Convert to expression body is forbidden for if without else #KT-12951 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/ConvertToExpressionBodyIntention.kt

@@ -109,6 +109,9 @@ class ConvertToExpressionBodyIntention : SelfTargetingOffsetIndependentIntention
                 val isUnit = KotlinBuiltIns.isUnit(expressionType)
                 if (!isUnit && !KotlinBuiltIns.isNothing(expressionType)) return null
                 if (isUnit) {
+                    if (statement.hasResultingIfWithoutElse()) {
+                        return null
+                    }
                     val resultingWhens = statement.resultingWhens()
                     if (resultingWhens.any { it.elseExpression == null && context.get(BindingContext.EXHAUSTIVE_WHEN, it) != true}) {
                         return null

idea/src/org/jetbrains/kotlin/idea/intentions/Utils.kt

@@ -141,6 +141,15 @@ fun KtExpression.resultingWhens(): List<KtWhenExpression> = when (this) {
     else -> listOf()
 }
 
+fun KtExpression?.hasResultingIfWithoutElse(): Boolean = when (this) {
+    is KtIfExpression -> `else` == null || then.hasResultingIfWithoutElse() || `else`.hasResultingIfWithoutElse()
+    is KtWhenExpression -> entries.any { it.expression.hasResultingIfWithoutElse() }
+    is KtBinaryExpression -> left.hasResultingIfWithoutElse() || right.hasResultingIfWithoutElse()
+    is KtUnaryExpression -> baseExpression.hasResultingIfWithoutElse()
+    is KtBlockExpression -> statements.lastOrNull().hasResultingIfWithoutElse()
+    else -> false
+}
+
 private fun KtExpression.specialNegation(): KtExpression? {
     val factory = KtPsiFactory(this)
     when (this) {

idea/testData/intentions/convertToExpressionBody/elvisIfElseUnit.kt

@@ -0,0 +1,9 @@
+// IS_APPLICABLE: true
+
+fun nullable() {}
+
+fun bar() {}
+
+fun foo(f: Boolean) {
+    <caret>nullable() ?: if (f) bar() else bar()
+}

idea/testData/intentions/convertToExpressionBody/elvisIfElseUnit.kt.after

@@ -0,0 +1,7 @@
+// IS_APPLICABLE: true
+
+fun nullable() {}
+
+fun bar() {}
+
+fun foo(f: Boolean) = nullable() ?: if (f) bar() else bar()

idea/testData/intentions/convertToExpressionBody/elvisIfUnit.kt

@@ -0,0 +1,9 @@
+// IS_APPLICABLE: false
+
+fun nullable() {}
+
+fun bar() {}
+
+fun foo(f: Boolean) {
+    <caret>nullable() ?: if (f) bar()
+}

idea/testData/intentions/convertToExpressionBody/ifElseUnit.kt

@@ -0,0 +1,7 @@
+// IS_APPLICABLE: true
+
+fun bar() {}
+
+fun foo(f: Boolean) {
+    <caret>if (f) bar() else bar()
+}

idea/testData/intentions/convertToExpressionBody/ifElseUnit.kt.after

@@ -0,0 +1,5 @@
+// IS_APPLICABLE: true
+
+fun bar() {}
+
+fun foo(f: Boolean) = if (f) bar() else bar()

idea/testData/intentions/convertToExpressionBody/ifUnit.kt

@@ -0,0 +1,7 @@
+// IS_APPLICABLE: false
+
+fun bar() {}
+
+fun foo(f: Boolean) {
+    <caret>if (f) bar()
+}

idea/testData/intentions/convertToExpressionBody/lambdaIfUnit.kt

@@ -0,0 +1,12 @@
+// IS_APPLICABLE: true
+
+fun <T> run(f: () -> T) = f()
+fun whenExpr(flag: Boolean) {
+    <caret>run {
+        println("run")
+        if (flag) {
+            println("flag")
+        }
+    }
+}
+fun println(s: String) {}

idea/testData/intentions/convertToExpressionBody/lambdaIfUnit.kt.after

@@ -0,0 +1,10 @@
+// IS_APPLICABLE: true
+
+fun <T> run(f: () -> T) = f()
+fun whenExpr(flag: Boolean) = run {
+    println("run")
+    if (flag) {
+        println("flag")
+    }
+}
+fun println(s: String) {}

idea/testData/intentions/convertToExpressionBody/whenIfUnitExhaustive.kt

@@ -0,0 +1,10 @@
+// IS_APPLICABLE: true
+enum class AccessMode { READ, WRITE, RW }
+fun whenExpr(mode: Boolean, access: AccessMode) {
+    <caret>when (access) {
+        AccessMode.READ -> if (mode) println("read") else println("noread")
+        AccessMode.WRITE -> if (mode) println("write") else println("nowrite")
+        AccessMode.RW -> if (mode) println("both") else println("no both")
+    }
+}
+fun println(s: String) {}

idea/testData/intentions/convertToExpressionBody/whenIfUnitExhaustive.kt.after

@@ -0,0 +1,8 @@
+// IS_APPLICABLE: true
+enum class AccessMode { READ, WRITE, RW }
+fun whenExpr(mode: Boolean, access: AccessMode) = when (access) {
+    AccessMode.READ -> if (mode) println("read") else println("noread")
+    AccessMode.WRITE -> if (mode) println("write") else println("nowrite")
+    AccessMode.RW -> if (mode) println("both") else println("no both")
+}
+fun println(s: String) {}

idea/testData/intentions/convertToExpressionBody/whenIfUnitNonExhaustive.kt

@@ -0,0 +1,10 @@
+// IS_APPLICABLE: false
+enum class AccessMode { READ, WRITE, RW }
+fun whenExpr(mode: Boolean, access: AccessMode) {
+    <caret>when (access) {
+        AccessMode.READ -> if (mode) println("read") else println("noread")
+        AccessMode.WRITE -> if (mode) println("write")
+        AccessMode.RW -> if (mode) println("both") else println("no both")
+    }
+}
+fun println(s: String) {}

idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java

@@ -4774,6 +4774,18 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("elvisIfElseUnit.kt")
+        public void testElvisIfElseUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/elvisIfElseUnit.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("elvisIfUnit.kt")
+        public void testElvisIfUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/elvisIfUnit.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("elvisWhenUnitNonExhaustive.kt")
         public void testElvisWhenUnitNonExhaustive() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/elvisWhenUnitNonExhaustive.kt");
@@ -4852,6 +4864,18 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("ifElseUnit.kt")
+        public void testIfElseUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/ifElseUnit.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("ifUnit.kt")
+        public void testIfUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/ifUnit.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("ifWhenUnitExhaustive.kt")
         public void testIfWhenUnitExhaustive() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/ifWhenUnitExhaustive.kt");
@@ -4864,6 +4888,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("lambdaIfUnit.kt")
+        public void testLambdaIfUnit() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/lambdaIfUnit.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("lambdaWhenUnitNonExhaustive.kt")
         public void testLambdaWhenUnitNonExhaustive() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/lambdaWhenUnitNonExhaustive.kt");
@@ -4900,6 +4930,18 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("whenIfUnitExhaustive.kt")
+        public void testWhenIfUnitExhaustive() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/whenIfUnitExhaustive.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("whenIfUnitNonExhaustive.kt")
+        public void testWhenIfUnitNonExhaustive() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/whenIfUnitNonExhaustive.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("whenUnitExhaustive.kt")
         public void testWhenUnitExhaustive() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/convertToExpressionBody/whenUnitExhaustive.kt");