FIR IDE: use WhenMissingCase in NoElseInWhen diagnostic

idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/HLDiagnosticConverter.kt

@@ -163,11 +163,6 @@ private object FirToKtConversionCreator {
             KtVariableSymbol::class.createType(),
             importsToAdd = listOf("org.jetbrains.kotlin.fir.declarations.FirProperty")
         ),
-        WhenMissingCase::class to HLFunctionCallConversion(
-            """TODO("WhenMissingCase conversion is not supported yet")""",
-            Any::class.createType(),
-            importsToAdd = listOf("org.jetbrains.kotlin.diagnostics.WhenMissingCase")
-        ),
     )
 
     private val allowedTypesWithoutTypeParams = setOf(
@@ -177,6 +172,7 @@ private object FirToKtConversionCreator {
         EventOccurrencesRange::class,
         KtModifierKeywordToken::class,
         Visibility::class,
+        WhenMissingCase::class,
     )
 
     private val KType.kClass: KClass<*>

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

@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.idea.frontend.api.fir.diagnostics
 
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiTypeElement
-import org.jetbrains.kotlin.diagnostics.WhenMissingCase
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirPsiDiagnostic
 import org.jetbrains.kotlin.fir.declarations.FirCallableDeclaration
@@ -1058,7 +1057,7 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
     add(FirErrors.NO_ELSE_IN_WHEN) { firDiagnostic ->
         NoElseInWhenImpl(
             firDiagnostic.a.map { whenMissingCase ->
-                TODO("WhenMissingCase conversion is not supported yet")
+                whenMissingCase
             },
             firDiagnostic as FirPsiDiagnostic<*>,
             token,

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

@@ -9,6 +9,7 @@ import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiTypeElement
 import org.jetbrains.kotlin.contracts.description.EventOccurrencesRange
 import org.jetbrains.kotlin.descriptors.Visibility
+import org.jetbrains.kotlin.diagnostics.WhenMissingCase
 import org.jetbrains.kotlin.idea.frontend.api.diagnostics.KtDiagnosticWithPsi
 import org.jetbrains.kotlin.idea.frontend.api.symbols.KtCallableSymbol
 import org.jetbrains.kotlin.idea.frontend.api.symbols.KtClassLikeSymbol
@@ -745,7 +746,7 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
 
     abstract class NoElseInWhen : KtFirDiagnostic<KtWhenExpression>() {
         override val diagnosticClass get() = NoElseInWhen::class
-        abstract val missingWhenCases: List<Any>
+        abstract val missingWhenCases: List<WhenMissingCase>
     }
 
     abstract class InvalidIfAsExpression : KtFirDiagnostic<KtIfExpression>() {

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

@@ -9,6 +9,7 @@ import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiTypeElement
 import org.jetbrains.kotlin.contracts.description.EventOccurrencesRange
 import org.jetbrains.kotlin.descriptors.Visibility
+import org.jetbrains.kotlin.diagnostics.WhenMissingCase
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirPsiDiagnostic
 import org.jetbrains.kotlin.idea.frontend.api.ValidityToken
 import org.jetbrains.kotlin.idea.frontend.api.fir.utils.weakRef
@@ -1198,7 +1199,7 @@ internal class UnsafeOperatorCallImpl(
 }
 
 internal class NoElseInWhenImpl(
-    override val missingWhenCases: List<Any>,
+    override val missingWhenCases: List<WhenMissingCase>,
     firDiagnostic: FirPsiDiagnostic<*>,
     override val token: ValidityToken,
 ) : KtFirDiagnostic.NoElseInWhen(), KtAbstractFirDiagnostic<KtWhenExpression> {