Here's a new draft. Significant changes:

I deleted the macros identifying all of the brand-new headers, from both
fundamentals and parallelism:

<optional> <any> <string_view> <memory_resource>
<exception_list> <execution_policy>

The proposal (with rationale) is now that non-const data for string
needs no macro, and similarly for enum construction rules.

I have added a macro, with proposed spelling and example (from Richard;
many thanks), for addressof (LWG2296).

The change to fold expressions is represented by bumping the value of
__cpp_fold_expressions. (There will be two adjacent lines in the C++17
table, giving different values to that macro, depending on how many
operators are given a default value.) I deleted the question mark.

Consensus seems to support bumping __cpp_constexpr to indicate that
it can apply to a lambda, so I deleted the question mark.

No one has suggested a better name than __cpp_aggregate_bases, so I
deleted the question mark.


The only question that doesn't seem to have been settled yet is the
name of the macro for this-capture. The contenders seem to be:

__cpp_capture_this
__cpp_capture_star_this

Different people have spoken in favor of each. Let the argument begin
in earnest.

Clark