From fbb8069d4d6e0c1127d38026a8509d8c16861fd4 Mon Sep 17 00:00:00 2001
From: MartinGC94 <mgc94@outlook.dk>
Date: Fri, 14 Apr 2023 18:03:29 +0200
Subject: [PATCH 1/2] Fix dynamic parameter completion

---
 .../CommandCompletion/CompletionCompleters.cs      | 13 ++++++++++++-
 .../CommandCompletion/PseudoParameterBinder.cs     | 11 +++++++++--
 .../Host/TabCompletion/TabCompletion.Tests.ps1     | 14 ++++++++++++++
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs b/src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs
index 7d7ecf9ab91..23976a9136f 100644
--- a/src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs
+++ b/src/System.Management.Automation/engine/CommandCompletion/CompletionCompleters.cs
@@ -707,7 +707,18 @@ private static List<CompletionResult> GetParameterCompletionResults(string param
                     break;
             }
 
-            Diagnostics.Assert(matchedParameterName != null, "we should find matchedParameterName from the BoundArguments");
+            if (matchedParameterName is null)
+            {
+                // The pseudo binder has skipped a parameter
+                // This will happen when completing parameters for commands with dynamic parameters.
+                result = GetParameterCompletionResults(
+                    parameterName,
+                    bindingInfo.ValidParameterSetsFlags,
+                    bindingInfo.UnboundParameters,
+                    withColon);
+                return result;
+            }
+
             MergedCompiledCommandParameter param = bindingInfo.BoundParameters[matchedParameterName];
 
             WildcardPattern pattern = WildcardPattern.Get(parameterName + "*", WildcardOptions.IgnoreCase);
diff --git a/src/System.Management.Automation/engine/CommandCompletion/PseudoParameterBinder.cs b/src/System.Management.Automation/engine/CommandCompletion/PseudoParameterBinder.cs
index a581a11af92..4201be16f93 100644
--- a/src/System.Management.Automation/engine/CommandCompletion/PseudoParameterBinder.cs
+++ b/src/System.Management.Automation/engine/CommandCompletion/PseudoParameterBinder.cs
@@ -982,7 +982,7 @@ internal PseudoBindingInfo DoPseudoParameterBinding(CommandAst command, Type pip
                             executionContext.LanguageMode = PSLanguageMode.ConstrainedLanguage;
                         }
 
-                        _bindingEffective = PrepareCommandElements(executionContext);
+                        _bindingEffective = PrepareCommandElements(executionContext, paramAstAtCursor);
                     }
                     finally
                     {
@@ -1189,7 +1189,7 @@ private void InitializeMembers()
             _duplicateParameters.Clear();
         }
 
-        private bool PrepareCommandElements(ExecutionContext context)
+        private bool PrepareCommandElements(ExecutionContext context, CommandParameterAst paramAtCursor)
         {
             int commandIndex = 0;
             bool dotSource = _commandAst.InvocationOperator == TokenKind.Dot;
@@ -1216,6 +1216,13 @@ private bool PrepareCommandElements(ExecutionContext context)
                 // Pre-processing the arguments -- command arguments
                 for (commandIndex++; commandIndex < _commandElements.Count; commandIndex++)
                 {
+                    if (implementsDynamicParameters && _commandElements[commandIndex] == paramAtCursor)
+                    {
+                        // Commands with dynamic parameters will try to bind the command elements.
+                        // A partially complete parameter will most likely cause a binding error and negatively affect the results.
+                        continue;
+                    }
+
                     var parameter = _commandElements[commandIndex] as CommandParameterAst;
                     if (parameter != null)
                     {
diff --git a/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1 b/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1
index d7c98b1589d..9e981f11866 100644
--- a/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1
+++ b/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1
@@ -883,6 +883,20 @@ class InheritedClassTest : System.Attribute
         $res.CompletionMatches.CompletionText | Should -Contain '-ProgressAction'
     }
 
+    It 'Should complete dynamic parameters with partial input' {
+        # See issue: #19498
+        try
+        {
+            Push-Location function:
+            $res = TabExpansion2 -inputScript 'Get-ChildItem -LiteralPath $PSHOME -File'
+            $res.CompletionMatches[0].CompletionText | Should -Be '-File'
+        }
+        finally
+        {
+            Pop-Location
+        }
+    }
+
     Context "Script name completion" {
         BeforeAll {
             Setup -f 'install-powershell.ps1' -Content ""

From 03ab9b1dd703b12e5826c60859cdeaa44afabde0 Mon Sep 17 00:00:00 2001
From: MartinGC94 <mgc94@outlook.dk>
Date: Tue, 16 May 2023 21:47:32 +0200
Subject: [PATCH 2/2] Fix test

---
 test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1 b/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1
index 9e981f11866..710abd5dbae 100644
--- a/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1
+++ b/test/powershell/Host/TabCompletion/TabCompletion.Tests.ps1
@@ -888,8 +888,8 @@ class InheritedClassTest : System.Attribute
         try
         {
             Push-Location function:
-            $res = TabExpansion2 -inputScript 'Get-ChildItem -LiteralPath $PSHOME -File'
-            $res.CompletionMatches[0].CompletionText | Should -Be '-File'
+            $res = TabExpansion2 -inputScript 'Get-ChildItem -LiteralPath $PSHOME -Fi'
+            $res.CompletionMatches[1].CompletionText | Should -Be '-File'
         }
         finally
         {