[FIR] Properly match expect fun interfaces with java interfaces

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/mpp/FirExpectActualMatchingContext.kt

@@ -79,8 +79,13 @@ class FirExpectActualMatchingContext(
         get() = asSymbol().resolvedStatus.isInline
     override val RegularClassSymbolMarker.isValue: Boolean
         get() = asSymbol().resolvedStatus.isInline
+
+    /*
+     * In this context java interfaces should be considered as not fun interface, so they will be later checked by [isNotSamInterface] function
+     */
     override val RegularClassSymbolMarker.isFun: Boolean
-        get() = asSymbol().resolvedStatus.isFun
+        get() = asSymbol().takeUnless { it.origin is FirDeclarationOrigin.Java }?.resolvedStatus?.isFun ?: false
+
     override val ClassLikeSymbolMarker.typeParameters: List<TypeParameterSymbolMarker>
         get() = asSymbol().typeParameterSymbols
 

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

@@ -367,7 +367,12 @@ internal abstract class IrExpectActualMatchingContext(
     }
 
     override fun RegularClassSymbolMarker.isNotSamInterface(): Boolean {
-        // TODO: is it correct for java classes?
+        /*
+         * This is incorrect for java classes (because all java interfaces are considered as fun interfaces),
+         *   but it's fine to not to check if some java interfaces is really SAM or not, because if one
+         *   tries to actualize `expect fun interface` with typealias to non-SAM java interface, frontend
+         *   will report an error and IR matching won't be invoked
+         */
         return !asIr().isFun
     }
 

compiler/testData/diagnostics/tests/multiplatform/headerClass/expectFunInterface.fir.kt

@@ -25,8 +25,19 @@ expect fun interface F5 {
     fun run()
 }<!>
 
+expect fun interface F7 {
+    fun run()
+}
+
 // MODULE: m2-jvm()()(m1-common)
 
+// FILE: NotSam.java
+public interface NotSam {
+    void run();
+    void somehtingElse();
+}
+
+// FILE: main.kt
 actual fun interface F1 {
     actual fun run()
 }
@@ -52,3 +63,5 @@ interface F6Typealias {
 }
 
 <!ACTUAL_WITHOUT_EXPECT!>actual typealias F6 = F6Typealias<!>
+
+<!ACTUAL_WITHOUT_EXPECT!>actual typealias F7 = NotSam<!>

compiler/testData/diagnostics/tests/multiplatform/headerClass/expectFunInterface.kt

@@ -25,8 +25,19 @@ expect fun interface F6 {
     fun run()
 }
 
+expect fun interface F7 {
+    fun run()
+}
+
 // MODULE: m2-jvm()()(m1-common)
 
+// FILE: NotSam.java
+public interface NotSam {
+    void run();
+    void somehtingElse();
+}
+
+// FILE: main.kt
 actual fun interface F1 {
     actual fun run()
 }
@@ -52,3 +63,5 @@ interface F6Typealias {
 }
 
 <!ACTUAL_WITHOUT_EXPECT!>actual<!> typealias F6 = F6Typealias
+
+<!ACTUAL_WITHOUT_EXPECT!>actual<!> typealias F7 = NotSam