Fix parameter completion when script requirements fail

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

@@ -1198,7 +1198,7 @@ private bool PrepareCommandElements(ExecutionContext context, CommandParameterAs
             string commandName = null;
             try
             {
-                processor = PrepareFromAst(context, out commandName) ?? context.CreateCommand(commandName, dotSource);
+                processor = PrepareFromAst(context, out commandName) ?? context.CreateCommand(commandName, dotSource, forCompletion:true);
             }
             catch (RuntimeException)
             {

src/System.Management.Automation/engine/CommandDiscovery.cs

@@ -262,6 +262,9 @@ internal void AddSessionStateCmdletEntryToCache(SessionStateCmdletEntry entry, b
         /// False if not.  Null if command discovery should default to something reasonable
         /// for the command discovered.
         /// </param>
+        /// <param name="forCompletion">
+        /// True if this for parameter completion and script requirements should be ignored.
+        /// </param>
         /// <returns>
         /// </returns>
         /// <exception cref="CommandNotFoundException">
@@ -271,22 +274,23 @@ internal void AddSessionStateCmdletEntryToCache(SessionStateCmdletEntry entry, b
         /// If the security manager is preventing the command from running.
         /// </exception>
         internal CommandProcessorBase LookupCommandProcessor(string commandName,
-            CommandOrigin commandOrigin, bool? useLocalScope)
+            CommandOrigin commandOrigin, bool? useLocalScope, bool forCompletion = false)
         {
             CommandProcessorBase processor = null;
             CommandInfo commandInfo = LookupCommandInfo(commandName, commandOrigin);
 
             if (commandInfo != null)
             {
-                processor = LookupCommandProcessor(commandInfo, commandOrigin, useLocalScope, null);
+                processor = LookupCommandProcessor(commandInfo, commandOrigin, useLocalScope, null, forCompletion);
+
                 // commandInfo.Name might be different than commandName - restore the original invocation name
                 processor.Command.MyInvocation.InvocationName = commandName;
             }
 
             return processor;
         }
 
-        internal static void VerifyRequiredModules(ExternalScriptInfo scriptInfo, ExecutionContext context)
+        internal static void VerifyRequiredModules(ExternalScriptInfo scriptInfo, ExecutionContext context, bool forCompletion = false)
         {
             // Check Required Modules
             if (scriptInfo.RequiresModules != null)
@@ -301,7 +305,7 @@ internal static void VerifyRequiredModules(ExternalScriptInfo scriptInfo, Execut
                         moduleManifestPath: null,
                         manifestProcessingFlags: ModuleCmdletBase.ManifestProcessingFlags.LoadElements | ModuleCmdletBase.ManifestProcessingFlags.WriteErrors,
                         error: out error);
-                    if (error != null)
+                    if (!forCompletion && error is not null)
                     {
                         ScriptRequiresException scriptRequiresException =
                             new ScriptRequiresException(
@@ -316,9 +320,9 @@ internal static void VerifyRequiredModules(ExternalScriptInfo scriptInfo, Execut
             }
         }
 
-        private CommandProcessorBase CreateScriptProcessorForSingleShell(ExternalScriptInfo scriptInfo, ExecutionContext context, bool useLocalScope, SessionStateInternal sessionState)
+        private CommandProcessorBase CreateScriptProcessorForSingleShell(ExternalScriptInfo scriptInfo, ExecutionContext context, bool useLocalScope, SessionStateInternal sessionState, bool forCompletion = false)
         {
-            VerifyScriptRequirements(scriptInfo, Context);
+            VerifyScriptRequirements(scriptInfo, Context, forCompletion);
 
             if (!string.IsNullOrEmpty(scriptInfo.RequiresApplicationID))
             {
@@ -340,12 +344,18 @@ private CommandProcessorBase CreateScriptProcessorForSingleShell(ExternalScriptI
         // #Requires -PSVersion
         // #Requires -PSEdition
         // #Requires -Module
-        internal static void VerifyScriptRequirements(ExternalScriptInfo scriptInfo, ExecutionContext context)
+        internal static void VerifyScriptRequirements(ExternalScriptInfo scriptInfo, ExecutionContext context, bool forCompletion = false)
         {
-            VerifyElevatedPrivileges(scriptInfo);
-            VerifyPSVersion(scriptInfo);
-            VerifyPSEdition(scriptInfo);
-            VerifyRequiredModules(scriptInfo, context);
+            // When completing script parameters we don't care if these requirements are met.
+            // VerifyRequiredModules will attempt to load the required modules which is useful for completion (so the correct types are loaded).
+            if (!forCompletion)
+            {
+                VerifyElevatedPrivileges(scriptInfo);
+                VerifyPSVersion(scriptInfo);
+                VerifyPSEdition(scriptInfo);
+            }
+
+            VerifyRequiredModules(scriptInfo, context, forCompletion);
         }
 
         internal static void VerifyPSVersion(ExternalScriptInfo scriptInfo)
@@ -426,6 +436,9 @@ internal static void VerifyElevatedPrivileges(ExternalScriptInfo scriptInfo)
         /// False if not.  Null if command discovery should default to something reasonable
         /// for the command discovered.
         /// </param>
+        /// <param name="forCompletion">
+        /// True if this for parameter completion and script requirements should be ignored.
+        /// </param>
         /// <param name="sessionState">The session state the commandInfo should be run in.</param>
         /// <returns>
         /// </returns>
@@ -436,7 +449,7 @@ internal static void VerifyElevatedPrivileges(ExternalScriptInfo scriptInfo)
         /// If the security manager is preventing the command from running.
         /// </exception>
         internal CommandProcessorBase LookupCommandProcessor(CommandInfo commandInfo,
-            CommandOrigin commandOrigin, bool? useLocalScope, SessionStateInternal sessionState)
+            CommandOrigin commandOrigin, bool? useLocalScope, SessionStateInternal sessionState, bool forCompletion = false)
         {
             CommandProcessorBase processor = null;
 
@@ -482,7 +495,7 @@ internal CommandProcessorBase LookupCommandProcessor(CommandInfo commandInfo,
                     scriptInfo.SignatureChecked = true;
                     try
                     {
-                        processor = CreateScriptProcessorForSingleShell(scriptInfo, Context, useLocalScope ?? true, sessionState);
+                        processor = CreateScriptProcessorForSingleShell(scriptInfo, Context, useLocalScope ?? true, sessionState, forCompletion);
                     }
                     catch (ScriptRequiresSyntaxException reqSyntaxException)
                     {

src/System.Management.Automation/engine/ExecutionContext.cs

@@ -477,7 +477,6 @@ internal LocationGlobber LocationGlobber
         /// The assemblies that have been loaded for this runspace.
         /// </summary>
         internal Dictionary<string, Assembly> AssemblyCache { get; private set; }
-
         #endregion Properties
 
         #region Engine State
@@ -634,12 +633,13 @@ internal HelpSystem HelpSystem
         /// </summary>
         /// <param name="command">The name of the command to lookup.</param>
         /// <param name="dotSource"></param>
+        /// <param name="forCompletion"></param>
         /// <returns>The command processor object.</returns>
-        internal CommandProcessorBase CreateCommand(string command, bool dotSource)
+        internal CommandProcessorBase CreateCommand(string command, bool dotSource, bool forCompletion = false)
         {
             CommandOrigin commandOrigin = this.EngineSessionState.CurrentScope.ScopeOrigin;
             CommandProcessorBase commandProcessor =
-                CommandDiscovery.LookupCommandProcessor(command, commandOrigin, !dotSource);
+                CommandDiscovery.LookupCommandProcessor(command, commandOrigin, !dotSource, forCompletion);
             // Reset the command origin for script commands... // BUGBUG - dotting can get around command origin checks???
             if (commandProcessor != null && commandProcessor is ScriptCommandProcessorBase)
             {

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

@@ -1659,6 +1659,36 @@ class InheritedClassTest : System.Attribute
         }
     }
 
+    Context "Script parameter completion" {
+        BeforeAll {
+            Setup -File -Path 'ModuleReqTest.ps1' -Content @'
+#requires -Modules ThisModuleDoesNotExist
+param ($Param1)
+'@
+            Setup -File -Path 'AdminReqTest.ps1' -Content @'
+#requires -RunAsAdministrator
+param ($Param1)
+'@
+            Push-Location ${TestDrive}\
+        }
+
+        AfterAll {
+            Pop-Location
+        }
+
+        It "Input should successfully complete script parameter for script with failed script requirements" {
+            $res = TabExpansion2 -inputScript '.\ModuleReqTest.ps1 -'
+            $res.CompletionMatches.Count | Should -BeGreaterThan 0
+            $res.CompletionMatches[0].CompletionText | Should -BeExactly '-Param1'
+        }
+
+        It "Input should successfully complete script parameter for admin script while not elevated" {
+            $res = TabExpansion2 -inputScript '.\AdminReqTest.ps1 -'
+            $res.CompletionMatches.Count | Should -BeGreaterThan 0
+            $res.CompletionMatches[0].CompletionText | Should -BeExactly '-Param1'
+        }
+    }
+
     Context "File name completion" {
         BeforeAll {
             $tempDir = Join-Path -Path $TestDrive -ChildPath "baseDir"