[FIR] Pass flow to local functions

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt

@@ -64,7 +64,13 @@ class FirDataFlowAnalyzer(transformer: FirBodyResolveTransformer) : BodyResolveC
     // ----------------------------------- Named function -----------------------------------
 
     fun enterFunction(function: FirFunction<*>) {
-        graphBuilder.enterFunction(function).mergeIncomingFlow()
+        val (functionEnterNode, previousNode) = graphBuilder.enterFunction(function)
+        if (previousNode == null) {
+            functionEnterNode.mergeIncomingFlow()
+        } else {
+            assert(functionEnterNode.previousNodes.isEmpty())
+            functionEnterNode.flow = logicSystem.forkFlow(previousNode.flow)
+        }
     }
 
     fun exitFunction(function: FirFunction<*>): ControlFlowGraph? {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/cfg/ControlFlowGraph.kt

@@ -12,10 +12,14 @@ import org.jetbrains.kotlin.fir.declarations.FirFunction
 import org.jetbrains.kotlin.fir.declarations.FirProperty
 import org.jetbrains.kotlin.fir.expressions.*
 
-class ControlFlowGraph(val name: String) {
+class ControlFlowGraph(val name: String, val kind: Kind) {
     val nodes = mutableListOf<CFGNode<*>>()
     lateinit var enterNode: CFGNode<*>
     lateinit var exitNode: CFGNode<*>
+
+    enum class Kind {
+        Function, ClassInitializer, PropertyInitializer, TopLevel
+    }
 }
 
 sealed class CFGNode<out E : FirElement>(val owner: ControlFlowGraph, val level: Int) {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/cfg/ControlFlowGraphBuilder.kt

@@ -16,7 +16,7 @@ import org.jetbrains.kotlin.fir.resolve.transformers.resultType
 import org.jetbrains.kotlin.fir.types.isNothing
 
 class ControlFlowGraphBuilder {
-    private val graphs: Stack<ControlFlowGraph> = stackOf(ControlFlowGraph("<DUMP_GRAPH_FOR_ENUMS>"))
+    private val graphs: Stack<ControlFlowGraph> = stackOf(ControlFlowGraph("<DUMP_GRAPH_FOR_ENUMS>", ControlFlowGraph.Kind.TopLevel))
     val graph: ControlFlowGraph get() = graphs.top()
 
     private val lexicalScopes: Stack<Stack<CFGNode<*>>> = stackOf(stackOf())
@@ -50,7 +50,11 @@ class ControlFlowGraphBuilder {
 
     // ----------------------------------- Named function -----------------------------------
 
-    fun enterFunction(function: FirFunction<*>): FunctionEnterNode {
+    /*
+     * Second argument of pair is not null only if function is local and it is a
+     *   previous node before function declaration
+     */
+    fun enterFunction(function: FirFunction<*>): Pair<FunctionEnterNode, CFGNode<*>?> {
         val name = when (function) {
             is FirNamedFunction -> function.name.asString()
             is FirAbstractPropertyAccessor -> if (function.isGetter) "<getter>" else "<setter>"
@@ -60,9 +64,17 @@ class ControlFlowGraphBuilder {
         }
         val invocationKind = function.invocationKind
         val isInplace = invocationKind.isInplace()
-        if (!isInplace) {
-            graphs.push(ControlFlowGraph(name))
+
+        val previousNode = if (!isInplace && graphs.topOrNull()?.let { it.kind != ControlFlowGraph.Kind.TopLevel } == true) {
+            lastNodes.top()
+        } else {
+            null
         }
+
+        if (!isInplace) {
+            graphs.push(ControlFlowGraph(name, ControlFlowGraph.Kind.Function))
+        }
+
         val enterNode = createFunctionEnterNode(function, isInplace).also {
             if (isInplace) {
                 addNewSimpleNode(it)
@@ -88,7 +100,7 @@ class ControlFlowGraphBuilder {
             exitNodes.push(exitNode)
         }
         levelCounter++
-        return enterNode
+        return enterNode to previousNode
     }
 
     fun exitFunction(function: FirFunction<*>): Pair<FunctionExitNode, ControlFlowGraph?> {
@@ -127,7 +139,7 @@ class ControlFlowGraphBuilder {
     // ----------------------------------- Property -----------------------------------
 
     fun enterProperty(property: FirProperty): PropertyInitializerEnterNode {
-        graphs.push(ControlFlowGraph("val ${property.name}"))
+        graphs.push(ControlFlowGraph("val ${property.name}", ControlFlowGraph.Kind.PropertyInitializer))
         val enterNode = createPropertyInitializerEnterNode(property)
         val exitNode = createPropertyInitializerExitNode(property)
         topLevelVariableInitializerExitNodes.push(exitNode)
@@ -522,7 +534,7 @@ class ControlFlowGraphBuilder {
     // ----------------------------------- Block -----------------------------------
 
     fun enterInitBlock(initBlock: FirAnonymousInitializer): InitBlockEnterNode {
-        graphs.push(ControlFlowGraph("init block"))
+        graphs.push(ControlFlowGraph("init block", ControlFlowGraph.Kind.ClassInitializer))
         val enterNode = createInitBlockEnterNode(initBlock).also {
             lexicalScopes.push(stackOf(it))
         }

compiler/fir/resolve/testData/resolve/cfg/lambdas.dot

@@ -112,7 +112,7 @@ digraph lambdas_kt {
       color=blue
       33 [label="Enter block"];
       34 [label="Access variable R|<local>/x|"];
-      35 [label="Function call: R|<local>/x|.<Ambiguity: inc, [kotlin/inc, kotlin/inc]>#()"];
+      35 [label="Function call: R|<local>/x|.R|kotlin/Int.inc|()"];
       36 [label="Exit block"];
     }
     37 [label="Exit function anonymousFunction" style="filled" fillcolor=red];
@@ -156,7 +156,7 @@ digraph lambdas_kt {
         subgraph cluster_19 {
           color=blue
           52 [label="Enter block"];
-          53 [label="Variable declaration: lval lambda: R|kotlin/Function0<class error: Ambiguity: inc, [kotlin/inc, kotlin/inc]>|"];
+          53 [label="Variable declaration: lval lambda: R|kotlin/Function0<kotlin/Int>|"];
           54 [label="Exit block"];
         }
         55 [label="Exit when branch result"];

compiler/fir/resolve/testData/resolve/cfg/lambdas.txt

@@ -18,8 +18,8 @@ FILE: lambdas.kt
     public final fun test_2(x: R|kotlin/Any?|): R|kotlin/Unit| {
         when () {
             (R|<local>/x| is R|kotlin/Int|) ->  {
-                lval lambda: R|kotlin/Function0<class error: Ambiguity: inc, [kotlin/inc, kotlin/inc]>| = fun <anonymous>(): <ERROR TYPE REF: Ambiguity: inc, [kotlin/inc, kotlin/inc]> {
-                    R|<local>/x|.<Ambiguity: inc, [kotlin/inc, kotlin/inc]>#()
+                lval lambda: R|kotlin/Function0<kotlin/Int>| = fun <anonymous>(): R|kotlin/Int| {
+                    R|<local>/x|.R|kotlin/Int.inc|()
                 }
 
             }