[FIR] Implement IMPLICIT_NOTHING_*_TYPE diagnostics

compiler/testData/diagnostics/tests/FunctionReturnTypes.fir.kt

@@ -136,7 +136,7 @@ fun blockNoReturnIfUnitInOneBranch(): Int {
 fun nonBlockReturnIfEmptyIf(): Int = <!RETURN_TYPE_MISMATCH!>if (1 < 2) {} else {}<!>
 fun nonBlockNoReturnIfUnitInOneBranch(): Int = <!RETURN_TYPE_MISMATCH!>if (1 < 2) {} else 2<!>
 
-val a = <!RETURN_NOT_ALLOWED!>return<!> 1
+val <!IMPLICIT_NOTHING_PROPERTY_TYPE!>a<!> = <!RETURN_NOT_ALLOWED!>return<!> 1
 
 class A() {
 }

compiler/testData/diagnostics/tests/controlStructures/ifToAnyDiscriminatingUsages.fir.kt

@@ -30,13 +30,13 @@ fun testReturnFromAnonFun() =
             return <!RETURN_TYPE_MISMATCH!>if (true) 42 else println()<!>
         })
 
-fun testReturn1() =
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>testReturn1<!>() =
         run {
             return <!RETURN_TYPE_MISMATCH!>if (true) 42
                    else println()<!>
         }
 
-fun testReturn2() =
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>testReturn2<!>() =
         run {
             return <!RETURN_TYPE_MISMATCH!>if (true) 42
                    else if (true) 42

compiler/testData/diagnostics/tests/controlStructures/kt10717.fir.kt

@@ -1,10 +1,10 @@
 // !DIAGNOSTICS: -UNUSED_EXPRESSION -UNREACHABLE_CODE -UNUSED_PARAMETER -RETURN_NOT_ALLOWED
 
-fun test1() = run {
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>test1<!>() = run {
     return <!RETURN_TYPE_MISMATCH!>"OK"<!>
 }
 
-fun test2() = run {
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>test2<!>() = run {
     fun local(): String {
         return ""
     }

compiler/testData/diagnostics/tests/controlStructures/kt799.fir.kt

@@ -14,7 +14,7 @@ fun test() {
 
 val a : Nothing = <!RETURN_NOT_ALLOWED!>return<!> 1
 
-val b = <!RETURN_NOT_ALLOWED!>return<!> 1
+val <!IMPLICIT_NOTHING_PROPERTY_TYPE!>b<!> = <!RETURN_NOT_ALLOWED!>return<!> 1
 
 val c = doSmth(if (true) 3 else <!RETURN_NOT_ALLOWED!>return<!>)
 

compiler/testData/diagnostics/tests/controlStructures/whenToAnyDiscriminatingUsages.fir.kt

@@ -24,7 +24,7 @@ fun testResultOfLambda2() =
             }
         }
 
-fun testReturn1() =
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>testReturn1<!>() =
         run {
             return <!RETURN_TYPE_MISMATCH!>when {
                 true -> 42
@@ -32,7 +32,7 @@ fun testReturn1() =
             }<!>
         }
 
-fun testReturn2() =
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>testReturn2<!>() =
         run {
             return <!RETURN_TYPE_MISMATCH!>when {
                 true -> 42
@@ -80,4 +80,4 @@ val testUsage5: Any get() =
         when {
             true -> 42
             else -> println()
-        }
+        }

compiler/testData/diagnostics/tests/implicitNothing.fir.kt

@@ -1,37 +1,37 @@
-fun foo() = throw Exception()
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>foo<!>() = throw Exception()
 
-fun bar() = null!!
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>bar<!>() = null!!
 
-fun baz() = bar()
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>baz<!>() = bar()
 
 fun gav(): Any = null!!
 
-val x = null!!
+val <!IMPLICIT_NOTHING_PROPERTY_TYPE!>x<!> = null!!
 
 val y: Nothing = throw Exception()
 
 fun check() {
     // Error: KT-10449
-    fun local() = bar()
+    fun <!IMPLICIT_NOTHING_RETURN_TYPE!>local<!>() = bar()
     // Unreachable / unused, but not implicit Nothing
     val x = null!!
 }
 
-fun nonLocalReturn() = run { <!RETURN_TYPE_MISMATCH!>return<!> }
+fun <!IMPLICIT_NOTHING_RETURN_TYPE!>nonLocalReturn<!>() = run { <!RETURN_TYPE_MISMATCH!>return<!> }
 
 class Klass {
-    fun bar() = null!!
+    fun <!IMPLICIT_NOTHING_RETURN_TYPE!>bar<!>() = null!!
 
-    val y = null!!
+    val <!IMPLICIT_NOTHING_PROPERTY_TYPE!>y<!> = null!!
 
     init {
-        fun local() = bar()
+        fun <!IMPLICIT_NOTHING_RETURN_TYPE!>local<!>() = bar()
         // Should be unreachable: see KT-5311
         val z = null!!
     }
 
     fun foo() {
-        fun local() = bar()
+        fun <!IMPLICIT_NOTHING_RETURN_TYPE!>local<!>() = bar()
 
         val x = y
     }

compiler/testData/diagnostics/tests/properties/inferenceFromGetters/nullAsNothing.fir.kt

@@ -1,6 +1,6 @@
 // !CHECK_TYPE
 val x get() = null
-val y get() = null!!
+val <!IMPLICIT_NOTHING_PROPERTY_TYPE!>y<!> get() = null!!
 
 fun foo() {
     x checkType { _<Nothing?>() }