Add `syntax-protect` to some macro expansions, especially macros in
contex where unsafe operations are imported, which means that a
combination of `local-expand` and `datum->syntaxa could provide access
to the unsafe bindings absent `syntax-protect`.
Inspired by the way the Chez Scheme number parser works, change the
one in the expander to be faster and probably clearer. This improved
performance brings number parsing almost back in line with the v6.12
parser's performance.
The revised parser is faster because it goes through an input string
just once. The new parser is also more xcomplete; it doesn't rely on a
host-system `number->string` (except for dummy extflonums when
extflonums are not supported).
If you're reading the commit history, beware that the note on commit
be19996953 is incorrect about the change to parsing divide-by-zero
errors. (It explains a change that was edited away before merging.)
This commit really does change the bahvior, though, again as a better
match for v6.12. Specifically, "/0" (with no hashes) always triggers
divide-by-zero in an otherwise well-formed number, even if `#i` is
used.
Speed up JSON parsing (usually around x4 to x8) by avoiding regexp
matching and using more direct byte and character operations. Along
similar lines, compute parsed numbers directly instead of converting
to a string and then using `string->number`.
The revised reader behaves differently only in the case of a bad input
stream, where it may consume more bytes from the stream than the old
one due to eagerly reading bytes instead of tentatively matching
peeked bytes. Also, a UTF-8 decoding error is just `exn:fail` like
other input-parsing errors, and not `exn:fail:contract`.
Related to PR #2472, marks a few other functions as NORETURN.
Namely:
- scheme_signal_error
- scheme_wrong_count
- scheme_wrong_count_m
- scheme_case_lambda_wrong_count
- scheme_wrong_type
- scheme_wrong_contract
- scheme_wrong_field_type
- scheme_wrong_field_contract
- scheme_arg_mismatch
- scheme_contract_error
- scheme_wrong_return_arity
- scheme_unbound_global
Unfortunately static analysis is done per compilation unit, so
although, for example, scheme_wrong_contract calls scheme_raise_exn
and the latter is already marked NORETURN, the analyzer does not know
this. Therefore we need to manually propagate the NORETURN for each
function declaration.
The unsafe-fd->evt interface is based on unsafe-{file-descriptor,socket}->semaphore.
The main differences are that these events are level-triggered, not edge-triggered, and
they do not cooperate with ports created by unsafe-{file-descriptor,socket}->port.
scheme_raise_exn raises an exception and doesn't return.
Static analysis tools find a huge amount of problems with regards
to memory leaks that are actually false positives because the tools
are not aware the function does not return. Marking it as such aids
further inspection of real problems.
The documentation and implementation were confused about whether \D,
\S, and \W match non-ASCII characters. Now they do. The new regexp
implementation (as used in Racket CS) already matched them.
