Smart cast impossible on when subject is no more recorded #KT-10061 Fixed

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/DataFlowAnalyzer.java

@@ -207,8 +207,8 @@ public class DataFlowAnalyzer {
             return expressionType;
         }
 
-        KotlinType possibleType = checkPossibleCast(expressionType, expression, c);
-        if (possibleType != null) return possibleType;
+        SmartCastResult castResult = checkPossibleCast(expressionType, expression, c);
+        if (castResult != null) return castResult.getResultType();
 
         c.trace.report(TYPE_MISMATCH.on(expression, c.expectedType, expressionType));
         if (hasError != null) hasError.set(true);
@@ -245,15 +245,14 @@ public class DataFlowAnalyzer {
     }
 
     @Nullable
-    public KotlinType checkPossibleCast(
+    public SmartCastResult checkPossibleCast(
             @NotNull KotlinType expressionType,
             @NotNull KtExpression expression,
             @NotNull ResolutionContext c
     ) {
         DataFlowValue dataFlowValue = DataFlowValueFactory.createDataFlowValue(expression, expressionType, c);
 
-        SmartCastResult result = SmartCastManager.checkAndRecordPossibleCast(dataFlowValue, c.expectedType, expression, c, null, false);
-        return result != null ? result.getResultType() : null;
+        return SmartCastManager.checkAndRecordPossibleCast(dataFlowValue, c.expectedType, expression, c, null, false);
     }
 
     public void recordExpectedType(@NotNull BindingTrace trace, @NotNull KtExpression expression, @NotNull KotlinType expectedType) {

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/PatternMatchingTypingVisitor.java

@@ -25,13 +25,11 @@ import org.jetbrains.kotlin.cfg.WhenChecker;
 import org.jetbrains.kotlin.descriptors.ClassDescriptor;
 import org.jetbrains.kotlin.diagnostics.Errors;
 import org.jetbrains.kotlin.psi.*;
-import org.jetbrains.kotlin.resolve.BindingContext;
-import org.jetbrains.kotlin.resolve.DescriptorUtils;
-import org.jetbrains.kotlin.resolve.PossiblyBareType;
-import org.jetbrains.kotlin.resolve.TypeResolutionContext;
+import org.jetbrains.kotlin.resolve.*;
 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.smartcasts.SmartCastResult;
 import org.jetbrains.kotlin.resolve.calls.util.CallMaker;
 import org.jetbrains.kotlin.resolve.scopes.LexicalWritableScope;
 import org.jetbrains.kotlin.types.*;
@@ -92,8 +90,15 @@ public class PatternMatchingTypingVisitor extends ExpressionTypingVisitor {
             subjectType = typeInfo.getType();
             assert subjectType != null;
             if (TypeUtils.isNullableType(subjectType) && !WhenChecker.containsNullCase(expression, context.trace)) {
-                ExpressionTypingContext subjectContext = context.replaceExpectedType(TypeUtils.makeNotNullable(subjectType));
-                components.dataFlowAnalyzer.checkPossibleCast(subjectType, KtPsiUtil.safeDeparenthesize(subjectExpression), subjectContext);
+                TemporaryBindingTrace trace = TemporaryBindingTrace.create(context.trace, "Temporary trace for when subject nullability");
+                ExpressionTypingContext subjectContext =
+                        context.replaceExpectedType(TypeUtils.makeNotNullable(subjectType)).replaceBindingTrace(trace);
+                SmartCastResult castResult = components.dataFlowAnalyzer.checkPossibleCast(
+                        subjectType, KtPsiUtil.safeDeparenthesize(subjectExpression), subjectContext
+                );
+                if (castResult != null && castResult.isCorrect()) {
+                    trace.commit();
+                }
             }
             context = context.replaceDataFlowInfo(typeInfo.getDataFlowInfo());
         }

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

@@ -0,0 +1,10 @@
+// See KT-10061
+
+class My {
+    val x: Int? get() = 42
+}
+
+fun foo(my: My) {
+    my.x!!
+    when (my.x) { }
+}

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

@@ -0,0 +1,11 @@
+package
+
+public fun foo(/*0*/ my: My): kotlin.Unit
+
+public final class My {
+    public constructor My()
+    public final val x: kotlin.Int?
+    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/testData/diagnostics/tests/smartCasts/whenSubjectImpossibleJava.kt

@@ -0,0 +1,11 @@
+// See KT-10061
+// FILE: My.java
+public class My {
+    String getSomething() { return "xyz"; }
+}
+
+// FILE: My.kt
+fun foo(my: My) {
+    my.something!!
+    when (my.something) { }
+}

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

@@ -0,0 +1,11 @@
+package
+
+public fun foo(/*0*/ my: My): kotlin.Unit
+
+public open class My {
+    public constructor My()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public/*package*/ open fun getSomething(): kotlin.String!
+    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

@@ -14922,6 +14922,18 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("whenSubjectImpossible.kt")
+            public void testWhenSubjectImpossible() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/whenSubjectImpossible.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("whenSubjectImpossibleJava.kt")
+            public void testWhenSubjectImpossibleJava() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/whenSubjectImpossibleJava.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("compiler/testData/diagnostics/tests/smartCasts/inference")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)