2585803ec1
# Summary This patch introduces the `_` token into the type grammar, with the meaning "infer this type". With this change, the following two lines become equivalent: ``` let x = foo(); let x: _ = foo(); ``` But due to its composability, it enables partial type hints like this: ``` let x: Bar<_> = baz(); ``` Using it on the item level is explicitly forbidden, as the Rust language does not enable global type inference by design. This implements the feature requested in https://github.com/mozilla/rust/issues/9508. # Things requiring clarification - The change to enable it is very small, but I have only limited understanding of the related code, so the approach here might be wrong. - In particular, while this patch works, it does so in a way not originally intended according to the code comments. - This probably needs more tests, or rather feedback for which tests are still missing. - I'm unsure how this interacts with lifetime parameters, and whether it is correct in regard to them. - Partial type hints on the right side of `as` like `&foo as *_` work in both a normal function contexts and in constexprs like `static foo: *int = &'static 123 as *_`. The question is whether this should be allowed in general. # Todo for this PR - The manual and tutorial still needs updating. # Bugs I'm unsure how to fix - Requesting inference for the top level of the right hand side of a `as` fails to infer correctly, even if all possible hints are given: ``` .../type_hole_1.rs:35:18: 35:22 error: the type of this value must be known in this context .../type_hole_1.rs:35 let a: int = 1u32 as _; ^~~~ ``` |
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| .. | ||
| compiler-rt@f4b221571c | ||
| compiletest | ||
| doc | ||
| driver | ||
| etc | ||
| gyp@1e46da1000 | ||
| libarena | ||
| libbacktrace | ||
| libcollections | ||
| libextra | ||
| libflate | ||
| libfourcc | ||
| libgetopts | ||
| libglob | ||
| libgreen | ||
| libhexfloat | ||
| libnative | ||
| libnum | ||
| librand | ||
| librustc | ||
| librustdoc | ||
| librustuv | ||
| libsemver | ||
| libserialize | ||
| libstd | ||
| libsync | ||
| libsyntax | ||
| libterm | ||
| libtest | ||
| libtime | ||
| libuuid | ||
| libuv@800b56fe6a | ||
| llvm@263c617d66 | ||
| rt | ||
| rustllvm | ||
| test | ||
| README.md | ||
| snapshots.txt | ||
This is a preliminary version of the Rust compiler, libraries and tools.
Source layout:
| Path | Description |
|---|---|
librustc/ |
The self-hosted compiler |
libstd/ |
The standard library (imported and linked by default) |
libextra/ |
The "extras" library (slightly more peripheral code) |
libgreen/ |
The M:N runtime library |
libnative/ |
The 1:1 runtime library |
libsyntax/ |
The Rust parser and pretty-printer |
libcollections/ |
A collection of useful data structures and containers |
libnum/ |
Extended number support library (complex, rational, etc) |
libtest/ |
Rust's test-runner code |
| ------------------- | --------------------------------------------------------- |
libarena/ |
The arena (a fast but limited) memory allocator |
libflate/ |
Simple compression library |
libfourcc/ |
Data format identifier library |
libgetopts/ |
Get command-line-options library |
libglob/ |
Unix glob patterns library |
libsemver/ |
Rust's semantic versioning library |
libserialize/ |
Encode-Decode types library |
libsync/ |
Concurrency mechanisms and primitives |
libterm/ |
ANSI color library for terminals |
libtime/ |
Time operations library |
libuuid/ |
UUID's handling code |
| ------------------- | --------------------------------------------------------- |
rt/ |
The runtime system |
rt/rust_*.c |
- Some of the runtime services |
rt/vg |
- Valgrind headers |
rt/msvc |
- MSVC support |
rt/sundown |
- The Markdown library used by rustdoc |
| ------------------- | --------------------------------------------------------- |
compiletest/ |
The test runner |
test/ |
Testsuite |
test/codegen |
- Tests for the LLVM IR infrastructure |
test/compile-fail |
- Tests that should fail to compile |
test/debug-info |
- Tests for the debuginfo tool |
test/run-fail |
- Tests that should compile, run and fail |
test/run-make |
- Tests that depend on a Makefile infrastructure |
test/run-pass |
- Tests that should compile, run and succeed |
test/bench |
- Benchmarks and miscellaneous |
test/pretty |
- Pretty-printer tests |
test/auxiliary |
- Dependencies of tests |
| ------------------- | --------------------------------------------------------- |
librustdoc/ |
The Rust API documentation tool |
libuv/ |
The libuv submodule |
librustuv/ |
Rust libuv support code |
| ------------------- | --------------------------------------------------------- |
llvm/ |
The LLVM submodule |
rustllvm/ |
LLVM support code |
| ------------------- | --------------------------------------------------------- |
etc/ |
Scripts, editors support, misc |
NOTE: This list (especially the second part of the table which contains modules and libraries) is highly volatile and subject to change.