K2: reproduce KT-59748

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

@@ -36627,6 +36627,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
             runTest("compiler/testData/diagnostics/testsWithStdLib/labelClashesWithContextReceivers.kt");
         }
 
+        @Test
+        @TestMetadata("listAssignmentInWhen.kt")
+        public void testListAssignmentInWhen() throws Exception {
+            runTest("compiler/testData/diagnostics/testsWithStdLib/listAssignmentInWhen.kt");
+        }
+
         @Test
         @TestMetadata("outstar.kt")
         public void testOutstar() throws Exception {

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

@@ -36627,6 +36627,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
             runTest("compiler/testData/diagnostics/testsWithStdLib/labelClashesWithContextReceivers.kt");
         }
 
+        @Test
+        @TestMetadata("listAssignmentInWhen.kt")
+        public void testListAssignmentInWhen() throws Exception {
+            runTest("compiler/testData/diagnostics/testsWithStdLib/listAssignmentInWhen.kt");
+        }
+
         @Test
         @TestMetadata("outstar.kt")
         public void testOutstar() throws Exception {

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

@@ -36627,6 +36627,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
             runTest("compiler/testData/diagnostics/testsWithStdLib/labelClashesWithContextReceivers.kt");
         }
 
+        @Test
+        @TestMetadata("listAssignmentInWhen.kt")
+        public void testListAssignmentInWhen() throws Exception {
+            runTest("compiler/testData/diagnostics/testsWithStdLib/listAssignmentInWhen.kt");
+        }
+
         @Test
         @TestMetadata("outstar.kt")
         public void testOutstar() throws Exception {

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

@@ -36741,6 +36741,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
             runTest("compiler/testData/diagnostics/testsWithStdLib/labelClashesWithContextReceivers.kt");
         }
 
+        @Test
+        @TestMetadata("listAssignmentInWhen.kt")
+        public void testListAssignmentInWhen() throws Exception {
+            runTest("compiler/testData/diagnostics/testsWithStdLib/listAssignmentInWhen.kt");
+        }
+
         @Test
         @TestMetadata("outstar.kt")
         public void testOutstar() throws Exception {

compiler/testData/diagnostics/testsWithStdLib/listAssignmentInWhen.fir.kt

@@ -0,0 +1,12 @@
+// ISSUE: KT-59748
+// FIR_DUMP
+
+fun foo(list: MutableList<Any?>, condition: Boolean): Unit = <!RETURN_TYPE_MISMATCH!>when {
+    condition -> list[0] = ""
+    else -> Unit
+}<!>
+
+fun bar(list: MutableList<Any?>, condition: Boolean): Unit = <!RETURN_TYPE_MISMATCH!>when {
+    condition -> list.set(0, "")
+    else -> Unit
+}<!>

compiler/testData/diagnostics/testsWithStdLib/listAssignmentInWhen.fir.txt

@@ -0,0 +1,23 @@
+FILE: listAssignmentInWhen.fir.kt
+    public final fun foo(list: R|kotlin/collections/MutableList<kotlin/Any?>|, condition: R|kotlin/Boolean|): R|kotlin/Unit| {
+        ^foo when () {
+            R|<local>/condition| ->  {
+                R|<local>/list|.R|SubstitutionOverride<kotlin/collections/MutableList.set: R|kotlin/Any?|>|(Int(0), String())
+            }
+            else ->  {
+                Q|kotlin/Unit|
+            }
+        }
+
+    }
+    public final fun bar(list: R|kotlin/collections/MutableList<kotlin/Any?>|, condition: R|kotlin/Boolean|): R|kotlin/Unit| {
+        ^bar when () {
+            R|<local>/condition| ->  {
+                R|<local>/list|.R|SubstitutionOverride<kotlin/collections/MutableList.set: R|kotlin/Any?|>|(Int(0), String())
+            }
+            else ->  {
+                Q|kotlin/Unit|
+            }
+        }
+
+    }

compiler/testData/diagnostics/testsWithStdLib/listAssignmentInWhen.kt

@@ -0,0 +1,12 @@
+// ISSUE: KT-59748
+// FIR_DUMP
+
+fun foo(list: MutableList<Any?>, condition: Boolean): Unit = when {
+    condition -> list[0] = ""
+    else -> Unit
+}
+
+fun bar(list: MutableList<Any?>, condition: Boolean): Unit = <!TYPE_MISMATCH!>when {
+    condition -> list.set(0, "")
+    else -> Unit
+}<!>

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

@@ -37745,6 +37745,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
             runTest("compiler/testData/diagnostics/testsWithStdLib/labelClashesWithContextReceivers.kt");
         }
 
+        @Test
+        @TestMetadata("listAssignmentInWhen.kt")
+        public void testListAssignmentInWhen() throws Exception {
+            runTest("compiler/testData/diagnostics/testsWithStdLib/listAssignmentInWhen.kt");
+        }
+
         @Test
         @TestMetadata("outstar.kt")
         public void testOutstar() throws Exception {