b355906919
Implement Unsized Rvalues This PR is the first step to implement RFC1909: unsized rvalues (#48055). ## Implemented - `Sized` is removed for arguments and local bindings. (under `#![feature(unsized_locals)]`) - Unsized locations are allowed in MIR - Unsized places and operands are correctly translated at codegen ## Not implemented in this PR - Additional `Sized` checks: - tuple struct constructor (accidentally compiles now) - closure arguments at closure generation (accidentally compiles now) - upvars (ICEs now) - Generating vtable for `fn method(self)` (ICEs now) - VLAs: `[e; n]` where `n` isn't const - Reduce unnecessary allocations ## Current status - [x] Fix `__rust_probestack` (rust-lang-nursery/compiler-builtins#244) - [x] Get the fix merged - [x] `#![feature(unsized_locals)]` - [x] Give it a tracking issue number - [x] Lift sized checks in typeck and MIR-borrowck - [ ] <del>Forbid `A(unsized-expr)`</del> will be another PR - [x] Minimum working codegen - [x] Add more examples and fill in unimplemented codegen paths - [ ] <del>Loosen object-safety rules (will be another PR)</del> - [ ] <del>Implement `Box<FnOnce>` (will be another PR)</del> - [ ] <del>Reduce temporaries (will be another PR)</del>
The syntax crate contains those things concerned purely with syntax
– that is, the AST ("abstract syntax tree"), parser, pretty-printer,
lexer, macro expander, and utilities for traversing ASTs.
For more information about how these things work in rustc, see the rustc guide: