[analyzer] Simplify documentationCommentOrNull and metadataOrEmpty

Change-Id: I8b903292b635714d9a7f52e7a212c6354ae6a8c4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/391404
Reviewed-by: Samuel Rawlins <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: DanTup

pkg/analyzer/lib/src/dart/element/element.dart

@@ -10710,29 +10710,32 @@ class _Sentinel {
 }
 
 extension on Fragment {
+  /// The content of the documentation comment (including delimiters) for this
+  /// element or fragment.
+  ///
+  /// If the receiver is an element that has fragments, the comment will be a
+  /// concatenation of the comments from all of the fragments.
+  ///
+  /// Returns `null` if the receiver does not have or does not support
+  /// documentation.
   String? get documentationCommentOrNull {
-    // TODO(brianwilkerson): I think that all fragments are annotatable. If
-    //  that's true then this getter isn't necessary and should be removed.
     return switch (this) {
-      LibraryFragment(:var documentationComment) => documentationComment,
-      TypeDefiningFragment(:var documentationComment) => documentationComment,
-      TypeParameterizedFragment(:var documentationComment) =>
-        documentationComment,
-      FormalParameterFragment(:var documentationComment) =>
-        documentationComment,
+      Annotatable(:var documentationComment) => documentationComment,
       _ => null,
     };
   }
 
+  /// The metadata associated with the element or fragment.
+  ///
+  /// If the receiver is an element that has fragments, the list will include
+  /// all of the metadata from all of the fragments.
+  ///
+  /// The list will be empty if the receiver does not have any metadata, does
+  /// not support metadata, or if the library containing this element has not
+  /// yet been fully resolved.
   Metadata get metadataOrEmpty {
-    // TODO(brianwilkerson): I think that all fragments are annotatable. If
-    //  that's true then this getter isn't necessary and should be removed.
     return switch (this) {
-      LibraryFragment(:var metadata2) => metadata2,
-      PropertyInducingFragment(:var metadata2) => metadata2,
-      TypeDefiningFragment(:var metadata2) => metadata2,
-      TypeParameterizedFragment(:var metadata2) => metadata2,
-      FormalParameterFragment(:var metadata2) => metadata2,
+      Annotatable(:var metadata2) => metadata2,
       _ => MetadataImpl(-1, const [], () => null),
     };
   }

pkg/analyzer/test/src/summary/elements/offsets_test.dart

@@ -4078,11 +4078,13 @@ library
   topLevelVariables
     hasDocComment
       firstFragment: <testLibraryFragment>::@topLevelVariable::hasDocComment
+      documentationComment: /// Comment 1.\n/// Comment 2.
       type: int
       getter: <testLibraryFragment>::@getter::hasDocComment#element
       setter: <testLibraryFragment>::@setter::hasDocComment#element
     hasDocComment2
       firstFragment: <testLibraryFragment>::@topLevelVariable::hasDocComment2
+      documentationComment: /// Comment 1.\n/// Comment 2.
       type: int
       getter: <testLibraryFragment>::@getter::hasDocComment2#element
       setter: <testLibraryFragment>::@setter::hasDocComment2#element
@@ -4124,6 +4126,7 @@ library
       setter: <testLibraryFragment>::@setter::hasAnnotation2#element
     annotationThenComment
       firstFragment: <testLibraryFragment>::@topLevelVariable::annotationThenComment
+      documentationComment: /// Comment 1.\n/// Comment 2.
       metadata
         Annotation
           atSign: @ @112
@@ -4142,6 +4145,7 @@ library
       setter: <testLibraryFragment>::@setter::annotationThenComment#element
     annotationThenComment2
       firstFragment: <testLibraryFragment>::@topLevelVariable::annotationThenComment2
+      documentationComment: /// Comment 1.\n/// Comment 2.
       metadata
         Annotation
           atSign: @ @112
@@ -4160,6 +4164,7 @@ library
       setter: <testLibraryFragment>::@setter::annotationThenComment2#element
     commentThenAnnotation
       firstFragment: <testLibraryFragment>::@topLevelVariable::commentThenAnnotation
+      documentationComment: /// Comment 1.\n/// Comment 2.
       metadata
         Annotation
           atSign: @ @234
@@ -4178,6 +4183,7 @@ library
       setter: <testLibraryFragment>::@setter::commentThenAnnotation#element
     commentThenAnnotation2
       firstFragment: <testLibraryFragment>::@topLevelVariable::commentThenAnnotation2
+      documentationComment: /// Comment 1.\n/// Comment 2.
       metadata
         Annotation
           atSign: @ @234
@@ -4196,6 +4202,7 @@ library
       setter: <testLibraryFragment>::@setter::commentThenAnnotation2#element
     commentAroundAnnotation
       firstFragment: <testLibraryFragment>::@topLevelVariable::commentAroundAnnotation
+      documentationComment: /// Comment 2.
       metadata
         Annotation
           atSign: @ @311
@@ -4214,6 +4221,7 @@ library
       setter: <testLibraryFragment>::@setter::commentAroundAnnotation#element
     commentAroundAnnotation2
       firstFragment: <testLibraryFragment>::@topLevelVariable::commentAroundAnnotation2
+      documentationComment: /// Comment 2.
       metadata
         Annotation
           atSign: @ @311

pkg/analyzer/test/src/summary/elements/top_level_variable_test.dart

@@ -1583,6 +1583,7 @@ library
   topLevelVariables
     x
       firstFragment: <testLibraryFragment>::@topLevelVariable::x
+      documentationComment: /**\n * Docs\n */
       type: dynamic
       getter: <testLibraryFragment>::@getter::x#element
       setter: <testLibraryFragment>::@setter::x#element