[bug] fn $FUNC($$$ARGS) { $$$ } does not match the function item of Rust

[kdy1]

⏯ Playground Link

Playground link with relevant code

💻 Code

Code:

#[turbo_tasks::function]
async fn read(name: String) -> Result<Vc<Option<String>>> {
    
}

Pattern:

id: update-function-parameters
language: rust
rule:
  pattern: 'fn $FUNC($$$ARGS) { $$$ }'

or pattern = fn $FUNC($$$ARGS) { $$$ } in the playground

🙁 Actual behavior

It didn't match any function.

🙂 Expected behavior

It should match all functions

[HerringtonDarkholme]

Thanks for the report.

There are two things in the repro:

1. fn $FUNC($$$ARGS) { $$$ } does not have a return type. So it does not match the fn read(name: String) -> Result<Vc<Option<String>>> because the latter has a return type. This is expected.

I recommend using any to combine these two cases.

id: update-function-parameters
language: rust
rule:
  any:
  - pattern: 'fn $FUNC($$$ARGS) { $$$ }'
  - pattern: 'fn $FUNC($$$ARGS) -> $RET { $$$ }'

2. However, the above YAML still does not match async function. This is also expected. Because async is an AST node function_modifiers, the pattern query does not specify the keyword.
   See the AST dump

This is the work around to avoid matching return type or async modifiers

id: update-function-parameters
language: rust
rule:
  kind: function_item
  has:
    kind: parameters
    pattern: $PARAMS
  

https://ast-grep.github.io/playground.html#eyJtb2RlIjoiQ29uZmlnIiwibGFuZyI6InJ1c3QiLCJxdWVyeSI6ImZuICRGVU5DKCQkJEFSR1MpIC0+ICRSRVQgeyAgJCQkIH0iLCJyZXdyaXRlIjoiIiwiY29uZmlnIjoiaWQ6IHVwZGF0ZS1mdW5jdGlvbi1wYXJhbWV0ZXJzXG5sYW5ndWFnZTogcnVzdFxucnVsZTpcbiAga2luZDogZnVuY3Rpb25faXRlbVxuICBoYXM6XG4gICAga2luZDogcGFyYW1ldGVyc1xuICAgIHBhdHRlcm46ICRQQVJBTVNcbiAgIiwic291cmNlIjoiI1t0dXJib190YXNrczo6ZnVuY3Rpb25dXG5hc3luYyBmbiByZWFkKG5hbWU6IFN0cmluZykgLT4gUmVzdWx0PFZjPE9wdGlvbjxTdHJpbmc+Pj4ge1xuICAgIFxufVxuIn0=