F# FAKE passing /gac to FxCopHelper - jenkins

Question

In my build script, when I run it on my local machine (Win 8.1 x64) the whole script works perfectly fine.
When I run it on my build server (Jenkins, Server 2012 r2 x64), the FxCop task fails, because it cannot resolve any of the System.* assembly references which are required by some of the 3rd party libs I'm using.
I know full well that the version of FxCop (10.0) being used is the same, because it is checked into the project's git repo.
I don't understand why it works ok on my local machine, and not on the build server, but as I understand it from the results of my googling, I should be able to pass the /gac switch to FxCop in order to tell it that it should look there to resolve references it needs when scanning assemblies.
I just can't work out how to pass that switch to FxCop, using FAKE.
The target is as follows, but it's honestly essentially the same as the FxCop tutorial on the FAKE website, I've just removed the names of some dlls and exes.
Target "FxCop" (fun _ ->
!! (build ## "**/*.dll")
++ (build ## "**/*.exe")
|> FxCop (fun p ->
{p with
ReportFileName = testResults + "FXCopResults.xml";
ToolPath = "./tools/FxCop/FxCopCmd.exe" })
)
I've had a look at the source of the FxCopHelper, but my F# isn't that great, and there doesn't appear (to me) to be a way of passing extra command line options other than the ones already specified.
Does anyone have any suggestions?

Answer 1

The parameter you are looking for is UseGACSwitch and it is a boolean.
https://github.com/fsharp/FAKE/blob/master/src/app/FakeLib/FXCopHelper.fs#L77
To update your example:
Target "FxCop" (fun _ ->
!! (build ## "**/*.dll")
++ (build ## "**/*.exe")
|> FxCop (fun p ->
{p with
ReportFileName = testResults + "FXCopResults.xml";
UseGACSwitch = true;
ToolPath = "./tools/FxCop/FxCopCmd.exe" })
)
That should get you what you need for your build server to be happy. You may have already found this out or something else, but it is good that everyone knows there are options. Thank you. Good day.