Do not replace function body with multiple exit points (#2273)

* Do not replace function body having a return statement only in case the return statement contains an intermediate exit point

Closes #2269

Author: paul-dingemans

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 * Fix indent of multiline object declaration inside class `indent` [#2257](https://github.com/pinterest/ktlint/issue/2257)
 * Ignore anonymous function in rule `function-naming` [#2260](https://github.com/pinterest/ktlint/issue/2260)
 * Do not force blank line before function in right hand side of assignment `blank-line-before-declaration` [#2260](https://github.com/pinterest/ktlint/issue/2260)
+* Do not replace function body having a return statement only in case the return statement contains an intermediate exit point 'function-expression-body' [#2269](https://github.com/pinterest/ktlint/issue/2269)
 
 ### Changed
 

ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionExpressionBodyRule.kt

@@ -21,7 +21,9 @@ import com.pinterest.ktlint.rule.engine.core.api.editorconfig.EditorConfig
 import com.pinterest.ktlint.rule.engine.core.api.editorconfig.INDENT_SIZE_PROPERTY
 import com.pinterest.ktlint.rule.engine.core.api.editorconfig.INDENT_STYLE_PROPERTY
 import com.pinterest.ktlint.rule.engine.core.api.editorconfig.MAX_LINE_LENGTH_PROPERTY
+import com.pinterest.ktlint.rule.engine.core.api.firstChildLeafOrSelf
 import com.pinterest.ktlint.rule.engine.core.api.isWhiteSpace
+import com.pinterest.ktlint.rule.engine.core.api.leavesIncludingSelf
 import com.pinterest.ktlint.rule.engine.core.api.nextSibling
 import com.pinterest.ktlint.rule.engine.core.api.prevSibling
 import com.pinterest.ktlint.ruleset.standard.StandardRule
@@ -109,6 +111,7 @@ public class FunctionExpressionBodyRule :
         require(block.elementType == BLOCK)
         block
             .takeIf { it.containingOnly(RETURN) }
+            ?.takeUnless { it.containsMultipleReturns() }
             ?.findChildByType(RETURN)
             ?.findChildByType(RETURN_KEYWORD)
             ?.nextSibling { !it.isWhiteSpace() }
@@ -161,6 +164,9 @@ public class FunctionExpressionBodyRule :
                 .singleOrNull()
                 ?.elementType
 
+    private fun ASTNode.containsMultipleReturns() =
+        firstChildLeafOrSelf().leavesIncludingSelf().count { it.elementType == RETURN_KEYWORD } > 1
+
     private fun ASTNode.createUnitTypeReference() =
         PsiFileFactory
             .getInstance(psi.project)

ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionExpressionBodyRuleTest.kt

@@ -153,4 +153,19 @@ class FunctionExpressionBodyRuleTest {
             .isFormattedAs(formattedCode)
             .hasLintViolation(1, 16, "Function body should be replaced with body expression")
     }
+
+    @Test
+    fun `Given a function with a single expression but having multiple return expression inside then do not covert as it results in a compilation error`() {
+        val code =
+            """
+            fun foo(): Any {
+                return if (true) {
+                    Foo()
+                } else {
+                    return Bar()
+                }
+            }
+            """.trimIndent()
+        functionExpressionBodyRule(code).hasNoLintViolations()
+    }
 }