Do not generate generic signature for SAM wrapper methods

#KT-23870 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/FunctionCodegen.java

@@ -25,7 +25,6 @@ import org.jetbrains.kotlin.codegen.state.GenerationState;
 import org.jetbrains.kotlin.codegen.state.KotlinTypeMapper;
 import org.jetbrains.kotlin.config.JvmDefaultMode;
 import org.jetbrains.kotlin.config.JvmTarget;
-import org.jetbrains.kotlin.config.LanguageFeature;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.descriptors.annotations.Annotated;
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor;
@@ -218,7 +217,7 @@ public class FunctionCodegen {
                                   flags,
                                   asmMethod.getName(),
                                   asmMethod.getDescriptor(),
-                                  jvmSignature.getGenericsSignature(),
+                                  strategy.skipGenericSignature() ? null : jvmSignature.getGenericsSignature(),
                                   getThrownExceptions(functionDescriptor, typeMapper)
                         ),
                         flags, asmMethod.getName(),
@@ -1546,13 +1545,15 @@ public class FunctionCodegen {
 
     public void genSamDelegate(@NotNull FunctionDescriptor functionDescriptor, FunctionDescriptor overriddenDescriptor, StackValue field) {
         FunctionDescriptor delegatedTo = overriddenDescriptor.getOriginal();
-        JvmDeclarationOrigin declarationOrigin =
-                JvmDeclarationOriginKt.SamDelegation(functionDescriptor);
+        JvmDeclarationOrigin declarationOrigin = JvmDeclarationOriginKt.SamDelegation(functionDescriptor);
+        // Skip writing generic signature for the SAM wrapper class method because it may reference type parameters from the SAM interface
+        // which would make little sense outside of that interface and may break Java reflection.
+        // E.g. functionDescriptor for a SAM wrapper for java.util.function.Predicate is the method `test` with signature "(T) -> Boolean"
         genDelegate(
-                functionDescriptor, delegatedTo,
-                declarationOrigin,
+                functionDescriptor, delegatedTo, declarationOrigin,
                 (ClassDescriptor) overriddenDescriptor.getContainingDeclaration(),
-                field);
+                field, true
+        );
     }
 
     public void genDelegate(@NotNull FunctionDescriptor functionDescriptor, FunctionDescriptor overriddenDescriptor, StackValue field) {
@@ -1568,7 +1569,7 @@ public class FunctionCodegen {
     ) {
         JvmDeclarationOrigin declarationOrigin =
                 JvmDeclarationOriginKt.Delegation(DescriptorToSourceUtils.descriptorToDeclaration(delegatedTo), delegateFunction);
-        genDelegate(delegateFunction, delegatedTo, declarationOrigin, toClass, field);
+        genDelegate(delegateFunction, delegatedTo, declarationOrigin, toClass, field, false);
     }
 
     private void genDelegate(
@@ -1576,7 +1577,8 @@ public class FunctionCodegen {
             FunctionDescriptor delegatedTo,
             @NotNull JvmDeclarationOrigin declarationOrigin,
             ClassDescriptor toClass,
-            StackValue field
+            StackValue field,
+            boolean skipGenericSignature
     ) {
         generateMethod(
                 declarationOrigin, delegateFunction,
@@ -1631,6 +1633,11 @@ public class FunctionCodegen {
                     public boolean skipNotNullAssertionsForParameters() {
                         return false;
                     }
+
+                    @Override
+                    public boolean skipGenericSignature() {
+                        return skipGenericSignature;
+                    }
                 }
         );
     }

compiler/backend/src/org/jetbrains/kotlin/codegen/FunctionGenerationStrategy.java

@@ -28,6 +28,10 @@ public abstract class FunctionGenerationStrategy {
 
     public abstract boolean skipNotNullAssertionsForParameters();
 
+    public boolean skipGenericSignature() {
+        return false;
+    }
+
     public MethodVisitor wrapMethodVisitor(@NotNull MethodVisitor mv, int access, @NotNull String name, @NotNull String desc) {
         return mv;
     }

compiler/testData/codegen/box/reflection/genericSignature/delegatedMembers.kt

@@ -0,0 +1,32 @@
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+// FILE: J.java
+
+import java.util.*;
+
+public interface J<T extends Number> {
+    T foo(List<T> p0, Map<T, ? extends Set<T>> p1);
+}
+
+// FILE: K.kt
+
+import kotlin.test.assertEquals
+
+object O : J<Long> {
+    override fun foo(p0: List<Long>, p1: Map<Long, out Set<Long>>): Long = 42L
+}
+
+class A : J<Long> by O
+
+fun box(): String {
+    val m = A::class.java.getDeclaredMethod("foo", List::class.java, Map::class.java)
+    assertEquals(
+        "[interface java.util.List, interface java.util.Map]",
+        m.parameterTypes.contentToString()
+    )
+    assertEquals(
+        "[java.util.List<java.lang.Long>, java.util.Map<java.lang.Long, ? extends java.util.Set<java.lang.Long>>]",
+        m.genericParameterTypes.contentToString()
+    )
+    return "OK"
+}

compiler/testData/codegen/box/reflection/genericSignature/samWrappedLambdaVsReference.kt

@@ -0,0 +1,50 @@
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+// FULL_JDK
+
+// FILE: Java.java
+
+import java.lang.reflect.Method;
+import java.util.function.Predicate;
+import java.util.*;
+
+public final class Java {
+    public static Method getTest(Predicate<Object> predicate) throws NoSuchMethodException {
+        return predicate.getClass().getMethod("test", Object.class);
+    }
+
+    public static Method getFoo(ComplexPredicate<Long> predicate) throws NoSuchMethodException {
+        return predicate.getClass().getMethod("foo", Number.class, List.class, Map.class);
+    }
+}
+
+// FILE: ComplexPredicate.java
+
+import java.util.*;
+
+public interface ComplexPredicate<T extends Number> {
+    boolean foo(T p0, List<T> p1, Map<T, ? extends Set<T>> p2);
+}
+
+// FILE: K.kt
+
+import java.lang.reflect.Method
+import java.util.*
+import kotlin.test.assertEquals
+
+fun check(title: String, expected: String, method: Method) {
+    assertEquals(expected, method.parameterTypes.contentToString(), "Fail parameterTypes of $title")
+    assertEquals(expected, method.genericParameterTypes.contentToString(), "Fail genericParameterTypes of $title")
+}
+
+private fun bar(p0: Long, p1: List<Long>, p2: Map<Long, Set<Long>>) = true
+
+fun box(): String {
+    check("SAM-implementing lambda 1", "[class java.lang.Object]", Java.getTest { Objects.nonNull(it) })
+    check("SAM-wrapped function reference 1", "[class java.lang.Object]", Java.getTest(Objects::nonNull))
+
+    check("SAM-implementing lambda 2", "[class java.lang.Number, interface java.util.List, interface java.util.Map]", Java.getFoo { p0, p1, p2 -> bar(p0, p1, p2) })
+    check("SAM-wrapped function reference 2", "[class java.lang.Number, interface java.util.List, interface java.util.Map]", Java.getFoo(::bar))
+
+    return "OK"
+}

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

@@ -17601,6 +17601,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/defaultImplsGenericSignature.kt");
             }
 
+            @TestMetadata("delegatedMembers.kt")
+            public void testDelegatedMembers() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/genericSignature/delegatedMembers.kt");
+            }
+
             @TestMetadata("functionLiteralGenericSignature.kt")
             public void testFunctionLiteralGenericSignature() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/functionLiteralGenericSignature.kt");
@@ -17631,6 +17636,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/kt6106.kt");
             }
 
+            @TestMetadata("samWrappedLambdaVsReference.kt")
+            public void testSamWrappedLambdaVsReference() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/genericSignature/samWrappedLambdaVsReference.kt");
+            }
+
             @TestMetadata("signatureOfDeepGenericInner.kt")
             public void testSignatureOfDeepGenericInner() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/signatureOfDeepGenericInner.kt");

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

@@ -17601,6 +17601,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/defaultImplsGenericSignature.kt");
             }
 
+            @TestMetadata("delegatedMembers.kt")
+            public void testDelegatedMembers() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/genericSignature/delegatedMembers.kt");
+            }
+
             @TestMetadata("functionLiteralGenericSignature.kt")
             public void testFunctionLiteralGenericSignature() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/functionLiteralGenericSignature.kt");
@@ -17631,6 +17636,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/kt6106.kt");
             }
 
+            @TestMetadata("samWrappedLambdaVsReference.kt")
+            public void testSamWrappedLambdaVsReference() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/genericSignature/samWrappedLambdaVsReference.kt");
+            }
+
             @TestMetadata("signatureOfDeepGenericInner.kt")
             public void testSignatureOfDeepGenericInner() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/signatureOfDeepGenericInner.kt");

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

@@ -17601,6 +17601,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/defaultImplsGenericSignature.kt");
             }
 
+            @TestMetadata("delegatedMembers.kt")
+            public void testDelegatedMembers() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/genericSignature/delegatedMembers.kt");
+            }
+
             @TestMetadata("functionLiteralGenericSignature.kt")
             public void testFunctionLiteralGenericSignature() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/functionLiteralGenericSignature.kt");
@@ -17631,6 +17636,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/kt6106.kt");
             }
 
+            @TestMetadata("samWrappedLambdaVsReference.kt")
+            public void testSamWrappedLambdaVsReference() throws Exception {
+                runTest("compiler/testData/codegen/box/reflection/genericSignature/samWrappedLambdaVsReference.kt");
+            }
+
             @TestMetadata("signatureOfDeepGenericInner.kt")
             public void testSignatureOfDeepGenericInner() throws Exception {
                 runTest("compiler/testData/codegen/box/reflection/genericSignature/signatureOfDeepGenericInner.kt");