[FIR] Report type-aliased 'Nothing' as return type

This warning was issued in K1, but lost in K2

^KT-59420 Fixed
^KT-59429 Fixed

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

@@ -2360,6 +2360,18 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.ABBREVIATED_NOTHING_RETURN_TYPE) { firDiagnostic ->
+        AbbreviatedNothingReturnTypeImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
+    add(FirErrors.ABBREVIATED_NOTHING_PROPERTY_TYPE) { firDiagnostic ->
+        AbbreviatedNothingPropertyTypeImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirErrors.CYCLIC_GENERIC_UPPER_BOUND) { firDiagnostic ->
         CyclicGenericUpperBoundImpl(
             firDiagnostic as KtPsiDiagnostic,

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

@@ -1678,6 +1678,14 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = ImplicitNothingPropertyType::class
     }
 
+    interface AbbreviatedNothingReturnType : KtFirDiagnostic<PsiElement> {
+        override val diagnosticClass get() = AbbreviatedNothingReturnType::class
+    }
+
+    interface AbbreviatedNothingPropertyType : KtFirDiagnostic<PsiElement> {
+        override val diagnosticClass get() = AbbreviatedNothingPropertyType::class
+    }
+
     interface CyclicGenericUpperBound : KtFirDiagnostic<PsiElement> {
         override val diagnosticClass get() = CyclicGenericUpperBound::class
     }

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

@@ -2017,6 +2017,16 @@ internal class ImplicitNothingPropertyTypeImpl(
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtFirDiagnostic.ImplicitNothingPropertyType
 
+internal class AbbreviatedNothingReturnTypeImpl(
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtFirDiagnostic.AbbreviatedNothingReturnType
+
+internal class AbbreviatedNothingPropertyTypeImpl(
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtFirDiagnostic.AbbreviatedNothingPropertyType
+
 internal class CyclicGenericUpperBoundImpl(
     firDiagnostic: KtPsiDiagnostic,
     token: KtLifetimeToken,