.Net: Allow hyphens in function name (#12389)

### Motivation, Context and Description

This PR allows hyphens in function names for seamless integration with
MCP tools and M.E.AI functions that support hyphens in their names.

Out of the scope of the PR is support for functions with hyphens in SK
prompt templates, which will need to be extended to support hyphens
when/if needed.

Author: SergeyMenshykh

dotnet/src/InternalUtilities/src/Diagnostics/KernelVerify.cs

@@ -13,16 +13,22 @@ internal static partial class KernelVerify
 {
 #if NET
     [GeneratedRegex("^[0-9A-Za-z_]*$")]
-    private static partial Regex AsciiLettersDigitsUnderscoresRegex();
+    private static partial Regex AllowedPluginNameSymbolsRegex();
+
+    [GeneratedRegex("^[0-9A-Za-z_-]*$")]
+    private static partial Regex AllowedFunctionNameSymbolsRegex();
 #else
-    private static Regex AsciiLettersDigitsUnderscoresRegex() => s_asciiLettersDigitsUnderscoresRegex;
-    private static readonly Regex s_asciiLettersDigitsUnderscoresRegex = new("^[0-9A-Za-z_]*$", RegexOptions.Compiled);
+    private static Regex AllowedPluginNameSymbolsRegex() => s_allowedPluginNameSymbolsRegex;
+    private static readonly Regex s_allowedPluginNameSymbolsRegex = new("^[0-9A-Za-z_]*$", RegexOptions.Compiled);
+
+    private static Regex AllowedFunctionNameSymbolsRegex() => s_allowedFunctionNameSymbolsRegex;
+    private static readonly Regex s_allowedFunctionNameSymbolsRegex = new("^[0-9A-Za-z_-]*$", RegexOptions.Compiled);
 #endif
 
     internal static void ValidPluginName([NotNull] string? pluginName, IReadOnlyKernelPluginCollection? plugins = null, [CallerArgumentExpression(nameof(pluginName))] string? paramName = null)
     {
         Verify.NotNullOrWhiteSpace(pluginName);
-        if (!AsciiLettersDigitsUnderscoresRegex().IsMatch(pluginName))
+        if (!AllowedPluginNameSymbolsRegex().IsMatch(pluginName))
         {
             Verify.ThrowArgumentInvalidName("plugin name", pluginName, paramName);
         }
@@ -36,7 +42,7 @@ internal static void ValidPluginName([NotNull] string? pluginName, IReadOnlyKern
     internal static void ValidFunctionName([NotNull] string? functionName, [CallerArgumentExpression(nameof(functionName))] string? paramName = null)
     {
         Verify.NotNullOrWhiteSpace(functionName);
-        if (!AsciiLettersDigitsUnderscoresRegex().IsMatch(functionName))
+        if (!AllowedFunctionNameSymbolsRegex().IsMatch(functionName))
         {
             Verify.ThrowArgumentInvalidName("function name", functionName, paramName);
         }

dotnet/src/InternalUtilities/src/Diagnostics/Verify.cs

@@ -15,15 +15,9 @@ namespace Microsoft.SemanticKernel;
 internal static partial class Verify
 {
 #if NET
-    [GeneratedRegex("^[0-9A-Za-z_]*$")]
-    private static partial Regex AsciiLettersDigitsUnderscoresRegex();
-
     [GeneratedRegex("^[^.]+\\.[^.]+$")]
     private static partial Regex FilenameRegex();
 #else
-    private static Regex AsciiLettersDigitsUnderscoresRegex() => s_asciiLettersDigitsUnderscoresRegex;
-    private static readonly Regex s_asciiLettersDigitsUnderscoresRegex = new("^[0-9A-Za-z_]*$", RegexOptions.Compiled);
-
     private static Regex FilenameRegex() => s_filenameRegex;
     private static readonly Regex s_filenameRegex = new("^[^.]+\\.[^.]+$", RegexOptions.Compiled);
 #endif
@@ -75,15 +69,6 @@ public static void True(bool condition, string message, [CallerArgumentExpressio
         }
     }
 
-    internal static void ValidFunctionName([NotNull] string? functionName, [CallerArgumentExpression(nameof(functionName))] string? paramName = null)
-    {
-        NotNullOrWhiteSpace(functionName);
-        if (!AsciiLettersDigitsUnderscoresRegex().IsMatch(functionName))
-        {
-            ThrowArgumentInvalidName("function name", functionName, paramName);
-        }
-    }
-
     internal static void ValidFilename([NotNull] string? filename, [CallerArgumentExpression(nameof(filename))] string? paramName = null)
     {
         NotNullOrWhiteSpace(filename);

dotnet/src/SemanticKernel.UnitTests/Functions/KernelFunctionFromMethodTests1.cs

@@ -1556,6 +1556,28 @@ static TestReturnType StaticMethod(TestParameterType p1)
         Assert.Equal("""{"type":"object","properties":{"Result":{"type":"integer"}}}""", metadata.ReturnParameter.Schema!.ToString());
     }
 
+    [InlineData("f_1", true)]
+    [InlineData("f-1", true)]
+    [InlineData("f+1", false)]
+    [InlineData("f?1", false)]
+    [Theory]
+    public void ItShouldValidateFunctionName(string name, bool allowed)
+    {
+        // Arrange & Act & Assert
+        if (allowed)
+        {
+            // Should not throw
+            KernelFunctionFactory.CreateFromMethod(() => { }, functionName: name);
+            KernelFunctionFactory.CreateFromMethod(() => { }, new KernelFunctionFromMethodOptions() { FunctionName = name });
+        }
+        else
+        {
+            // Should throw
+            Assert.Throws<ArgumentException>(() => KernelFunctionFactory.CreateFromMethod(() => { }, functionName: name));
+            Assert.Throws<ArgumentException>(() => KernelFunctionFactory.CreateFromMethod(() => { }, new KernelFunctionFromMethodOptions() { FunctionName = name }));
+        }
+    }
+
 #pragma warning disable CA1812 // Avoid uninstantiated internal classes
     private sealed class CustomTypeForJsonTests
 #pragma warning restore CA1812 // Avoid uninstantiated internal classes