[module.context] Instantiation context is inconsistently defined

[sdkrystian]

The definition of instantiation context is as follows:

The instantiation context is a set of points within the program that determines which names are visible to argument-dependent name lookup and which declarations are reachable in the context of a particular declaration or template instantiation.

(side note: I'm pretty sure "template instantiation" should be "specialization" here)

We further go on to state:

In any other case, the instantiation context at a point within the program comprises that point.

The last bullet here seems to be inconsistent with the rest of the definition; we defined instantiation context to be relative to a declaration (or specialization), but then we specify what it is in the context of a program point.

Also, instead of "during the instantiation of [...]" we should say "in the context of [...]" as the lookup would be performed within the specialization/implicit definition.

[jensmaurer]

I think we intentionally refer to "template instantiation" (i.e. the act of producing a specialization), because that's a situation where name lookup happens (again). Once you have an instantiated specialization, name lookup is a thing of the past.

For the second issue, I'm not seeing it either. We say an instantiation context is a set of points, and we specify in an "otherwise" a set with a single element.

[sdkrystian]

@jensmaurer For the second issue, the problem there is not what we define instantiation context as, but the context for which we define it (i.e. for a point in the program, the instantiation context is [...])

Reachability (in [module.reach]) is defined as:

A declaration D is reachable if, for any point P in the instantiation context [...]

This doesn't provide a context (i.e. the program point) from which we are "getting" the instantiation context.