Menu
Wrt. the proposed dupe: Since this here queston suggests the opposite of the linked question, I'd rather like to think it is not a dupe.
First, I did read What is the best practice for “Copy Local” and with project references? (also this) and I'll have to try this out anyway, but getting general feedback on this seems necessary as the docs on this stuff are horrible and I'm only on VS2010 and maybe they changed something in newer versions that'll be nice to know.
Second, I'm only interested in project references for this question as I've read that assemblies from the GAC are handled differently and the GAC is irrelevant for my problem.
Third, after reading the suggested dupe, but more so the nice answer here by @Albireo, it would also appear that it is important to differentiate file dependencies, where the dependency references a dll assembly file and project dependencies (i.e. what I'm asking about), where the dependency references a project and implicitly the output file of that project.
/x1 for executable 1 project/x2 for executable 2 project/lib for all the dll assembliesThe DLL assemblies all have Copy Localset to false for their project references, as they all build to the same output directory.
The 2 executable projects have set Copy Local to true for all the DLL assembly project references they reference directly, so that the DLLs will be copied into /x1 /x2 respectively.
The question now is wrt. to DLLs that are not directly referenced by an executable project, but only transitively through a referenced assembly: Will assemblies, that are only referenced transitively through another assembly, be copied into the output folder of the executable, when "Copy Local" is set to true on the first assembly?
Example:
x1.csproj (e.g.Output = x1/one.exe) dlA.csproj ( e.g. Output = lib/a.dll) with Copy Local = *true* dlA.csproj ( e.g. Output = lib/a.dll) dlB.csproj ( e.g. Output = lib/b.dll) with Copy Local = **false** dlC.csproj ( e.g. Output = lib/c.dll) Thus, we have a logical dependency of one.exe -> a.dll -> b.dll -> c.dll, where only a.dll with obviously be copied to the output directory of one.exe. Will the other two dlls also be copied to the output directory? Is this documented somewhere?
And, yes, I tried it. And, yes, it seems to work, but I haven't poked it hard enough yet and anyway there maybe something more to it that I may have missed. (And also there's the question wrt. any official docs.)
588
When ReSharper speaks of a transitive reference, it means a reference to an assembly that is made implicitly by referencing another, intermediary assembly. For example, say I have a project with an assembly "Core. dll". I create a project called "Features. dll" that references Core.
The Copy Local property (corresponding to CopyLocal) determines whether a reference is copied to the local bin path. At run time, a reference must be located in either the Global Assembly Cache (GAC) or the output path of the project.
The way to project reference to a project related to, click on "References", right click on "Reference" inside Projects Solution, you can see the list of projects, and you should check this one and you press "okay." As you can see now, My Library is listed under references, and now you can use any types provided by ...
The Copy Local property is set in the Reference Properties dialog box, available from the References pane of the Project Designer. 1. In Solution Explorer, click the Show All Files button to display the References node. 2. Open the References node for the project. 3. Right-click a reference in the References list, and click Properties. 4.
I suggest having copy local = false for almost all projects except the one that is at the top of the dependency tree. And for all the references in the one at the top set copy local = true. I see many people suggesting sharing an output directory; I think this is a horrible idea based on experience.
If the value is true, the reference is copied to the output path of the project at run time. If false, the reference is not copied. The common language runtime does not track the changes to the reference to determine if the local copy needs to be updated. Changes are tracked by the project system.
CC.Net VS projects rely on the copy local reference assembly option set to true. [...] Not only this increase significantly the compilation time (x3 in the case of NUnit), but also it messes up your working environment. Last but not least, doing so introduces the risk for versioning potential problems.
it would also appear that it is important to differentiate file dependencies, where the dependency references a dll assembly file and project dependencies (i.e. what I'm asking about), where the dependency references a project and implicitly the output file of that project.
Not really, no.
MSBuild doesn't really care if the reference points to another project in the solution or to a DLL.
If ProjectA depends on ProjectB to build ProjectA ProjectB must be already built (and up-to-date), MSBuild will then pull its DLL (not its C# code) and link it to ProjectA.
Adding a project reference instead of a DLL is "syntactic sugar" for your convenience: this way MSBuild knows it must pick the output of the referenced project, whatever the output is.
Otherwise, you'll have to manually pre-build the dependency, find its DLL and link it to the project, repeating the process whenever you switch build configuration, move or rename things. Not really practical.
Will the other two dlls also be copied to the output directory?
If any kind of element from a dependency is used directly from the project where the assembly is referenced, that reference will be copied.
An example could be this solution layout:
With this dependency chain:
If you build this solution you'll notice that in MySolution.ConsoleApplication output directory there will be the DLLs for MySolution.FirstDependency, MySolution.SecondDependency and MySolution.ThirdDependency but no DLL for MySolution.FourthDependency.
Why is it so? When MSBuild builds MySolution.SecondDependency it notices that there's a dependency declared to MySolution.FourthDependency, but since it can't find any usage of any kind of element from MySolution.FourthDependency in MySolution.SecondDependency code it decides to perform some "optimization" and omits MySolution.FourthDependency assembly from the output.
This same issue bit me in the past when I added through NuGet AutoMapper to a "deep dependency": adding AutoMapper adds two assembly references, AutoMapper and AutoMapper.Net4, where the second assembly is loaded by the first through reflection when it needs to perform certain kind of action on the new collection objects introduced by the .NET Framework 4. Since the second assembly is loaded through reflection MSBuild thinks it's unused and doesn't bother to copy it around.
So, yes, they will be copied as long as you're using them directly and not through reflection.
Is this documented somewhere?
This behavior seems to be a "feature" of MSBuild, I managed to find a blog post by some folks from Microsoft back when I experienced this issue, but I can't find it again at the moment.
127
It is very straight forward, doesn't have anything to do with Copy Local. MSBuild looks in the metadata of an assembly to see what the dependencies are for an assembly. So can you, run ildasm.exe on the assembly and double-click the Manifest. Be sure to try this to get insight. You'll see the .assembly directives. Inserted by the compiler when it built the assembly, only the referenced assemblies you actually used in your code will be listed.
If MSBuild can find such an assembly in the same directory then it will automatically copy it. If not then it will silently skip the copy.
From this, you can deduce the failure modes. It cannot copy unmanaged DLLs, they do not appear in the metadata. It cannot copy assemblies that you have an indirect dependency on through Assembly.Load/From(), they don't appear in the metadata either. It cannot copy assemblies that haven't been built yet, a build order problem. And it cannot copy assemblies whose Copy Local property you set to False. Which is normally only a valid choice if the assembly is present in the GAC, no copy required.
For such cases you need to help, XCOPY in a post-build event gets the job done.
38
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
