Elvis DFA: now only left part is taken into account #KT-9100 Fixed

I had to fix a few incorrect tests using something like x!! in Elvis right part, and also one bug in our code

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

@@ -1173,10 +1173,16 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
         boolean loopBreakContinuePossible = leftTypeInfo.getJumpOutPossible() || rightTypeInfo.getJumpOutPossible();
         JetType rightType = rightTypeInfo.getType();
 
-        DataFlowInfo dataFlowInfo = resolvedCall.getDataFlowInfoForArguments().getResultInfo();
-        if (leftType != null && rightType != null && KotlinBuiltIns.isNothingOrNullableNothing(rightType) && !rightType.isMarkedNullable()) {
-            DataFlowValue value = createDataFlowValue(left, leftType, context);
-            dataFlowInfo = dataFlowInfo.disequate(value, DataFlowValue.NULL);
+        // Only left argument DFA is taken into account here: we cannot be sure that right argument is executed
+        DataFlowInfo dataFlowInfo = resolvedCall.getDataFlowInfoForArguments().getInfo(call.getValueArguments().get(1));
+        if (leftType != null) {
+            DataFlowValue leftValue = createDataFlowValue(left, leftType, context);
+            DataFlowInfo rightDataFlowInfo = resolvedCall.getDataFlowInfoForArguments().getResultInfo();
+            // left argument is considered not-null if it's not-null also in right part or if we have jump in right part
+            if ((rightType != null && KotlinBuiltIns.isNothingOrNullableNothing(rightType) && !rightType.isMarkedNullable())
+                || !rightDataFlowInfo.getNullability(leftValue).canBeNull()) {
+                dataFlowInfo = dataFlowInfo.disequate(leftValue, DataFlowValue.NULL);
+            }
         }
         JetType type = resolvedCall.getResultingDescriptor().getReturnType();
         if (type == null || rightType == null) return TypeInfoFactoryPackage.noTypeInfo(dataFlowInfo);

compiler/testData/diagnostics/tests/resolve/specialConstructions/elvisAsCall.kt

@@ -21,12 +21,14 @@ fun testElvis(a: Int?, b: Int?) {
 fun testDataFlowInfo1(a: Int?, b: Int?) {
     val c: Int = a ?: b!!
     doInt(c)
-    <!DEBUG_INFO_SMARTCAST!>b<!> + 1
+    // b is nullable if a != null
+    b <!UNSAFE_INFIX_CALL!>+<!> 1
 }
 
 fun testDataFlowInfo2(a: Int?, b: Int?) {
     doInt(a ?: b!!)
-    <!DEBUG_INFO_SMARTCAST!>b<!> + 1
+    // b is nullable if a != null
+    b <!UNSAFE_INFIX_CALL!>+<!> 1
 }
 
 fun testTypeMismatch(a: String?, b: Any) {

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

@@ -0,0 +1,9 @@
+// Based on KT-9100
+fun test(x: Any?, y: Any?): Any {
+    val z = x ?: y!!
+    y<!UNSAFE_CALL!>.<!>hashCode()
+    // !! / ?. is necessary here, because y!! above may not be executed
+    y?.hashCode()
+    y!!.hashCode()
+    return z
+}

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

@@ -0,0 +1,3 @@
+package
+
+public fun test(/*0*/ x: kotlin.Any?, /*1*/ y: kotlin.Any?): kotlin.Any

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

@@ -0,0 +1,6 @@
+fun test(x: Any?): Any {
+    val z = x ?: x!!
+    // x is not null in both branches
+    <!DEBUG_INFO_SMARTCAST!>x<!>.hashCode()
+    return z
+}

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

@@ -0,0 +1,3 @@
+package
+
+public fun test(/*0*/ x: kotlin.Any?): kotlin.Any

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

@@ -0,0 +1,27 @@
+// FILE: p/My.java
+
+package p;
+
+import org.jetbrains.annotations.*;
+
+class My {
+    @Nullable static String create() {
+        return "";
+    }
+}
+
+// FILE: test.kt
+
+package p
+
+fun bar(x: String) = x
+
+fun test(x: String?): Any {
+    val y = My.create()
+    val z = x ?: y!!
+    bar(<!TYPE_MISMATCH!>y<!>)
+    // !! / ?. is necessary here, because y!! above may not be executed
+    y?.hashCode()
+    y!!.hashCode()
+    return z
+}

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

@@ -0,0 +1,16 @@
+package
+
+package p {
+    public fun bar(/*0*/ x: kotlin.String): kotlin.String
+    public fun test(/*0*/ x: kotlin.String?): kotlin.Any
+
+    public/*package*/ open class My {
+        public/*package*/ constructor My()
+        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
+
+        // Static members
+        org.jetbrains.annotations.Nullable() public/*package*/ open fun create(): kotlin.String?
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/loops/assignElvisIfBreakInsideWhileTrue.kt

@@ -3,8 +3,8 @@ public fun foo(x: String?, y: String?): Int {
         val z = x ?: if (y == null) break else <!DEBUG_INFO_SMARTCAST!>y<!>
         // z is not null in both branches
         z.length()
-        // y is not null in both branches
-        <!DEBUG_INFO_SMARTCAST!>y<!>.length()
+        // y is nullable if x != null
+        y<!UNSAFE_CALL!>.<!>length()
     }
     // y is null because of the break
     return y<!UNSAFE_CALL!>.<!>length()

compiler/testData/diagnostics/tests/smartCasts/loops/elvisIfBreakInsideWhileTrue.kt

@@ -1,8 +1,8 @@
 public fun foo(x: String?, y: String?): Int {
     while (true) {
         x ?: if (y == null) break
-        // y is not null in both branches
-        <!DEBUG_INFO_SMARTCAST!>y<!>.length()
+        // y is nullable if x != null
+        y<!UNSAFE_CALL!>.<!>length()
     }
     // y is null because of the break
     return y<!UNSAFE_CALL!>.<!>length()

compiler/testData/diagnostics/tests/smartCasts/loops/elvisLeftBreakInsideWhileTrue.kt

@@ -1,8 +1,8 @@
 public fun foo(x: String?, y: String?): Int {
     while (true) {
         (if (x != null) break else y) ?: y!!
-        // x is not null in both branches
-        <!DEBUG_INFO_SMARTCAST!>y<!>.length()
+        // y is not null in both branches but it's hard to determine
+        y<!UNSAFE_CALL!>.<!>length()
     }
     // y can be null because of the break
     return y<!UNSAFE_CALL!>.<!>length()

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

@@ -13167,6 +13167,24 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("elvisExclExcl.kt")
+            public void testElvisExclExcl() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/elvisExclExcl.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("elvisExclExclMerge.kt")
+            public void testElvisExclExclMerge() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/elvisExclExclMerge.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("elvisExclExclPlatform.kt")
+            public void testElvisExclExclPlatform() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/elvisExclExclPlatform.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("elvisNothingRHS.kt")
             public void testElvisNothingRHS() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/elvisNothingRHS.kt");

idea/tests/org/jetbrains/kotlin/idea/stubs/DebugTextByStubTest.kt

@@ -81,7 +81,7 @@ public class DebugTextByStubTest : LightCodeInsightFixtureTestCase() {
         val toCheckAgainst = "STUB: " + (expectedText ?: classByPsi!!.getText())
         Assert.assertEquals(toCheckAgainst, psiFromStub.getDebugText())
         if (expectedText != null) {
-            Assert.assertNotEquals("Expected text should not be specified", classByPsi.getDebugText(), psiFromStub.getDebugText())
+            Assert.assertNotEquals("Expected text should not be specified", classByPsi!!.getDebugText(), psiFromStub.getDebugText())
         }
     }