MIR episode 5
This PR inits drop support (it is very broken at this stage, some things are dropped multiple time, drop scopes are wrong, ...) and adds stdout support (`println!` doesn't work since its expansion is dummy, but `stdout().write(b"hello world\n")` works if you use `RA_SYSROOT_HACK`) for interpreting. There is no useful unit test that it can interpret yet, but it is a good sign that it didn't hit a major road block yet.
In MIR lowering, it adds support for slice pattern and anonymous const blocks, and some fixes so that we can evaluate `SmolStr::new_inline` in const eval. With these changes, 57 failed mir body remains.
fix: Diagnose non-value return and break type mismatches
Could definitely deserve more polished diagnostics, but this at least brings the message across for now.
fix(analysis-stats): divided by zero error
## What does this PR try to resolve?
2023-05-15 rust-analyzer suffers from
```
thread 'main' panicked at 'attempt to divide by zero', crates/rust-analyzer/src/cli/analysis_stats.rs:230:56
```
This commit <51e8b8ff14> might be the culprit.
This PR uses `percentage` function to avoid the classic “division by zero” bug.
## Reproducer
```console
cargo new ra-test
pushd ra-test
echo "pub type Foo = u32;" >> src/lib.rs
rust-analyzer analysis-stats .
```
Support `#[macro_use(name, ...)]`
This PR adds support for another form of the `macro_use` attribute: `#[macro_use(name, ...)]` ([reference]).
Note that this form of the attribute is only applicable to extern crate decls, not to mod decls.
[reference]: https://doc.rust-lang.org/reference/macros-by-example.html#the-macro_use-attribute
Parse associated return type bounds
This PR implements parser support for associated return type bounds: `T: Foo<bar(): Send>`. This PR does not implement associated return types (`T::bar(): Send`) because it's not implemented even in rustc, and also removes `(..)`-style return type notation because it has been removed in rust-lang/rust#110203 (effectively reverting #14465).
I don't plan to proactively follow this unstable feature unless an RFC is accepted and my main motivation here is to remove no-longer-valid syntax `(..)` from our parser, nevertheless adding minimal parser support so anyone interested (as can be seen in #14465) can experiment it without rust-analyzer's syntax errors.
Expand more single ident macro calls upon item collection
Addresses https://github.com/rust-lang/rust-analyzer/pull/14781#issuecomment-1546201022
I believe this (almost) brings the number of unresolved names back to pre-#14781:
|r-a version|`analysis-stats compiler/rustc` (rust-lang/rust@69fef92ab2) |
|---|---|
|pre-#14781 (b069eb720b) | exprs: 2747778, ??ty: 122236 (4%), ?ty: 107826 (3%), !ty: 728 |
| #14781 (a7944a93a1) | exprs: 2713080, ??ty: 139651 (5%), ?ty: 114444 (4%), !ty: 730 |
| with this fix | exprs: 2747871, ??ty: 122237 (4%), ?ty: 108171 (3%), !ty: 676 |
(I haven't investigated on the increase in some numbers but hopefully not too much of a problem)
This is only a temporary solution. The core problem is that we haven't fully implemented the textual scope of legacy macros. For example, we *have been* failing to resolve `foo` in the following snippet, even before #14781 or after this patch. As noted in a FIXME, we need a way to resolve names in textual scope without eager expansion during item collection.
```rust
//- /main.rs crate:main deps:lib
lib::mk_foo!();
const A: i32 = foo!();
//^^^^^^ unresolved-macro-call
//- /lib.rs crate:lib
#[macro_export]
macro_rules! mk_foo {
() => {
macro_rules! foo { () => { 42 } }
}
}
```
