JVM_IR KT-50856 fix generic signature for SAM proxy function

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

@@ -23517,6 +23517,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                     runTest("compiler/testData/codegen/box/invokedynamic/sam/functionRefToJavaInterface/kt49613.kt");
                 }
 
+                @Test
+                @TestMetadata("kt50856.kt")
+                public void testKt50856() throws Exception {
+                    runTest("compiler/testData/codegen/box/invokedynamic/sam/functionRefToJavaInterface/kt50856.kt");
+                }
+
                 @Test
                 @TestMetadata("localFunction1.kt")
                 public void testLocalFunction1() throws Exception {

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/FunctionReferenceLowering.kt

@@ -335,7 +335,7 @@ internal class FunctionReferenceLowering(private val context: JvmBackendContext)
 
         val proxyFun = context.irFactory.buildFun {
             name = Name.identifier("${targetFun.name.asString()}__proxy")
-            returnType = targetFun.returnType
+            returnType = targetFun.returnType.eraseTypeParameters()
             visibility = DescriptorVisibilities.LOCAL
             modality = Modality.FINAL
             isSuspend = false
@@ -372,6 +372,7 @@ internal class FunctionReferenceLowering(private val context: JvmBackendContext)
                     updateFrom(originalParameter)
                     name = Name.identifier("p$proxyParameterIndex\$${originalParameter.name.asString()}")
                     index = proxyParameterIndex
+                    type = originalParameter.type.eraseTypeParameters()
                     proxyParameterIndex++
                 }.apply {
                     parent = proxyFun

compiler/testData/codegen/box/invokedynamic/sam/functionRefToJavaInterface/kt50856.kt

@@ -0,0 +1,24 @@
+// TARGET_BACKEND: JVM_IR
+// JVM_TARGET: 1.8
+// WITH_STDLIB
+// FILE: box.kt
+fun <U> get(x: Sam<U>): U =
+    x.get()
+
+fun test() {
+    get<Map<String, String>>(::mutableMapOf)
+}
+
+fun box(): String {
+    test()
+    return "OK"
+}
+
+// FILE: Sam.java
+public interface Sam<T> {
+    T get();
+
+    static void run() {
+        BoxKt.test();
+    }
+}

compiler/testData/codegen/bytecodeListing/sam/indySamConversionViaProxyFun.kt

@@ -1,4 +1,6 @@
 // IGNORE_BACKEND: JVM
+// WITH_SIGNATURES
+// WITH_STDLIB
 
 // FILE: indySamConversionViaProxyFun.kt.kt
 inline fun ifn() {}
@@ -14,10 +16,15 @@ fun test() {
 
     // Proxy function for arrayOf fun should be non-synthetic
     use(Sam3(::intArrayOf))
+
+    // Proxy function for generic fun should have valid generic signature
+    use4<Map<String, String>>(::mutableMapOf)
 }
 
 fun use(x: Any) {}
 
+fun <U> use4(x: Sam4<U>) {}
+
 // FILE: Sam1.java
 public interface Sam1 {
     String get(String x, Object y);
@@ -31,4 +38,9 @@ public interface Sam2 {
 // FILE: Sam3.java
 public interface Sam3 {
     int[] get(int[] s);
-}
+}
+
+// FILE: Sam4.java
+public interface Sam4<T> {
+    T get();
+}

compiler/testData/codegen/bytecodeListing/sam/indySamConversionViaProxyFun.txt

@@ -1,12 +1,14 @@
 @kotlin.Metadata
-public final class IndySamConversionViaProxyFun_ktKt {
+public final class<null>  IndySamConversionViaProxyFun_ktKt {
     // source: 'indySamConversionViaProxyFun.kt.kt'
-    public final static method ifn(): void
-    private final static method test$ifn__proxy(): void
-    private varargs final static method test$intArrayOf__proxy(p0: int[]): int[]
-    private synthetic final static method test$plus__proxy(p0: java.lang.String, p1: java.lang.Object): java.lang.String
-    private synthetic final static method test$plus__proxy-0(p0: java.lang.String, p1: java.lang.Object): java.lang.String
-    private synthetic final static method test$plus__proxy-1(p0: java.lang.String, p1: java.lang.Object): java.lang.String
-    public final static method test(): void
-    public final static method use(@org.jetbrains.annotations.NotNull p0: java.lang.Object): void
+    private final static <()Ljava/util/Map<Ljava/lang/Object;Ljava/lang/Object;>;> method test$mutableMapOf__proxy(): java.util.Map
+    public final static <<U:Ljava/lang/Object;>(LSam4<TU;>;)V> method use4(@org.jetbrains.annotations.NotNull p0: Sam4): void
+    public final static <null> method ifn(): void
+    private final static <null> method test$ifn__proxy(): void
+    private varargs final static <null> method test$intArrayOf__proxy(p0: int[]): int[]
+    private synthetic final static <null> method test$plus__proxy(p0: java.lang.String, p1: java.lang.Object): java.lang.String
+    private synthetic final static <null> method test$plus__proxy-0(p0: java.lang.String, p1: java.lang.Object): java.lang.String
+    private synthetic final static <null> method test$plus__proxy-1(p0: java.lang.String, p1: java.lang.Object): java.lang.String
+    public final static <null> method test(): void
+    public final static <null> method use(@org.jetbrains.annotations.NotNull p0: java.lang.Object): void
 }

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

@@ -23517,6 +23517,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                     runTest("compiler/testData/codegen/box/invokedynamic/sam/functionRefToJavaInterface/kt49613.kt");
                 }
 
+                @Test
+                @TestMetadata("kt50856.kt")
+                public void testKt50856() throws Exception {
+                    runTest("compiler/testData/codegen/box/invokedynamic/sam/functionRefToJavaInterface/kt50856.kt");
+                }
+
                 @Test
                 @TestMetadata("localFunction1.kt")
                 public void testLocalFunction1() throws Exception {