Raw FIR: make sure loop target preparation and loop configuration match

by using the generated loop target during preparation in a message
passing fashion

compiler/fir/raw-fir/light-tree2fir/src/org/jetbrains/kotlin/fir/lightTree/converter/ExpressionsConverter.kt

@@ -891,10 +891,11 @@ class ExpressionsConverter(
         var firCondition: FirExpression =
             buildErrorExpression(null, ConeSimpleDiagnostic("No condition in do-while loop", DiagnosticKind.Syntax))
 
+        val target: FirLoopTarget
         return FirDoWhileLoopBuilder().apply {
             source = doWhileLoop.toFirSourceElement()
             // For break/continue in the do-while loop condition, prepare the loop target first so that it can refer to the same loop.
-            prepareTarget()
+            target = prepareTarget()
             doWhileLoop.forEachChildren {
                 when (it.tokenType) {
                     BODY -> block = it
@@ -902,7 +903,7 @@ class ExpressionsConverter(
                 }
             }
             condition = firCondition
-        }.configure { convertLoopBody(block) }
+        }.configure(target) { convertLoopBody(block) }
     }
 
     /**
@@ -919,13 +920,14 @@ class ExpressionsConverter(
             }
         }
 
+        val target: FirLoopTarget
         return FirWhileLoopBuilder().apply {
             source = whileLoop.toFirSourceElement()
             condition = firCondition
             // break/continue in the while loop condition will refer to an outer loop if any.
             // So, prepare the loop target after building the condition.
-            prepareTarget()
-        }.configure { convertLoopBody(block) }
+            target = prepareTarget()
+        }.configure(target) { convertLoopBody(block) }
     }
 
     /**
@@ -944,6 +946,7 @@ class ExpressionsConverter(
             }
         }
 
+        val target: FirLoopTarget
         return buildBlock {
             source = forLoop.toFirSourceElement()
             val iteratorVal = generateTemporaryVariable(
@@ -962,8 +965,8 @@ class ExpressionsConverter(
                 }
                 // break/continue in the for loop condition will refer to an outer loop if any.
                 // So, prepare the loop target after building the condition.
-                prepareTarget()
-            }.configure {
+                target = prepareTarget()
+            }.configure(target) {
                 // NB: just body.toFirBlock() isn't acceptable here because we need to add some statements
                 buildBlock block@{
                     source = blockNode?.toFirSourceElement()

compiler/fir/raw-fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/RawFirBuilder.kt

@@ -1650,28 +1650,31 @@ open class RawFirBuilder(
             }
 
         override fun visitDoWhileExpression(expression: KtDoWhileExpression, data: Unit): FirElement {
+            val target: FirLoopTarget
             return FirDoWhileLoopBuilder().apply {
                 source = expression.toFirSourceElement()
                 // For break/continue in the do-while loop condition, prepare the loop target first so that it can refer to the same loop.
-                prepareTarget()
+                target = prepareTarget()
                 condition = expression.condition.toFirExpression("No condition in do-while loop")
-            }.configure { expression.body.toFirBlock() }
+            }.configure(target) { expression.body.toFirBlock() }
         }
 
         override fun visitWhileExpression(expression: KtWhileExpression, data: Unit): FirElement {
+            val target: FirLoopTarget
             return FirWhileLoopBuilder().apply {
                 source = expression.toFirSourceElement()
                 condition = expression.condition.toFirExpression("No condition in while loop")
                 // break/continue in the while loop condition will refer to an outer loop if any.
                 // So, prepare the loop target after building the condition.
-                prepareTarget()
-            }.configure { expression.body.toFirBlock() }
+                target = prepareTarget()
+            }.configure(target) { expression.body.toFirBlock() }
         }
 
         override fun visitForExpression(expression: KtForExpression, data: Unit?): FirElement {
             val rangeExpression = expression.loopRange.toFirExpression("No range in for loop")
             val ktParameter = expression.loopParameter
             val fakeSource = expression.toFirPsiSourceElement(FirFakeSourceElementKind.DesugaredForLoop)
+            val target: FirLoopTarget
             return buildBlock {
                 source = fakeSource
                 val rangeSource = expression.loopRange?.toFirSourceElement(FirFakeSourceElementKind.DesugaredForLoop)
@@ -1699,8 +1702,8 @@ open class RawFirBuilder(
                     }
                     // break/continue in the for loop condition will refer to an outer loop if any.
                     // So, prepare the loop target after building the condition.
-                    prepareTarget()
-                }.configure {
+                    target = prepareTarget()
+                }.configure(target) {
                     // NB: just body.toFirBlock() isn't acceptable here because we need to add some statements
                     val blockBuilder = when (val body = expression.body) {
                         is KtBlockExpression -> configureBlockWithoutBuilding(body)

compiler/fir/raw-fir/raw-fir.common/src/org/jetbrains/kotlin/fir/builder/BaseFirBuilder.kt

@@ -216,16 +216,20 @@ abstract class BaseFirBuilder<T>(val baseSession: FirSession, val context: Conte
         }
     }
 
-    fun FirLoopBuilder.prepareTarget() {
+    fun FirLoopBuilder.prepareTarget(): FirLoopTarget {
         label = context.firLabels.pop()
         val target = FirLoopTarget(label?.name)
         context.firLoopTargets += target
+        return target
     }
 
-    fun FirLoopBuilder.configure(generateBlock: () -> FirBlock): FirLoop {
+    fun FirLoopBuilder.configure(target: FirLoopTarget, generateBlock: () -> FirBlock): FirLoop {
         block = generateBlock()
         val loop = build()
-        val target = context.firLoopTargets.removeLast()
+        val stackTopTarget = context.firLoopTargets.removeLast()
+        assert(target == stackTopTarget) {
+            "Loop target preparation and loop configuration mismatch"
+        }
         target.bind(loop)
         return loop
     }