Enable building with a dotnet not on PATH

src/Compilers/Core/MSBuildTaskTests/TestUtilities/TaskTestUtil.cs

@@ -4,6 +4,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -40,7 +41,23 @@ public static void AssertCommandLine(
 
  var message = engine.BuildMessages.OfType<TaskCommandLineEventArgs>().Single();
  var commandLine = message.CommandLine.Replace(" ", " ").Trim();
- Assert.Equal($@"{RuntimeHostInfo.GetDotNetPathOrDefault()} exec ""{task.PathToManagedTool}"" {line}", commandLine);
+
+ var dotnetPath = RuntimeHostInfo.GetDotNetPathOrDefault();
+ var expectedCommandLine = $@"{dotnetPath} exec ""{task.PathToManagedTool}"" {line}";
+
+ bool isOnlyFileName = Path.GetFileName(dotnetPath).Length == dotnetPath.Length;
+ if (isOnlyFileName)
+ {
+ // When ToolTask.GenerateFullPathToTool() returns only a file name (not a path to a file), MSBuild's ToolTask
+ // will search the %PATH% (see https://github.com/dotnet/msbuild/blob/5410bf323451e04e99e79bcffd158e6d8d378149/src/Utilities/ToolTask.cs#L494-L513)
+ // and log the full path to the exe. In this case, only assert that the commandLine ends with the expected
+ // command line, and ignore the full path at the beginning.
+ Assert.EndsWith(expectedCommandLine, commandLine);
+ }
+ else
+ {
+ Assert.Equal(expectedCommandLine, commandLine);
+ }
 
  compilerTask.NoConfig = true;
  Assert.Equal("/noconfig", compilerTask.GenerateToolArguments());

src/Compilers/Shared/RuntimeHostInfo.cs

@@ -49,40 +49,15 @@ internal static (string processFilePath, string commandLineArguments, string too
 
  internal static bool IsCoreClrRuntime => true;
 
+ private const string DotNetHostPathEnvironmentName = "DOTNET_HOST_PATH";
+
  /// <summary>
- /// Get the path to the dotnet executable. In the case the host did not provide this information
+ /// Get the path to the dotnet executable. In the case the .NET SDK did not provide this information
  /// in the environment this will return simply "dotnet".
  /// </summary>
- /// <remarks>
- /// See the following issue for rationale why only %PATH% is considered
- /// https://github.com/dotnet/runtime/issues/88754
- /// </remarks>
- internal static string GetDotNetPathOrDefault()
- {
- var (fileName, sep) = PlatformInformation.IsWindows
- ? ("dotnet.exe", ';')
- : ("dotnet", ':');
-
- var path = Environment.GetEnvironmentVariable("PATH") ?? "";
- foreach (var item in path.Split(sep, StringSplitOptions.RemoveEmptyEntries))
- {
- try
- {
- var filePath = Path.Combine(item, fileName);
- if (File.Exists(filePath))
- {
- return filePath;
- }
- }
- catch
- {
- // If we can't read a directory for any reason just skip it
- }
- }
-
- return fileName;
- }
-
+ internal static string GetDotNetPathOrDefault() =>
+ Environment.GetEnvironmentVariable(DotNetHostPathEnvironmentName) ??
+ (PlatformInformation.IsWindows ? "dotnet.exe" : "dotnet");
 #else
 
  internal static bool IsCoreClrRuntime => false;