C# attribute usage: only allow attributes on a property with specific data type [duplicate]

Answer 1

You could write a custom FxCop/ Code Analysis rule to check for this.

FxCop is integrated in VS 2010 under the name "Code Analyis", you can change the ruleset in the project properties.

Answer 2

No, this is not possible.

A good workaround is to build a unit test which will traverse all classes, their properties and check for this additional applicability criteria. It's not that comfortable as a compile-time error message, but will serve the purpose. In case you have some kind of build automation infrastructure, the quality assurance level will be the same in practice.