For example, `auth_auth_valid`.

This reverts commit 59280f68.
It was not actually needed.

wtf, sed?!??

Preserve identifiers in binders where possible, analogous to the support
for destructing existentials in !479.

Fixes #336.

Tej Chajed authored 4 years ago and Robbert Krebbers committed 4 years ago

When running `iDestruct "H" as (?) "H"`, use the name of the binder in
"H". For example, if "H" has type `∃ y, Φ y`,  we now use `y` as the
name of the variable after freshening. Previously the name was always
the equivalent of running `fresh H`.

The implementation achieves this by forwarding the desired identifier
name through the `IntoExist` typeclass. Identifiers are serialized in
Gallina by using them as the name of a function of type `ident_name :=
unit -> unit`.