Fix member completion for PowerShell Enum class (#19740)

src/System.Management.Automation/engine/parser/TypeInferenceVisitor.cs

@@ -364,7 +364,22 @@ namespace System.Management.Automation
                 filterToCall = filter;
             }
 
-            results.AddRange(GetMembersByInferredType(new PSTypeName(typeof(object)), isStatic, filterToCall));
+            PSTypeName baseMembersType;
+            if (typename.TypeDefinitionAst.IsEnum)
+            {
+                if (!isStatic)
+                {
+                    results.Add(new PSInferredProperty("value__", new PSTypeName(typeof(int))));
+                }
+
+                baseMembersType = new PSTypeName(typeof(Enum));
+            }
+            else
+            {
+                baseMembersType = new PSTypeName(typeof(object));
+            }
+
+            results.AddRange(GetMembersByInferredType(baseMembersType, isStatic, filterToCall));
         }
 
         internal void AddMembersByInferredTypeCimType(PSTypeName typename, List<object> results, Func<object, bool> filterToCall)

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

@@ -961,6 +961,12 @@ class InheritedClassTest : System.Attribute
         $res.CompletionMatches.CompletionText | Should -Contain '-ProgressAction'
     }
 
+    it 'Should complete enum class members for Enums in script text' {
+        $res = TabExpansion2 -inputScript 'enum Test1 {Val1};([Test1]"").'
+        $res.CompletionMatches.CompletionText[0] | Should -Be 'value__'
+        $res.CompletionMatches.CompletionText | Should -Contain 'HasFlag('
+    }
+
     Context "Script name completion" {
         BeforeAll {
             Setup -f 'install-powershell.ps1' -Content ""