More correct handling of possible type set during assignment #KT-8229 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/smartcasts/DelegatingDataFlowInfo.java

@@ -175,7 +175,7 @@ import static org.jetbrains.kotlin.resolve.calls.smartcasts.Nullability.NOT_NULL
         putNullability(nullability, a, nullabilityOfB);
 
         SetMultimap<DataFlowValue, KotlinType> newTypeInfo = newTypeInfo();
-        Set<KotlinType> typesForB = collectTypesFromMeAndParents(b);
+        Set<KotlinType> typesForB = getPossibleTypes(b);
         // Own type of B must be recorded separately, e.g. for a constant
         // But if its type is the same as A or it's null, there is no reason to do it
         // because usually null type or own type are not saved in this set

compiler/testData/diagnostics/tests/smartCasts/variables/assignmentConversion.kt

@@ -0,0 +1,35 @@
+fun foo(x: String) = x
+
+fun test1() {
+    var c: Any? = "XXX"
+    if (c !is String) return
+
+    val newC: String? = "YYY"
+    if (newC != null) {
+        c = newC
+    }
+    foo(<!DEBUG_INFO_SMARTCAST!>c<!>)
+}
+
+fun test2() {
+    var c: Any? = "XXX"
+    if (c !is String) return
+
+    val newC: String? = "YYY"
+    if (newC is String) {
+        c = newC
+    }
+    foo(<!DEBUG_INFO_SMARTCAST!>c<!>)
+}
+
+fun test3() {
+    var c: Any? = "XXX"
+    if (c !is String) return
+
+    val newC: String? = "YYY"
+    if (newC == null) return
+    c = newC
+
+    foo(<!DEBUG_INFO_SMARTCAST!>c<!>)
+}
+

compiler/testData/diagnostics/tests/smartCasts/variables/assignmentConversion.txt

@@ -0,0 +1,6 @@
+package
+
+public fun foo(/*0*/ x: kotlin.String): kotlin.String
+public fun test1(): kotlin.Unit
+public fun test2(): kotlin.Unit
+public fun test3(): kotlin.Unit

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

@@ -15344,6 +15344,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("assignmentConversion.kt")
+                public void testAssignmentConversion() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/variables/assignmentConversion.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("doWhileWithMiddleBreak.kt")
                 public void testDoWhileWithMiddleBreak() throws Exception {
                     String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/variables/doWhileWithMiddleBreak.kt");