From 5a3db984c52d625828a6259bc23c7ab3431350cb Mon Sep 17 00:00:00 2001
From: Adam Sitnik <adam.sitnik@gmail.com>
Date: Thu, 15 Dec 2022 16:57:46 +0100
Subject: [PATCH 1/3] don't create unnecessary lambdas

---
 src/System.CommandLine/Argument{T}.cs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/System.CommandLine/Argument{T}.cs b/src/System.CommandLine/Argument{T}.cs
index 85467134f2..c2008032f3 100644
--- a/src/System.CommandLine/Argument{T}.cs
+++ b/src/System.CommandLine/Argument{T}.cs
@@ -39,7 +39,7 @@ public Argument(
             Func<T> defaultValueFactory, 
             string? description = null) : this(name, description)
         {
-            SetDefaultValueFactory(() => defaultValueFactory());
+            SetDefaultValueFactory(defaultValueFactory);
         }
 
         /// <summary>
@@ -63,7 +63,7 @@ public Argument(
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="defaultValueFactory"/> is null.</exception>
         public Argument(Func<T> defaultValueFactory) : this()
         {
-            SetDefaultValueFactory(() => defaultValueFactory());
+            SetDefaultValueFactory(defaultValueFactory);
         }
 
         /// <summary>
@@ -132,7 +132,7 @@ public Argument(Func<ArgumentResult, T> parse, bool isDefault = false) : this(nu
         /// <param name="value">The default value for the argument.</param>
         public void SetDefaultValue(T value)
         {
-            SetDefaultValueFactory(() => value);
+            SetDefaultValueFactory(_ => value);
         }
 
         /// <summary>

From 20525f6ca985b2bd023ae285b188cb79ee8c83f2 Mon Sep 17 00:00:00 2001
From: Adam Sitnik <adam.sitnik@gmail.com>
Date: Thu, 15 Dec 2022 16:58:11 +0100
Subject: [PATCH 2/3] the Argument<T> ctor will throw for null anyway

---
 src/System.CommandLine/Option{T}.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/System.CommandLine/Option{T}.cs b/src/System.CommandLine/Option{T}.cs
index 1f75694a78..38a7b21949 100644
--- a/src/System.CommandLine/Option{T}.cs
+++ b/src/System.CommandLine/Option{T}.cs
@@ -51,7 +51,7 @@ public Option(
             Func<T> defaultValueFactory,
             string? description = null) 
             : this(name, description, 
-                  new Argument<T>(defaultValueFactory ?? throw new ArgumentNullException(nameof(defaultValueFactory))))
+                  new Argument<T>(defaultValueFactory))
         { }
 
         /// <inheritdoc/>
@@ -59,7 +59,7 @@ public Option(
             string[] aliases,
             Func<T> defaultValueFactory,
             string? description = null)
-            : this(aliases, description, new Argument<T>(defaultValueFactory ?? throw new ArgumentNullException(nameof(defaultValueFactory))))
+            : this(aliases, description, new Argument<T>(defaultValueFactory))
         {
         }
 

From 0f80fd2047705aee0d309229c91843e9d0772cae Mon Sep 17 00:00:00 2001
From: Adam Sitnik <adam.sitnik@gmail.com>
Date: Thu, 15 Dec 2022 16:59:08 +0100
Subject: [PATCH 3/3] avoid closure allocations

---
 src/System.CommandLine/Argument{T}.cs | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/System.CommandLine/Argument{T}.cs b/src/System.CommandLine/Argument{T}.cs
index c2008032f3..500259f150 100644
--- a/src/System.CommandLine/Argument{T}.cs
+++ b/src/System.CommandLine/Argument{T}.cs
@@ -210,10 +210,10 @@ void UnrecognizedArgumentError(ArgumentResult argumentResult)
         /// <returns>The configured argument.</returns>
         public Argument<T> AcceptLegalFilePathsOnly()
         {
-            var invalidPathChars = Path.GetInvalidPathChars();
-
-            Validators.Add(result =>
+            Validators.Add(static result =>
             {
+                var invalidPathChars = Path.GetInvalidPathChars();
+
                 for (var i = 0; i < result.Tokens.Count; i++)
                 {
                     var token = result.Tokens[i];
@@ -239,10 +239,10 @@ public Argument<T> AcceptLegalFilePathsOnly()
         /// <returns>The configured argument.</returns>
         public Argument<T> AcceptLegalFileNamesOnly()
         {
-            var invalidFileNameChars = Path.GetInvalidFileNameChars();
-
-            Validators.Add(result =>
+            Validators.Add(static result =>
             {
+                var invalidFileNameChars = Path.GetInvalidFileNameChars();
+
                 for (var i = 0; i < result.Tokens.Count; i++)
                 {
                     var token = result.Tokens[i];