rust-lang / rust-lang/rust-analyzer
Feature request: Infer generate-function return type from usage as inverted conditional
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Description
Given
fn main() {
if !foo() {}
}
it's almost certain that foo returns a bool¹. Currently, using the generate-function assist on it generates
fn foo() -> _ {
todo!()
}
but I think it should generate
fn foo() -> bool {
todo!()
}
¹ it could theoretically return any other type that implements std::ops::Not<Output = bool>, but I have never seen any code with an impl like that
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by locating the generate-function assist and tracing how it infers return types from call-site usage, especially the inverted conditional shown in the issue. Update the behavior so this example produces a bool return type, and verify the assist output with the relevant existing checks or tests.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 48/100