'Else' is not required in 'when' if Unit is expected

compiler/testData/codegen/box/when/noElseAssigned.kt

@@ -0,0 +1,9 @@
+fun box(): String {
+    var r = "Fail 0"
+    val x = 1
+    val y: Unit = when (x) {
+        1 -> { r = "OK" }
+        2 -> { r = "Fail 1" }
+    }
+    return r
+}

compiler/testData/codegen/box/when/noElseInRetunedExpression.kt

@@ -0,0 +1,11 @@
+var r = "Fail 0"
+
+fun foo(x: Int) {
+    return when (x) {
+        1 -> { r = "OK" }
+    }
+}
+fun box(): String {
+    foo(1)
+    return r
+}

compiler/testData/codegen/box/when/noElseInStatement.kt

@@ -0,0 +1,7 @@
+fun box(): String {
+    val x = 1
+    when (x) {
+        1 -> return "OK"
+    }
+    return "Fail 1"
+}

compiler/testData/diagnostics/tests/when/NoElseExpectedUnit.kt

@@ -0,0 +1,7 @@
+fun foo(x: Int) {
+    val y: Unit = when (x) {
+        2 -> {}
+        3 -> {}
+    }
+    return y
+}

compiler/testData/diagnostics/tests/when/NoElseNoExpectedType.kt

@@ -0,0 +1,6 @@
+fun foo(x: Int): Any {
+    val v = <!NO_ELSE_IN_WHEN!>when<!> (x) {
+        2 -> 0
+    }
+    return v
+}

compiler/testData/diagnostics/tests/when/NoElseReturnedCoercionToUnit.kt

@@ -0,0 +1,11 @@
+fun foo(x: Int) {
+    r {
+        when (x) {
+            2 -> 0
+        }
+    }
+}
+
+fun r(f: () -> Unit) {
+    f()
+}

compiler/testData/diagnostics/tests/when/NoElseReturnedFromLambdaExpectedInt.kt

@@ -0,0 +1,11 @@
+fun foo(x: Int) {
+    r {
+        <!NO_ELSE_IN_WHEN!>when<!> (x) {
+            2 -> 0
+        }
+    }
+}
+
+fun r(f: () -> Int) {
+    f()
+}

compiler/testData/diagnostics/tests/when/NoElseReturnedNonUnit.kt

@@ -0,0 +1,5 @@
+fun foo(x: Int): Any {
+    return <!NO_ELSE_IN_WHEN!>when<!> (x) {
+        2 -> 0
+    }
+}

compiler/testData/diagnostics/tests/when/NoElseReturnedUnit.kt

@@ -0,0 +1,6 @@
+fun foo(x: Int) {
+    return when (x) {
+        2 -> {}
+        3 -> {}
+    }
+}

compiler/testData/diagnostics/tests/when/NoElseWhenStatement.kt

@@ -0,0 +1,6 @@
+fun foo(x: Int) {
+    when (x) {
+        2 -> {}
+        3 -> {}
+    }
+}

compiler/testData/diagnostics/tests/when/When.kt

@@ -24,7 +24,7 @@ fun test() {
   val x = 1;
   val s = "";
 
-  <!NO_ELSE_IN_WHEN!>when<!> (x) {
+  when (x) {
     <!INCOMPATIBLE_TYPES!>s<!> -> 1
     <!INCOMPATIBLE_TYPES!>""<!> -> 1
     x -> 1