MSBuild TypeScript Compile Targets

Question

I have a T4 template that generates a handful of .d.ts files that I want to include in my TypeScript build. I want to understand better when the TypeScript compiler actually gets run as part of a build (or from a .ts file save) so that I can be sure to run my T4 generating target prior to the TypeScript build.

Can anyone give me more details of:

1. When CompileTypeScript target actually runs?
2. What PreComputeCompileTypeScript target is actually doing?
3. Is there a suggested way to ensure that an MSBuild target runs prior to the TypeScript build?

(In case it matters, I am using VS2013 Update 3.)

Answer 1

1.When CompileTypeScript target actually runs?

CompileTypeScript is added to the CompileDependsOn list, this list is defined here: "C:\Program Files (x86)\MSBuild\12.0\Bin\Microsoft.Common.CurrentVersion.targets". The default target (normally build), depends on CoreBuild which in turn requires the Compile target to be executed, see target compile (line 2762) and target corebuild (line 703).

So when the target is build, it executes the TypeScript build because build requires BeforeBuild, CoreBuild and AfterBuild to run. The CoreBuild target requires a lot of targets including compile and TypeScipt added itself in the Microsoft.TypeScript.targets file ("C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v12.0\TypeScript\Microsoft.TypeScript.targets"). See:

<PropertyGroup>
    <CompileDependsOn>
      CompileTypeScript;
      $(CompileDependsOn);
    </CompileDependsOn>
</PropertyGroup>

2.What PreComputeCompileTypeScript target is actually doing?

It tries to find the most common path for the outDir option when used. Also, when there are no TypeScript files, this task is the one which gives the error: No files to compile (or something). When single output (the --out parameter) is specifiek It does different things. It looks likte VS is providing full paths to the compiler and this task is making them relative when possible (I don't know the reason for this though).

3.Is there a suggested way to ensure that an MSBuild target runs prior to the TypeScript build?

When you create your own msbuild task you can modify the compileDependsOn target. You should do this after you imported the Microsoft.TypeScript.targets. You can change it like this:

<PropertyGroup>
    <CompileDependsOn>
      CompileYourTarget;
      $(CompileDependsOn);
    </CompileDependsOn>
</PropertyGroup>

edit: I changes part 2 of the answer