How or why is MSBuild choosing the x64 platform when I don’t specify it instead of AnyCPU

64-bitmsbuild

I'm running msbuild.exe via Rake from a regular PowerShell console. This is the command as printed from a diagnostic level run

"C:\Windows\Microsoft.NET\Framework\v4.0.30319\msbuild.exe" "D:/Projects/machine.specifications/Source/Machine.Specifications/Machine.Specifications.csproj31881140" /maxcpucount /target:Build /verbosity:diagnostic /property:Configuration=Debug /property:TrackFileAccess=false /property:BuildInParallel=false /property:BuildRunner=Rake

And the build is failing because msbuild is picking x64 as the Platform.

C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(483,9): error : The OutputPath property is not set for project 'Machine.Specifications.csproj37103470'. Please check to make sure that you have specified a valid combination of Configuration and Platform for this project. Configuration='Debug' Platform='X64'. You may be seeing this message because you are trying to build a project without a solution file, and have specified a non-default Configuration or Platform that doesn't exist for this project.

I'm not passing it in on the command line (or from the script). The csproj has a default configuration 

<Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
<Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>

and two specific configurations

<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">

So, I expected the AnyCPU platform to be selected. But, for some reason, something is picking or sending in x64. I don't think the Rake system is a problem here, I've seen this behavior before on raw cmd line calls to msbuild (but I haven't documented them).

I'm on 64-bit Windows 7, calling msbuild 4.0. I don't know if that's relevant.

I am loading the 64-bit Visual Studio tools (C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\bin\amd64) using Invoke-BatchFile in my PowerShell profile. Could that be the culprit?

Why would msbuild deliberately choose x64 anyway? The 32-bit version doesn't choose x86 for you.

*1: The PowerShell console is at %SystemRoot%\system32\WindowsPowerShell\v1.0\powershell.exe
*2: I'm running the MSpec build (here's the rakefile and the msbuild call)

Best Answer

When you launch Visual Studio x64 command window, it sets an environment variable :

Platform=X64

This is a difference from the 32 bit command window, where this environment variable is not defined, and MSBuild then uses the conditional logic to use default platform.

You can either remove the Platform environment variable in your batch file, or pass in explicit Platform property as a parameter to MSBuild.

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