"],
-        )
-        fun `Given that the function signature and a single line body expression body fit on the same line then do not reformat function signature but move the body expression to a separate line`(
-            bodyExpressionWrapping: FunctionBodyExpressionWrapping,
-        ) {
+        @Test
+        fun `Given that the function signature and a single line body expression body fit on the same line then do not reformat function signature but move the body expression to a separate line`() {
             val code =
                 """
                 // $MAX_LINE_LENGTH_MARKER                  $EOL_CHAR
@@ -765,12 +760,35 @@ class FunctionSignatureRuleTest {
             functionSignatureWrappingRuleAssertThat(code)
                 .setMaxLineLength()
                 .withEditorConfigOverride(FORCE_MULTILINE_WHEN_PARAMETER_COUNT_GREATER_OR_EQUAL_THAN_PROPERTY to "unset")
-                .withEditorConfigOverride(FUNCTION_BODY_EXPRESSION_WRAPPING_PROPERTY to bodyExpressionWrapping)
+                .withEditorConfigOverride(FUNCTION_BODY_EXPRESSION_WRAPPING_PROPERTY to always)
                 .addAdditionalRuleProvider { IndentationRule() }
                 .hasLintViolation(2, 33, "Newline expected before expression body")
                 .isFormattedAs(formattedCode)
         }
 
+        @ParameterizedTest(name = "code style: {0}")
+        @EnumSource(value = CodeStyleValue::class)
+        fun `Issue 2827 - Given that no max_line_length set, and the function signature is a single line body expression body that does fit on the same line then wrap the body expression to a separate line`(
+            codeStyleValue: CodeStyleValue,
+        ) {
+            val code =
+                """
+                fun f(a: Any, b: Any): String = "some-result"
+                """.trimIndent()
+            val formattedCode =
+                """
+                fun f(a: Any, b: Any): String =
+                    "some-result"
+                """.trimIndent()
+            functionSignatureWrappingRuleAssertThat(code)
+                .withEditorConfigOverride(CODE_STYLE_PROPERTY to codeStyleValue)
+                .withEditorConfigOverride(FORCE_MULTILINE_WHEN_PARAMETER_COUNT_GREATER_OR_EQUAL_THAN_PROPERTY to "unset")
+                .withEditorConfigOverride(FUNCTION_BODY_EXPRESSION_WRAPPING_PROPERTY to always)
+                .addAdditionalRuleProvider { IndentationRule() }
+                .hasLintViolation(1, 33, "Newline expected before expression body")
+                .isFormattedAs(formattedCode)
+        }
+
         @ParameterizedTest(name = "bodyExpressionWrapping: {0}")
         @EnumSource(
             value = FunctionBodyExpressionWrapping::class,