diff --git a/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.kt b/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.kt
new file mode 100644
index 00000000000..7433c144bd5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// See KT-27260
+
+class A(val x: String?) {
+    fun foo(other: A) {
+        when {
+            x == null && other.x == null -> "1"
+            <!DEBUG_INFO_SMARTCAST!>x<!>.length > 0 -> "2"
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.txt b/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.txt
new file mode 100644
index 00000000000..72171de2bd1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.txt
@@ -0,0 +1,10 @@
+package
+
+public final class A {
+    public constructor A(/*0*/ x: kotlin.String?)
+    public final val x: kotlin.String?
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final fun foo(/*0*/ other: A): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
index 5ceed36006f..7847d7d6a32 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
@@ -19377,6 +19377,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 runTest("compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.kt");
             }
 
+            @TestMetadata("smartcastOnSameFieldOfDifferentInstances.kt")
+            public void testSmartcastOnSameFieldOfDifferentInstances() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.kt");
+            }
+
             @TestMetadata("thisWithLabel.kt")
             public void testThisWithLabel() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/smartCasts/thisWithLabel.kt");
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
index 7ac4d1a4e53..486ad61745c 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java
@@ -19377,6 +19377,11 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                 runTest("compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.kt");
             }
 
+            @TestMetadata("smartcastOnSameFieldOfDifferentInstances.kt")
+            public void testSmartcastOnSameFieldOfDifferentInstances() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.kt");
+            }
+
             @TestMetadata("thisWithLabel.kt")
             public void testThisWithLabel() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/smartCasts/thisWithLabel.kt");