Capturing a type argument in the enclosing scope should be an error --
this commit implements that check in resolve, avoiding a potential
assertion failure in trans.
Closes#648.
Typestate was failing to check some code because if it saw an item,
it would quit immediately. This was to avoid checking nested items
in the same context as the lexically enclosing item, but it was
having the wrong effect: not checking the code after the item at all.
Fixed by switching to visit and skipping over items in a proper
nested fashion. Closes#668.
A check in trans didn't have a corresponding check in typeck, causing
some programs (to wit, compile-fail/chan-parameterized-args.rs - part of this
commit) to fail with an assertion failure in trans instead of a type error.
Fixed it. In short, arguments that are future thunk arguments (any spawn
arguments, and _ arguments in bind) need to either not contain type params
or type vars, or be by-reference.
Closes#665.
You can now say
expr_move(?dst, ?src) | expr_assign(?dst, ?src) { ... }
to match both expr_move and expr_assign. The names, types, and number
of bound names have to match in all the patterns.
Closes#449.
This is important since we are going to be making functions noncopyable
soon, which means we'll be seeing a lot of boxed functions.
(*f)(...) is really just too heavyweight.
Doing the autodereferencing was a very little bit tricky since
trans_call works with an *lval* of the function whereas existing
autoderef code was not for lvals.
Resources are now defined like...
resource fd(int n) { close(n); }
Calling fd with an int will then produce a non-copyable value
that, when dropped, will call close on the given int.
Wrote some small test cases that use while loops and moves, to
make sure the poststate for the loop body gets propagated into the
new prestate and deinitialization gets reflected.
Along with that, rewrite the code for intersecting states. I still
find it dodgy, but I guess I'll continue trying to add more tests.
Also, I'll probably feel better about it once I start formalizing
the algorithm.
Includes assignment operations. Add regression tests for lots of less useful,
less used or unexpected combinations, as well as a selection of compile-fail
tests. Closes#500 (again!)
Modified typestate to throw away any constraints mentioning a
variable on the LHS of an assignment, recv, assign_op, or on
either side of a swap.
Some code cleanup as well.
If you use a function expecting an alias argument in a context that
expects a function expecting a value argument, or vice versa, the
previous error message complained that the number of arguments was
wrong. Fixed the error message to be accurate.
typestate now drops constraints correctly in the post-state of
a move expression or a declaration whose op is a move. It doesn't
yet drop constraints mentioning variables that get updated.
To do this, I had to change typestate to use trit-vectors instead
of bit-vectors, because for every constraint, there are three
possible values: known-to-be-false (e.g. after x <- y, init(y) is
known-to-be-false), known-to-be-true, and unknown. Before, we
conflated known-to-be-false with unknown. But move requires them
to be treated differently. Consider:
(program a)
(a1) x = 1;
(a2) y <- x;
(a3) log x;
(program b)
(b1) x = 1;
(b2) y <- z;
(b3) log x;
With only two values, the postcondition of statement a2 for
constraint init(x) is the same as that of b2: 0. But in (a2)'s
postcondition, init(x) *must* be false, but in (b2)'s condition,
it's just whatever it was in the postcondition of the preceding statement.
This code was causing a bounds check failure:
fn hd[U](&vec[U] v) -> U {
fn hd1(&vec[U] w) -> U {
ret w.(0);
}
ret hd1(v);
}
because in hd1, U was being treated as if it referred to a type
parameter of hd1, rather than referring to the lexically enclosing binding
for U that's part of hd.
I'm actually not sure whether this is a legit program or not. But I wanted
to get rid of the bounds check error, so I assumed that program shouldn't
compile and made it a proper error message.
This involved, in part, changing the ast::def type so that a def_fn
has a "purity" field. This lets the typechecker determine whether
functions defined in other crates are pure.
It also required updating some error messages in tests. As a test
for cross-crate constrained functions, I added a safe_slice function
to std::str (slice(), with one of the asserts replaced with a
function precondition) and some test cases (various versions of
fn-constraint.rs) that call it. Also, I changed "fn" to "pred" for
some of the boolean functions in std::uint.
I noticed that typestate was being lazier than it should be,
because it was only checking typestate for statements and
top-level expression (that is, the expression in a stmt_expr, but
not any subexpressions). So I rewrote the checks in tstate/ck.rs
to use walk, which exposed a few bugs in typestate that I fixed.
Also added some more test cases for if-check.
