Silence switch covers known cases warnings when building with resilience.

Author: tshortli

Sources/SwiftCompilerPluginMessageHandling/Macros.swift

@@ -167,6 +167,9 @@ extension PluginProviderMessageHandler {
         switch macroDefinition.formatMode {
         case .auto: collapseIndentationWidth = nil
         case .disabled: collapseIndentationWidth = []
+        #if RESILIENT_LIBRARIES
+        @unknown default: fatalError()
+        #endif
         }
         // Make a single element array by collapsing the results into a string.
         expandedSources = [

Sources/SwiftSyntaxMacroExpansion/MacroExpansion.swift

@@ -404,6 +404,9 @@ public func expandAttachedMacro<Context: MacroExpansionContext>(
     switch definition.formatMode {
     case .auto: collapseIndentationWidth = indentationWidth
     case .disabled: collapseIndentationWidth = []
+    #if RESILIENT_LIBRARIES
+    @unknown default: fatalError()
+    #endif
     }
     return collapse(
       expansions: expandedSources,