65c043fdd2
More systematic error reporting in path resolution
Path resolution for types, expressions and patterns used various heuristics to give more helpful messages on unresolved or incorrectly resolved paths.
This PR combines these heuristics and applies them to all non-import paths.
First a path is resolved in all namespaces, starting from its primary namespace (to give messages like "expected function, found macro, you probably forgot `!`").
If this resolution doesn't give a desired result we create a base error - either "path is not resolved" or "path is resolved, but the resolution is not acceptable in this context".
Other helps and notes are applied to this base error using heuristics.
Here's the list of heuristics for a path with a last segment `name` in order.
First we issue special messages for unresolved `Self` and `self`.
Second we try to find free items named `name` in other modules and suggest to import them.
Then we try to find fields and associated items named `name` and suggest `self.name` or `Self::name`.
After that we try several deterministic context dependent heuristics like "expected value, found struct, you probably forgot `{}`".
If nothing of the above works we try to find candidates with other names using Levenshtein distance.
---
Some alternatives/notes/unresolved questions:
- ~~I had a strong desire to migrate all affected tests to `test/ui`, diagnostics comparison becomes much more meaningful, but I did this only for few tests so far.~~ (Done)
- ~~Labels for "unresolved path" errors are mostly useless now, it may make sense to move some help/notes to these labels, help becomes closer to the error this way.~~ (Done)
- ~~Currently only the first successful heuristic results in additional message shown to the user, it may make sense to print them all, they are rarely compatible, so the diagnostics bloat is unlikely.~~ (Done)
- Now when https://github.com/rust-lang/rust/pull/38014 landed `resolve_path` can potentially be replaced with `smart_resolve_path` in couple more places - e.g. ~~visibilities~~ (done), ~~import prefixes~~ (done), HIR paths.
---
Some additional fixes:
- Associated suggestions and typo suggestions are filtered with a context specific predicate to avoid inapplicable suggestions.
- `adjust_local_def` works properly in speculative resolution.
- I also fixed a recently introduced ICE in partially resolved UFCS paths (see test `ufcs-partially-resolved.rs`). Minimal reproduction:
```
enum E {}
fn main() {
<u8 as E>::A;
}
```
Fixes https://github.com/rust-lang/rust/issues/38409, fixes https://github.com/rust-lang/rust/issues/38504 (duplicates).
- Some bugs in resolution of visibilities are fixed - `pub(Enum)`, `pub(Trait)`, `pub(non::local::path)`.
- Fixes https://github.com/rust-lang/rust/issues/38012.
---
r? @jseyfried for technical details + @jonathandturner for diagnostics changes
How to read the patch: `smart_resolve_path(_fragment)/resolve_qpath_anywhere` are written anew and replace `resolve_trait_reference`/`resolve_type`/`resolve_pattern_path`/`resolve_struct_path`/`resolve_expr` for `ExprKind::Path`, everything else can be read as a diff.
The Rust Programming Language
This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.
Quick Start
Read "Installing Rust" from The Book.
Building from Source
-
Make sure you have installed the dependencies:
g++4.7 or later orclang++3.xpython2.7 (but not 3.x)- GNU
make3.81 or later cmake3.4.3 or latercurlgit
-
Clone the source with
git:$ git clone https://github.com/rust-lang/rust.git $ cd rust
-
Build and install:
$ ./configure $ make && sudo make installNote: Install locations can be adjusted by passing a
--prefixargument toconfigure. Various other options are also supported – pass--helpfor more information on them.When complete,
sudo make installwill place several programs into/usr/local/bin:rustc, the Rust compiler, andrustdoc, the API-documentation tool. This install does not include Cargo, Rust's package manager, which you may also want to build.
Building on Windows
There are two prominent ABIs in use on Windows: the native (MSVC) ABI used by Visual Studio, and the GNU ABI used by the GCC toolchain. Which version of Rust you need depends largely on what C/C++ libraries you want to interoperate with: for interop with software produced by Visual Studio use the MSVC build of Rust; for interop with GNU software built using the MinGW/MSYS2 toolchain use the GNU build.
MinGW
MSYS2 can be used to easily build Rust on Windows:
-
Grab the latest MSYS2 installer and go through the installer.
-
Run
mingw32_shell.batormingw64_shell.batfrom wherever you installed MSYS2 (i.e.C:\msys64), depending on whether you want 32-bit or 64-bit Rust. (As of the latest version of MSYS2 you have to runmsys2_shell.cmd -mingw32ormsys2_shell.cmd -mingw64from the command line instead) -
From this terminal, install the required tools:
# Update package mirrors (may be needed if you have a fresh install of MSYS2) $ pacman -Sy pacman-mirrors # Install build tools needed for Rust. If you're building a 32-bit compiler, # then replace "x86_64" below with "i686". If you've already got git, python, # or CMake installed and in PATH you can remove them from this list. Note # that it is important that the `python2` and `cmake` packages **not** used. # The build has historically been known to fail with these packages. $ pacman -S git \ make \ diffutils \ tar \ mingw-w64-x86_64-python2 \ mingw-w64-x86_64-cmake \ mingw-w64-x86_64-gcc -
Navigate to Rust's source code (or clone it), then configure and build it:
$ ./configure $ make && make install
MSVC
MSVC builds of Rust additionally require an installation of Visual Studio 2013
(or later) so rustc can use its linker. Make sure to check the “C++ tools”
option.
With these dependencies installed, you can build the compiler in a cmd.exe
shell with:
> python x.py build
If you're running inside of an msys shell, however, you can run:
$ ./configure --build=x86_64-pc-windows-msvc
$ make && make install
Currently building Rust only works with some known versions of Visual Studio. If you have a more recent version installed the build system doesn't understand then you may need to force rustbuild to use an older version. This can be done by manually calling the appropriate vcvars file before running the bootstrap.
CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.bat"
python x.py build
Building Documentation
If you’d like to build the documentation, it’s almost the same:
$ ./configure
$ make docs
The generated documentation will appear in a top-level doc directory,
created by the make rule.
Notes
Since the Rust compiler is written in Rust, it must be built by a precompiled "snapshot" version of itself (made in an earlier state of development). As such, source builds require a connection to the Internet, to fetch snapshots, and an OS that can execute the available snapshot binaries.
Snapshot binaries are currently built and tested on several platforms:
| Platform / Architecture | x86 | x86_64 |
|---|---|---|
| Windows (7, 8, Server 2008 R2) | ✓ | ✓ |
| Linux (2.6.18 or later) | ✓ | ✓ |
| OSX (10.7 Lion or later) | ✓ | ✓ |
You may find that other platforms work, but these are our officially supported build environments that are most likely to work.
Rust currently needs between 600MiB and 1.5GiB to build, depending on platform. If it hits swap, it will take a very long time to build.
There is more advice about hacking on Rust in CONTRIBUTING.md.
Getting Help
The Rust community congregates in a few places:
- Stack Overflow - Direct questions about using the language.
- users.rust-lang.org - General discussion and broader questions.
- /r/rust - News and general discussion.
Contributing
To contribute to Rust, please see CONTRIBUTING.
Rust has an IRC culture and most real-time collaboration happens in a variety of channels on Mozilla's IRC network, irc.mozilla.org. The most popular channel is #rust, a venue for general discussion about Rust. And a good place to ask for help would be #rust-beginners.
License
Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.
See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.