In C# I am declaring an interface, which will be exposed to COM for use by C++. Our spec says one integer parameter should be [in]UINT uiVal. I'm using int in C# and it is being exposed as long.
It's not a big deal, but how can I force it to marshall to UINT rather than long? Some specific .Net type, or do I need to add attributes to the C# parameter somehow?
UINT is a type alias from the Windows SDK, you will never get it out of a type library. Tooling that translates type libraries, like the #import directive you are using, pick native C types. History plays a role, COM was originally designed for the 16-bit version of Windows. When long was important to declare a 32-bit integer.
Closest you can get is uint in the C# declaration, it will be translated to unsigned long in your C++ code. Which is fine, it is still a 32-bit type, Microsoft chose the LLP64 data model for 64-bit code. They did not have much of a choice. Unlike the LP64 model chosen in *nix. They did not have much of a choice either, the Y2K38 disaster is approaching fast :)