[FIR] Assume smartacsts on member properties from friend modules as stable

^KT-57893 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -29764,6 +29764,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
                 runTest("compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.kt");
             }
 
+            @Test
+            @TestMetadata("smartcastInFriendModule.kt")
+            public void testSmartcastInFriendModule() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/smartcastInFriendModule.kt");
+            }
+
             @Test
             @TestMetadata("smartcastOnSameFieldOfDifferentInstances.kt")
             public void testSmartcastOnSameFieldOfDifferentInstances() throws Exception {

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -29764,6 +29764,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
                 runTest("compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.kt");
             }
 
+            @Test
+            @TestMetadata("smartcastInFriendModule.kt")
+            public void testSmartcastInFriendModule() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/smartcastInFriendModule.kt");
+            }
+
             @Test
             @TestMetadata("smartcastOnSameFieldOfDifferentInstances.kt")
             public void testSmartcastOnSameFieldOfDifferentInstances() throws Exception {

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

@@ -29764,6 +29764,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
                 runTest("compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.kt");
             }
 
+            @Test
+            @TestMetadata("smartcastInFriendModule.kt")
+            public void testSmartcastInFriendModule() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/smartcastInFriendModule.kt");
+            }
+
             @Test
             @TestMetadata("smartcastOnSameFieldOfDifferentInstances.kt")
             public void testSmartcastOnSameFieldOfDifferentInstances() throws Exception {

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

@@ -29860,6 +29860,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
                 runTest("compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.kt");
             }
 
+            @Test
+            @TestMetadata("smartcastInFriendModule.kt")
+            public void testSmartcastInFriendModule() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/smartcastInFriendModule.kt");
+            }
+
             @Test
             @TestMetadata("smartcastOnSameFieldOfDifferentInstances.kt")
             public void testSmartcastOnSameFieldOfDifferentInstances() throws Exception {

compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/dfa/VariableStorageImpl.kt

@@ -176,7 +176,9 @@ class VariableStorageImpl(private val session: FirSession) : VariableStorage() {
                 val propertyModuleData = property.originalOrSelf().moduleData
                 val currentModuleData = session.moduleData
                 when (propertyModuleData) {
-                    currentModuleData, in currentModuleData.dependsOnDependencies -> PropertyStability.STABLE_VALUE
+                    currentModuleData,
+                    in currentModuleData.friendDependencies,
+                    in currentModuleData.dependsOnDependencies -> PropertyStability.STABLE_VALUE
                     else -> PropertyStability.ALIEN_PUBLIC_PROPERTY
                 }
             }

compiler/testData/diagnostics/tests/smartCasts/smartcastInFriendModule.fir.kt

@@ -0,0 +1,26 @@
+// ISSUE: KT-57893
+// MODULE: main
+internal class A {
+    val x: String? = null
+}
+
+class B {
+    internal val x: String? = null
+}
+
+class C {
+    val x: String? = null
+}
+
+// MODULE: test()(main)
+internal fun test(a: A, b: B, c: C) {
+    if (a.x != null) {
+        a.x.length
+    }
+    if (b.x != null) {
+        b.x.length
+    }
+    if (c.x != null) {
+        c.x.length
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/smartcastInFriendModule.kt

@@ -0,0 +1,26 @@
+// ISSUE: KT-57893
+// MODULE: main
+internal class A {
+    val x: String? = null
+}
+
+class B {
+    internal val x: String? = null
+}
+
+class C {
+    val x: String? = null
+}
+
+// MODULE: test()(main)
+internal fun test(a: A, b: B, c: C) {
+    if (a.x != null) {
+        <!DEBUG_INFO_SMARTCAST!>a.x<!>.length
+    }
+    if (b.x != null) {
+        <!DEBUG_INFO_SMARTCAST!>b.x<!>.length
+    }
+    if (c.x != null) {
+        <!SMARTCAST_IMPOSSIBLE!>c.x<!>.length
+    }
+}

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

@@ -30626,6 +30626,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.kt");
             }
 
+            @Test
+            @TestMetadata("smartcastInFriendModule.kt")
+            public void testSmartcastInFriendModule() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/smartcastInFriendModule.kt");
+            }
+
             @Test
             @TestMetadata("smartcastOnSameFieldOfDifferentInstances.kt")
             public void testSmartcastOnSameFieldOfDifferentInstances() throws Exception {