[FIR] Add description to NO_ELSE_IN_WHEN and fill it for expect enum or sealed declarations

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -3822,6 +3822,7 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             firDiagnostic.a.map { whenMissingCase ->
                 whenMissingCase
             },
+            firDiagnostic.b,
             firDiagnostic as KtPsiDiagnostic,
             token,
         )

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -2670,6 +2670,7 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
     interface NoElseInWhen : KtFirDiagnostic<KtWhenExpression> {
         override val diagnosticClass get() = NoElseInWhen::class
         val missingWhenCases: List<WhenMissingCase>
+        val description: String
     }
 
     interface NonExhaustiveWhenStatement : KtFirDiagnostic<KtWhenExpression> {

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -3217,6 +3217,7 @@ internal class ExpectedConditionImpl(
 
 internal class NoElseInWhenImpl(
     override val missingWhenCases: List<WhenMissingCase>,
+    override val description: String,
     firDiagnostic: KtPsiDiagnostic,
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<KtWhenExpression>(firDiagnostic, token), KtFirDiagnostic.NoElseInWhen

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt

@@ -18,10 +18,8 @@ import org.jetbrains.kotlin.descriptors.EffectiveVisibility
 import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.diagnostics.WhenMissingCase
 import org.jetbrains.kotlin.fir.FirModuleData
-import org.jetbrains.kotlin.util.PrivateForInline
 import org.jetbrains.kotlin.fir.checkers.generator.diagnostics.model.*
 import org.jetbrains.kotlin.fir.declarations.FirFunction
-import org.jetbrains.kotlin.fir.declarations.FirTypeAlias
 import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.*
@@ -38,6 +36,7 @@ import org.jetbrains.kotlin.resolve.deprecation.DeprecationInfo
 import org.jetbrains.kotlin.resolve.multiplatform.ExpectActualCompatibility
 import org.jetbrains.kotlin.resolve.multiplatform.ExpectActualCompatibility.Incompatible
 import org.jetbrains.kotlin.types.Variance
+import org.jetbrains.kotlin.util.PrivateForInline
 import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadOnlyProperty
 
@@ -1315,6 +1314,7 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         val EXPECTED_CONDITION by error<KtWhenCondition>()
         val NO_ELSE_IN_WHEN by error<KtWhenExpression>(PositioningStrategy.WHEN_EXPRESSION) {
             parameter<List<WhenMissingCase>>("missingWhenCases")
+            parameter<String>("description")
         }
         val NON_EXHAUSTIVE_WHEN_STATEMENT by warning<KtWhenExpression>(PositioningStrategy.WHEN_EXPRESSION) {
             parameter<String>("type")

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -683,7 +683,7 @@ object FirErrors {
 
     // When expressions
     val EXPECTED_CONDITION by error0<KtWhenCondition>()
-    val NO_ELSE_IN_WHEN by error1<KtWhenExpression, List<WhenMissingCase>>(SourceElementPositioningStrategies.WHEN_EXPRESSION)
+    val NO_ELSE_IN_WHEN by error2<KtWhenExpression, List<WhenMissingCase>, String>(SourceElementPositioningStrategies.WHEN_EXPRESSION)
     val NON_EXHAUSTIVE_WHEN_STATEMENT by warning2<KtWhenExpression, String, List<WhenMissingCase>>(SourceElementPositioningStrategies.WHEN_EXPRESSION)
     val INVALID_IF_AS_EXPRESSION by error0<KtIfExpression>(SourceElementPositioningStrategies.IF_EXPRESSION)
     val ELSE_MISPLACED_IN_WHEN by error0<KtWhenEntry>(SourceElementPositioningStrategies.ELSE_ENTRY)

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirExhaustiveWhenChecker.kt

@@ -5,16 +5,18 @@
 
 package org.jetbrains.kotlin.fir.analysis.checkers.expression
 
-import org.jetbrains.kotlin.KtSourceElement
 import org.jetbrains.kotlin.KtNodeTypes
+import org.jetbrains.kotlin.KtSourceElement
 import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.Modality
-import org.jetbrains.kotlin.diagnostics.WhenMissingCase
-import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
+import org.jetbrains.kotlin.diagnostics.WhenMissingCase
 import org.jetbrains.kotlin.diagnostics.reportOn
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
+import org.jetbrains.kotlin.fir.declarations.utils.isEnumClass
+import org.jetbrains.kotlin.fir.declarations.utils.isExpect
 import org.jetbrains.kotlin.fir.declarations.utils.modality
 import org.jetbrains.kotlin.fir.expressions.ExhaustivenessStatus
 import org.jetbrains.kotlin.fir.expressions.FirWhenExpression
@@ -22,6 +24,7 @@ import org.jetbrains.kotlin.fir.expressions.impl.FirElseIfTrueCondition
 import org.jetbrains.kotlin.fir.expressions.isExhaustive
 import org.jetbrains.kotlin.fir.languageVersionSettings
 import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
+import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 import org.jetbrains.kotlin.fir.types.coneType
 import org.jetbrains.kotlin.fir.types.isBooleanOrNullableBoolean
 import org.jetbrains.kotlin.fir.types.lowerBoundIfFlexible
@@ -38,16 +41,18 @@ object FirExhaustiveWhenChecker : FirWhenExpressionChecker() {
 
         val source = whenExpression.source ?: return
 
+        val subjectType = whenExpression.subject?.typeRef?.coneType?.lowerBoundIfFlexible()
+        val subjectClassSymbol = subjectType?.fullyExpandedType(context.session)?.toRegularClassSymbol(context.session)
+
         if (whenExpression.usedAsExpression) {
             if (source.isIfExpression) {
                 reporter.reportOn(source, FirErrors.INVALID_IF_AS_EXPRESSION, context)
                 return
             } else if (source.isWhenExpression) {
-                reporter.reportOn(source, FirErrors.NO_ELSE_IN_WHEN, whenExpression.missingCases, context)
+                reportNoElseInWhen(reporter, source, whenExpression, subjectClassSymbol, context)
             }
         } else {
-            val subjectType = whenExpression.subject?.typeRef?.coneType?.lowerBoundIfFlexible() ?: return
-            val subjectClassSymbol = subjectType.fullyExpandedType(context.session).toRegularClassSymbol(context.session) ?: return
+            if (subjectClassSymbol == null) return
             val kind = when {
                 subjectClassSymbol.modality == Modality.SEALED -> AlgebraicTypeKind.Sealed
                 subjectClassSymbol.classKind == ClassKind.ENUM_CLASS -> AlgebraicTypeKind.Enum
@@ -56,13 +61,30 @@ object FirExhaustiveWhenChecker : FirWhenExpressionChecker() {
             }
 
             if (context.session.languageVersionSettings.supportsFeature(LanguageFeature.ProhibitNonExhaustiveWhenOnAlgebraicTypes)) {
-                reporter.reportOn(source, FirErrors.NO_ELSE_IN_WHEN, whenExpression.missingCases, context)
+                reportNoElseInWhen(reporter, source, whenExpression, subjectClassSymbol, context)
             } else {
                 reporter.reportOn(source, FirErrors.NON_EXHAUSTIVE_WHEN_STATEMENT, kind.displayName, whenExpression.missingCases, context)
             }
         }
     }
 
+    private fun reportNoElseInWhen(
+        reporter: DiagnosticReporter,
+        source: KtSourceElement,
+        whenExpression: FirWhenExpression,
+        subjectClassSymbol: FirRegularClassSymbol?,
+        context: CheckerContext,
+    ) {
+        val description = when (subjectClassSymbol?.isExpect) {
+            true -> {
+                val declarationType = if (subjectClassSymbol.isEnumClass) "enum" else "sealed"
+                " ('when' with expect $declarationType subject cannot be exhaustive without else branch)"
+            }
+            else -> ""
+        }
+        reporter.reportOn(source, FirErrors.NO_ELSE_IN_WHEN, whenExpression.missingCases, description, context)
+    }
+
     private val FirWhenExpression.missingCases: List<WhenMissingCase>
         get() = (exhaustivenessStatus as ExhaustivenessStatus.NotExhaustive).reasons
 

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt

@@ -24,7 +24,6 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.CALL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.DECLARATION_NAME
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.FQ_NAMES_IN_TYPES
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.FUNCTIONAL_TYPE_KINDS
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.SYMBOLS_ON_NEWLINE_WITH_INDENT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.MODULE_DATA
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.NAME_OF_CONTAINING_DECLARATION_OR_FILE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.NAME_OF_DECLARATION_OR_FILE
@@ -34,6 +33,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.REND
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.RENDER_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.SYMBOL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.SYMBOLS
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.SYMBOLS_ON_NEWLINE_WITH_INDENT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.VARIABLE_NAME
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirDiagnosticRenderers.WHEN_MISSING_CASES
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ABSENCE_OF_PRIMARY_CONSTRUCTOR_FOR_VALUE_CLASS
@@ -140,7 +140,6 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CONST_VAL_WITH_GE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CONST_VAL_WITH_NON_CONST_INITIALIZER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CONTRACT_NOT_ALLOWED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CREATING_AN_INSTANCE_OF_ABSTRACT_CLASS
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NO_CONSTRUCTOR
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLE_IN_ANNOTATION_PARAMETER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLIC_CONSTRUCTOR_DELEGATION_CALL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLIC_GENERIC_UPPER_BOUND
@@ -165,6 +164,8 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DELEGATE_USES_EXT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DELEGATION_IN_INTERFACE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DELEGATION_NOT_TO_INTERFACE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DELEGATION_SUPER_CALL_IN_ENUM_CONSTRUCTOR
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DEPRECATED_BINARY_MOD
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DEPRECATED_IDENTITY_EQUALS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DEPRECATED_MODIFIER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DEPRECATED_MODIFIER_CONTAINING_DECLARATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DEPRECATED_MODIFIER_FOR_TARGET
@@ -181,6 +182,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DESERIALIZATION_E
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DIVISION_BY_ZERO
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DSL_SCOPE_VIOLATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DUPLICATE_LABEL_IN_WHEN
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DYNAMIC_NOT_ALLOWED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DYNAMIC_RECEIVER_NOT_ALLOWED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DYNAMIC_SUPERTYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DYNAMIC_UPPER_BOUND
@@ -200,10 +202,14 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_DECLARAT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_DELEGATED_PROPERTY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_ENUM_CONSTRUCTOR
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_ENUM_ENTRY_WITH_BODY
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_EXTERNAL_DECLARATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_FUNCTION_SOURCE_WITH_DEFAULT_ARGUMENTS_NOT_FOUND
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_LATEINIT_PROPERTY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_PRIVATE_DECLARATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_PROPERTY_INITIALIZER
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_TAILREC_FUNCTION
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECT_ACTUAL_OPT_IN_ANNOTATION
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECT_CLASS_AS_FUNCTION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPLICIT_BACKING_FIELD_IN_ABSTRACT_PROPERTY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPLICIT_BACKING_FIELD_IN_EXTENSION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPLICIT_BACKING_FIELD_IN_INTERFACE
@@ -212,6 +218,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPLICIT_TYPE_ARG
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPOSED_FUNCTION_RETURN_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPOSED_PARAMETER_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPOSED_PROPERTY_TYPE
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPOSED_PROPERTY_TYPE_IN_CONSTRUCTOR
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPOSED_RECEIVER_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPOSED_SUPER_CLASS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPOSED_SUPER_INTERFACE
@@ -226,14 +233,6 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXTENSION_PROPERT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.FINAL_SUPERTYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.FINAL_UPPER_BOUND
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.FLOAT_LITERAL_OUT_OF_RANGE
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DEPRECATED_BINARY_MOD
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPOSED_PROPERTY_TYPE_IN_CONSTRUCTOR
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DEPRECATED_IDENTITY_EQUALS
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DYNAMIC_NOT_ALLOWED
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_EXTERNAL_DECLARATION
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECTED_TAILREC_FUNCTION
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECT_ACTUAL_OPT_IN_ANNOTATION
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.EXPECT_CLASS_AS_FUNCTION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.FORBIDDEN_BINARY_MOD
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.FORBIDDEN_IDENTITY_EQUALS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.FORBIDDEN_IDENTITY_EQUALS_WARNING
@@ -322,10 +321,10 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ITERATOR_MISSING
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ITERATOR_ON_NULLABLE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.KCLASS_WITH_NULLABLE_TYPE_PARAMETER_IN_SIGNATURE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_FIELD_IN_VAL_PROPERTY
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_INTRINSIC_CALL_ON_NON_LITERAL
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_INTRINSIC_CALL_ON_NON_LATEINIT
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_INTRINSIC_CALL_ON_NON_ACCESSIBLE_PROPERTY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_INTRINSIC_CALL_IN_INLINE_FUNCTION
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_INTRINSIC_CALL_ON_NON_ACCESSIBLE_PROPERTY
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_INTRINSIC_CALL_ON_NON_LATEINIT
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_INTRINSIC_CALL_ON_NON_LITERAL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_NULLABLE_BACKING_FIELD
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LATEINIT_PROPERTY_FIELD_DECLARATION_WITH_INITIALIZER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.LEAKED_IN_PLACE_LAMBDA
@@ -346,7 +345,6 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MISSING_STDLIB_CL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MISSING_VAL_ON_ANNOTATION_PARAMETER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MODIFIER_FORM_FOR_NON_BUILT_IN_SUSPEND_FUN
-import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_A_MULTIPLATFORM_COMPILATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MULTIPLE_ARGUMENTS_APPLICABLE_FOR_CONTEXT_RECEIVER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MULTIPLE_VARARG_PARAMETERS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.MULTI_FIELD_VALUE_CLASS_PRIMARY_CONSTRUCTOR_DEFAULT_PARAMETER
@@ -391,6 +389,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_AN_ANNOTATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_A_CLASS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_A_FUNCTION_LABEL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_A_LOOP_LABEL
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_A_MULTIPLATFORM_COMPILATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_A_SUPERTYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_NULL_ASSERTION_ON_CALLABLE_REFERENCE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_NULL_ASSERTION_ON_LAMBDA_EXPRESSION
@@ -398,6 +397,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NOT_YET_SUPPORTED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NO_ACTUAL_CLASS_MEMBER_FOR_EXPECTED_CLASS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NO_ACTUAL_FOR_EXPECT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NO_COMPANION_OBJECT
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NO_CONSTRUCTOR
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NO_CONTEXT_RECEIVER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NO_ELSE_IN_WHEN
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.NO_EXPLICIT_RETURN_TYPE_IN_API_MODE
@@ -1973,7 +1973,7 @@ object FirErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
 
         // When expressions
         map.put(EXPECTED_CONDITION, "Expected condition of type Boolean")
-        map.put(NO_ELSE_IN_WHEN, "''when'' expression must be exhaustive, add necessary {0}", WHEN_MISSING_CASES)
+        map.put(NO_ELSE_IN_WHEN, "''when'' expression must be exhaustive, add necessary {0}{1}", WHEN_MISSING_CASES, STRING)
         map.put(INVALID_IF_AS_EXPRESSION, "'if' must have both main and 'else' branches if used as an expression")
         map.put(
             NON_EXHAUSTIVE_WHEN_STATEMENT,