swiftlang/swift

Missing fix-it when opaque property type is inferred

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#69,241 opened on Oct 18, 2023

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compilerdiagnostics qualityfix-itsgood first issueimprovementopaque result typesopaque typesswift 6.0type checker

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Description

Description When the type of a variable or property is inferred as an opaque type, the compiler emits an error to that effect:

Property definition has inferred type 'some Proto', involving the 'some' return type of another declaration

Steps to reproduce When compiling this code, the last line has the above error attached.:

protocol Proto {}
struct Concrete: Proto {}
func getProto() -> some Proto { Concrete() }

let value = getProto() // error

Expected behavior Since the fix is straightforward and included in the error message, the compiler should offer a fixit that would rectify the problem:

let value: some Proto = getProto()

Environment

  • Swift compiler version info Apple Swift version 5.9 (swiftlang-5.9.0.128.108 clang-1500.0.40.1) Target: arm64-apple-macosx14.0

Contributor guide

Research direction
Locate the diagnostic emission for the error 'Property definition has inferred type ...' in the Swift compiler source code, then add a fix it that inserts the explicit opaque type annotation (e.g., `: some Proto`). Refer to existing fix its for similar diagnostics as a guide.
Tech stack
swift
Domain
developer experience
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitSwift
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65