The old `cast' didn't work right for a mismatch between
a pointer GCableness and the source or target types, and
it didn't work right for an GCable pointer with a non-zero
offset. While those pitfalls were documented, the first
of them definitely has been a source of bugs in code that
I wrote.
Also added `cpointer-gcable?'
* The old function was removed completely, people will get it from
`racket/base' anyway.
* I also removed its documentation. I thought about leaving a note in,
but if `define-ffi-definer' is the preferred style, then this should
be done when there's a way to make `define-ffi-definer' use it. (Eg,
some new #:keyword that adds a way to change the defined name.)
* Note that the function is added to `racket/private/string' and not to
`racket/string' because the latter deals only with strings, and the
new function accepts byte strings too. It might be better to start a
new `racket/regexp' module for these functions.
Also, fix FFI procedures to preserve names: change `ptr-ref' with
`_fpointer' on an `ffi-obj' value to return the `ffi-obj'
value, so that the name in the `ffi-obj' value can be used
by `_cprocedure'.
Closes PR 12645
Extend `define-cstruct' to support #:property specs, which causes
the constructor and C->Racket coercsions to wrap the pointer in
a structure instance with the specified properties. Of course,
the wrapper structure has a `prop:cpointer' property so that the
wrapper can be used transparently as a C pointer.
Add missing tests and documentation for the id`->list', `list->'id,
id`->list*', and `list*->'id bindings created by `define-cstruct'.
I originally picked "under" as the preposition to go before
a platform name, but obviously you should build "on" a
platform, and "under" suddenly annoys me. The choice of "on"
is now codified in the documentation style guide. Meanwhile,
"Unix" insted of "X" seems more clear and consistent in the
`racket/gui' docs.
More usefully, this patch also fixes a few out-of-date
platform-specific claims.
