There are currently a number of return values from the std::comm methods, not
all of which are necessarily completely expressive:
Sender::try_send(t: T) -> bool
This method currently doesn't transmit back the data `t` if the send fails
due to the other end having disconnected. Additionally, this shares the name
of the synchronous try_send method, but it differs in semantics in that it
only has one failure case, not two (the buffer can never be full).
SyncSender::try_send(t: T) -> TrySendResult<T>
This method accurately conveys all possible information, but it uses a
custom type to the std::comm module with no convenience methods on it.
Additionally, if you want to inspect the result you're forced to import
something from `std::comm`.
SyncSender::send_opt(t: T) -> Option<T>
This method uses Some(T) as an "error value" and None as a "success value",
but almost all other uses of Option<T> have Some/None the other way
Receiver::try_recv(t: T) -> TryRecvResult<T>
Similarly to the synchronous try_send, this custom return type is lacking in
terms of usability (no convenience methods).
With this number of drawbacks in mind, I believed it was time to re-work the
return types of these methods. The new API for the comm module is:
Sender::send(t: T) -> ()
Sender::send_opt(t: T) -> Result<(), T>
SyncSender::send(t: T) -> ()
SyncSender::send_opt(t: T) -> Result<(), T>
SyncSender::try_send(t: T) -> Result<(), TrySendError<T>>
Receiver::recv() -> T
Receiver::recv_opt() -> Result<T, ()>
Receiver::try_recv() -> Result<T, TryRecvError>
The notable changes made are:
* Sender::try_send => Sender::send_opt. This renaming brings the semantics in
line with the SyncSender::send_opt method. An asychronous send only has one
failure case, unlike the synchronous try_send method which has two failure
cases (full/disconnected).
* Sender::send_opt returns the data back to the caller if the send is guaranteed
to fail. This method previously returned `bool`, but then it was unable to
retrieve the data if the data was guaranteed to fail to send. There is still a
race such that when `Ok(())` is returned the data could still fail to be
received, but that's inherent to an asynchronous channel.
* Result is now the basis of all return values. This not only adds lots of
convenience methods to all return values for free, but it also means that you
can inspect the return values with no extra imports (Ok/Err are in the
prelude). Additionally, it's now self documenting when something failed or not
because the return value has "Err" in the name.
Things I'm a little uneasy about:
* The methods send_opt and recv_opt are not returning options, but rather
results. I felt more strongly that Option was the wrong return type than the
_opt prefix was wrong, and I coudn't think of a much better name for these
methods. One possible way to think about them is to read the _opt suffix as
"optionally".
* Result<T, ()> is often better expressed as Option<T>. This is only applicable
to the recv_opt() method, but I thought it would be more consistent for
everything to return Result rather than one method returning an Option.
Despite my two reasons to feel uneasy, I feel much better about the consistency
in return values at this point, and I think the only real open question is if
there's a better suffix for {send,recv}_opt.
Closes#11527
Closes#13441 (debuginfo: Fixes and improvements for #12840, #12886, and #13213)
Closes#13433 (Remove references to @Trait from a compiler error message)
Closes#13430 (Fix outdated lint warning about inner attribute)
Closes#13425 (Remove a pile of (mainly) internal `~[]` uses)
Closes#13419 (Stop using transmute_mut in RefCell)
Closes#13417 (Remove an unnecessary file `src/libnative/io/p`.)
Closes#13409 (Closing assorted resolve bugs)
Closes#13406 (Generalized the pretty-print entry points to support `-o <file>`.)
Closes#13403 (test: Add a test for #7663)
Closes#13402 (rustdoc: Prune the paths that do not appear in the index.)
Closes#13396 (rustc: Remove absolute rpaths)
Closes#13371 (Rename ast::Purity and ast::Impure Function. Closes#7287)
Closes#13350 (collections: replace all ~[T] with Vec<T>.)
Previously, a private use statement would shadow a public use statement, all of
a sudden publicly exporting the privately used item. The correct behavior here
is to only shadow the use for the module in question, but for now it just
reverts the entire name to private so the pub use doesn't have much effect.
The behavior isn't exactly what we want, but this no longer has backwards
compatibility hazards.
Previously resolve was checking the "import resolution" for whether an import
had succeeded or not, but this was the same structure filled in by a previous
import if a name is shadowed. Instead, this alters resolve to consult the local
resolve state (as opposed to the shared one) to test whether an import succeeded
or not.
Closes#13404
Resolve is currently erroneously allowing imports through private `use`
statements in some circumstances, even across module boundaries. For example,
this code compiles successfully today:
use std::c_str;
mod test {
use c_str::CString;
}
This should not be allowed because it was explicitly decided that private `use`
statements are purely bringing local names into scope, they are not
participating further in name resolution.
As a consequence of this patch, this code, while valid today, is now invalid:
mod test {
use std::c_str;
unsafe fn foo() {
::test::c_str::CString::new(0 as *u8, false);
}
}
While plausibly acceptable, I found it to be more consistent if private imports
were only considered candidates to resolve the first component in a path, and no
others.
Closes#12612
When calculating the sysroot, it's more accurate to use realpath() rather than
just one readlink() to account for any intermediate symlinks that the rustc
binary resolves itself to.
For rpath, realpath() is necessary because the rpath must dictate a relative
rpath from the destination back to the originally linked library, which works
more robustly if there are no symlinks involved.
Concretely, any binary generated on OSX into $TMPDIR requires an absolute rpath
because the temporary directory is behind a symlink with one layer of
indirection. This symlink causes all relative rpaths to fail to resolve.
cc #11734
cc #11857
Concerns have been raised about using absolute rpaths in #11746, and this is the
first step towards not relying on rpaths at all. The only current use case for
an absolute rpath is when a non-installed rust builds an executable that then
moves from is built location. The relative rpath back to libstd and absolute
rpath to the installation directory still remain (CFG_PREFIX).
Closes#11746
Rebasing of #12754
I think that the test case from this issue has become out of date with resolve
changes in the past 9 months, and it's not entirely clear to me what the
original bug was.
Regardless, it seems like tricky resolve behavior, so tests were added to make
sure things resolved correctly and warnings were correctly reported.
Closes#7663
This commit makes sure that code inlined from other functions isn't assigned the source position of the call site, since this leads to undesired behavior when setting line breakpoints (issue #12886)
This fixes the categorization of the upvars of procs (represented internally
as once fns) to consider usage to require a loan. In doing so, upvars are no
longer allowed to be moved out of repeatedly in loops and such.
Closes#10398Closes#12041Closes#12127
This fixes the categorization of the upvars of procs (represented internally
as once fns) to consider usage to require a loan. In doing so, upvars are no
longer allowed to be moved out of repeatedly in loops and such.
Closes#10398Closes#12041Closes#12127
Closes#13394 (sync: remove unsafe and add Send+Share to Deref (enabled by autoderef vtables))
Closes#13389 (Made libflate functions return Options instead of outright failing)
Closes#13388 (doc: Document flavorful variations of paths)
Closes#13387 (Register new snapshots)
Closes#13386 (std: Add more docs for ptr mod)
Closes#13384 (Tweak crate loading to load less metadata)
Closes#13382 (fix ~ZeroSizeType rvalues)
Closes#13378 (Update tidy script, replace XXX with FIXME)
Closes#13377 (std: User a smaller stdin buffer on windows)
Closes#13369 (Fix spelling errors in comments.)
Closes#13314 (Made 'make install' include libs for additional targets)
Closes#13278 (std: make vec!() macro handle a trailing comma)
Closes#13276 (Add test for #11881)
Apparently windows doesn't like reading from stdin with a large buffer size, and
it also apparently is ok with a smaller buffer size. This changes the reader
returned by stdin() to return an 8k buffered reader for stdin rather than a 64k
buffered reader.
Apparently libuv has run into this before, taking a peek at their code, with a
specific comment in their console code saying that "ReadConsole can't handle big
buffers", which I presume is related to invoking ReadFile as if it were a file
descriptor.
Closes#13304
Few places where previous version of tidy script cannot find XXX:
* inside one-line comment preceding by a few spaces;
* inside multiline comments (now it finds it if multiline comment starts
on the same line with XXX).
Change occurences of XXX found by new tidy script.
This is an optimization which is quite impactful for compiling small crates.
Reading libstd's metadata takes about 50ms, and a hello world before this change
took about 100ms (this change halves that time).
Recent changes made it such that this optimization wasn't performed, but I think
it's a better idea do to this for now. See #10786 for tracking this issue.
