Daniel has provided the solution:
[System.Collections.Generic.Dictionary`2+Enumerator[string, int]]
returns the type of interest (note that the nested [...] around the individual generic type arguments, string and int, are optional).
That is, before being able to specify type arguments in order to construct a generic type, you must first specify its open form, which requires specifying the generic arity (the count of type arguments, <n>) in the form `<n> following the type name, namely `2 in the case of System.Collections.Generic.Dictionary<TKey,TValue> (expressed in C# notation), using the language-agnostic .NET API notation, as explained in this answer.
- If no nested type (suffixed with
+<typename>) is involved, specifying the arity is optional if all type arguments are specified; e.g., instead of [System.Collections.Generic.Dictionary`2[string, int]], [System.Collections.Generic.Dictionary[string, int]] is sufficient.
However, the enumerator type in question has no public constructor, so you cannot instantiate it directly; rather, it is the type returned when you call .GetEnumerator() on (a constructed form of) the enclosing type, [System.Collections.Generic.Dictionary`2]; verify with:
Get-Member -InputObject ([System.Collections.Generic.Dictionary[string, int]])::new().GetEnumerator()
[System.Collections.Generic.Dictionary`2+Enumerator[[String],[Int32]]]::new()but it doesn't work.InvalidOperation: An error occurred while enumerating through a collection: Object reference not set to an instance of an object..(I found this by newing up a dictionary, getting the enumerator and checking it's type info.)::new()but instead called.GetEnumerator()on the underlying dictionary implementation