[FIR] Implement checker for exhaustive when's in expression position

compiler/testData/diagnostics/tests/sealed/ExhaustiveOnRoot.fir.kt

@@ -13,11 +13,11 @@ fun test(x: Stmt): String =
         }
 
 fun test2(x: Stmt): String =
-        when (x) {
+        <!NO_ELSE_IN_WHEN!>when<!> (x) {
             is Expr -> "expr"
         }
 
 fun test3(x: Expr): String =
-        when (x) {
+        <!NO_ELSE_IN_WHEN!>when<!> (x) {
             is Stmt -> "stmt"
-        }
+        }

compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTree.fir.kt

@@ -15,7 +15,7 @@ sealed class Base {
         // No else required
     }
 
-    fun bar() = when (this) {
+    fun bar() = <!NO_ELSE_IN_WHEN!>when<!> (this) {
         is A -> 1
         is B.B1 -> 2
     }
@@ -31,4 +31,4 @@ sealed class Base {
         A.A1 -> 2
         is A.A2 -> 3
     }
-}
+}

compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTriangleStar.fir.kt

@@ -1,24 +0,0 @@
-sealed class A
-sealed class B : A()
-
-class C : B()
-class D : B()
-
-fun test(a: A): Any {
-    return when (a) {
-        is C -> ""
-        is D -> ""
-    }
-}
-
-fun test2(a: A): Any {
-    return when (a) {
-        is B -> ""
-    }
-}
-
-fun test3(a: A): Any {
-    return when (a) {
-        is D -> ""
-    }
-}

compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTriangleStar.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 sealed class A
 sealed class B : A()
 

compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenMultipleInner.fir.kt

@@ -1,47 +0,0 @@
-sealed class Sealed() {
-    object First: Sealed()
-    open class NonFirst: Sealed() {
-        class NonSecond: NonFirst() {
-            object Third: Sealed()
-            class NonThird: Sealed() {
-                object Fourth: NonFirst()
-                class Fifth: Sealed()
-            }    
-        }
-        object Second: Sealed()
-    }    
-}
-
-fun foo(s: Sealed) = when(s) {
-    Sealed.First -> 1
-    is Sealed.NonFirst -> 2
-    Sealed.NonFirst.Second -> 4
-    Sealed.NonFirst.NonSecond.Third -> 6
-    is Sealed.NonFirst.NonSecond.NonThird -> 8
-    is Sealed.NonFirst.NonSecond.NonThird.Fifth -> 10
-    // no else required
-}
-
-fun fooWithElse(s: Sealed) = when(s) {
-    Sealed.First -> 1
-    Sealed.NonFirst.NonSecond.Third -> 6
-    is Sealed.NonFirst.NonSecond.NonThird.Fifth -> 10
-    else -> 0
-}
-
-fun fooWithoutElse(s: Sealed) = when(s) {
-    Sealed.First -> 1
-    is Sealed.NonFirst -> 2
-    Sealed.NonFirst.NonSecond.Third -> 6
-    is Sealed.NonFirst.NonSecond.NonThird -> 8
-    is Sealed.NonFirst.NonSecond.NonThird.Fifth -> 10
-}
-
-fun barWithoutElse(s: Sealed) = when(s) {
-    Sealed.First -> 1
-    is Sealed.NonFirst -> 2
-    Sealed.NonFirst.Second -> 4
-    is Sealed.NonFirst.NonSecond.NonThird -> 8
-    is Sealed.NonFirst.NonSecond.NonThird.Fifth -> 10
-}
-

compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenMultipleInner.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 sealed class Sealed() {
     object First: Sealed()
     open class NonFirst: Sealed() {

compiler/testData/diagnostics/tests/sealed/ExhaustiveWithFreedom.fir.kt

@@ -1,64 +0,0 @@
-// ISSUE: KT-13495
-// !DIAGNOSTICS: -UNUSED_VARIABLE
-// !LANGUAGE: +AllowSealedInheritorsInDifferentFilesOfSamePackage
-
-// FILE: Base.kt
-
-sealed class Base {
-    class A : Base()
-}
-
-// FILE: B.kt
-
-class B : Base()
-
-// FILE: Container.kt
-
-class Containter {
-    class C : Base()
-
-    inner class D : Base()
-}
-
-// FILE: main.kt
-
-fun test_OK(base: Base) {
-    val x = when (base) {
-        is Base.A -> 1
-        is B -> 2
-        is Containter.C -> 3
-        is Containter.D -> 4
-    }
-}
-
-fun test_error_1(base: Base) {
-    val x = when (base) {
-        is B -> 2
-        is Containter.C -> 3
-        is Containter.D -> 4
-    }
-}
-
-fun test_error_2(base: Base) {
-    val x = when (base) {
-        is Base.A -> 1
-        is Containter.C -> 3
-        is Containter.D -> 4
-    }
-}
-
-fun test_error_3(base: Base) {
-    val x = when (base) {
-        is Base.A -> 1
-        is B -> 2
-        is Containter.D -> 4
-    }
-}
-
-fun test_error_4(base: Base) {
-    val x = when (base) {
-        is Base.A -> 1
-        is B -> 2
-        is Containter.C -> 3
-    }
-}

compiler/testData/diagnostics/tests/sealed/ExhaustiveWithFreedom.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // ISSUE: KT-13495
 // !DIAGNOSTICS: -UNUSED_VARIABLE
 // !LANGUAGE: +AllowSealedInheritorsInDifferentFilesOfSamePackage

compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhen.fir.kt

@@ -1,14 +0,0 @@
-sealed class Sealed(val x: Int) {
-    object First: Sealed(12)
-    open class NonFirst(x: Int, val y: Int): Sealed(x) {
-        object Second: NonFirst(34, 2)
-        object Third: NonFirst(56, 3)
-    }
-}
-
-fun foo(s: Sealed): Int {
-    return when(s) {
-        is Sealed.NonFirst -> 0
-    }
-}
-

compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhen.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 sealed class Sealed(val x: Int) {
     object First: Sealed(12)
     open class NonFirst(x: Int, val y: Int): Sealed(x) {

compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenNegated.fir.kt

@@ -1,14 +0,0 @@
-sealed class Sealed(val x: Int) {
-    object First: Sealed(12)
-    open class NonFirst(x: Int, val y: Int): Sealed(x) {
-        object Second: NonFirst(34, 2)
-        object Third: NonFirst(56, 3)
-    }
-}
-
-fun foo(s: Sealed): Int {
-    return when(s) {
-        !is Sealed.NonFirst -> 1
-    }
-}
-

compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenNegated.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 sealed class Sealed(val x: Int) {
     object First: Sealed(12)
     open class NonFirst(x: Int, val y: Int): Sealed(x) {

compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAdditionalCase.fir.kt

@@ -1,22 +0,0 @@
-sealed class Sealed(val x: Int) {
-    interface ITuple {
-        val x: Int
-        val y: Int
-    }
-    class Tuple(override val x: Int, override val y: Int): ITuple
-    object First: Sealed(12)
-    open class NonFirst(tuple: Tuple): Sealed(tuple.x), ITuple {
-        override val y: Int = tuple.y
-        object Second: NonFirst(Tuple(34, 2))
-        class Third: NonFirst(Tuple(56, 3))
-    }
-}
-
-fun foo(s: Sealed): Int {
-    return when(s) {
-        is Sealed.First -> 1
-        !is Sealed.ITuple -> 0
-        // else required
-    }
-}
-

compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAdditionalCase.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 sealed class Sealed(val x: Int) {
     interface ITuple {
         val x: Int

compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAnyCase.fir.kt

@@ -7,7 +7,7 @@ sealed class Sealed {
 }
 
 fun foo(s: Sealed): Int {
-    return when(s) {
+    return <!NO_ELSE_IN_WHEN!>when<!>(s) {
         is Sealed.First -> 1
         !is Any -> 0
     }

compiler/testData/diagnostics/tests/sealed/TreeWhenFunctionalNoIs.fir.kt

@@ -9,7 +9,7 @@ sealed class Tree {
         is Node  -> this.left.max()
     }
 
-    fun maxIsClass(): Int = when(this) {
+    fun maxIsClass(): Int = <!NO_ELSE_IN_WHEN!>when<!>(this) {
         Empty -> -1
         Leaf  -> 0
         is Node  -> this.left.max()
@@ -20,4 +20,4 @@ sealed class Tree {
         is Node  -> this.left.max()
         else -> -1
     }
-}
+}

compiler/testData/diagnostics/tests/sealed/WhenOnEmptySealed.fir.kt

@@ -1,11 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_EXPRESSION
-sealed class Sealed {
-
-}
-
-fun foo(s: Sealed): Int {
-    return when(s) {
-        // We do not return anything, so else branch must be here
-    }
-}
-

compiler/testData/diagnostics/tests/sealed/WhenOnEmptySealed.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_EXPRESSION
 sealed class Sealed {