8 files changed, 119 insertions, 46 deletions

diff --git a/src/WixToolset.BuildTasks/HeatTask.cs b/src/WixToolset.BuildTasks/HeatTask.cs
index 586f02f7..5feed26d 100644
--- a/src/WixToolset.BuildTasks/HeatTask.cs
+++ b/src/WixToolset.BuildTasks/HeatTask.cs
@@ -59,7 +59,8 @@ namespace WixToolset.BuildTasks
             set { this.transforms = value; }
         }
 
-        protected override string TaskShortName => "HEAT";
+        protected sealed override string TaskShortName => "HEAT";
+        protected sealed override string ToolName => "heat.exe";
 
         /// <summary>
         /// Gets the name of the heat operation performed by the task.
@@ -71,10 +72,8 @@ namespace WixToolset.BuildTasks
             get;
         }
 
-        protected override void ExecuteCore(IWixToolsetServiceProvider serviceProvider, IMessageListener listener, string commandLineString)
+        protected sealed override int ExecuteCore(IWixToolsetServiceProvider serviceProvider, IMessageListener listener, string commandLineString)
         {
-            this.Log.LogMessage(MessageImportance.Normal, "heat.exe " + commandLineString);
-
             var messaging = serviceProvider.GetService<IMessaging>();
             messaging.SetListener(listener);
 
@@ -83,7 +82,7 @@ namespace WixToolset.BuildTasks
 
             var commandLine = HeatCommandLineFactory.CreateCommandLine(serviceProvider, true);
             var command = commandLine.ParseStandardCommandLine(arguments);
-            command?.Execute();
+            return command?.Execute() ?? -1;
         }
 
         /// <summary>
diff --git a/src/WixToolset.BuildTasks/ToolsetTask.cs b/src/WixToolset.BuildTasks/ToolsetTask.cs
index 713a938b..fe6812fc 100644
--- a/src/WixToolset.BuildTasks/ToolsetTask.cs
+++ b/src/WixToolset.BuildTasks/ToolsetTask.cs
@@ -3,14 +3,16 @@
 namespace WixToolset.BuildTasks
 {
     using System;
+    using System.IO;
     using System.Runtime.InteropServices;
+    using Microsoft.Build.Framework;
     using Microsoft.Build.Utilities;
     using WixToolset.Core;
     using WixToolset.Data;
     using WixToolset.Extensibility;
     using WixToolset.Extensibility.Services;
 
-    public abstract class ToolsetTask : Task
+    public abstract class ToolsetTask : ToolTask
     {
         /// <summary>
         /// Gets or sets additional options that are appended the the tool command-line.
@@ -27,6 +29,12 @@ namespace WixToolset.BuildTasks
         public bool NoLogo { get; set; }
 
         /// <summary>
+        /// Gets or sets a flag indicating whether the task
+        /// should be run as separate process or in-proc.
+        /// </summary>
+        public bool RunAsSeparateProcess { get; set; }
+
+        /// <summary>
         /// Gets or sets whether all warnings should be suppressed.
         /// </summary>
         public bool SuppressAllWarnings { get; set; }
@@ -51,19 +59,27 @@ namespace WixToolset.BuildTasks
         /// </summary>
         public bool VerboseOutput { get; set; }
 
-        public override bool Execute()
+        protected sealed override int ExecuteTool(string pathToTool, string responseFileCommands, string commandLineCommands)
         {
-            var serviceProvider = WixToolsetServiceProviderFactory.CreateServiceProvider();
+            if (this.RunAsSeparateProcess)
+            {
+                return base.ExecuteTool(pathToTool, responseFileCommands, commandLineCommands);
+            }
+
+            return this.ExecuteInProc($"{commandLineCommands} {responseFileCommands}");
+        }
 
+        private int ExecuteInProc(string commandLineString)
+        {
+            this.Log.LogMessage(MessageImportance.Normal, $"({this.ToolName}){commandLineString}");
+
+            var serviceProvider = WixToolsetServiceProviderFactory.CreateServiceProvider();
             var listener = new MsbuildMessageListener(this.Log, this.TaskShortName, this.BuildEngine.ProjectFileOfTaskNode);
+            int exitCode = -1;
 
             try
             {
-                var commandLineBuilder = new WixCommandLineBuilder();
-                this.BuildCommandLine(commandLineBuilder);
-
-                var commandLineString = commandLineBuilder.ToString();
-                this.ExecuteCore(serviceProvider, listener, commandLineString);
+                exitCode = this.ExecuteCore(serviceProvider, listener, commandLineString);
             }
             catch (WixException e)
             {
@@ -79,7 +95,47 @@ namespace WixToolset.BuildTasks
                 }
             }
 
-            return !this.Log.HasLoggedErrors;
+            if (exitCode == 0 && this.Log.HasLoggedErrors)
+            {
+                exitCode = -1;
+            }
+            return exitCode;
+        }
+
+        /// <summary>
+        /// Get the path to the executable.
+        /// </summary>
+        /// <remarks>
+        /// ToolTask only calls GenerateFullPathToTool when the ToolPath property is not set.
+        /// WiX never sets the ToolPath property, but the user can through $(WixToolDir).
+        /// If we return only a file name, ToolTask will search the system paths for it.
+        /// </remarks>
+        protected sealed override string GenerateFullPathToTool()
+        {
+            var thisDllPath = new Uri(typeof(ToolsetTask).Assembly.CodeBase).AbsolutePath;
+            if (this.RunAsSeparateProcess)
+            {
+                return Path.Combine(Path.GetDirectoryName(thisDllPath), this.ToolExe);
+            }
+
+            // We need to return a path that exists, so if we're not actually going to run the tool then just return this dll path.
+            return thisDllPath;
+        }
+
+        protected sealed override string GenerateResponseFileCommands()
+        {
+            var commandLineBuilder = new WixCommandLineBuilder();
+            this.BuildCommandLine(commandLineBuilder);
+            return commandLineBuilder.ToString();
+        }
+
+        protected sealed override void LogToolCommand(string message)
+        {
+            // Only log this if we're actually going to do it.
+            if (this.RunAsSeparateProcess)
+            {
+                base.LogToolCommand(message);
+            }
         }
 
         /// <summary>
@@ -98,7 +154,7 @@ namespace WixToolset.BuildTasks
             commandLineBuilder.AppendIfTrue("-wx", this.TreatWarningsAsErrors);
         }
 
-        protected abstract void ExecuteCore(IWixToolsetServiceProvider serviceProvider, IMessageListener messageListener, string commandLineString);
+        protected abstract int ExecuteCore(IWixToolsetServiceProvider serviceProvider, IMessageListener messageListener, string commandLineString);
 
         protected abstract string TaskShortName { get; }
     }
diff --git a/src/WixToolset.BuildTasks/WixBuild.cs b/src/WixToolset.BuildTasks/WixBuild.cs
index b8fb4136..c15bc2f7 100644
--- a/src/WixToolset.BuildTasks/WixBuild.cs
+++ b/src/WixToolset.BuildTasks/WixBuild.cs
@@ -4,10 +4,7 @@ namespace WixToolset.BuildTasks
 {
     using System;
     using System.Collections.Generic;
-    using System.Runtime.InteropServices;
     using Microsoft.Build.Framework;
-    using Microsoft.Build.Utilities;
-    using WixToolset.Core;
     using WixToolset.Data;
     using WixToolset.Extensibility;
     using WixToolset.Extensibility.Data;
@@ -80,11 +77,10 @@ namespace WixToolset.BuildTasks
         public string AdditionalCub { get; set; }
 
         protected override string TaskShortName => "WIX";
+        protected override string ToolName => "wix.exe";
 
-        protected override void ExecuteCore(IWixToolsetServiceProvider serviceProvider, IMessageListener listener, string commandLineString)
+        protected override int ExecuteCore(IWixToolsetServiceProvider serviceProvider, IMessageListener listener, string commandLineString)
         {
-            this.Log.LogMessage(MessageImportance.Normal, "wix.exe " + commandLineString);
-
             var messaging = serviceProvider.GetService<IMessaging>();
             messaging.SetListener(listener);
 
@@ -95,7 +91,7 @@ namespace WixToolset.BuildTasks
             commandLine.ExtensionManager = this.CreateExtensionManagerWithStandardBackends(serviceProvider, messaging, arguments.Extensions);
             commandLine.Arguments = arguments;
             var command = commandLine.ParseStandardCommandLine();
-            command?.Execute();
+            return command?.Execute() ?? -1;
         }
 
         protected override void BuildCommandLine(WixCommandLineBuilder commandLineBuilder)
diff --git a/src/WixToolset.MSBuild/tools/wix.harvest.targets b/src/WixToolset.MSBuild/tools/wix.harvest.targets
index e4d866ea..dea44469 100644
--- a/src/WixToolset.MSBuild/tools/wix.harvest.targets
+++ b/src/WixToolset.MSBuild/tools/wix.harvest.targets
@@ -3,6 +3,10 @@
 
 
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <!-- These properties can be overridden to support non-default installations. -->
+  <PropertyGroup>
+    <HeatToolDir Condition=" '$(HeatToolDir)' == '' ">$(WixToolDir)</HeatToolDir>
+  </PropertyGroup>
 
   <!-- These tasks are extensions for harvesting WiX source code from other sources. -->
   <UsingTask TaskName="HeatFile" AssemblyFile="$(WixTasksPath)" />
@@ -274,7 +278,10 @@
       Configuration="%(_AllHeatProjects.Configuration)"
       Platform="%(_AllHeatProjects.Platform)"
       GenerateWixVariables="$(HarvestProjectsGenerateWixVariables)"
-      AdditionalOptions="$(HarvestProjectsAdditionalOptions)">
+      AdditionalOptions="$(HarvestProjectsAdditionalOptions)"
+      RunAsSeparateProcess="$(RunWixToolsOutOfProc)"
+      ToolExe="$(HeatToolExe)"
+      ToolPath="$(HeatToolDir)">
 
       <Output TaskParameter="OutputFile" ItemName="Compile" />
       <Output TaskParameter="OutputFile" ItemName="FileWrites" />
@@ -359,7 +366,10 @@
       SuppressCom="%(HarvestDirectory.SuppressCom)"
       SuppressRootDirectory="%(HarvestDirectory.SuppressRootDirectory)"
       SuppressRegistry="%(HarvestDirectory.SuppressRegistry)"
-      AdditionalOptions="$(HarvestDirectoryAdditionalOptions)">
+      AdditionalOptions="$(HarvestDirectoryAdditionalOptions)"
+      RunAsSeparateProcess="$(RunWixToolsOutOfProc)"
+      ToolExe="$(HeatToolExe)"
+      ToolPath="$(HeatToolDir)">
 
       <Output TaskParameter="OutputFile" ItemName="Compile" />
       <Output TaskParameter="OutputFile" ItemName="FileWrites" />
@@ -432,7 +442,10 @@
       SuppressCom="%(HarvestFile.SuppressCom)"
       SuppressRegistry="%(HarvestFile.SuppressRegistry)"
       SuppressRootDirectory="%(HarvestFile.SuppressRootDirectory)"
-      AdditionalOptions="$(HarvestFileAdditionalOptions)">
+      AdditionalOptions="$(HarvestFileAdditionalOptions)"
+      RunAsSeparateProcess="$(RunWixToolsOutOfProc)"
+      ToolExe="$(HeatToolExe)"
+      ToolPath="$(HeatToolDir)">
 
       <Output TaskParameter="OutputFile" ItemName="Compile" />
       <Output TaskParameter="OutputFile" ItemName="FileWrites" />
diff --git a/src/WixToolset.MSBuild/tools/wix.targets b/src/WixToolset.MSBuild/tools/wix.targets
index 62414017..6914d03e 100644
--- a/src/WixToolset.MSBuild/tools/wix.targets
+++ b/src/WixToolset.MSBuild/tools/wix.targets
@@ -249,11 +249,6 @@
 
     <Error
       Code="WIX102"
-      Condition=" '$(MSBuildToolsVersion)' == '' OR '$(MSBuildToolsVersion)' &lt; '4.0' "
-      Text="MSBuild v$(MSBuildToolsVersion) is not supported by the project &quot;$(MSBuildProjectFile)&quot;. You must use MSBuild v4.0 or later." />
-
-    <Error
-      Code="WIX103"
       Condition=" '$(WixPdbType)' != 'none' and '$(WixPdbType)' != 'full' "
       Text="The WixPdbType property '$(WixPdbType)' is not valid in project &quot;$(MSBuildProjectFile)&quot;. Supported values are: 'full', 'none'" />
 
@@ -695,7 +690,11 @@
 
         SuppressValidation="$(SuppressValidation)"
         SuppressIces="$(SuppressIces)"
-        AdditionalCub="$(AdditionalCub)" />
+        AdditionalCub="$(AdditionalCub)"
+
+        RunAsSeparateProcess="$(RunWixToolsOutOfProc)"
+        ToolExe="$(WixToolExe)"
+        ToolPath="$(WixToolDir)" />
 
     <!--
     SuppressAllWarnings="$(CompilerSuppressAllWarnings);$(LinkerSuppressAllWarnings)"
diff --git a/src/test/WixToolsetTest.MSBuild/MsbuildFixture.cs b/src/test/WixToolsetTest.MSBuild/MsbuildFixture.cs
index 210473fa..6862f2a8 100644
--- a/src/test/WixToolsetTest.MSBuild/MsbuildFixture.cs
+++ b/src/test/WixToolsetTest.MSBuild/MsbuildFixture.cs
@@ -28,9 +28,6 @@ namespace WixToolsetTest.MSBuild
                 var result = MsbuildUtilities.BuildProject(buildSystem, projectPath);
                 result.AssertSuccess();
 
-                var platformSwitches = result.Output.Where(line => line.TrimStart().StartsWith("wix.exe build -platform x86"));
-                Assert.Single(platformSwitches);
-
                 var warnings = result.Output.Where(line => line.Contains(": warning"));
                 Assert.Empty(warnings);
 
@@ -63,9 +60,6 @@ namespace WixToolsetTest.MSBuild
                 var result = MsbuildUtilities.BuildProject(buildSystem, projectPath);
                 result.AssertSuccess();
 
-                var platformSwitches = result.Output.Where(line => line.TrimStart().StartsWith("wix.exe build -platform x86"));
-                Assert.Single(platformSwitches);
-
                 var warnings = result.Output.Where(line => line.Contains(": warning"));
                 Assert.Empty(warnings);
 
@@ -98,7 +92,7 @@ namespace WixToolsetTest.MSBuild
                 var result = MsbuildUtilities.BuildProject(buildSystem, projectPath);
                 result.AssertSuccess();
 
-                var platformSwitches = result.Output.Where(line => line.TrimStart().StartsWith("wix.exe build -platform x86"));
+                var platformSwitches = result.Output.Where(line => line.Contains("-platform x86"));
                 Assert.Single(platformSwitches);
 
                 var warnings = result.Output.Where(line => line.Contains(": warning"));
@@ -223,7 +217,7 @@ namespace WixToolsetTest.MSBuild
                 });
                 result.AssertSuccess();
 
-                var platformSwitches = result.Output.Where(line => line.TrimStart().StartsWith("wix.exe build -platform x64"));
+                var platformSwitches = result.Output.Where(line => line.Contains("-platform x64"));
                 Assert.Single(platformSwitches);
 
                 var paths = Directory.EnumerateFiles(binFolder, @"*.*", SearchOption.AllDirectories)
@@ -287,9 +281,11 @@ namespace WixToolsetTest.MSBuild
         }
 
         [Theory]
-        [InlineData(BuildSystem.MSBuild)]
-        [InlineData(BuildSystem.MSBuild64)]
-        public void CanBuildSimpleMsiPackageAsWixipl(BuildSystem buildSystem)
+        [InlineData(BuildSystem.MSBuild, null)]
+        [InlineData(BuildSystem.MSBuild, true)]
+        [InlineData(BuildSystem.MSBuild64, null)]
+        [InlineData(BuildSystem.MSBuild64, true)]
+        public void CanBuildSimpleMsiPackageAsWixipl(BuildSystem buildSystem, bool? outOfProc)
         {
             var sourceFolder = TestData.Get(@"TestData\SimpleMsiPackage\MsiPackage");
 
@@ -303,9 +299,14 @@ namespace WixToolsetTest.MSBuild
                 var result = MsbuildUtilities.BuildProject(buildSystem, projectPath, new[]
                 {
                     "-p:OutputType=IntermediatePostLink",
-                });
+                }, outOfProc: outOfProc);
                 result.AssertSuccess();
 
+                var expectedOutOfProc = outOfProc.HasValue && outOfProc.Value;
+                var expectedWixCommand = $"{(expectedOutOfProc ? "wix.exe" : "(wix.exe)")} build";
+                var buildCommands = result.Output.Where(line => line.TrimStart().Contains(expectedWixCommand));
+                Assert.Single(buildCommands);
+
                 var path = Directory.EnumerateFiles(binFolder, @"*.*", SearchOption.AllDirectories)
                     .Select(s => s.Substring(baseFolder.Length + 1))
                     .Single();
diff --git a/src/test/WixToolsetTest.MSBuild/MsbuildHeatFixture.cs b/src/test/WixToolsetTest.MSBuild/MsbuildHeatFixture.cs
index 038da241..b5c71f86 100644
--- a/src/test/WixToolsetTest.MSBuild/MsbuildHeatFixture.cs
+++ b/src/test/WixToolsetTest.MSBuild/MsbuildHeatFixture.cs
@@ -31,7 +31,9 @@ namespace WixToolsetTest.MSBuild
                 var result = MsbuildUtilities.BuildProject(buildSystem, projectPath);
                 result.AssertSuccess();
 
-                var heatCommandLines = result.Output.Where(line => line.TrimStart().StartsWith("heat.exe file"));
+                var expectedOutOfProc = false;
+                var expectedHeatCommand = $"{(expectedOutOfProc ? "heat.exe" : "(heat.exe)")} file";
+                var heatCommandLines = result.Output.Where(line => line.Contains(expectedHeatCommand));
                 Assert.Single(heatCommandLines);
 
                 var warnings = result.Output.Where(line => line.Contains(": warning"));
@@ -86,7 +88,9 @@ namespace WixToolsetTest.MSBuild
                 var result = MsbuildUtilities.BuildProject(buildSystem, projectPath);
                 result.AssertSuccess();
 
-                var heatCommandLines = result.Output.Where(line => line.TrimStart().StartsWith("heat.exe file"));
+                var expectedOutOfProc = false;
+                var expectedHeatCommand = $"{(expectedOutOfProc ? "heat.exe" : "(heat.exe)")} file";
+                var heatCommandLines = result.Output.Where(line => line.Contains(expectedHeatCommand));
                 Assert.Equal(2, heatCommandLines.Count());
 
                 var warnings = result.Output.Where(line => line.Contains(": warning"));
diff --git a/src/test/WixToolsetTest.MSBuild/MsbuildUtilities.cs b/src/test/WixToolsetTest.MSBuild/MsbuildUtilities.cs
index 633fffe0..6a6f32e0 100644
--- a/src/test/WixToolsetTest.MSBuild/MsbuildUtilities.cs
+++ b/src/test/WixToolsetTest.MSBuild/MsbuildUtilities.cs
@@ -17,7 +17,7 @@ namespace WixToolsetTest.MSBuild
     {
         public static readonly string WixPropsPath = Path.Combine(new Uri(typeof(MsbuildUtilities).Assembly.CodeBase).AbsolutePath, "..", "..", "publish", "WixToolset.MSBuild", "build", "WixToolset.MSBuild.props");
 
-        public static MsbuildRunnerResult BuildProject(BuildSystem buildSystem, string projectPath, string[] arguments = null, string configuration = "Release")
+        public static MsbuildRunnerResult BuildProject(BuildSystem buildSystem, string projectPath, string[] arguments = null, string configuration = "Release", bool? outOfProc = null)
         {
             var allArgs = new List<string>
             {
@@ -28,6 +28,11 @@ namespace WixToolsetTest.MSBuild
                 "-nr:false",
             };
 
+            if (outOfProc.HasValue)
+            {
+                allArgs.Add($"-p:RunWixToolsOutOfProc={outOfProc.Value}");
+            }
+
             if (arguments != null)
             {
                 allArgs.AddRange(arguments);