Cleanup: drop unused LanguageFeature.State.ENABLED_WITH_ERROR

Review: https://jetbrains.team/p/kt/reviews/7418

compiler/frontend.common-psi/src/org/jetbrains/kotlin/diagnostics/rendering/LanguageFeatureMessageRenderer.kt

@@ -18,8 +18,7 @@ class LanguageFeatureMessageRenderer @JvmOverloads constructor(
 
     enum class Type {
         UNSUPPORTED,
-        WARNING,
+        WARNING
-        ERROR
     }
 
     override fun render(obj: Pair<LanguageFeature, LanguageVersionSettings>, renderingContext: RenderingContext): String {
@@ -43,7 +42,6 @@ class LanguageFeatureMessageRenderer @JvmOverloads constructor(
                 }
 
             Type.WARNING -> sb.append("experimental")
-            Type.ERROR -> sb.append("experimental and disabled")
         }
 
         val hintUrl = feature.hintUrl

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -71,8 +71,6 @@ public interface Errors {
 
     DiagnosticFactory1<PsiElement, Pair<LanguageFeature, LanguageVersionSettings>> EXPERIMENTAL_FEATURE_WARNING =
             DiagnosticFactory1.create(WARNING);
-    DiagnosticFactory1<PsiElement, Pair<LanguageFeature, LanguageVersionSettings>> EXPERIMENTAL_FEATURE_ERROR =
-            DiagnosticFactory1.create(ERROR);
 
     DiagnosticFactory0<KtElement> EXPLICIT_BACKING_FIELDS_UNSUPPORTED = DiagnosticFactory0.create(ERROR);
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -745,7 +745,6 @@ public class DefaultErrorMessages {
 
         MAP.put(UNSUPPORTED_FEATURE, "{0}", new LanguageFeatureMessageRenderer(LanguageFeatureMessageRenderer.Type.UNSUPPORTED));
         MAP.put(EXPERIMENTAL_FEATURE_WARNING, "{0}", new LanguageFeatureMessageRenderer(LanguageFeatureMessageRenderer.Type.WARNING));
-        MAP.put(EXPERIMENTAL_FEATURE_ERROR, "{0}", new LanguageFeatureMessageRenderer(LanguageFeatureMessageRenderer.Type.ERROR));
 
         MAP.put(EXPLICIT_BACKING_FIELDS_UNSUPPORTED, "Explicit backing field declarations are not supported in FE 1.0");
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.kt

@@ -226,10 +226,6 @@ object ModifierCheckerCore {
                 LanguageFeature.State.ENABLED_WITH_WARNING -> {
                     trace.report(Errors.EXPERIMENTAL_FEATURE_WARNING.on(node.psi, diagnosticData))
                 }
-                LanguageFeature.State.ENABLED_WITH_ERROR -> {
-                    trace.report(Errors.EXPERIMENTAL_FEATURE_ERROR.on(node.psi, diagnosticData))
-                    return false
-                }
                 LanguageFeature.State.DISABLED -> {
                     trace.report(Errors.UNSUPPORTED_FEATURE.on(node.psi, diagnosticData))
                     return false

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -330,7 +330,6 @@ enum class LanguageFeature(
     enum class State(override val description: String) : DescriptionAware {
         ENABLED("Enabled"),
         ENABLED_WITH_WARNING("Enabled with warning"),
-        ENABLED_WITH_ERROR("Disabled"), // TODO: consider dropping this and using DISABLED instead
         DISABLED("Disabled");
     }
 
@@ -525,7 +524,7 @@ class LanguageVersionSettingsImpl @JvmOverloads constructor(
             val char = when (state) {
                 LanguageFeature.State.ENABLED -> '+'
                 LanguageFeature.State.ENABLED_WITH_WARNING -> '~'
-                LanguageFeature.State.ENABLED_WITH_ERROR, LanguageFeature.State.DISABLED -> '-'
+                LanguageFeature.State.DISABLED -> '-'
             }
             append(" $char$feature")
         }