How can I get MSBUILD to evaluate and print the full path when given a relative path?

Question

How can I get MSBuild to evaluate and print in a <Message /> task an absolute path given a relative path?

Property Group

<Source_Dir>..\..\..\Public\Server\</Source_Dir>
<Program_Dir>c:\Program Files (x86)\Program\</Program_Dir>

Task

<Message Importance="low" Text="Copying '$(Source_Dir.FullPath)' to '$(Program_Dir)'" />

Output

Copying '' to 'c:\Program Files (x86)\Program\'

Answer 1

In MSBuild 4.0, the easiest way is the following:

$([System.IO.Path]::GetFullPath('$(MSBuildThisFileDirectory)\your\path'))

This method works even if the script is <Import>ed into another script; the path is relative to the file containing the above code.

(consolidated from Aaron's answer as well as the last part of Sayed's answer)

---

In MSBuild 3.5, you can use the ConvertToAbsolutePath task:

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003"
         DefaultTargets="Test"
         ToolsVersion="3.5">
  <PropertyGroup>
    <Source_Dir>..\..\..\Public\Server\</Source_Dir>
    <Program_Dir>c:\Program Files (x86)\Program\</Program_Dir>
  </PropertyGroup>

  <Target Name="Test">
    <ConvertToAbsolutePath Paths="$(Source_Dir)">
      <Output TaskParameter="AbsolutePaths" PropertyName="Source_Dir_Abs"/>
    </ConvertToAbsolutePath>
    <Message Text='Copying "$(Source_Dir_Abs)" to "$(Program_Dir)".' />
  </Target>
</Project>

Relevant output:

Project "P:\software\perforce1\main\XxxxxxXxxx\Xxxxx.proj" on node 0 (default targets).
  Copying "P:\software\Public\Server\" to "c:\Program Files (x86)\Program\".

A little long-winded if you ask me, but it works. This will be relative to the "original" project file, so if placed inside a file that gets <Import>ed, this won't be relative to that file.

---

In MSBuild 2.0, there is an approach which doesn't resolve "..". It does however behave just like an absolute path:

<PropertyGroup>
    <Source_Dir_Abs>$(MSBuildProjectDirectory)\$(Source_Dir)</Source_Dir_Abs>
</PropertyGroup>

The $(MSBuildProjectDirectory) reserved property is always the directory of the script that contains this reference.

This will also be relative to the "original" project file, so if placed inside a file that gets <Import>ed, this won't be relative to that file.