Deprecate simplification of complex boolean constant expressions in whens and loops

^KT-39883 In Progress

compiler/testData/diagnostics/tests/when/ExhaustiveBooleanComplex.fir.kt

@@ -1,18 +0,0 @@
-/*
- * KOTLIN DIAGNOSTICS SPEC TEST (NEGATIVE)
- *
- * SPEC VERSION: 0.1-313
- * PRIMARY LINKS: expressions, when-expression -> paragraph 5 -> sentence 1
- * expressions, when-expression, exhaustive-when-expressions -> paragraph 2 -> sentence 3
- * expressions, when-expression, exhaustive-when-expressions -> paragraph 2 -> sentence 4
- * expressions, when-expression, exhaustive-when-expressions -> paragraph 2 -> sentence 5
- */
-
-// See also: KT-3743
-fun foo(arg: Boolean): String {
-    // Must be exhaustive
-    return <!NO_ELSE_IN_WHEN!>when<!>(arg) {
-        2 == 2 -> "truth"
-        2 == 1 -> "falsehood"
-    }
-}

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

@@ -1,3 +1,5 @@
+// FIR_IDENTICAL
+// !LANGUAGE: +ProhibitSimplificationOfNonTrivialConstBooleanExpressions
 /*
  * KOTLIN DIAGNOSTICS SPEC TEST (NEGATIVE)
  *
@@ -11,7 +13,7 @@
 // See also: KT-3743
 fun foo(arg: Boolean): String {
     // Must be exhaustive
-    return when(arg) {
+    return <!NO_ELSE_IN_WHEN!>when<!>(arg) {
         2 == 2 -> "truth"
         2 == 1 -> "falsehood"
     }

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

@@ -0,0 +1,32 @@
+// FIR_IDENTICAL
+// !LANGUAGE: +ProhibitSimplificationOfNonTrivialConstBooleanExpressions
+// ISSUE: KT-39883
+
+// Should always work
+fun test_0(b: Boolean): String = when (b) {
+    true -> "true"
+    false -> "false"
+}
+
+// Deprecated
+fun test_1(b: Boolean): String = <!NO_ELSE_IN_WHEN!>when<!> (b) {
+    1 == 1 -> "true"
+    "" != "" -> "false"
+}
+
+const val TRUE = true
+
+// Already not working
+fun test_2(b: Boolean): String = <!NO_ELSE_IN_WHEN!>when<!>(b) {
+    TRUE -> "true"
+    false -> "false"
+}
+
+const val s1 = "s1"
+const val s2 = "s2"
+
+// Already not working
+fun test_3(b: Boolean): String = <!NO_ELSE_IN_WHEN!>when<!>(b) {
+    true -> "true"
+    s1 == s2 -> "false"
+}

compiler/testData/diagnostics/tests/when/exhaustiveBooleanWhenWithUntrivialConst_error.txt

@@ -0,0 +1,9 @@
+package
+
+public const val TRUE: kotlin.Boolean = true
+public const val s1: kotlin.String = "s1"
+public const val s2: kotlin.String = "s2"
+public fun test_0(/*0*/ b: kotlin.Boolean): kotlin.String
+public fun test_1(/*0*/ b: kotlin.Boolean): kotlin.String
+public fun test_2(/*0*/ b: kotlin.Boolean): kotlin.String
+public fun test_3(/*0*/ b: kotlin.Boolean): kotlin.String

compiler/testData/diagnostics/tests/when/exhaustiveBooleanWhenWithUntrivialConst_warning.fir.kt

@@ -0,0 +1,31 @@
+// !LANGUAGE: -ProhibitSimplificationOfNonTrivialConstBooleanExpressions
+// ISSUE: KT-39883
+
+// Should always work
+fun test_0(b: Boolean): String = when (b) {
+    true -> "true"
+    false -> "false"
+}
+
+// Deprecated
+fun test_1(b: Boolean): String = <!NO_ELSE_IN_WHEN!>when<!> (b) {
+    1 == 1 -> "true"
+    "" != "" -> "false"
+}
+
+const val TRUE = true
+
+// Already not working
+fun test_2(b: Boolean): String = <!NO_ELSE_IN_WHEN!>when<!>(b) {
+    TRUE -> "true"
+    false -> "false"
+}
+
+const val s1 = "s1"
+const val s2 = "s2"
+
+// Already not working
+fun test_3(b: Boolean): String = <!NO_ELSE_IN_WHEN!>when<!>(b) {
+    true -> "true"
+    s1 == s2 -> "false"
+}

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

@@ -0,0 +1,31 @@
+// !LANGUAGE: -ProhibitSimplificationOfNonTrivialConstBooleanExpressions
+// ISSUE: KT-39883
+
+// Should always work
+fun test_0(b: Boolean): String = when (b) {
+    true -> "true"
+    false -> "false"
+}
+
+// Deprecated
+fun test_1(b: Boolean): String = when (b) {
+    <!NON_TRIVIAL_BOOLEAN_CONSTANT!>1 == 1<!> -> "true"
+    <!NON_TRIVIAL_BOOLEAN_CONSTANT!>"" != ""<!> -> "false"
+}
+
+const val TRUE = true
+
+// Already not working
+fun test_2(b: Boolean): String = <!NO_ELSE_IN_WHEN!>when<!>(b) {
+    TRUE -> "true"
+    false -> "false"
+}
+
+const val s1 = "s1"
+const val s2 = "s2"
+
+// Already not working
+fun test_3(b: Boolean): String = <!NO_ELSE_IN_WHEN!>when<!>(b) {
+    true -> "true"
+    s1 == s2 -> "false"
+}

compiler/testData/diagnostics/tests/when/exhaustiveBooleanWhenWithUntrivialConst_warning.txt

@@ -0,0 +1,9 @@
+package
+
+public const val TRUE: kotlin.Boolean = true
+public const val s1: kotlin.String = "s1"
+public const val s2: kotlin.String = "s2"
+public fun test_0(/*0*/ b: kotlin.Boolean): kotlin.String
+public fun test_1(/*0*/ b: kotlin.Boolean): kotlin.String
+public fun test_2(/*0*/ b: kotlin.Boolean): kotlin.String
+public fun test_3(/*0*/ b: kotlin.Boolean): kotlin.String