LNK2022 metadata operation: Inconsistent layout information in duplicated types

The fix for me was to set Configuration Properties -> C/C++ -> Code Generation -> Struct Member Alignment -> 16 Bytes (/Zp16)

Seems like my Visual Studio was in some broken state. I was the only one getting that error. I had no changes. I recheck out the project on the side and it was fixed. Maybe it was a problem with my user files.

Alright, so I solved it! There was another SO question that was actually a big help. It ended up linking to this article, which had a bit more detail about the problem. Basically it's some issue with the standard library strings getting compiled in both managed and unmanaged code. The solution was to only enable the CLR on files which required it. In detail, here's what I did:

1. Removed the /clr switch which applied to the whole project
2. Selected the two .cpp files that actually required the CLR, and manually selected /clr under C/C++ -> General -> Common Language RunTime Support.
3. Switched the whole project to Program Database /Zi from Program Database for Edit and Continue /ZI. This got rid of warnings, because I think /clr support appeared to disable incremental linking, and then my native code was throwing warnings because it was trying to use Edit and Continue.
4. I then got some ExtensionAttribute warnings, which I fixed by adding the following switches to my /clr-enabled files: /clr:nostdlib /AI"%ProgramFiles%\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0"
5. In Debug builds, I had to disable a bunch of debug options on the /clr-enabled files. Specifically, under C/C++ -> Code Generation, I set Enable Minimal Rebuild to No (/RM-), and Basic Runtime Checks to Default. This got rid of a bunch of warnings also.
6. In Debug and Release builds, set Enable C++ Exceptions to No on the clr-enabled files.

Hope this helps!