Avoid binding positional parameters when completing parameter in front of value (#17693)

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

@@ -533,6 +533,7 @@ namespace System.Management.Automation
                 return result;
             }
 
+            bool bindPositionalParameters = true;
             if (parameterAst != null)
             {
                 // Parent must be a command
@@ -551,10 +552,24 @@ namespace System.Management.Automation
                 // Parent must be a command
                 commandAst = (CommandAst)dashAst.Parent;
                 partialName = string.Empty;
+
+                // If the user tries to tab complete a new parameter in front of a positional argument like: dir -<Tab> C:\
+                // the user may want to add the parameter name so we don't want to bind positional arguments
+                if (commandAst is not null)
+                {
+                    foreach (var element in commandAst.CommandElements)
+                    {
+                        if (element.Extent.StartOffset > context.TokenAtCursor.Extent.StartOffset)
+                        {
+                            bindPositionalParameters = element is CommandParameterAst;
+                            break;
+                        }
+                    }
+                }
             }
 
             PseudoBindingInfo pseudoBinding = new PseudoParameterBinder()
-                                                .DoPseudoParameterBinding(commandAst, null, parameterAst, PseudoParameterBinder.BindingType.ParameterCompletion);
+                                                .DoPseudoParameterBinding(commandAst, null, parameterAst, PseudoParameterBinder.BindingType.ParameterCompletion, bindPositionalParameters);
             // The command cannot be found or it's not a cmdlet, not a script cmdlet, not a function.
             // Try completing as if it the parameter is a command argument for native command completion.
             if (pseudoBinding == null)

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

@@ -949,8 +949,9 @@ namespace System.Management.Automation.Language
         /// <param name="pipeArgumentType">Indicate the type of the piped-in argument.</param>
         /// <param name="paramAstAtCursor">The CommandParameterAst the cursor is pointing at.</param>
         /// <param name="bindingType">Indicates whether pseudo binding is for argument binding, argument completion, or parameter completion.</param>
+        /// <param name="bindPositional">Indicates if the pseudo binding should bind positional parameters</param>
         /// <returns>PseudoBindingInfo.</returns>
-        internal PseudoBindingInfo DoPseudoParameterBinding(CommandAst command, Type pipeArgumentType, CommandParameterAst paramAstAtCursor, BindingType bindingType)
+        internal PseudoBindingInfo DoPseudoParameterBinding(CommandAst command, Type pipeArgumentType, CommandParameterAst paramAstAtCursor, BindingType bindingType, bool bindPositional = true)
         {
             if (command == null)
             {
@@ -1008,12 +1009,15 @@ namespace System.Management.Automation.Language
                 unboundArguments = BindNamedParameters();
                 _bindingEffective = _currentParameterSetFlag != 0;
 
-                // positional binding
-                unboundArguments = BindPositionalParameter(
-                    unboundArguments,
-                    _currentParameterSetFlag,
-                    _defaultParameterSetFlag,
-                    bindingType);
+                if (bindPositional)
+                {
+                    // positional binding
+                    unboundArguments = BindPositionalParameter(
+                        unboundArguments,
+                        _currentParameterSetFlag,
+                        _defaultParameterSetFlag,
+                        bindingType);
+                }
 
                 // VFRA/pipeline binding if the given command is a binary cmdlet or a script cmdlet
                 if (!_function)

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

@@ -691,6 +691,13 @@ ConstructorTestClass(int i, bool b)
         $completionText -join ' ' | Should -BeExactly 'blg csv tsv'
     }
 
+    it 'Should include positionally bound parameters when completing in front of parameter value' {
+        $TestString = 'Get-ChildItem -^ $HOME'
+        $CursorIndex = $TestString.IndexOf('^')
+        $res = TabExpansion2 -inputScript $TestString.Remove($CursorIndex, 1) -cursorColumn $CursorIndex
+        $res.CompletionMatches.CompletionText | Should -Contain "-Path"
+    }
+
     Context "Script name completion" {
         BeforeAll {
             Setup -f 'install-powershell.ps1' -Content ""