Handle trait alias definitions
Part of #2773
This PR adds a bunch of structs and enum variants for trait aliases. Trait aliases should be handled as an independent item because they are semantically distinct from traits.
I basically started by adding `TraitAlias{Id, Loc}` to `hir_def::item_tree` and iterated adding necessary stuffs until compiler stopped complaining what's missing. Let me know if there's still anything I need to add.
I'm opening up this PR for early review and stuff. I'm planning to add tests for IDE functionalities in this PR, but not type-related support, for which I put FIXME notes.
Fix associated item visibility in block-local impls
Fixes#14046
When we're resolving visibility of block-local items...
> `self` normally refers to the containing non-block module, and `super` to its parent (etc.). However, visibilities must only refer to a module in the DefMap they're written in, so we restrict them when that happens. ([link])
...unless we're resolving visibility of associated items in block-local impls, because that impl is semantically "hoisted" to the nearest (non-block) module. With this PR, we skip the adjustment for such items.
Since visibility representation of those items is modified, this PR also adjusts visibility rendering in `HirDisplay`.
[link]: a6603fc21d/crates/hir-def/src/nameres/path_resolution.rs (L101-L103)
Fix: Run doctests for structs with lifetime parameters from IDE
Fixes#14142: Doctests can't be triggered for structs with lifetimes
This MR adds lifetime parameters to the structs path for runnables so that they can be triggered from an IDE as well.
This is my first MR for rust-analyzer, please let me know if I should change something, either in code or the description here.
Beginning of MIR
This pull request introduces the initial implementation of MIR lowering and interpreting in Rust Analyzer.
The implementation of MIR has potential to bring several benefits:
- Executing a unit test without compiling it: This is my main goal. It can be useful for quickly testing code changes and print-debugging unit tests without the need for a full compilation (ideally in almost zero time, similar to languages like python and js). There is a probability that it goes nowhere, it might become slower than rustc, or it might need some unreasonable amount of memory, or we may fail to support a common pattern/function that make it unusable for most of the codes.
- Constant evaluation: MIR allows for easier and more correct constant evaluation, on par with rustc. If r-a wants to fully support the type system, it needs full const eval, which means arbitrary code execution, which needs MIR or something similar.
- Supporting more diagnostics: MIR can be used to detect errors, most famously borrow checker and lifetime errors, but also mutability errors and uninitialized variables, which can be difficult/impossible to detect in HIR.
- Lowering closures: With MIR we can find out closure capture modes, which is useful in detecting if a closure implements the `FnMut` or `Fn` traits, and calculating its size and data layout.
But the current PR implements no diagnostics and doesn't support closures. About const eval, I removed the old const eval code and it now uses the mir interpreter. Everything that is supported in stable rustc is either implemented or is super easy to implement. About interpreting unit tests, I added an experimental config, disabled by default, that shows a `pass` or `fail` on hover of unit tests (ideally it should be a button similar to `Run test` button, but I didn't figured out how to add them). Currently, no real world test works, due to missing features including closures, heap allocation, `dyn Trait` and ... so at this point it is only useful for me selecting what to implement next.
The implementation of MIR is based on the design of rustc, the data structures are almost copy paste (so it should be easy to migrate it to a possible future stable-mir), but the lowering and interpreting code is from me.
fix: Don't expand macros in the same expansion tree after overflow
This patch fixes 2 bugs:
- In `Expander::enter_expand_id()` (and in code paths it's called), we never check whether we've reached the recursion limit. Although it hasn't been reported as far as I'm aware, this may cause hangs or stack overflows if some malformed attribute macro is used on associated items.
- We keep expansion even when recursion limit is reached. Take the following for example:
```rust
macro_rules! foo { () => {{ foo!(); foo!(); }} }
fn main() { foo!(); }
```
We keep expanding the first `foo!()` in each expansion and would reach the limit at some point, *after which* we would try expanding the second `foo!()` in each expansion until it hits the limit again. This will (by default) lead to ~2^128 expansions.
This is essentially what's happening in #14074. Unlike rustc, we don't just stop expanding macros when we fail as long as it produces some tokens so that we can provide completions and other services in incomplete macro calls.
This patch provides a method that takes care of recursion depths (`Expander::within_limit()`) and stops macro expansions in the whole macro expansion tree once it detects recursion depth overflow. To be honest, I'm not really satisfied with this fix because it can still be used in unintended ways to bypass overflow checks, and I'm still seeking ways such that misuses are caught by the compiler by leveraging types or something.
Fixes#14074
