In a pattern like
a*b
a naive attempt to match will take quadratic time on an input that
contains all "a"s an no "b". To improve that case, the regexp compiler
detects that a match will require a "b" and checks the input for a "b"
to enable linear-time failure.
That optimization mishandled `(?!...)` and `(?<!...)` patterns,
treating the must-not-match subpatterns as things that must match.
So,
(regexp-match "a*(?!b)" "aaaxy")
returned false, because the input doesn't contain "b".
Thie commit repairs the optimization.
Closes#1468
Fix a regression relative to v6.4 caused by a refactoring of the
compiler between v6.4 and v6.5. The refactoring lost information about
letrecs that are converted internally to let* when a mutable variable
is involved, and it ends up allocating a closure before the box of a
mutable variable that is referenced by the closure. Something like
`with-continuation-mark` is needed around the closure's `lambda` to
prevent other optimizations from hiding the bug.
Closes#1462
lookup-errno now returns #f when given an unknown symbol instead
of raising a contract error. It should not return #f for any
symbol that it previously accepted.
The `if` case of the compiler's space-safety pass abused its "last
non-tail call relative to the closest enclosing binding" state as
"last non-tail call relative to the enclosing run time", which could
cause it to not clear a stack position as needed to maintain space
safety.
* add lang-reader-module-paths to syntax/module-reader
to be used as the third argument to make-meta-reader in lang-extensions
like at-exp
* document lang-reader-module-paths
* use lang-reader-module-paths in at-exp
* Make relative directory argument for resolve-module-path-* have a default to #f
The resolve-module-path-* functions effectively already had a default argument,
which is #f, this allows you to just directly call it with one argument.
* Add tests for resolve-module-path-* with optional argument
