The desired name for an attribute in an attribute context should not have hte attribute suffix.

src/Features/Core/Portable/CodeFixes/AddImport/AbstractAddImportCodeFixProvider.cs

@@ -474,8 +474,10 @@ private async Task<IList<SymbolReference>> GetMatchingTypesAsync(SearchScope sea
                 // also lookup type symbols with the "Attribute" suffix.
                 if (inAttributeContext)
                 {
+                    var attributeSymbols = await searchScope.FindDeclarationsAsync(name + "Attribute", SymbolFilter.Type).ConfigureAwait(false);
+
                     symbols = symbols.Concat(
-                        await searchScope.FindDeclarationsAsync(name + "Attribute", SymbolFilter.Type).ConfigureAwait(false));
+                        attributeSymbols.Select(r => r.WithDesiredName(r.DesiredName.GetWithoutAttributeSuffix(isCaseSensitive: false))));
                 }
 
                 return OfType<ITypeSymbol>(symbols);
@@ -749,6 +751,11 @@ public SearchResult(string desiredName, T symbol, double weight)
             {
                 return new SearchResult<T2>(this.DesiredName, symbol, this.Weight);
             }
+
+            internal SearchResult<T> WithDesiredName(string desiredName)
+            {
+                return new SearchResult<T>(desiredName, Symbol, Weight);
+            }
         }
 
         private struct SearchResult