Make old-fashioned functions in the `std::os` module utilize `IoResult`.
I'm still investigating the possibility to include more functions in this pull request. Currently, it covers `getcwd()`, `make_absolute()`, and `change_dir()`. The issues covered by this PR are #16946 and #16315.
A few concerns:
- Should we provide `OsError` in distinction from `IoError`? I'm saying this because in Python, those two are distinguished. One advantage that we keep using `IoError` is that we can make the error cascade down other functions whose return type also includes `IoError`. An example of such functions is `std::io::TempDir::new_in()`, which uses `os::make_absolute()` as well as returns `IoResult<TempDir>`.
- `os::getcwd()` uses an internal buffer whose size is 2048 bytes, which is passed to `getcwd(3)`. There is no upper limitation of file paths in the POSIX standard, but typically it is set to 4096 bytes such as in Linux. Should we increase the buffer size? One thing that makes me nervous is that the size of 2048 bytes already seems a bit excessive, thinking that in normal cases, there would be no filenames that even exceeds 512 bytes.
Fixes#16946.
Fixes#16315.
Any ideas are welcomed. Thanks!
os::getcwd() panics if the current directory is not available. According
to getcwd(3), there are three cases:
- EACCES: Permission denied.
- ENOENT: The current working directory has been removed.
- ERANGE: The buffer size is less than the actual absolute path.
This commit makes os::getcwd() return IoResult<Path>, not just Path,
preventing it from panicking.
As os::make_absolute() depends on os::getcwd(), it is also modified to
return IoResult<Path>.
Fixes#16946.
[breaking-change]
region binding at the impl site, so for method types that come from impls,
it is necessary to liberate/instantiate late-bound regions at multiple
depths.
Reduces memory usage significantly and opens opportunities for more parallel compilation.
This PR was previously #19002 but I closed it because bors didn't seem to recognize the `r+` annotations there.
The trait has an obvious, sensible implementation directly on vectors so
the MemWriter wrapper is unnecessary. This will halt the trend towards
providing all of the vector methods on MemWriter along with eliminating
the noise caused by conversions between the two types. It also provides
the useful default Writer methods on Vec<u8>.
After the type is removed and code has been migrated, it would make
sense to add a new implementation of MemWriter with seeking support. The
simple use cases can be covered with vectors alone, and ones with the
need for seeks can use a new MemWriter implementation.
The trait has an obvious, sensible implementation directly on vectors so
the MemWriter wrapper is unnecessary. This will halt the trend towards
providing all of the vector methods on MemWriter along with eliminating
the noise caused by conversions between the two types. It also provides
the useful default Writer methods on Vec<u8>.
After the type is removed and code has been migrated, it would make
sense to add a new implementation of MemWriter with seeking support. The
simple use cases can be covered with vectors alone, and ones with the
need for seeks can use a new MemWriter implementation.
Hello,
`dylib` [seems][1] to be no longer an option for the `kind` key of the `link` attribute.
UPDATE: It should be the other way around: It [seems][1] `dylib` has been lost as a possible variant of the `kind` key of the `link` attribute. See the comment below.
Regards,
Ivan
[1]: 8f87538786/src/librustc/metadata/creader.rs (L237)
creating a new Id object requires the format to match a subset of `ID` format defined by the DOT language. When the format did not match, the function called assert. This was not mentioned in the docs or the spec. I made the failure explicit by returning an Result<Id, ()>.
Following [the collections reform RFC](https://github.com/rust-lang/rfcs/pull/235), this PR:
* Adds a new `borrow` module to libcore. The module contains traits for borrowing data (`BorrowFrom` and `BorrowFromMut`), generalized cloning (`ToOwned`), and a clone-on-write smartpointer (`Cow`).
* Deprecates the `_equiv` family of methods on `HashMap` and `HashSet` by instead generalizing the "normal" methods like `get` and `remove` to use the new `std::borrow` infrastructure.
* Generalizes `TreeMap`, `TreeSet`, `BTreeMap` and `BTreeSet` to use the new `std::borrow` infrastructure for lookups.
[breaking-change]
This is especially useful for declaring a static with external linkage in an executable. There isn't any way to do that currently since we mark everything in an executable as internal by default.
Also, a quick fix to have the no-compiler-rt target option respected when building staticlibs as well.
groundwork for better performance.
Key points:
- Separate out determining which method to use from actually selecting
a method (this should enable caching, as well as the pcwalton fast-reject strategy).
- Merge the impl selection back into method resolution and don't rely on
trait matching (this should perform better but also is needed to resolve some
kind of conflicts, see e.g. `method-two-traits-distinguished-via-where-clause.rs`)
- Purge a lot of out-of-date junk and coercions from method lookups.
