Data flow values for Elvis / parenthesized expressions, smart casts on them

compiler/testData/diagnostics/tests/smartCasts/elvisExprNotNull.kt

@@ -0,0 +1,37 @@
+fun foo(s: Any?): String {
+    val t = when {
+        // To resolve: String U Nothing? = String?
+        s is String -> s
+        else -> null
+    } ?: ""
+    // Ideally we should have smart cast to String here
+    return <!TYPE_MISMATCH!>t<!>
+}
+
+fun bar(s: Any?): String {
+    // To resolve: String U Nothing? = String?
+    val t = (if (s == null) {
+        null
+    }
+    else {
+        val u: Any? = null
+        if (u !is String) return ""
+        u
+    }) ?: "xyz"
+    // Ideally we should have smart cast to String here
+    return <!TYPE_MISMATCH!>t<!>
+}
+
+fun baz(s: String?, r: String?): String {
+    val t = r ?: when {
+        s != null -> s
+        else -> ""
+    }
+    return <!DEBUG_INFO_SMARTCAST!>t<!>
+}
+
+fun withNull(s: String?): String {
+    val t = s ?: null
+    // Error: nullable
+    return <!TYPE_MISMATCH!>t<!>
+}

compiler/testData/diagnostics/tests/smartCasts/elvisExprNotNull.txt

@@ -0,0 +1,6 @@
+package
+
+public fun bar(/*0*/ s: kotlin.Any?): kotlin.String
+public fun baz(/*0*/ s: kotlin.String?, /*1*/ r: kotlin.String?): kotlin.String
+public fun foo(/*0*/ s: kotlin.Any?): kotlin.String
+public fun withNull(/*0*/ s: kotlin.String?): kotlin.String

compiler/testData/diagnostics/tests/smartCasts/smartCastOnElvis.kt

@@ -0,0 +1,15 @@
+fun foo(s: String) = s.length
+
+fun baz(s: String?, r: String?): Int {
+    return foo(<!DEBUG_INFO_SMARTCAST!>r ?: when {
+        s != null -> s
+        else -> ""
+    }<!>)
+}
+
+fun bar(s: String?, r: String?): Int {
+    return <!DEBUG_INFO_SMARTCAST!>(r ?: when {
+        s != null -> s
+        else -> ""
+    })<!>.length
+}

compiler/testData/diagnostics/tests/smartCasts/smartCastOnElvis.txt

@@ -0,0 +1,5 @@
+package
+
+public fun bar(/*0*/ s: kotlin.String?, /*1*/ r: kotlin.String?): kotlin.Int
+public fun baz(/*0*/ s: kotlin.String?, /*1*/ r: kotlin.String?): kotlin.Int
+public fun foo(/*0*/ s: kotlin.String): kotlin.Int