[NI] Fix substitution in builder-inference for empty common system

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/CoroutineInferenceSession.kt

@@ -105,7 +105,13 @@ class CoroutineInferenceSession(
         lambda: ResolvedLambdaAtom,
         initialStorage: ConstraintStorage,
         diagnosticsHolder: KotlinDiagnosticsHolder
-    ): Map<TypeConstructor, UnwrappedType> {
+    ): Map<TypeConstructor, UnwrappedType>? {
+        if (partiallyResolvedCallsInfo.isEmpty() && commonCalls.isEmpty()) {
+            val emptyCommonSystem = NewConstraintSystemImpl(callComponents.constraintInjector, builtIns)
+            updateCalls(lambda, emptyCommonSystem)
+            return null
+        }
+
         val commonSystem = buildCommonSystem(initialStorage)
 
         val context = commonSystem.asConstraintSystemCompleterContext()
@@ -281,9 +287,8 @@ class CoroutineInferenceSession(
 
 class ComposedSubstitutor(val left: NewTypeSubstitutor, val right: NewTypeSubstitutor) : NewTypeSubstitutor {
     override fun substituteNotNullTypeWithConstructor(constructor: TypeConstructor): UnwrappedType? {
-        return left.substituteNotNullTypeWithConstructor(
+        val rightSubstitution = right.substituteNotNullTypeWithConstructor(constructor)
-            right.substituteNotNullTypeWithConstructor(constructor)?.constructor ?: constructor
+        return left.substituteNotNullTypeWithConstructor(rightSubstitution?.constructor ?: constructor) ?: rightSubstitution
-        )
     }
 
     override val isEmpty: Boolean get() = left.isEmpty && right.isEmpty

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/InferenceSession.kt

@@ -40,7 +40,7 @@ interface InferenceSession {
         lambda: ResolvedLambdaAtom,
         initialStorage: ConstraintStorage,
         diagnosticsHolder: KotlinDiagnosticsHolder
-    ): Map<TypeConstructor, UnwrappedType>
+    ): Map<TypeConstructor, UnwrappedType>?
 
     fun writeOnlyStubs(callInfo: SingleCallResolutionResult): Boolean
     fun callCompleted(resolvedAtom: ResolvedAtom): Boolean

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/PostponedArgumentsAnalyzer.kt

@@ -159,6 +159,10 @@ class PostponedArgumentsAnalyzer(
             val storageSnapshot = c.getBuilder().currentStorage()
 
             val postponedVariables = inferenceSession.inferPostponedVariables(lambda, storageSnapshot, diagnosticHolder)
+            if (postponedVariables == null) {
+                c.getBuilder().removePostponedVariables()
+                return
+            }
 
             for ((constructor, resultType) in postponedVariables) {
                 val variableWithConstraints = storageSnapshot.notFixedTypeVariables[constructor] ?: continue

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemBuilder.kt

@@ -34,6 +34,7 @@ interface ConstraintSystemOperation {
     fun registerVariable(variable: TypeVariableMarker)
     fun markPostponedVariable(variable: TypeVariableMarker)
     fun unmarkPostponedVariable(variable: TypeVariableMarker)
+    fun removePostponedVariables()
 
     fun addSubtypeConstraint(lowerType: KotlinTypeMarker, upperType: KotlinTypeMarker, position: ConstraintPosition)
     fun addEqualityConstraint(a: KotlinTypeMarker, b: KotlinTypeMarker, position: ConstraintPosition)

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/inference/model/NewConstraintSystemImpl.kt

@@ -103,6 +103,10 @@ class NewConstraintSystemImpl(
         storage.postponedTypeVariables -= variable
     }
 
+    override fun removePostponedVariables() {
+        storage.postponedTypeVariables.clear()
+    }
+
     override fun addSubtypeConstraint(lowerType: KotlinTypeMarker, upperType: KotlinTypeMarker, position: ConstraintPosition) =
         constraintInjector.addInitialSubtypeConstraint(
             apply { checkState(State.BUILDING, State.COMPLETION, State.TRANSACTION) },

compiler/testData/codegen/box/coroutines/emptyCommonConstraintSystemForCoroutineInferenceCall.kt

@@ -0,0 +1,52 @@
+// WITH_RUNTIME
+// WITH_COROUTINES
+// KJS_WITH_FULL_RUNTIME
+// IGNORE_BACKEND_FIR: JVM_IR
+
+import helpers.*
+import kotlin.coroutines.*
+import kotlin.coroutines.intrinsics.*
+import kotlin.experimental.ExperimentalTypeInference
+
+fun test() {
+    flow {
+        emit(1)
+    }.flatMapLatest<Int, Long> {
+        flow {}
+    }
+
+    flow {
+        emit(1)
+    }.flatMap {
+        if (it == 1)
+            flow {}
+        else
+            flow<Int> {}
+    }
+
+    flow {
+        emit(1)
+    }.flatMap {
+        if (it == 1)
+            flow {}
+        else flow {}
+    }
+}
+
+fun <T> Flow<T>.flatMap(mapper: suspend (T) -> Flow<T>): Flow<T> = TODO()
+
+@OptIn(ExperimentalTypeInference::class)
+fun <T> flow(@BuilderInference block: suspend FlowCollector<T>.() -> Unit): Flow<T> = TODO()
+
+@OptIn(ExperimentalTypeInference::class)
+inline fun <T, R> Flow<T>.flatMapLatest(@BuilderInference crossinline transform: suspend (value: T) -> Flow<R>): Flow<R> = TODO()
+
+interface Flow<out T>
+
+interface FlowCollector<in T> {
+    suspend fun emit(value: T)
+}
+
+fun box(): String {
+    return "OK"
+}

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -6200,6 +6200,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/emptyClosure.kt", "kotlin.coroutines");
         }
 
+        @TestMetadata("emptyCommonConstraintSystemForCoroutineInferenceCall.kt")
+        public void testEmptyCommonConstraintSystemForCoroutineInferenceCall() throws Exception {
+            runTest("compiler/testData/codegen/box/coroutines/emptyCommonConstraintSystemForCoroutineInferenceCall.kt");
+        }
+
         @TestMetadata("epam.kt")
         public void testEpam_1_2() throws Exception {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/epam.kt", "kotlin.coroutines.experimental");

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -6200,6 +6200,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/emptyClosure.kt", "kotlin.coroutines");
         }
 
+        @TestMetadata("emptyCommonConstraintSystemForCoroutineInferenceCall.kt")
+        public void testEmptyCommonConstraintSystemForCoroutineInferenceCall() throws Exception {
+            runTest("compiler/testData/codegen/box/coroutines/emptyCommonConstraintSystemForCoroutineInferenceCall.kt");
+        }
+
         @TestMetadata("epam.kt")
         public void testEpam_1_2() throws Exception {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/epam.kt", "kotlin.coroutines.experimental");

compiler/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java

@@ -6080,6 +6080,11 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/emptyClosure.kt", "kotlin.coroutines");
         }
 
+        @TestMetadata("emptyCommonConstraintSystemForCoroutineInferenceCall.kt")
+        public void testEmptyCommonConstraintSystemForCoroutineInferenceCall() throws Exception {
+            runTest("compiler/testData/codegen/box/coroutines/emptyCommonConstraintSystemForCoroutineInferenceCall.kt");
+        }
+
         @TestMetadata("epam.kt")
         public void testEpam_1_3() throws Exception {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/epam.kt", "kotlin.coroutines");

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -6080,6 +6080,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/emptyClosure.kt", "kotlin.coroutines");
         }
 
+        @TestMetadata("emptyCommonConstraintSystemForCoroutineInferenceCall.kt")
+        public void testEmptyCommonConstraintSystemForCoroutineInferenceCall() throws Exception {
+            runTest("compiler/testData/codegen/box/coroutines/emptyCommonConstraintSystemForCoroutineInferenceCall.kt");
+        }
+
         @TestMetadata("epam.kt")
         public void testEpam_1_3() throws Exception {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/epam.kt", "kotlin.coroutines");

js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java

@@ -5130,6 +5130,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/emptyClosure.kt", "kotlin.coroutines");
         }
 
+        @TestMetadata("emptyCommonConstraintSystemForCoroutineInferenceCall.kt")
+        public void testEmptyCommonConstraintSystemForCoroutineInferenceCall() throws Exception {
+            runTest("compiler/testData/codegen/box/coroutines/emptyCommonConstraintSystemForCoroutineInferenceCall.kt");
+        }
+
         @TestMetadata("epam.kt")
         public void testEpam_1_3() throws Exception {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/epam.kt", "kotlin.coroutines");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -5130,6 +5130,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/emptyClosure.kt", "kotlin.coroutines");
         }
 
+        @TestMetadata("emptyCommonConstraintSystemForCoroutineInferenceCall.kt")
+        public void testEmptyCommonConstraintSystemForCoroutineInferenceCall() throws Exception {
+            runTest("compiler/testData/codegen/box/coroutines/emptyCommonConstraintSystemForCoroutineInferenceCall.kt");
+        }
+
         @TestMetadata("epam.kt")
         public void testEpam_1_3() throws Exception {
             runTestWithPackageReplacement("compiler/testData/codegen/box/coroutines/epam.kt", "kotlin.coroutines");