Add feature that allows references to synthetic properties with warning

See KT-35933 for details

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirOldFrontendDiagnosticsTestGenerated.java

@@ -22647,6 +22647,11 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirOldFronte
                 runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OverrideGetterOnly.kt");
             }
 
+            @TestMetadata("PartiallySupportedSyntheticJavaPropertyReference.kt")
+            public void testPartiallySupportedSyntheticJavaPropertyReference() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/PartiallySupportedSyntheticJavaPropertyReference.kt");
+            }
+
             @TestMetadata("SetterHasHigherAccess.kt")
             public void testSetterHasHigherAccess() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterHasHigherAccess.kt");

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/checkers/UnsupportedSyntheticCallableReferenceChecker.kt

@@ -17,6 +17,8 @@
 package org.jetbrains.kotlin.resolve.jvm.checkers
 
 import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.diagnostics.Errors.CALLABLE_REFERENCE_TO_JAVA_SYNTHETIC_PROPERTY
 import org.jetbrains.kotlin.diagnostics.Errors.UNSUPPORTED
 import org.jetbrains.kotlin.resolve.calls.callUtil.isCallableReference
 import org.jetbrains.kotlin.resolve.calls.checkers.CallChecker
@@ -28,7 +30,16 @@ class UnsupportedSyntheticCallableReferenceChecker : CallChecker {
     override fun check(resolvedCall: ResolvedCall<*>, reportOn: PsiElement, context: CallCheckerContext) {
         // TODO: support references to synthetic Java extension properties (KT-8575)
         if (resolvedCall.call.isCallableReference() && resolvedCall.resultingDescriptor is SyntheticJavaPropertyDescriptor) {
-            context.trace.report(UNSUPPORTED.on(reportOn, "reference to the synthetic extension property for a Java get/set method"))
+            val diagnostic = if (
+                context.languageVersionSettings.supportsFeature(LanguageFeature.NewInference) &&
+                context.languageVersionSettings.supportsFeature(LanguageFeature.ReferencesToSyntheticJavaProperties)
+            ) {
+                CALLABLE_REFERENCE_TO_JAVA_SYNTHETIC_PROPERTY.on(reportOn)
+            } else {
+                UNSUPPORTED.on(reportOn, "reference to the synthetic extension property for a Java get/set method")
+            }
+
+            context.trace.report(diagnostic)
         }
     }
 }

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -784,6 +784,8 @@ public interface Errors {
     DiagnosticFactory0<KtExpression> NULLABLE_TYPE_IN_CLASS_LITERAL_LHS = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory1<KtExpression, KotlinType> EXPRESSION_OF_NULLABLE_TYPE_IN_CLASS_LITERAL_LHS = DiagnosticFactory1.create(ERROR);
 
+    DiagnosticFactory0<PsiElement> CALLABLE_REFERENCE_TO_JAVA_SYNTHETIC_PROPERTY = DiagnosticFactory0.create(WARNING);
+
     // Destructuring-declarations
 
     DiagnosticFactory0<KtDestructuringDeclaration> INITIALIZER_REQUIRED_FOR_DESTRUCTURING_DECLARATION = DiagnosticFactory0.create(ERROR, DEFAULT);

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -965,6 +965,8 @@ public class DefaultErrorMessages {
         MAP.put(NULLABLE_TYPE_IN_CLASS_LITERAL_LHS, "Type in a class literal must not be nullable");
         MAP.put(EXPRESSION_OF_NULLABLE_TYPE_IN_CLASS_LITERAL_LHS, "Expression in a class literal has a nullable type ''{0}'', use !! to make the type non-nullable", RENDER_TYPE);
 
+        MAP.put(CALLABLE_REFERENCE_TO_JAVA_SYNTHETIC_PROPERTY, "References to the synthetic extension properties for a Java get/set methods aren't supported fully, please use reference to a method");
+
         //Inline
         MAP.put(NON_PUBLIC_CALL_FROM_PUBLIC_INLINE, "Public-API inline function cannot access non-public-API ''{0}''", SHORT_NAMES_IN_TYPES, SHORT_NAMES_IN_TYPES);
         MAP.put(PRIVATE_CLASS_MEMBER_FROM_INLINE, "Non-private inline function cannot access members of private classes: ''{0}''", SHORT_NAMES_IN_TYPES, SHORT_NAMES_IN_TYPES);

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/PartiallySupportedSyntheticJavaPropertyReference.fir.kt

@@ -0,0 +1,17 @@
+// !LANGUAGE: +NewInference +ReferencesToSyntheticJavaProperties
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+// FILE: KotlinFile.kt
+
+fun call(c: Any) {}
+
+fun test() {
+    JavaClass::foo
+    call(JavaClass::foo)
+}
+
+// FILE: JavaClass.java
+
+public class JavaClass {
+    public String getFoo() {}
+}

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/PartiallySupportedSyntheticJavaPropertyReference.kt

@@ -0,0 +1,17 @@
+// !LANGUAGE: +NewInference +ReferencesToSyntheticJavaProperties
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+// FILE: KotlinFile.kt
+
+fun call(c: Any) {}
+
+fun test() {
+    JavaClass::<!CALLABLE_REFERENCE_TO_JAVA_SYNTHETIC_PROPERTY!>foo<!>
+    call(JavaClass::<!CALLABLE_REFERENCE_TO_JAVA_SYNTHETIC_PROPERTY!>foo<!>)
+}
+
+// FILE: JavaClass.java
+
+public class JavaClass {
+    public String getFoo() {}
+}

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/PartiallySupportedSyntheticJavaPropertyReference.txt

@@ -0,0 +1,12 @@
+package
+
+public fun call(/*0*/ c: kotlin.Any): kotlin.Unit
+public fun test(): kotlin.Unit
+
+public open class JavaClass {
+    public constructor JavaClass()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun getFoo(): kotlin.String!
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SyntheticJavaPropertyReference.fir.kt

@@ -1,6 +1,14 @@
+// !LANGUAGE: -ReferencesToSyntheticJavaProperties
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
 // FILE: KotlinFile.kt
 
-fun bar() = JavaClass::foo
+fun call(c: Any) {}
+
+fun test() {
+    JavaClass::foo
+    call(JavaClass::foo)
+}
 
 // FILE: JavaClass.java
 

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SyntheticJavaPropertyReference.kt

@@ -1,6 +1,14 @@
+// !LANGUAGE: -ReferencesToSyntheticJavaProperties
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
 // FILE: KotlinFile.kt
 
-fun bar() = JavaClass::<!UNSUPPORTED!>foo<!>
+fun call(c: Any) {}
+
+fun test() {
+    JavaClass::<!UNSUPPORTED!>foo<!>
+    call(JavaClass::<!UNSUPPORTED!>foo<!>)
+}
 
 // FILE: JavaClass.java
 

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SyntheticJavaPropertyReference.txt

@@ -1,6 +1,7 @@
 package
 
-public fun bar(): kotlin.reflect.KProperty1<JavaClass, kotlin.String!>
+public fun call(/*0*/ c: kotlin.Any): kotlin.Unit
+public fun test(): kotlin.Unit
 
 public open class JavaClass {
     public constructor JavaClass()

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -22729,6 +22729,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OverrideGetterOnly.kt");
                 }
 
+                @TestMetadata("PartiallySupportedSyntheticJavaPropertyReference.kt")
+                public void testPartiallySupportedSyntheticJavaPropertyReference() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/PartiallySupportedSyntheticJavaPropertyReference.kt");
+                }
+
                 @TestMetadata("SetterHasHigherAccess.kt")
                 public void testSetterHasHigherAccess() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterHasHigherAccess.kt");

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -22649,6 +22649,11 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                     runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OverrideGetterOnly.kt");
                 }
 
+                @TestMetadata("PartiallySupportedSyntheticJavaPropertyReference.kt")
+                public void testPartiallySupportedSyntheticJavaPropertyReference() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/PartiallySupportedSyntheticJavaPropertyReference.kt");
+                }
+
                 @TestMetadata("SetterHasHigherAccess.kt")
                 public void testSetterHasHigherAccess() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterHasHigherAccess.kt");

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -148,6 +148,7 @@ enum class LanguageFeature(
     NewDataFlowForTryExpressions(sinceVersion = KOTLIN_1_3, defaultState = State.DISABLED),
     FunctionReferenceWithDefaultValueAsOtherType(sinceVersion = KOTLIN_1_3, defaultState = State.DISABLED),
     NonStrictOnlyInputTypesChecks(KOTLIN_1_4),
+    ReferencesToSyntheticJavaProperties(sinceVersion = KOTLIN_1_3, defaultState = State.DISABLED),
     // ------
     // Next features can be enabled regardless of new inference