swiftlang/swift

[SR-5058] Redundant Conformance Diagnostic should have an associated fixit

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#47,634 opened on May 31, 2017

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bugcompilerdiagnostics qualitygood first issue

Description
Previous ID SR-5058
Radar rdar://32431756
Original Reporter @CodaFi
Type Bug
Status In Progress
Resolution

Attachment: Download
Votes 1
Component/s Compiler
Labels Bug, DiagnosticsQoI, StarterBug
Assignee interfere (JIRA)
Priority Medium

md5: 5985872320450fd433971928ef7a5b14

Issue Description:

The redundant conformance diagnostic can point at the protocol that is redundant, but doesn’t actually offer to remove it.

protocol Foo {}
struct Bar {}

extension Bar: Foo {}
extension Bar: Foo {} // redundant conformance of 'Bar' to protocol 'Foo'

Contributor guide

Tech stack
swift
Domain
tooling
Issue type
bug
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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Swift languageSwift compiler basicsDiagnostic fixit API
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
The issue is to add a fixit for the redundant conformance diagnostic. Look for the diagnostic emission in the Swift compiler source, likely in lib/Sema or lib/AST. The diagnostic message is about redundant conformance, and the fixit should suggest removing the duplicate conformance declaration. Investigate existing fixits in the compiler (e.g., in LLVM's DiagnosticConsumers) to understand the API for adding fixits. The issue is labeled StarterBug and involves a localized change.