FIR: handle synthetic properties with unstable smartcast

Synthetic properties from Java getter/setters need to be specially
handled so that candidates from such symbols are marked with unstable.

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -26664,6 +26664,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                     runTest("compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt");
                 }
 
+                @Test
+                @TestMetadata("syntheticPropertyOnUnstableSmartcast.kt")
+                public void testSyntheticPropertyOnUnstableSmartcast() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/inference/syntheticPropertyOnUnstableSmartcast.kt");
+                }
+
                 @Test
                 @TestMetadata("unneededUnstableSmartcast.kt")
                 public void testUnneededUnstableSmartcast() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java

@@ -26664,6 +26664,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                     runTest("compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt");
                 }
 
+                @Test
+                @TestMetadata("syntheticPropertyOnUnstableSmartcast.kt")
+                public void testSyntheticPropertyOnUnstableSmartcast() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/inference/syntheticPropertyOnUnstableSmartcast.kt");
+                }
+
                 @Test
                 @TestMetadata("unneededUnstableSmartcast.kt")
                 public void testUnneededUnstableSmartcast() throws Exception {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/Synthetics.kt

@@ -118,7 +118,13 @@ class FirSyntheticPropertiesScope(
             delegateGetter = getter
             delegateSetter = matchingSetter
         }
-        processor(property.symbol)
+        val syntheticSymbol = property.symbol
+        (baseScope as? FirUnstableSmartcastTypeScope)?.apply {
+            if (isSymbolFromUnstableSmartcast(getterSymbol)) {
+                markSymbolFromUnstableSmartcast(syntheticSymbol)
+            }
+        }
+        processor(syntheticSymbol)
     }
 
     private fun FirNamedFunctionSymbol.hasJavaOverridden(): Boolean {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/scopes/FirUnstableSmartcastTypeScope.kt

@@ -45,7 +45,7 @@ class FirUnstableSmartcastTypeScope(
         }
         smartcastScope.process(name) {
             if (it !in unique) {
-                symbolsFromUnstableSmartcast += it
+                markSymbolFromUnstableSmartcast(it)
                 processor(it)
             }
         }
@@ -72,7 +72,7 @@ class FirUnstableSmartcastTypeScope(
 
         smartcastScope.process(name) { symbol, firTypeScope ->
             if (symbol !in unique) {
-                symbolsFromUnstableSmartcast += symbol
+                markSymbolFromUnstableSmartcast(symbol)
                 processor(symbol, firTypeScope)
             } else {
                 ProcessorAction.NEXT
@@ -83,6 +83,10 @@ class FirUnstableSmartcastTypeScope(
 
     fun isSymbolFromUnstableSmartcast(symbol: AbstractFirBasedSymbol<*>) = symbol in symbolsFromUnstableSmartcast
 
+    fun markSymbolFromUnstableSmartcast(symbol: FirCallableSymbol<*>) {
+        symbolsFromUnstableSmartcast += symbol
+    }
+
     override fun processDirectOverriddenFunctionsWithBaseScope(
         functionSymbol: FirNamedFunctionSymbol,
         processor: (FirNamedFunctionSymbol, FirTypeScope) -> ProcessorAction

compiler/testData/diagnostics/tests/smartCasts/inference/syntheticPropertyOnUnstableSmartcast.kt

@@ -0,0 +1,29 @@
+// FIR_IDENTICAL
+// FILE: p/Super.java
+
+package p
+
+public interface Super {
+    public String getName()
+    public void setName(String name)
+}
+
+// FILE: p/test.kt
+
+package p
+
+class Sub : Super {
+    val onlyInSub: Int = 1
+    override fun getName(): String = ""
+    override fun setName(name: String) {}
+}
+
+var s: Super = Sub()
+
+fun test() {
+    if (s is Sub) {
+        s.name
+        s.name = ""
+        <!SMARTCAST_IMPOSSIBLE!>s<!>.onlyInSub
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/inference/syntheticPropertyOnUnstableSmartcast.txt

@@ -0,0 +1,25 @@
+package
+
+package p {
+    public var s: p.Super
+    public fun test(): kotlin.Unit
+
+    public final class Sub : p.Super {
+        public constructor Sub()
+        public final val onlyInSub: kotlin.Int = 1
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ fun getName(): kotlin.String
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ fun setName(/*0*/ name: kotlin.String): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+
+    public interface Super {
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public abstract fun getName(): kotlin.String!
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public abstract fun setName(/*0*/ name: kotlin.String!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}
+

compiler/testData/diagnostics/tests/smartCasts/intersectionScope/unstableSmartCast.fir.kt

@@ -1,37 +0,0 @@
-// !CHECK_TYPE
-
-interface A {
-    fun foo(): CharSequence?
-    fun baz(x: Any) {}
-}
-
-interface B {
-    fun foo(): String
-    fun baz(x: Int): String =""
-    fun baz(x: Int, y: Int) {}
-
-    fun foobar(): CharSequence?
-}
-
-interface C {
-    fun foo(): String
-    fun baz(x: Int): String =""
-    fun baz(x: Int, y: Int) {}
-
-    fun foobar(): String
-}
-
-var x: A = null!!
-
-fun test() {
-    x.foo().checkType { _<CharSequence?>() }
-
-    if (x is B && x is C) {
-        x.foo().checkType { _<CharSequence?>() }
-        x.baz("")
-        x.baz(1).checkType { _<Unit>() }
-        x.baz(1, <!TOO_MANY_ARGUMENTS!>2<!>)
-
-        x.<!UNRESOLVED_REFERENCE!>foobar<!>().checkType { _<String>() }
-    }
-}

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

@@ -26754,6 +26754,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                     runTest("compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt");
                 }
 
+                @Test
+                @TestMetadata("syntheticPropertyOnUnstableSmartcast.kt")
+                public void testSyntheticPropertyOnUnstableSmartcast() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/inference/syntheticPropertyOnUnstableSmartcast.kt");
+                }
+
                 @Test
                 @TestMetadata("unneededUnstableSmartcast.kt")
                 public void testUnneededUnstableSmartcast() throws Exception {

idea/idea-frontend-fir/idea-fir-low-level-api/tests/org/jetbrains/kotlin/idea/fir/low/level/api/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java

@@ -23321,6 +23321,11 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                     runTest("compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt");
                 }
 
+                @TestMetadata("syntheticPropertyOnUnstableSmartcast.kt")
+                public void testSyntheticPropertyOnUnstableSmartcast() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/inference/syntheticPropertyOnUnstableSmartcast.kt");
+                }
+
                 @TestMetadata("unneededUnstableSmartcast.kt")
                 public void testUnneededUnstableSmartcast() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/smartCasts/inference/unneededUnstableSmartcast.kt");