This fixes a major issue in arm 32bits, detected by ubsan, where
conversion of type to milliseconds results in overflow.
```
rktio_time.c:92:21: runtime error: signed integer overflow: 1584975753 * 1000 cannot be represented in type 'long int'
```
GCC 9.3 things that `h2` might reach line 385 uninitialized.
```
./hash.c:385:14: warning: 'h2' may be used uninitialized in this function [-Wmaybe-uninitialized]
385 | h = (h + h2) & mask;
| ~~~^~~~~
```
A Chez Scheme garbage collection involves a rendezvous among threads
that are used to implement places and futures (and potentially other
things that create Chez-level threads). The thread that is used to
drive the garbage collection was not formerly specified, and callbacks
like the GC icon in DrRacket can only be run in the initial thread.
When a major collection was run in a non-initial thread, the callback
was simply skipped.
The Racket branch of Chez Scheme now drives a collection in the
initial thread whenever that thread is active. In Racket CS, the
initial thread can be inactive if it's waiting for external events,
and a place can meanwhile trigger a GC. Now, when the Racket CS GC
callback is called for a major collection in any thread other than the
initial one, it defers the major collection to an asynchornous
callback in the main thread (and meanwhile performs a minor
collection).
So, a major collection might now be delayed by just a little while if
the main thread is inactive, such as when it's waiting for external
events, but callbacks like the GC icon in DrRacket will be reliably
invoked for major collections.
It's still unclear what the specification of syntax->string regarding whitespace
before closing parens should be. The implementation also has not dealt with
the issue. This PR therefore removes whitespace before closing parens from
the tests.
Once the discussion at
https://github.com/racket/racket/issues/3071#issuecomment-601984438
has reached a conclusion and implemented, we can add these tests back.
Implementing a thorough `clean` target for a repo-based is tedious and
error-prone. Instead, make the `clean` target suggest `git clean -d -x
-f .`, which is more effective in most situations (but seems too
dangerous to run automatically).
The `call-in-continuation` function generalizes applying a
continuation to values by accepting a thunk that is called in the
restored continuation. In other words, insteda of having to use the
pattern
((call/cc (lambda (k)
.... (set! saved-k k) ...
(lambda ()
original-result))))
...
(saved-k (lambda () new-result))
The extra call and thunk on the capture side can be omitted:
(call/cc (lambda (k)
.... (set! saved-k k) ...
original-result))
...
(call-in-continuation saved-k (lambda () new-result))
At the Chez Scheme level, a `call-in-continuation` in tail position
within a function can avoid forming a closure for its second argument.
The `call-in-continuation` function at the Racket CS level doesn't yet
provide that benefit.
The `call-in-continuation` operation is called `continuation-slice` in
Feeley's "A Better API for First-Class Continuations".
Expansion of a procedure with keywords is quadratic due to generating
a nested sequence of `let`s, but speed it up by roughly a constant
factor by using a dintinct symbol for each nested layer.
Related to #3070
Using `call-in-continuation` to apply a thunk within a continuation
slightly simplifies and speeds up parts of the implementation of
delimited continuations.
The expansion of `struct` created far too much code to parameterize
`struct-field-index`, making expansion of a `struct` form with just
100 or 200 fields take a noticeably long time to expand.
PR #2678 unintentionally removed this attribute, but it was used
at least by "collections-lib" and "static-rename-lib".
cc @sorawee @lexi-lambda @jackfirth @rmculpepper
- reword the first-page explanation of chaperone contracts;
try to give a positive description by talking about wrappers first
(rather than starting with what chaperones maybe don't do)
- name the recognizer functions for chaperone & impersonator contracts
(on the first page)
- clarify that `contract-projection` and `contract-val-first-projection`
are bad --- that there's a preferred alternative
- describe the outputs of `contract-projection` and
`contract-val-first-projection`; their docs were identical before, but
now re-use prose from sec 8.7 (Building New Contract Combinators)
Use a consistent style for the "good / bad" examples:
- start the code at the far left of each box
- keep a little space between the top of the box & the label
GitHub's CDN seems to have recently started returning the `Location` header for a redirect with a lowercase `l`, which breaks the redirect logic. The HTTP spec says that header names are case-insensitive, so we need to look for either version.
