Fix type completion for attribute tokens (#17484)

src/System.Management.Automation/engine/CommandCompletion/CompletionAnalysis.cs

@@ -424,7 +424,7 @@ namespace System.Management.Automation
                     case TokenKind.Generic:
                     case TokenKind.MinusMinus: // for native commands '--'
                     case TokenKind.Identifier:
-                        if (tokenAtCursor.TokenFlags != TokenFlags.TypeName)
+                        if (!tokenAtCursor.TokenFlags.HasFlag(TokenFlags.TypeName))
                         {
                             result = GetResultForIdentifier(completionContext, ref replacementIndex, ref replacementLength, isQuotedString);
                         }
@@ -1021,7 +1021,7 @@ namespace System.Management.Automation
                     }
                 }
                 
-                if (typeNameToComplete is null && tokenAtCursor?.TokenFlags == TokenFlags.TypeName)
+                if (typeNameToComplete is null && tokenAtCursor?.TokenFlags.HasFlag(TokenFlags.TypeName) == true)
                 {
                     typeNameToComplete = new TypeName(tokenAtCursor.Extent, tokenAtCursor.Text);
                 }

test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1

@@ -1209,6 +1209,12 @@ ConstructorTestClass(int i, bool b)
             $res.CompletionMatches[1].CompletionText | Should -BeExactly 'DarkCyan'
         }
 
+        It "Tab completion for attribute type" {
+            $inputStr = '[validateset()]$var1'
+            $res = TabExpansion2 -inputScript $inputStr -cursorColumn 2
+            $res.CompletionMatches.CompletionText | Should -Contain 'ValidateSet'
+        }
+
         It "Tab completion for ArgumentCompleter when AST is passed to CompleteInput" {
             $scriptBl = {
                 function Test-Completion {