Add TryGetAbsolutePath to TaskEnvironment public API

src/Build.UnitTests/BackEnd/TaskEnvironment_Tests.cs

@@ -14,14 +14,11 @@ namespace Microsoft.Build.UnitTests
 {
     public class TaskEnvironment_Tests
     {
-        private const string StubEnvironmentName = "Stub";
-        private const string MultithreadedEnvironmentName = "Multithreaded";
-
         public static TheoryData<string> EnvironmentTypes =>
             new TheoryData<string>
             {
-                StubEnvironmentName,
-                MultithreadedEnvironmentName
+                nameof(MultiProcessTaskEnvironmentDriver),
+                nameof(MultiThreadedTaskEnvironmentDriver)
             };
 
         // CA2000 is suppressed because the caller is responsible for disposal via DisposeTaskEnvironment
@@ -30,8 +27,8 @@ private static TaskEnvironment CreateTaskEnvironment(string environmentType)
         {
             return environmentType switch
             {
-                StubEnvironmentName => TaskEnvironmentHelper.CreateForTest(),
-                MultithreadedEnvironmentName => new TaskEnvironment(new MultiThreadedTaskEnvironmentDriver(GetResolvedTempPath())),
+                nameof(MultiProcessTaskEnvironmentDriver) => TaskEnvironmentHelper.CreateForTest(),
+                nameof(MultiThreadedTaskEnvironmentDriver) => new TaskEnvironment(new MultiThreadedTaskEnvironmentDriver(GetResolvedTempPath())),
                 _ => throw new ArgumentException($"Unknown environment type: {environmentType}")
             };
         }
@@ -196,7 +193,7 @@ public void TaskEnvironment_SetAndGetProjectDirectory_ShouldWork(string environm
                 newRetrievedDirectory.Value.ShouldBe(alternateDirectory);
 
                 // Verify behavior differs based on environment type
-                if (environmentType == StubEnvironmentName)
+                if (environmentType == nameof(MultiProcessTaskEnvironmentDriver))
                 {
                     // Stub should change system current directory
                     Directory.GetCurrentDirectory().ShouldBe(alternateDirectory);
@@ -257,6 +254,56 @@ public void TaskEnvironment_GetAbsolutePath_WithAlreadyAbsolutePath_ShouldReturn
                 DisposeTaskEnvironment(taskEnvironment);
             }
         }
+
+        [Theory]
+        [MemberData(nameof(EnvironmentTypes))]
+        public void TaskEnvironment_TryGetAbsolutePath_ShouldReturnTrueForValidPaths(string environmentType)
+        {
+            var taskEnvironment = CreateTaskEnvironment(environmentType);
+            string baseDirectory = GetResolvedTempPath();
+            string relativePath = Path.Combine("subdir", "file.txt");
+            string originalDirectory = Directory.GetCurrentDirectory();
+
+            try
+            {
+                taskEnvironment.ProjectDirectory = new AbsolutePath(baseDirectory, ignoreRootedCheck: true);
+
+                var expected = taskEnvironment.GetAbsolutePath(relativePath);
+
+                bool result = taskEnvironment.TryGetAbsolutePath(relativePath, out AbsolutePath actual);
+
+                result.ShouldBeTrue();
+                actual.Value.ShouldBe(expected.Value);
+            }
+            finally
+            {
+                DisposeTaskEnvironment(taskEnvironment);
+                Directory.SetCurrentDirectory(originalDirectory);
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(EnvironmentTypes))]
+        public void TaskEnvironment_TryGetAbsolutePath_ShouldReturnFalseForInvalidPath(string environmentType)
+        {
+            var taskEnvironment = CreateTaskEnvironment(environmentType);
+
+            try
+            {
+                // Construct a path containing an invalid path character
+                char invalidChar = Path.GetInvalidPathChars().FirstOrDefault();
+                string invalidPath = "invalid" + invalidChar + "path";
+
+                bool result = taskEnvironment.TryGetAbsolutePath(invalidPath, out AbsolutePath _);
+
+                // TryGetAbsolutePath should return false rather than throw
+                result.ShouldBeFalse();
+            }
+            finally
+            {
+                DisposeTaskEnvironment(taskEnvironment);
+            }
+        }
 
         [Theory]
         [MemberData(nameof(EnvironmentTypes))]
@@ -277,7 +324,7 @@ public void TaskEnvironment_GetProcessStartInfo_ShouldConfigureCorrectly(string
 
                 processStartInfo.ShouldNotBeNull();
 
-                if (environmentType == StubEnvironmentName)
+                if (environmentType == nameof(MultiProcessTaskEnvironmentDriver))
                 {
                     // Stub should reflect system environment, but working directory should be empty
                     processStartInfo.WorkingDirectory.ShouldBe(string.Empty);

src/Build/BackEnd/TaskExecutionHost/MultiProcessTaskEnvironmentDriver.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.IO;
 using Microsoft.Build.Framework;
 using Microsoft.Build.Internal;
 
@@ -41,7 +40,13 @@ public AbsolutePath ProjectDirectory
         /// <inheritdoc/>
         public AbsolutePath GetAbsolutePath(string path)
         {
-            return new AbsolutePath(Path.GetFullPath(path), ignoreRootedCheck: true);
+#pragma warning disable IDE0002
+            // Calling to the System.IO.Path.Combine via fully-qualified name,
+            // as Microsoft.IO.Path.Combine does not throw on illegal characters in the path.
+            // We would like to keep the behavior consistent between dotnet build and msbuild.exe.           
+            return new AbsolutePath(System.IO.Path.Combine(NativeMethodsShared.GetCurrentDirectory(), path), ignoreRootedCheck: true);
+#pragma warning restore IDE0002
+
         }
 
         /// <inheritdoc/>

src/Build/BackEnd/TaskExecutionHost/MultiThreadedTaskEnvironmentDriver.cs

@@ -63,7 +63,7 @@ public AbsolutePath ProjectDirectory
             {
                 _currentDirectory = value;
                 // Keep the thread-static in sync for use by Expander and Modifiers during property/item expansion.
-                // This allows Path.GetFullPath and %(FullPath) to resolve relative paths correctly in multithreaded mode.
+                // This allows Path.GetFullPath and %(FullPath) functions used in project files to resolve relative paths correctly in multithreaded mode.
                 FileUtilities.CurrentThreadWorkingDirectory = value.Value;
             }
         }

src/Framework/ITaskEnvironmentDriver.cs

@@ -25,6 +25,9 @@ internal interface ITaskEnvironmentDriver : IDisposable
         /// </summary>
         /// <param name="path">The path to convert to absolute.</param>
         /// <returns>An absolute path representation.</returns>
+        /// <remarks>
+        /// May throw exceptions in case of invalid input (the exceptions are thrown by <see cref="System.IO.Path.Combine(string,string)"/> that is used internally in both implementations).
+        /// </remarks>
         AbsolutePath GetAbsolutePath(string path);
 
         /// <summary>

src/Framework/PathHelpers/AbsolutePath.cs

@@ -85,7 +85,19 @@ private static void ValidatePath(string path)
         /// </summary>
         /// <param name="path">The path to combine with the base path.</param>
         /// <param name="basePath">The base path to combine with.</param>
-        public AbsolutePath(string path, AbsolutePath basePath) => Value = Path.Combine(basePath.Value, path);
+        /// <exception cref="System.ArgumentException">
+        /// Thrown when either <paramref name="path"/> or <paramref name="basePath"/> contains one or more invalid path characters as
+        /// returned by <see cref="System.IO.Path.GetInvalidPathChars"/>.
+        /// </exception>
+        public AbsolutePath(string path, AbsolutePath basePath)
+        {
+#pragma warning disable IDE0002
+            // Calling to the System.IO.Path.Combine via fully-qualified name,
+            // as Microsoft.IO.Path.Combine does not throw on illegal characters in the path.
+            // We would like to keep the behavior consistent between dotnet build and msbuild.exe.           
+            Value = System.IO.Path.Combine(basePath.Value, path);
+#pragma warning restore IDE0002
+        }
 
         /// <summary>
         /// Implicitly converts an AbsolutePath to a string.

src/Framework/TaskEnvironment.cs

@@ -33,12 +33,37 @@ public AbsolutePath ProjectDirectory
 
         /// <summary>
         /// Converts a relative or absolute path string to an absolute path.
-        /// This function resolves paths relative to ProjectDirectory.
+        /// This function resolves paths relative to <see cref="ProjectDirectory"/>.
         /// </summary>
         /// <param name="path">The path to convert.</param>
         /// <returns>An absolute path representation.</returns>
+        /// <exception cref="System.ArgumentException">
+        /// Thrown when <paramref name="path"/> contains one or more invalid path characters as
+        /// returned by <see cref="System.IO.Path.GetInvalidPathChars"/>.
+        /// </exception>
         public AbsolutePath GetAbsolutePath(string path) => _driver.GetAbsolutePath(path);
 
+        /// <summary>
+        /// Converts a relative or absolute path string to an absolute path.
+        /// This function resolves paths relative to <see cref="ProjectDirectory"/>.
+        /// </summary>
+        /// <param name="path">The path to convert to absolute.</param>
+        /// <param name="absolutePath">The resulting absolute path if the conversion succeeded; default otherwise.</param>
+        /// <returns>True if the conversion succeeded; false otherwise.</returns>
+        public bool TryGetAbsolutePath(string path, out AbsolutePath absolutePath)
+        {
+            try
+            {
+                absolutePath = GetAbsolutePath(path);
+                return true;
+            }
+            catch
+            {
+                absolutePath = default;
+                return false;
+            }
+        }
+
         /// <summary>
         /// Gets the value of an environment variable.
         /// </summary>
@@ -77,4 +102,4 @@ public AbsolutePath ProjectDirectory
         /// </summary>
         internal void Dispose() => _driver.Dispose();
     }
-}
+}