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 } }
}
}
```
fix: Add macro modifier for highlighting tokens in macro calls
Followup to https://github.com/rust-lang/rust-analyzer/pull/14777 we have to tell the client about the semantic tokens inside macro calls as those can be remapped. Adding a modifier will force this behavior.
Introduce macro sub-namespaces and `macro_use` prelude
This PR implements two mechanisms needed for correct macro name resolution: macro sub-namespace and `macro_use` prelude.
- [macro sub-namespaces][subns-ref]
Macros have two sub-namespaces: one for function-like macro and the other for those in attributes (including custom derive macros). When we're resolving a macro name for function-like macro, we should ignore non-function-like macros, and vice versa.
This helps resolve single-segment macro names because we can (and should, as rustc does) fallback to names in preludes when the name in the current module scope is in different sub-namespace.
- [`macro_use` prelude][prelude-ref]
`#[macro_use]`'d extern crate declarations (including the standard library) bring their macros into scope, but they should not be prioritized over local macros (those defined in place and those explicitly imported).
We have been bringing them into legacy (textual) macro scope, which has the highest precedence in name resolution. This PR introduces the `macro_use` prelude in crate-level `DefMap`s, whose precedence is lower than local macros but higher than the standard library prelude.
The first 3 commits are drive-by fixes/refactors.
Fixes#8828 (prelude)
Fixes#12505 (prelude)
Fixes#12734 (prelude)
Fixes#13683 (prelude)
Fixes#13821 (prelude)
Fixes#13974 (prelude)
Fixes#14254 (namespace)
[subns-ref]: https://doc.rust-lang.org/reference/names/namespaces.html#sub-namespaces
[prelude-ref]: https://doc.rust-lang.org/reference/names/preludes.html#macro_use-prelude
We've already removed non-sysroot proc macro server, which effectively
removed support for Rust <1.64.0, so this removal of fallback path
shouldn't be problem at this point.
