This has been a long time coming. Conditions in rust were initially envisioned
as being a good alternative to error code return pattern. The idea is that all
errors are fatal-by-default, and you can opt-in to handling the error by
registering an error handler.
While sounding nice, conditions ended up having some unforseen shortcomings:
* Actually handling an error has some very awkward syntax:
let mut result = None;
let mut answer = None;
io::io_error::cond.trap(|e| { result = Some(e) }).inside(|| {
answer = Some(some_io_operation());
});
match result {
Some(err) => { /* hit an I/O error */ }
None => {
let answer = answer.unwrap();
/* deal with the result of I/O */
}
}
This pattern can certainly use functions like io::result, but at its core
actually handling conditions is fairly difficult
* The "zero value" of a function is often confusing. One of the main ideas
behind using conditions was to change the signature of I/O functions. Instead
of read_be_u32() returning a result, it returned a u32. Errors were notified
via a condition, and if you caught the condition you understood that the "zero
value" returned is actually a garbage value. These zero values are often
difficult to understand, however.
One case of this is the read_bytes() function. The function takes an integer
length of the amount of bytes to read, and returns an array of that size. The
array may actually be shorter, however, if an error occurred.
Another case is fs::stat(). The theoretical "zero value" is a blank stat
struct, but it's a little awkward to create and return a zero'd out stat
struct on a call to stat().
In general, the return value of functions that can raise error are much more
natural when using a Result as opposed to an always-usable zero-value.
* Conditions impose a necessary runtime requirement on *all* I/O. In theory I/O
is as simple as calling read() and write(), but using conditions imposed the
restriction that a rust local task was required if you wanted to catch errors
with I/O. While certainly an surmountable difficulty, this was always a bit of
a thorn in the side of conditions.
* Functions raising conditions are not always clear that they are raising
conditions. This suffers a similar problem to exceptions where you don't
actually know whether a function raises a condition or not. The documentation
likely explains, but if someone retroactively adds a condition to a function
there's nothing forcing upstream users to acknowledge a new point of task
failure.
* Libaries using I/O are not guaranteed to correctly raise on conditions when an
error occurs. In developing various I/O libraries, it's much easier to just
return `None` from a read rather than raising an error. The silent contract of
"don't raise on EOF" was a little difficult to understand and threw a wrench
into the answer of the question "when do I raise a condition?"
Many of these difficulties can be overcome through documentation, examples, and
general practice. In the end, all of these difficulties added together ended up
being too overwhelming and improving various aspects didn't end up helping that
much.
A result-based I/O error handling strategy also has shortcomings, but the
cognitive burden is much smaller. The tooling necessary to make this strategy as
usable as conditions were is much smaller than the tooling necessary for
conditions.
Perhaps conditions may manifest themselves as a future entity, but for now
we're going to remove them from the standard library.
Closes#9795Closes#8968
This has been a long time coming. Conditions in rust were initially envisioned
as being a good alternative to error code return pattern. The idea is that all
errors are fatal-by-default, and you can opt-in to handling the error by
registering an error handler.
While sounding nice, conditions ended up having some unforseen shortcomings:
* Actually handling an error has some very awkward syntax:
let mut result = None;
let mut answer = None;
io::io_error::cond.trap(|e| { result = Some(e) }).inside(|| {
answer = Some(some_io_operation());
});
match result {
Some(err) => { /* hit an I/O error */ }
None => {
let answer = answer.unwrap();
/* deal with the result of I/O */
}
}
This pattern can certainly use functions like io::result, but at its core
actually handling conditions is fairly difficult
* The "zero value" of a function is often confusing. One of the main ideas
behind using conditions was to change the signature of I/O functions. Instead
of read_be_u32() returning a result, it returned a u32. Errors were notified
via a condition, and if you caught the condition you understood that the "zero
value" returned is actually a garbage value. These zero values are often
difficult to understand, however.
One case of this is the read_bytes() function. The function takes an integer
length of the amount of bytes to read, and returns an array of that size. The
array may actually be shorter, however, if an error occurred.
Another case is fs::stat(). The theoretical "zero value" is a blank stat
struct, but it's a little awkward to create and return a zero'd out stat
struct on a call to stat().
In general, the return value of functions that can raise error are much more
natural when using a Result as opposed to an always-usable zero-value.
* Conditions impose a necessary runtime requirement on *all* I/O. In theory I/O
is as simple as calling read() and write(), but using conditions imposed the
restriction that a rust local task was required if you wanted to catch errors
with I/O. While certainly an surmountable difficulty, this was always a bit of
a thorn in the side of conditions.
* Functions raising conditions are not always clear that they are raising
conditions. This suffers a similar problem to exceptions where you don't
actually know whether a function raises a condition or not. The documentation
likely explains, but if someone retroactively adds a condition to a function
there's nothing forcing upstream users to acknowledge a new point of task
failure.
* Libaries using I/O are not guaranteed to correctly raise on conditions when an
error occurs. In developing various I/O libraries, it's much easier to just
return `None` from a read rather than raising an error. The silent contract of
"don't raise on EOF" was a little difficult to understand and threw a wrench
into the answer of the question "when do I raise a condition?"
Many of these difficulties can be overcome through documentation, examples, and
general practice. In the end, all of these difficulties added together ended up
being too overwhelming and improving various aspects didn't end up helping that
much.
A result-based I/O error handling strategy also has shortcomings, but the
cognitive burden is much smaller. The tooling necessary to make this strategy as
usable as conditions were is much smaller than the tooling necessary for
conditions.
Perhaps conditions may manifest themselves as a future entity, but for now
we're going to remove them from the standard library.
Closes#9795Closes#8968
This commit removes the -c, --emit-llvm, -s, --rlib, --dylib, --staticlib,
--lib, and --bin flags from rustc, adding the following flags:
* --emit=[asm,ir,bc,obj,link]
* --crate-type=[dylib,rlib,staticlib,bin,lib]
The -o option has also been redefined to be used for *all* flavors of outputs.
This means that we no longer ignore it for libraries. The --out-dir remains the
same as before.
The new logic for files that rustc emits is as follows:
1. Output types are dictated by the --emit flag. The default value is
--emit=link, and this option can be passed multiple times and have all options
stacked on one another.
2. Crate types are dictated by the --crate-type flag and the #[crate_type]
attribute. The flags can be passed many times and stack with the crate
attribute.
3. If the -o flag is specified, and only one output type is specified, the
output will be emitted at this location. If more than one output type is
specified, then the filename of -o is ignored, and all output goes in the
directory that -o specifies. The -o option always ignores the --out-dir
option.
4. If the --out-dir flag is specified, all output goes in this directory.
5. If -o and --out-dir are both not present, all output goes in the directory of
the crate file.
6. When multiple output types are specified, the filestem of all output is the
same as the name of the CrateId (derived from a crate attribute or from the
filestem of the crate file).
Closes#7791Closes#11056Closes#11667
This commit removes the -c, --emit-llvm, -s, --rlib, --dylib, --staticlib,
--lib, and --bin flags from rustc, adding the following flags:
* --emit=[asm,ir,bc,obj,link]
* --crate-type=[dylib,rlib,staticlib,bin,lib]
The -o option has also been redefined to be used for *all* flavors of outputs.
This means that we no longer ignore it for libraries. The --out-dir remains the
same as before.
The new logic for files that rustc emits is as follows:
1. Output types are dictated by the --emit flag. The default value is
--emit=link, and this option can be passed multiple times and have all
options stacked on one another.
2. Crate types are dictated by the --crate-type flag and the #[crate_type]
attribute. The flags can be passed many times and stack with the crate
attribute.
3. If the -o flag is specified, and only one output type is specified, the
output will be emitted at this location. If more than one output type is
specified, then the filename of -o is ignored, and all output goes in the
directory that -o specifies. The -o option always ignores the --out-dir
option.
4. If the --out-dir flag is specified, all output goes in this directory.
5. If -o and --out-dir are both not present, all output goes in the current
directory of the process.
6. When multiple output types are specified, the filestem of all output is the
same as the name of the CrateId (derived from a crate attribute or from the
filestem of the crate file).
Closes#7791Closes#11056Closes#11667
- `extra::json` didn't make the cut, because of `extra::json` required
dep on `extra::TreeMap`. If/when `extra::TreeMap` moves out of `extra`,
then `extra::json` could move into `serialize`
- `libextra`, `libsyntax` and `librustc` depend on the newly created
`libserialize`
- The extensions to various `extra` types like `DList`, `RingBuf`, `TreeMap`
and `TreeSet` for `Encodable`/`Decodable` were moved into the respective
modules in `extra`
- There is some trickery, evident in `src/libextra/lib.rs` where a stub
of `extra::serialize` is set up (in `src/libextra/serialize.rs`) for
use in the stage0 build, where the snapshot rustc is still making
deriving for `Encodable` and `Decodable` point at extra. Big props to
@huonw for help working out the re-export solution for this
extra: inline extra::serialize stub
fix stuff clobbered in rebase + don't reexport serialize::serialize
no more globs in libserialize
syntax: fix import of libserialize traits
librustc: fix bad imports in encoder/decoder
add serialize dep to librustdoc
fix failing run-pass tests w/ serialize dep
adjust uuid dep
more rebase de-clobbering for libserialize
fixing tests, pushing libextra dep into cfg(test)
fix doc code in extra::json
adjust index.md links to serialize and uuid library
Previously, the check-fast and check-lite test suites weren't picking up all
target crates, rather just std/extra. In order to ensure that all of our crates
work on windows, I've modified these rules to build the test suites for all
TARGET_CRATES members. Note that this still excludes rustc/syntax/rustdoc.
In line with the dissolution of libextra - #8784 - this moves arena and glob into
their own respective modules. Updates .gitignore with the entries
doc/{arena,glob} in accordance.
This changes android testing to upload *all* target crates rather than just a
select subset. This should unblock #11867 which is introducing a libglob
dependency in testing.
This changes android testing to upload *all* target crates rather than just a
select subset. This should unblock #11867 which is introducing a libglob
dependency in testing.
In line with the dissolution of libextra - #8784 - moves arena to its own library libarena.
Changes based on PR #11787. Updates .gitignore to ignore doc/arena.
It was decided a long, long time ago that libextra should not exist, but rather its modules should be split out into smaller independent libraries maintained outside of the compiler itself. The theory was to use `rustpkg` to manage dependencies in order to move everything out of the compiler, but maintain an ease of usability.
Sadly, the work on `rustpkg` isn't making progress as quickly as expected, but the need for dissolving libextra is becoming more and more pressing. Because of this, we've thought that a good interim solution would be to simply package more libraries with the rust distribution itself. Instead of dissolving libextra into libraries outside of the mozilla/rust repo, we can dissolve libraries into the mozilla/rust repo for now.
Work on this has been excruciatingly painful in the past because the makefiles are completely opaque to all but a few. Adding a new library involved adding about 100 lines spread out across 8 files (incredibly error prone). The first commit of this pull request targets this pain point. It does not rewrite the build system, but rather refactors large portions of it. Afterwards, adding a new library is as simple as modifying 2 lines (easy, right?). The build system automatically keeps track of dependencies between crates (rust *and* native), promotes binaries between stages, tracks dependencies of installed tools, etc, etc.
With this newfound buildsystem power, I chose the `extra::flate` module as the first candidate for removal from libextra. While a small module, this module is relative complex in that is has a C dependency and the compiler requires it (messing with the dependency graph a bit). Albeit I modified more than 2 lines of makefiles to accomodate libflate (the native dependency required 2 extra lines of modifications), but the removal process was easy to do and straightforward.
---
Testing-wise, I've cross-compiled, run tests, built some docs, installed, uninstalled, etc. I'm still working out a few kinks, and I'm sure that there's gonna be built system issues after this, but it should be working well for basic use!
cc #8784
This is hopefully the beginning of the long-awaited dissolution of libextra.
Using the newly created build infrastructure for building libraries, I decided
to move the first module out of libextra.
While not being a particularly meaty module in and of itself, the flate module
is required by rustc and additionally has a native C dependency. I was able to
very easily split out the C dependency from rustrt, update librustc, and
magically everything gets installed to the right locations and built
automatically.
This is meant to be a proof-of-concept commit to how easy it is to remove
modules from libextra now. I didn't put any effort into modernizing the
interface of libflate or updating it other than to remove the one glob import it
had.
Before this patch, if you wanted to add a crate to the build system you had to
change about 100 lines across 8 separate makefiles. This is highly error prone
and opaque to all but a few. This refactoring is targeted at consolidating this
effort so adding a new crate adds one line in one file in a way that everyone
can understand it.
The new macro loading infrastructure needs the ability to force a
procedural-macro crate to be built with the host architecture rather than the
target architecture (because the compiler is just about to dlopen it).
The official documentation sorely needs an explanation of the rust runtime and what it is exactly, and I want this guide to provide that information.
I'm unsure of whether I've been too light on some topics while too heavy on others. I also feel like a few things are still missing. As always, feedback is appreciated, especially about things you'd like to see written about!
If we bootstrap a cross compile from a stage1 compiler, then the stage1 compiler
already knows about the rustc => rustlib change, so we need to not add the extra
flag if it's a stage0 version of a target from a stage1 of another target.
If we bootstrap a cross compile from a stage1 compiler, then the stage1 compiler
already knows about the rustc => rustlib change, so we need to not add the extra
flag if it's a stage0 version of a target from a stage1 of another target.
This reorganizes the documentation index to be more focused on the in-tree docs, and to clean up the style, and it also adds @steveklabnik's pointer guide.
All the copying of files amongst one another was apparently causing something to
get corrupted. Instead of having files fly around, just update the directories
to link to.
The makefiles and the windows installer disagree on the name of this file. In practical terms this change only means that the '-pre' installers will be named 'rust-0.9-pre-install.exe' instead 'rust-0.9-install.exe'.
This is not done yet but I'm posting it to get feedback.
The wiki has a ton of different tutorials/manuals/faq and so forth. Instead of migrating all of them right now, I just migrated the following:
* The general main wiki page
* Language FAQ
* Project FAQ
If this feels reasonable, please comment so that I can continue with confidence.
Ensure configure creates doc/guides directory
Fix configure makefile and tests
Remove old guides dir and configure option, convert testing to guide
Remove ignored files
Fix submodule issue
prepend dir in makefile so that bor knows how to build the docs
S to uppercase
In a multi-host build the mklldeps.py tool is getting called before
all the llvm-configs are built. I am not actually sure the cause. I
had convinced myself that DEF_LLVM_RULES needed to be called before
the llvmdeps.rs rule, but now looking at it again I can't see why.
This pull request extracts all scheduling functionality from libstd, moving it into its own separate crates. The new libnative and libgreen will be the new way in which 1:1 and M:N scheduling is implemented. The standard library still requires an interface to the runtime, however, (think of things like `std::comm` and `io::println`). The interface is now defined by the `Runtime` trait inside of `std::rt`.
The booting process is now that libgreen defines the start lang-item and that's it. I want to extend this soon to have libnative also have a "start lang item" but also allow libgreen and libnative to be linked together in the same process. For now though, only libgreen can be used to start a program (unless you define the start lang item yourself). Again though, I want to change this soon, I just figured that this pull request is large enough as-is.
This certainly wasn't a smooth transition, certain functionality has no equivalent in this new separation, and some functionality is now better enabled through this new system. I did my best to separate all of the commits by topic and keep things fairly bite-sized, although are indeed larger than others.
As a note, this is currently rebased on top of my `std::comm` rewrite (or at least an old copy of it), but none of those commits need reviewing (that will all happen in another pull request).
It only really makes sense to run tests for the build target anyway because it's
not guaranteed that you can execute other targets.
This is blocking the next snapshot
The rmake tests should depend on the target libraries (for linking), not just
the host libraries (for running). The host file dependencies are also correct
now because HLIBRUSTC_DEFAULT doesn't actually exist.
Note that this removes a number of run-pass tests which are exercising behavior
of the old runtime. This functionality no longer exists and is thoroughly tested
inside of libgreen and libnative. There isn't really the notion of "starting the
runtime" any more. The major notion now is "bootstrapping the initial task".
Turns out libuv's build system doesn't like us telling them that the build
directory is a relative location, as it always spits out a warning about a
circular dependency being dropped. By using an absolute path, turns out the
warnings isn't spit out, who knew?
Closes#11067
Turns out libuv's build system doesn't like us telling them that the build
directory is a relative location, as it always spits out a warning about a
circular dependency being dropped. By using an absolute path, turns out the
warnings isn't spit out, who knew?
Closes#11067
rustdoc:
- fix search-bar layout
doc: CSS:
- switch to native pandoc toc depth
- rm some dead code
- clamp width to be readable (we're not Wikipedia!)
- don't background-color titles, it's bloating
- make syntax-highlighting colors inline with rust-lang.org
- space indents
@alexcrichton
