8524: Fix extract function with partial block selection r=matklad a=brandondong
**Reproduction:**
```rust
fn foo() {
let n = 1;
let mut v = $0n * n;$0
v += 1;
}
```
1. Select the snippet ($0) and use the "Extract into function" assist.
2. Extracted function is incorrect and does not compile:
```rust
fn foo() {
let n = 1;
let mut v = fun_name(n);
v += 1;
}
fn fun_name(n: i32) {}
```
3. Omitting the ending semicolon from the selection fixes the extracted function:
```rust
fn fun_name(n: i32) -> i32 {
n * n
}
```
**Cause:**
- When `extraction_target` uses a block extraction (semicolon case) instead of an expression extraction (no semicolon case), the user selection is directly used as the TextRange.
- However, the existing function extraction logic for blocks requires that the TextRange spans from start to end of complete statements to work correctly.
- For example:
```rust
fn foo() {
let m = 2;
let n = 1;
let mut v = m $0* n;
let mut w = 3;$0
v += 1;
w += 1;
}
```
produces
```rust
fn foo() {
let m = 2;
let n = 1;
let mut v = m let mut w = fun_name(n);
v += 1;
w += 1;
}
fn fun_name(n: i32) -> i32 {
let mut w = 3;
w
}
```
- The user selected TextRange is directly replaced by the function call which is now in the middle of another statement. The extracted function body only contains statements that were fully covered by the TextRange and so the `* n` code is deleted. The logic for calculating variable usage and outlived variables for the function parameters and return type respectively search within the TextRange and so do not include `m` or `v`.
**Fix:**
- Only extract full statements when using block extraction. If a user selected part of a statement, extract that full statement.
8527: Switch introduce_named_lifetime assist to use mutable syntax tree r=matklad a=iDawer
This extends `GenericParamsOwnerEdit` trait with `get_or_create_generic_param_list` method
Co-authored-by: Brandon <brandondong604@hotmail.com>
Co-authored-by: Dawer <7803845+iDawer@users.noreply.github.com>
7620: Support control flow in `extract_function` assist r=matklad a=cpud36
Support `return`ing from outer function, `break`ing and `continue`ing outer loops when extracting function.
# Example
Transforms
```rust
fn foo() -> i32 {
let items = [1,2,3];
let mut sum = 0;
for &item in items {
<|>if item == 42 {
break;
}<|>
sum += item;
}
sum
}
```
Into
```rust
fn foo() -> i32 {
let items = [1,2,3];
let mut sum = 0;
for &item in items {
if fun_name(item) {
break;
}
sum += item;
}
sum
}
fn fun_name(item: i32) -> bool {
if item == 42 {
return true;
}
false
}
```
# Features
Supported variants
- break and function does not return => uses `bool` and plain if
- break and function does return => uses `Option<T>` and matches on it
- break with value and function does not return => uses `Option<T>` and if let
- break with value and function does return => uses `Result<T, U>` and matches on t
- same for `return` and `continue`(but we can't continue with value)
Assist does handle nested loops and nested items(like functions, modules, impls)
Try `expr?` operator is allowed together with `return Err(_)` and `return None`.
`return expr` is not allowed.
# Not supported
## Mixing `return` with `break` or `continue`
If we have e.g. a `return` and a `break` in the selected code, it is unclear what the produced code should look like.
We can try `Result<T, Option<U>>` or something like that, but it isn't idiomatic, nor it is established. Otherwise, implementation
is relatively simple.
## `break` with label
Not sure how to handle different labels for multiple `break`s.
[edit] implemented try `expr?`
Co-authored-by: Vladyslav Katasonov <cpud47@gmail.com>
