TargetFramework is not "undefined," but getting it is skipped for vcxproj

[Forgind]

Issue Description

We SkipGetTargetFrameworkProperties on .vcxproj by default, but we're not adding TargetFramework to UndefineProperties. This means that with cross-targeting, MSBuild can be confused when building the exact same project, lock the dll as it writes, and fail.

Steps to Reproduce

I think this will work, although I haven't actually tested it, since I don't want to download C++ 😄 :
Create a .vcxproj as normal
Specify TargetFrameworks="net462"
Build

Expected Behavior

It builds for net462 alone.

Actual Behavior

CL : fatal error C1083: Cannot open compiler intermediate file: ...
Permission denied

[BartoszKlonowski]

I have a full C++ setup, so I can work on this.
@Forgind Please assign me to this item.

[rainersigwald]

@BartoszKlonowski this is a pretty tricky area. Please check in after you get a repro and some idea of what to work on before sinking a bunch of time into it.

[BartoszKlonowski]

@rainersigwald Thank you for that, I will.

[BartoszKlonowski]

@Forgind I've tried to set the TargetFramework (and TargetFrameworks, as there's a difference) by specifying it like below:

  <PropertyGroup Label="Globals">
    <VCProjectVersion>16.0</VCProjectVersion>
    <Keyword>Win32Proj</Keyword>
    <ProjectGuid>{0024ce18-4706-418f-b3e6-f0d9bb50d143}</ProjectGuid>
    <RootNamespace>Examples</RootNamespace>
    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
    <TargetFrameworks>net462</TargetFrameworks>
  </PropertyGroup>

And when I ran the MSBuild without any more parameters, the build was just fine...

Please let me know if this is the reproduction scenario you were thinking about.

---

(I've also attached the full configuration, so you can verify it. Hope that helps!)
5565-Example-vcxproj.zip

[Forgind]

I don't remember all the context for this, but looking at the description, I think I fixed this in 16.9 and forgot about it: #5838

If rainersigwald and I both forgot about that PR in the intervening months and should have closed this—sorry! I'll look more next week to see if we should just close this.

[BartoszKlonowski]

@Forgind No problem if you've already fixed it. Just let me know once you'll double check the status 👍

[Forgind]

I just chatted with rainersigwald offline, and we agreed we'd just forgotten to chase this down. Thanks for the reminder!