fix: rewrite code_action `generate_delegate_trait`
I've made substantial enhancements to the "generate delegate trait" code action in rust-analyzer. Here's a summary of the changes:
#### Resolved the "Can’t find CONST_ARG@158..159 in AstIdMap" error
Fix#15804, fix#15968, fix#15108
The issue stemmed from an incorrect application of PathTransform in the original code. Previously, a new 'impl' was generated first and then transformed, causing PathTransform to fail in locating the correct AST node, resulting in an error. I rectified this by performing the transformation before generating the new 'impl' (using make::impl_trait), ensuring a step-by-step transformation of associated items.
#### Rectified generation of `Self` type
`generate_delegate_trait` is unable to properly handle trait with `Self` type.
Let's take the following code as an example:
```rust
trait Trait {
fn f() -> Self;
}
struct B {}
impl Trait for B {
fn f() -> B { B{} }
}
struct S {
b: B,
}
```
Here, if we implement `Trait` for `S`, the type of `f` should be `() -> Self`, i.e. `() -> S`. However we cannot automatically generate a function that constructs `S`.
To ensure that the code action doesn't generate delegate traits for traits with Self types, I add a function named `has_self_type` to handle it.
#### Extended support for generics in structs and fields within this code action
The former version of `generate_delegate_trait` cannot handle structs with generics properly. Here's an example:
```rust
struct B<T> {
a: T
}
trait Trait<T> {
fn f(a: T);
}
impl<T1, T2> Trait<T1> for B<T2> {
fn f(a: T1) -> T2 { self.a }
}
struct A {}
struct S {
b$0 : B<A>,
}
```
The former version will generates improper code:
```rust
impl<T1, T2> Trait<T1, T2> for S {
fn f(&self, a: T1) -> T1 {
<B as Trait<T1, T2>>::f( &self.b , a)
}
}
```
The rewritten version can handle generics properly:
```rust
impl<T1> Trait<T1> for S {
fn f(&self, a: T1) -> T1 {
<B<A> as Trait<T1>>::f(&self.b, a)
}
}
```
See more examples in added unit tests.
I enabled support for generic structs in `generate_delegate_trait` through the following steps (using the code example provided):
1. Initially, to prevent conflicts between the generic parameters in struct `S` and the ones in the impl of `B`, I renamed the generic parameters of `S`.
2. Then, since `B`'s parameters are instantiated within `S`, the original generic parameters of `B` needed removal within `S` (to avoid errors from redundant parameters). An important consideration here arises when Trait and B share parameters in `B`'s impl. In such cases, these shared generic parameters cannot be removed.
3. Next, I addressed the matching of types between `B`'s type in `S` and its type in the impl. Given that some generic parameters in the impl are instantiated in `B`, I replaced these parameters with their instantiated results using PathTransform. For instance, in the example provided, matching `B<A>` and `B<T2>`, where `T2` is instantiated as `A`, I replaced all occurrences of `T2` in the impl with `A` (i.e. apply the instantiated generic arguments to the params).
4. Finally, I performed transformations on each assoc item (also to prevent the initial issue) and handled redundant where clauses.
For a more detailed explanation, please refer to the code and comments. I welcome suggestions and any further questions!
Don't trim trailing whitespace from doc comments
Don't trim trailing whitespace from doc comments as multiple trailing spaces indicates a hard line break in Markdown.
I'd have liked to add a unit test for `docs_from_attrs`, but couldn't find a reasonable way to get an `&Attrs` object for use in the test.
Fixes#15877.
feat: generate descriptors for all unstable features
Most unstable features don't have their own chapter in the unstable book, so a rustc helper tool (`src/tools/unstable-book-gen`) generates shims to fill the gaps.
Run this tool to generate the full unstable-book source before parsing it.
Fix autoimport does nothing when importing trait that is as _ imports
Potentially fixes#15128
There are two cases of imports:
1. With simple path
2. With use tree list (or say complex path).
On deeper inspection, the [`recursive_merge`](994df3d6a3/crates/ide-db/src/imports/merge_imports.rs (L87)) function (called by [`try_merge_trees_mut`)](994df3d6a3/crates/ide-db/src/imports/merge_imports.rs (L69)) is meaningful only in the case of complex path (i.e when the UseTree contains a UseTreeList).
The [`recursive_merge`](994df3d6a3/crates/ide-db/src/imports/merge_imports.rs (L87)) function has [match with `Ok` arm](994df3d6a3/crates/ide-db/src/imports/merge_imports.rs (L106)), that is only executed when both LHS and RHS has `PathSegment` with same `NameRef`. The removal of underscore is implemented in this arm in the case of complex path.
For simple paths, the underscore is removed by checking if both LHS and RHS are simple paths and if their `Path` is same (the check is done [here](994df3d6a3/crates/ide-db/src/imports/merge_imports.rs (L74))) and remove the underscore if one is found (I made an assumption here that RHS will always be what rust-analyzer suggests to import, because at this point I'm not sure how to remove underscore with help of `ted::replace`).
This fixes a typo first appearing in #94624
in which test-macro diagnostic uses "a" article twice.
Since I searched sources for " a a " sequences,
I also fixed the same issue in a few source files where I found it.
Signed-off-by: Petr Portnov <gh@progrm-jarvis.ru>
Automatically instaciate trivially instaciable structs in "Generate new" and "Fill struct fields"
As proposed in #12535 this PR changes the "Generate new" and "Fill struct fields" assist/diagnostic to instanciate structs with no fields and enums with a single empty variant.
For example:
```rust
pub enum Bar {
Bar {},
}
struct Foo<T> {
a: usize,
bar: Bar,
_phantom: std::marker::PhantomData<T>,
}
impl<T> Foo<T> {
/* generate new */
fn random() -> Self {
Self { /* Fill struct fields */ }
}
}
```
was previously:
```rust
impl<T> Foo<T> {
fn new(a: usize, bar: Bar, _phantom: std::marker::PhantomData<T>) -> Self {
Self { a, bar, _phantom }
}
fn random() -> Self {
Self {
a: todo!(),
bar: todo!(),
_phantom: todo!(),
}
}
}
```
and is now:
```rust
impl<T> Foo<T> {
fn new(a: usize) -> Self {
Self {
a,
bar: Bar::Bar {},
_phantom: std::marker::PhantomData
}
}
fn random() -> Self {
Self {
a: todo!(),
bar: Bar::Bar {},
_phantom: std::marker::PhantomData,
}
}
}
```
I'd be happy about any suggestions.
## TODO
- [x] deduplicate `use_trivial_constructor` (unclear how to do as it's used in two separate crates)
- [x] write tests
Closes#12535
The selected imports have to have a common prefix in paths.
Before
```rust
$0use std::fmt::Display;
use std::fmt::Debug;$0
```
After
```rust
use std::fmt::{Display, Debug};
```
