Report an error when a part-of refers to an unnamed library.

pkg/analyzer/lib/src/generated/resolver.dart

Index: pkg/analyzer/lib/src/generated/resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index 76acec6f78f02f5a1898b208cfb0ffd40a7d9706..0f68b7355a242411780c3156d48a53339f032944 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -4955,6 +4955,22 @@ class ResolverErrorCode extends ErrorCode {
       const ResolverErrorCode('MISSING_LIBRARY_DIRECTIVE_WITH_PART',
           "Libraries that have parts must have a library directive");
 
+  /**
+   * Parts: It is a static warning if the referenced part declaration
+   * <i>p</i> names a library that does not have a library tag.
+   *
+   * Parameters:
+   * 0: the URI of the expected library
+   * 1: the non-matching actual library name from the "part of" declaration
+   */
+  static const ResolverErrorCode PART_OF_UNNAMED_LIBRARY =
+      const ResolverErrorCode(
+          'PART_OF_UNNAMED_LIBRARY',
+          "Library is unnamed. Expected a URI not a library name '{0}' in the "
+          "part-of directive.",
+          "Try changing the part-of directive to a URI, or try including a"
+          " different part.");
+
   /**
    * Initialize a newly created error code to have the given [name]. The message
    * associated with the error will be created from the given [message]