Data flow values: more accurate handling of postfix ++ and --

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

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.cfg.ControlFlowInformationProvider
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.impl.LocalVariableDescriptor
 import org.jetbrains.kotlin.descriptors.impl.SyntheticFieldDescriptor
+import org.jetbrains.kotlin.lexer.KtToken
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.before
@@ -140,10 +141,11 @@ object DataFlowValueFactory {
             type: KotlinType
     ) = DataFlowValue(ExpressionIdentifierInfo(expression, stableComplex = true), type)
 
-    private data class PostfixIdentifierInfo(val argumentInfo: IdentifierInfo) : IdentifierInfo {
+    // For only ++ and -- postfix operations
+    private data class PostfixIdentifierInfo(val argumentInfo: IdentifierInfo, val op: KtToken) : IdentifierInfo {
         override val kind: DataFlowValue.Kind get() = argumentInfo.kind
 
-        override fun toString() = "$argumentInfo (postfix)"
+        override fun toString() = "$argumentInfo($op)"
     }
 
     class ExpressionIdentifierInfo(val expression: KtExpression, stableComplex: Boolean = false) : IdentifierInfo {
@@ -157,12 +159,12 @@ object DataFlowValueFactory {
         override fun toString() = expression.text ?: "(empty expression)"
     }
 
-    private fun postfix(argumentInfo: IdentifierInfo) =
+    private fun postfix(argumentInfo: IdentifierInfo, op: KtToken) =
             if (argumentInfo == IdentifierInfo.NO) {
                 IdentifierInfo.NO
             }
             else {
-                PostfixIdentifierInfo(argumentInfo)
+                PostfixIdentifierInfo(argumentInfo, op)
             }
 
     private fun getIdForStableIdentifier(
@@ -195,7 +197,8 @@ object DataFlowValueFactory {
             is KtPostfixExpression -> {
                 val operationType = expression.operationReference.getReferencedNameElementType()
                 if (operationType === KtTokens.PLUSPLUS || operationType === KtTokens.MINUSMINUS) {
-                    postfix(getIdForStableIdentifier(expression.baseExpression, bindingContext, containingDeclarationOrModule))
+                    postfix(getIdForStableIdentifier(expression.baseExpression, bindingContext, containingDeclarationOrModule),
+                            operationType)
                 }
                 else {
                     IdentifierInfo.NO

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

@@ -0,0 +1,20 @@
+fun foo(arg: Int?): Int {
+    var i = arg
+    if (i != null && <!DEBUG_INFO_SMARTCAST!>i<!>++ == 5) {
+        return <!DEBUG_INFO_SMARTCAST!><!DEBUG_INFO_SMARTCAST!>i<!>--<!> + <!DEBUG_INFO_SMARTCAST!>i<!>
+    }
+    return 0
+}
+
+operator fun Long?.inc() = this?.let { it + 1 }
+
+fun bar(arg: Long?): Long {
+    var i = arg
+    if (i++ == 5L) {
+        return i<!UNSAFE_CALL!>--<!> <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>+<!> i
+    }
+    if (i++ == 7L) {
+        return i++ <!NONE_APPLICABLE!>+<!> i
+    }
+    return 0L
+}

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

@@ -0,0 +1,5 @@
+package
+
+public fun bar(/*0*/ arg: kotlin.Long?): kotlin.Long
+public fun foo(/*0*/ arg: kotlin.Int?): kotlin.Int
+public operator fun kotlin.Long?.inc(): kotlin.Long?

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

@@ -18728,6 +18728,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("plusplusMinusminus.kt")
+                public void testPlusplusMinusminus() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/plusplusMinusminus.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("postfixNotnullClassIncrement.kt")
                 public void testPostfixNotnullClassIncrement() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNotnullClassIncrement.kt");