Bug 56633 - CodeTaskFactory no longer exists in Microsoft.Build.Tasks.v4.0.dll
Summary: CodeTaskFactory no longer exists in Microsoft.Build.Tasks.v4.0.dll
Alias: None
Product: Tools
Classification: Mono
Component: msbuild ()
Version: unspecified
Hardware: PC Mac OS
: Highest critical
Target Milestone: 15.4
Assignee: Ankit Jain
Depends on:
Reported: 2017-05-18 17:58 UTC by Jonathan Pryor
Modified: 2017-09-04 11:26 UTC (History)
5 users (show)

Tags: Shiproom
Is this bug a regression?: Yes
Last known good build:

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Description Jonathan Pryor 2017-05-18 17:58:03 UTC
The Microsoft.VSSDK.BuildTools NuGet package contains assemblies and MSBuild project files and targets to create Visual Studio .vsix files:


The `build/Microsoft.VSSDK.BuildTools.targets` file contains this XML fragment:

> <UsingTask TaskName="SetVsSDKEnvironmentVariables" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll">

This fragment fails when running on Mono 5.2 (2017-04), *not* mono 5.0 (2017-02) or mono 4.8:

> error MSB4174: The task factory "CodeTaskFactory" could not be found in the assembly 
> "/Library/Frameworks/Mono.framework/Versions/5.2.0/lib/mono/msbuild/15.0/bin/Microsoft.Build.Tasks.v4.0.dll"

Simplified test case, courtesy Alexander Köplinger:

  <UsingTask TaskName="foo" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll">
           Log.LogMessage(MessageImportance.High, Text);
  <Target Name="BeforeBuild">
    <foo Text="Hello, World!" />
Comment 1 Luis Aguilera 2017-07-24 18:15:41 UTC
after discussing with Ankit, we've agreed this bug is best fixed in 15.4 given that it's not trivial and may require extensive testing.
Comment 2 Jon Douglas [MSFT] 2017-07-24 20:31:34 UTC
I can CONFIRM this issue using Jon P's basic repro in https://bugzilla.xamarin.com/show_bug.cgi?id=56633#c0

I have also identified that this happens in Mono 5.0.1, so it's likely this isn't an immediate regression.

I believe this is similar to the following:


In which a similar workaround could be used:

<?xml version="1.0" encoding="utf-8"?>
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003"> 
  <When Condition="'$(MSBuildToolsVersion)'=='15.0'">
<UsingTask TaskName="foo" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\$(TasksAssemblyName).dll">
           Log.LogMessage(MessageImportance.High, Text);
   <Target Name="BeforeBuild">
    <foo Text="$(MSBuildToolsPath)" />

Either way, it looks like things were renamed and moved. Mono doesn't seem to reflect that compared to MSBuild on windows.