Use the const-ness of an element when completing in a const context using available declarations

Change-Id: Ia950ad81ed571cbcf1f0060da0cba26406206ad1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/151031
Commit-Queue: Brian Wilkerson <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>

Author: bwilkerson

pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart

@@ -266,6 +266,11 @@ class DartCompletionManager implements CompletionContributor {
   void _addIncludedSuggestionRelevanceTags(DartCompletionRequestImpl request) {
     var target = request.target;
 
+    if (request.inConstantContext && request.useNewRelevance) {
+      includedSuggestionRelevanceTags.add(IncludedSuggestionRelevanceTag(
+          'isConst', RelevanceBoost.constInConstantContext));
+    }
+
     void addTypeTag(DartType type) {
       if (type is InterfaceType) {
         var element = type.element;

pkg/analyzer/lib/src/services/available_declarations.dart

@@ -1333,6 +1333,9 @@ class _File {
       if (Identifier.isPrivateName(name.name)) {
         return null;
       }
+      if (isConst) {
+        relevanceTags = [...?relevanceTags, 'isConst'];
+      }
 
       var locationOffset = name.offset;
       var lineLocation = lineInfo.getLocation(locationOffset);

pkg/analyzer/test/src/services/available_declarations_test.dart

@@ -1210,7 +1210,7 @@ class C {
       DeclarationKind.FIELD,
       isConst: true,
       isStatic: true,
-      relevanceTags: ['dart:core::int'],
+      relevanceTags: ['dart:core::int', 'isConst'],
       returnType: 'int',
     );
     _assertDeclaration(
@@ -2419,7 +2419,7 @@ final double e = 2.7;
       'd',
       DeclarationKind.VARIABLE,
       isConst: true,
-      relevanceTags: ['dart:core::int'],
+      relevanceTags: ['dart:core::int', 'isConst'],
       returnType: '',
     );
     _assertDeclaration(

pkg/analyzer_plugin/lib/utilities/completion/relevance.dart

@@ -102,4 +102,8 @@ abstract class RelevanceBoost {
   /// The relevance boost used when suggesting an enum constant from an
   /// available declaration set.
   static const int availableEnumConstant = 100;
+
+  /// The relevance boost used when suggesting a constant value / constructor
+  /// from an available declaration set in a constant context.
+  static const int constInConstantContext = 200;
 }