Handle nested when with subject properly

Hack: callee expression for when with subject variable is the subject
variable declaration. This solves the problem that all sub-calls in the
expression are implicitly considered to have a single common lexical
scope (and 'when (val x = ...)' introduces a new lexical scope, which
contains 'x').

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/util/callUtil.kt

@@ -142,6 +142,13 @@ fun KtElement.getCall(context: BindingContext): Call? {
     // Do not use Call bound to outer call expression (if any) to prevent stack overflow during analysis
     if (element is KtCallElement && element.calleeExpression == null) return null
 
+    if (element is KtWhenExpression) {
+        val subjectVariable = element.subjectVariable
+        if (subjectVariable != null) {
+            return subjectVariable.getCall(context)
+        }
+    }
+
     val parent = element.parent
     val reference: KtExpression? = when (parent) {
         is KtInstanceExpressionWithLabel -> parent

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

@@ -95,7 +95,7 @@ class PatternMatchingTypingVisitor internal constructor(facade: ExpressionTyping
         protected abstract fun createDataFlowValue(contextAfterSubject: ExpressionTypingContext, builtIns: KotlinBuiltIns): DataFlowValue
         abstract fun makeValueArgument(): ValueArgument?
         abstract val valueExpression: KtExpression?
-        open fun makeCalleeExpressionForSpecialCall(): KtExpression? = null
+        open fun getCalleeExpressionForSpecialCall(): KtExpression? = null
 
         lateinit var dataFlowValue: DataFlowValue; private set
 
@@ -146,8 +146,8 @@ class PatternMatchingTypingVisitor internal constructor(facade: ExpressionTyping
                     )
                 }
 
-            override fun makeCalleeExpressionForSpecialCall(): KtExpression? =
-                KtPsiFactory(variable.project, true).createExpression(variable.name!!)
+            override fun getCalleeExpressionForSpecialCall(): KtExpression? =
+                variable
 
             override val valueExpression: KtExpression?
                 get() = variable.initializer
@@ -208,11 +208,6 @@ class PatternMatchingTypingVisitor internal constructor(facade: ExpressionTyping
         val contextWithExpectedTypeAndSubjectVariable =
             subject.scopeWithSubject?.let { contextWithExpectedType.replaceScope(it) } ?: contextWithExpectedType
 
-//        val subjectType = subjectTypeInfo?.type ?: ErrorUtils.createErrorType("Unknown type")
-//        val jumpOutPossibleInSubject: Boolean = subjectTypeInfo?.jumpOutPossible ?: false
-//        val subjectDataFlowValue = subjectExpression?.let {
-//            facade.components.dataFlowValueFactory.createDataFlowValue(it, subjectType, contextAfterSubject)
-//        } ?: DataFlowValue.nullValue(components.builtIns)
         subject.initDataFlowValue(contextAfterSubject, components.builtIns)
 
         val possibleTypesForSubject =
@@ -283,11 +278,8 @@ class PatternMatchingTypingVisitor internal constructor(facade: ExpressionTyping
         val scopeWithSubjectVariable =
             ExpressionTypingUtils.newWritableScopeImpl(contextBeforeSubject, LexicalScopeKind.WHEN, components.overloadChecker)
 
-        // Destructuring causes SOE in UAST :(
-        val resolveResult =
-            components.localVariableResolver.process(subjectVariable, contextBeforeSubject, contextBeforeSubject.scope, facade)
-        val typeInfo = resolveResult.first
-        val descriptor = resolveResult.second
+        val (typeInfo, descriptor) =
+                components.localVariableResolver.process(subjectVariable, contextBeforeSubject, contextBeforeSubject.scope, facade)
 
         scopeWithSubjectVariable.addVariableDescriptor(descriptor)
 
@@ -313,7 +305,7 @@ class PatternMatchingTypingVisitor internal constructor(facade: ExpressionTyping
         val wrappedArgumentExpressions = wrapWhenEntryExpressionsAsSpecialCallArguments(expression)
         val callForWhen = createCallForSpecialConstruction(
             expression,
-            subject.makeCalleeExpressionForSpecialCall() ?: expression,
+            subject.getCalleeExpressionForSpecialCall() ?: expression,
             wrappedArgumentExpressions
         )
         val dataFlowInfoForArguments = createDataFlowInfoForArgumentsOfWhenCall(

compiler/testData/diagnostics/tests/when/withSubjectVariable/nestedWhenWithSubject.kt

@@ -0,0 +1,41 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -UNUSED_VALUE
+
+fun foo() {}
+fun <T> bar(x: T, y: T) {}
+
+fun test1() {
+    when (1) {
+        1 ->
+            when (val y = 2) {
+                2 -> foo()
+            }
+    }
+}
+
+fun test2() {
+    when (val x = 1) {
+        1 ->
+            when (val y = 2) {
+                2 -> foo()
+            }
+    }
+}
+
+fun test3() {
+    when (val x = 1) {
+        1 ->
+            when (val <!NAME_SHADOWING!>x<!> = 2) {
+                2 -> foo()
+            }
+    }
+}
+
+fun test4() {
+    when (val x = 1) {
+        1 ->
+            when (val y = 2) {
+                2 -> bar(x, y)
+            }
+    }
+}

compiler/testData/diagnostics/tests/when/withSubjectVariable/nestedWhenWithSubject.txt

@@ -0,0 +1,8 @@
+package
+
+public fun </*0*/ T> bar(/*0*/ x: T, /*1*/ y: T): kotlin.Unit
+public fun foo(): kotlin.Unit
+public fun test1(): kotlin.Unit
+public fun test2(): kotlin.Unit
+public fun test3(): kotlin.Unit
+public fun test4(): kotlin.Unit

compiler/tests-common/tests/org/jetbrains/kotlin/checkers/AbstractDiagnosticsTest.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.checkers
 
 import com.intellij.openapi.util.io.FileUtil
 import com.intellij.openapi.util.text.StringUtil
+import com.intellij.psi.PsiElement
 import com.intellij.psi.search.GlobalSearchScope
 import junit.framework.TestCase
 import org.jetbrains.kotlin.analyzer.AnalysisResult
@@ -570,19 +571,28 @@ abstract class AbstractDiagnosticsTest : BaseDiagnosticsTest() {
         if (ktFiles.any { file -> AnalyzingUtils.getSyntaxErrorRanges(file).isNotEmpty() }) return
 
         val resolvedCallsEntries = bindingContext.getSliceContents(BindingContext.RESOLVED_CALL)
+        val unresolvedCallsOnElements = ArrayList<PsiElement>()
+
         for ((call, resolvedCall) in resolvedCallsEntries) {
             val element = call.callElement
 
-            val lineAndColumn = DiagnosticUtils.getLineAndColumnInPsiFile(element.containingFile, element.textRange)
-
             if (!configuredLanguageVersionSettings.supportsFeature(LanguageFeature.NewInference)) {
-                assertTrue(
-                    "Resolved call for '${element.text}'$lineAndColumn is not completed",
-                    (resolvedCall as MutableResolvedCall<*>).isCompleted
-                )
+                if (!(resolvedCall as MutableResolvedCall<*>).isCompleted) {
+                    unresolvedCallsOnElements.add(element)
+                }
             }
         }
 
+        if (unresolvedCallsOnElements.isNotEmpty()) {
+            TestCase.fail(
+                "There are uncompleted resolved calls for the following elements:\n" +
+                        unresolvedCallsOnElements.joinToString(separator = "\n") { element ->
+                            val lineAndColumn = DiagnosticUtils.getLineAndColumnInPsiFile(element.containingFile, element.textRange)
+                            "'${element.text}'$lineAndColumn"
+                        }
+            )
+        }
+
         checkResolvedCallsInDiagnostics(bindingContext, configuredLanguageVersionSettings)
     }
 

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

@@ -22475,6 +22475,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     runTest("compiler/testData/diagnostics/tests/when/withSubjectVariable/invisibleOutsideOfWhen.kt");
                 }
 
+                @TestMetadata("nestedWhenWithSubject.kt")
+                public void testNestedWhenWithSubject() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/when/withSubjectVariable/nestedWhenWithSubject.kt");
+                }
+
                 @TestMetadata("reassignmentToWhenSubjectVariable.kt")
                 public void testReassignmentToWhenSubjectVariable() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/when/withSubjectVariable/reassignmentToWhenSubjectVariable.kt");

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -22475,6 +22475,11 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                     runTest("compiler/testData/diagnostics/tests/when/withSubjectVariable/invisibleOutsideOfWhen.kt");
                 }
 
+                @TestMetadata("nestedWhenWithSubject.kt")
+                public void testNestedWhenWithSubject() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/when/withSubjectVariable/nestedWhenWithSubject.kt");
+                }
+
                 @TestMetadata("reassignmentToWhenSubjectVariable.kt")
                 public void testReassignmentToWhenSubjectVariable() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/when/withSubjectVariable/reassignmentToWhenSubjectVariable.kt");