[FIR2IR] Adapt IrActualizer to HMPP modules

Previously it collected actual declaration only from platform module

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -33142,6 +33142,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 runTest("compiler/testData/codegen/box/multiplatform/multiModule/getRidOfDoubleBindingInFir2IrLazyProperty.kt");
             }
 
+            @Test
+            @TestMetadata("hmppSimple.kt")
+            public void testHmppSimple() throws Exception {
+                runTest("compiler/testData/codegen/box/multiplatform/multiModule/hmppSimple.kt");
+            }
+
             @Test
             @TestMetadata("independentCommonSourceModules.kt")
             public void testIndependentCommonSourceModules() throws Exception {

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/actualizer/ExpectActualCollector.kt

@@ -33,7 +33,10 @@ internal class ExpectActualCollector(private val mainFragment: IrModuleFragment,
         val allActualDeclarations = mutableSetOf<IrDeclaration>()
         val typeAliasMap = mutableMapOf<FqName, FqName>() // It's used to link members from expect class that have typealias actual
 
-        ActualClassifiersCollector(actualClassifiers, allActualDeclarations, typeAliasMap).visitModuleFragment(mainFragment, false)
+        val fragmentsWithActuals = (dependentFragments.drop(1) + mainFragment)
+        for (fragment in fragmentsWithActuals) {
+            ActualClassifiersCollector(actualClassifiers, allActualDeclarations, typeAliasMap).visitModuleFragment(fragment, false)
+        }
 
         val linkCollector = ClassifiersLinkCollector(this, actualClassifiers)
         dependentFragments.forEach { linkCollector.visitModuleFragment(it) }
@@ -187,4 +190,4 @@ internal class ExpectActualCollector(private val mainFragment: IrModuleFragment,
             element.acceptChildrenVoid(this)
         }
     }
-}
+}

compiler/testData/codegen/box/multiplatform/multiModule/hmppSimple.kt

@@ -0,0 +1,69 @@
+// TARGET_BACKEND: JVM_IR
+// !LANGUAGE: +MultiPlatformProjects
+
+// MODULE: common
+// TARGET_PLATFORM: Common
+// FILE: common.kt
+
+expect class A constructor() {
+    fun foo(): String
+}
+
+expect class B constructor() {
+    fun bar(): String
+}
+
+expect fun func(): String
+
+expect var prop: String
+
+fun test_1(): String {
+    val a = A()
+    val b = B()
+    prop = "Set prop in common."
+    return "${func()} $prop ${a.foo()} ${b.bar()}"
+}
+
+// MODULE: intermediate()()(common)
+// TARGET_PLATFORM: Common
+// FILE: intermediate.kt
+
+actual fun func(): String = "Actual func."
+
+actual class B actual constructor() {
+    actual fun bar(): String = "Actual B."
+}
+
+expect class C constructor() {
+    fun baz(): String
+}
+
+fun test_2(): String {
+    val a = A()
+    val b = B()
+    val c = C()
+    prop = "Set prop in intermediate."
+    return "${func()} $prop ${a.foo()} ${b.bar()} ${c.baz()}"
+}
+
+// MODULE: jvm()()(intermediate)
+// TARGET_PLATFORM: JVM
+// FILE: main.kt
+
+actual var prop: String = "!"
+
+actual class A actual constructor() {
+    actual fun foo(): String = "Actual A."
+}
+
+actual class C actual constructor() {
+    actual fun baz(): String = "Actual C."
+}
+
+fun box(): String {
+    val s1 = test_1()
+    if (s1 != "Actual func. Set prop in common. Actual A. Actual B.") return s1
+    val s2 = test_2()
+    if (s2 != "Actual func. Set prop in intermediate. Actual A. Actual B. Actual C.") return s2
+    return "OK"
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -33142,6 +33142,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/multiplatform/multiModule/getRidOfDoubleBindingInFir2IrLazyProperty.kt");
             }
 
+            @Test
+            @TestMetadata("hmppSimple.kt")
+            public void testHmppSimple() throws Exception {
+                runTest("compiler/testData/codegen/box/multiplatform/multiModule/hmppSimple.kt");
+            }
+
             @Test
             @TestMetadata("independentCommonSourceModules.kt")
             public void testIndependentCommonSourceModules() throws Exception {