Fix completion for PSCustomObject variable properties (#18682)

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

@@ -427,7 +427,29 @@ namespace System.Management.Automation
                 value = PSObject.Base(value);
                 if (value != null)
                 {
-                    type = new PSTypeName(value.GetType());
+                    var typeObject = value.GetType();
+                    
+                    if (typeObject.FullName.Equals("System.Management.Automation.PSObject", StringComparison.Ordinal))
+                    {
+                        var psobjectPropertyList = new List<PSMemberNameAndType>();
+                        foreach (var property in ((PSObject)value).Properties)
+                        {
+                            if (property.IsHidden)
+                            {
+                                continue;
+                            }
+
+                            var propertyTypeName = new PSTypeName(property.TypeNameOfValue);
+                            psobjectPropertyList.Add(new PSMemberNameAndType(property.Name, propertyTypeName, property.Value));
+                        }
+
+                        type = PSSyntheticTypeName.Create(typeObject, psobjectPropertyList);
+                    }
+                    else
+                    {
+                        type = new PSTypeName(typeObject);
+                    }
+                    
                     return true;
                 }
             }

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

@@ -633,6 +633,13 @@ ConstructorTestClass(int i, bool b)
         $res.CompletionMatches[0].CompletionText | Should -BeExactly 'Length'
     }
 
+    It 'Should complete psobject members for variable' {
+        $TestVar = Get-Command Get-Command | Select-Object CommandType
+        $res = TabExpansion2 -inputScript '$TestVar | ForEach-Object {$_.commandtype'
+        $res | Should -HaveCount 1
+        $res.CompletionMatches[0].CompletionText | Should -BeExactly 'CommandType'
+    }
+
     Context "Format cmdlet's View paramter completion" {
         BeforeAll {
             $viewDefinition = @'