swiftlang/swift

Diagnostic for `static nonmutating` should be improved

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#77,835 opened on Nov 25, 2024

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bugcompilerdeclarationsdiagnostics qualitygood first issuemutatingstatic declarationsswift 6.1type checker

Description

Description

No response

Reproduction

struct S {
  nonmutating static func foo() {}
}

430 | 
431 | struct S {
432 |   nonmutating static func foo() {}
    |   `- error: static functions must not be declared mutating [static_functions_not_mutating]
433 | }
434 |

Expected behavior

An example approach to improving this error message is to list both modifiers.

We can also tailor it to call out the modifier in question as it currently does in the case of mutating. The drawback of this option is that it conveys less information about language grammar.s

Environment

Swift version 6.1-dev (26e888e45e6ede4)

Additional information

No response

Contributor guide

Tech stack
swift
Domain
developer experience
Issue type
refactor
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.
1-3 hours
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
Swift programming language
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
Locate the diagnostic for 'static functions not mutating' in the Swift compiler source, likely in lib/Sema or a similar diagnostic file. Modify the error message to list both 'static' and 'nonmutating' modifiers as suggested in the issue. Review the discussion for additional context on the expected behavior.