Improve checking of patches.

sdk/lib/_internal/compiler/implementation/warnings.dart

Index: sdk/lib/_internal/compiler/implementation/warnings.dart
diff --git a/sdk/lib/_internal/compiler/implementation/warnings.dart b/sdk/lib/_internal/compiler/implementation/warnings.dart
index 343ad14d991d4941cc281ec93ccd8fff84f01fb8..9c67abb3601874c2cffbcfa73e51cbf006edda57 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -385,6 +385,53 @@ Length: #{length}''');
   static const EXTERNAL_WITHOUT_IMPLEMENTATION = const MessageKind(
       "External method without an implementation.");
 
+  static const PATCH_POINT_TO_FUNCTION = const MessageKind(
+      "Info: This is the function patch '#{functionName}'.");
+
+  static const PATCH_POINT_TO_CLASS = const MessageKind(
+      "Info: This is the class patch '#{className}'.");
+
+  static const PATCH_POINT_TO_GETTER = const MessageKind(
+      "Info: This is the getter patch '#{getterName}'.");
+
+  static const PATCH_POINT_TO_SETTER = const MessageKind(
+      "Info: This is the setter patch '#{setterName}'.");
+
+  static const PATCH_POINT_TO_CONSTRUCTOR = const MessageKind(
+      "Info: This is the constructor patch '#{constructorName}'.");
+
+  static const PATCH_NON_EXISTING = const MessageKind(
+      "Error: Origin does not exist for patch '#{name}'.");
+
+  static const PATCH_NONPATCHABLE = const MessageKind(
+      "Error: Only classes and functions can be patched.");
+
+  static const PATCH_NON_EXTERNAL = const MessageKind(
+      "Error: Only external functions can be patched.");
+
+  static const PATCH_NON_CLASS = const MessageKind(
+      "Error: Patching non-class with class patch '#{className}'.");
+
+  static const PATCH_NON_GETTER = const MessageKind(
+      "Error: Cannot patch non-getter '#{name}' with getter patch.");
+
+  static const PATCH_NO_GETTER = const MessageKind(
+      "Error: No getter found for getter patch '#{getterName}'.");
+
+  static const PATCH_NON_SETTER = const MessageKind(
+      "Error: Cannot patch non-setter '#{name}' with setter patch.");
+
+  static const PATCH_NO_SETTER = const MessageKind(
+      "Error: No setter found for setter patch '#{setterName}'.");
+
+  static const PATCH_NON_CONSTRUCTOR = const MessageKind(
+      "Error: Cannot patch non-constructor with constructor patch "
+      "'#{constructorName}'.");
+
+  static const PATCH_NON_FUNCTION = const MessageKind(
+      "Error: Cannot patch non-function with function patch "
+      "'#{functionName}'.");
+
   static const TOP_LEVEL_VARIABLE_DECLARED_STATIC = const MessageKind(
       "Top-level variable cannot be declared static.");