Add regression tests for whitespace parameter names in LLVM IR generation and fix LlvmIrFunction constructor

Co-authored-by: jonathanpeppers <840039+jonathanpeppers@users.noreply.github.com>

Author: Copilot

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/LlvmIrGeneratorTests.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using Microsoft.Build.Utilities;
+using NUnit.Framework;
+using Xamarin.Android.Tasks.LLVMIR;
+using Xamarin.Android.Tools;
+
+namespace Xamarin.Android.Build.Tests.Tasks
+{
+	[TestFixture]
+	public class LlvmIrGeneratorTests
+	{
+		/// <summary>
+		/// Regression test for https://github.com/dotnet/android/issues/10086
+		///
+		/// When a managed method parameter has a whitespace-only name, the LLVM IR
+		/// generator would produce invalid IR like:
+		///   define void @test(ptr noundef % )
+		///
+		/// The fix ensures whitespace-only names are normalized to null before
+		/// creating LlvmIrFunctionParameter instances, so that LlvmIrFunction
+		/// assigns them valid numeric names (e.g., %0, %1).
+		/// </summary>
+		[Test]
+		[TestCase (null, Description = "Null parameter name")]
+		[TestCase ("", Description = "Empty parameter name")]
+		[TestCase (" ", Description = "Space-only parameter name")]
+		[TestCase ("  ", Description = "Multiple spaces parameter name")]
+		[TestCase ("\t", Description = "Tab-only parameter name")]
+		public void FunctionParameterWithInvalidName_GetsNumericName (string? paramName)
+		{
+			var parameters = new List<LlvmIrFunctionParameter> {
+				new LlvmIrFunctionParameter (typeof (IntPtr), "env"),
+				new LlvmIrFunctionParameter (typeof (IntPtr), "klass"),
+				new LlvmIrFunctionParameter (typeof (IntPtr), paramName),
+			};
+
+			var func = new LlvmIrFunction ("test_function", typeof (void), parameters);
+
+			// The third parameter should have been assigned a numeric name
+			var thirdParam = func.Signature.Parameters[2];
+			Assert.IsNotNull (thirdParam.Name, "Parameter name should not be null after LlvmIrFunction construction");
+			Assert.IsNotEmpty (thirdParam.Name, "Parameter name should not be empty after LlvmIrFunction construction");
+			Assert.That (thirdParam.Name.Trim (), Is.Not.Empty, "Parameter name should not be whitespace-only after LlvmIrFunction construction");
+		}
+
+		/// <summary>
+		/// Verifies that the LLVM IR generator produces valid function signatures
+		/// when parameters have valid names, including numeric names assigned to
+		/// previously unnamed parameters.
+		/// </summary>
+		[Test]
+		public void GeneratedIR_FunctionWithUnnamedParameter_ProducesValidOutput ()
+		{
+			var parameters = new List<LlvmIrFunctionParameter> {
+				new LlvmIrFunctionParameter (typeof (IntPtr), "env"),
+				new LlvmIrFunctionParameter (typeof (IntPtr), "klass"),
+				new LlvmIrFunctionParameter (typeof (IntPtr), null), // unnamed parameter
+			};
+
+			var func = new LlvmIrFunction ("test_function", typeof (void), parameters);
+
+			var log = new TaskLoggingHelper (new MockBuildEngine (TestContext.Out, [], [], []), "test");
+			var module = new LlvmIrModule (new LlvmIrTypeCache (), log);
+			func.Body.Ret (typeof (void));
+			module.Add (func);
+			module.AfterConstruction ();
+
+			var generator = LlvmIrGenerator.Create (AndroidTargetArch.Arm64, "test.ll");
+			using var writer = new StringWriter ();
+			generator.Generate (writer, module);
+
+			string output = writer.ToString ();
+			// The output should contain valid parameter declarations - no "% " pattern
+			Assert.That (output, Does.Not.Contain ("% "), "Generated LLVM IR should not contain whitespace-only parameter names");
+			Assert.That (output, Does.Contain ("@test_function"), "Generated LLVM IR should contain the function name");
+		}
+	}
+}

src/Xamarin.Android.Build.Tasks/Utilities/LlvmIrGenerator/LlvmIrFunction.cs

@@ -442,7 +442,7 @@ public LlvmIrFunction (LlvmIrFunctionSignature signature, LlvmIrFunctionAttribut
 					continue;
 				}
 
-				if (!String.IsNullOrEmpty (parameter.Name)) {
+				if (!String.IsNullOrWhiteSpace (parameter.Name)) {
 					continue;
 				}