DFA: only stable values or qualified with stable receiver can be bound in x = y #KT-15792 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/LocalVariableResolver.kt

@@ -30,6 +30,7 @@ import org.jetbrains.kotlin.psi.KtPsiUtil
 import org.jetbrains.kotlin.psi.KtVariableDeclaration
 import org.jetbrains.kotlin.resolve.calls.context.ContextDependency
 import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowInfo
+import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValue
 import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValueFactory
 import org.jetbrains.kotlin.resolve.calls.util.isSingleUnderscore
 import org.jetbrains.kotlin.resolve.lazy.ForceResolveUtil
@@ -98,7 +99,7 @@ class LocalVariableResolver(
             val type = typeInfo.type
             if (type != null) {
                 val initializerDataFlowValue = DataFlowValueFactory.createDataFlowValue(initializer, type, context)
-                if (!propertyDescriptor.isVar) {
+                if (!propertyDescriptor.isVar && initializerDataFlowValue.canBeBound) {
                     context.trace.record(BindingContext.BOUND_INITIALIZER_VALUE, propertyDescriptor, initializerDataFlowValue)
                 }
                 // At this moment we do not take initializer value into account if type is given for a property

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/smartcasts/DataFlowValue.kt

@@ -69,6 +69,8 @@ class DataFlowValue(val identifierInfo: IdentifierInfo,
      */
     val isStable = (kind == Kind.STABLE_VALUE || kind == Kind.STABLE_VARIABLE || kind == Kind.STABLE_COMPLEX_EXPRESSION)
 
+    val canBeBound get() = identifierInfo.canBeBound
+
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
         if (other !is DataFlowValue) return false

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/smartcasts/IdentifierInfo.kt

@@ -27,6 +27,8 @@ interface IdentifierInfo {
 
     val kind: DataFlowValue.Kind get() = OTHER
 
+    val canBeBound get() = false
+
     object NO : IdentifierInfo {
         override fun toString() = "NO_IDENTIFIER_INFO"
     }
@@ -45,6 +47,9 @@ interface IdentifierInfo {
             val bound: DataFlowValue?
     ) : IdentifierInfo {
 
+        override val canBeBound
+            get() = kind == STABLE_VALUE
+
         override fun equals(other: Any?) = other is Variable && variable == other.variable
 
         override fun hashCode() = variable.hashCode()
@@ -74,6 +79,9 @@ interface IdentifierInfo {
     ) : IdentifierInfo {
         override val kind: DataFlowValue.Kind get() = if (receiverInfo.kind == STABLE_VALUE) selectorInfo.kind else OTHER
 
+        override val canBeBound
+            get() = receiverInfo.canBeBound
+
         override fun equals(other: Any?) = other is Qualified && receiverInfo == other.receiverInfo && selectorInfo == other.selectorInfo
 
         override fun hashCode() = 31 * receiverInfo.hashCode() + selectorInfo.hashCode()

compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializerWrong.kt

@@ -0,0 +1,45 @@
+// KT-15792 and related
+
+fun foo() {
+    var x: String? = ""
+    val y = x
+    x = null
+    if (y != null) {
+        <!DEBUG_INFO_CONSTANT!>x<!><!UNSAFE_CALL!>.<!>hashCode()
+    }
+}
+
+fun foo2() {
+    var x: String? = ""
+    val y = x
+    if (y != null) {
+        x<!UNSAFE_CALL!>.<!>hashCode()
+    }
+}
+
+fun bar(s: String?) {
+    var ss = s
+    val hashCode = ss?.hashCode()
+    ss = null
+    if (hashCode != null) {
+        <!DEBUG_INFO_CONSTANT!>ss<!><!UNSAFE_CALL!>.<!>hashCode()
+    }
+}
+
+fun bar2(s: String?) {
+    var ss = s
+    val hashCode = ss?.hashCode()
+    if (hashCode != null) {
+        ss<!UNSAFE_CALL!>.<!>hashCode()
+    }
+}
+
+class Some(var s: String?)
+
+fun baz(arg: Some?) {
+    val ss = arg?.s
+    if (ss != null) {
+        <!DEBUG_INFO_SMARTCAST!>arg<!>.hashCode()
+        <!SMARTCAST_IMPOSSIBLE!><!DEBUG_INFO_SMARTCAST!>arg<!>.s<!>.hashCode()
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializerWrong.txt

@@ -0,0 +1,15 @@
+package
+
+public fun bar(/*0*/ s: kotlin.String?): kotlin.Unit
+public fun bar2(/*0*/ s: kotlin.String?): kotlin.Unit
+public fun baz(/*0*/ arg: Some?): kotlin.Unit
+public fun foo(): kotlin.Unit
+public fun foo2(): kotlin.Unit
+
+public final class Some {
+    public constructor Some(/*0*/ s: kotlin.String?)
+    public final var s: kotlin.String?
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -20652,6 +20652,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("boundInitializerWrong.kt")
+                public void testBoundInitializerWrong() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializerWrong.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("doWhileWithBreak.kt")
                 public void testDoWhileWithBreak() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/doWhileWithBreak.kt");