swiftlang/swift

[SR-9795] Cannot use `super` in lazy property: 'super' cannot be used outside of class members

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#52,220 opened on Jan 29, 2019

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 (12 comments) (0 reactions) (1 assignee)Swift (69,989 stars) (10,719 forks)batch import
bugcompilergood first issue

Description
Previous ID SR-9795
Radar None
Original Reporter @marcomasser
Type Bug

Tested with Swift 4.2.1 (Xcode 10.1) and Swift 5 from Xcode 10.2 beta (swiftlang-1001.0.45.7 clang-1001.0.37.7).
Votes 0
Component/s Compiler
Labels Bug, StarterBug
Assignee @theblixguy
Priority Medium

md5: 75741cacf781b9db21044152b379d272

Issue Description:

I’m not sure this is a bug or if this works as expected:

class Foo {
    var name = "Default Name"
}

class Bar: Foo {
    lazy var fullName: String = {
        return super.name // error: 'super' cannot be used outside of class members
    }()
}

Is there a good reason why super isn’t permitted here? Replacing super with self works fine, as I’d expect because the instance must be fully initialized when lazy properties are accessed.

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.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Swift language basicsUnderstanding of lazy properties
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35
Research direction
The issue is a compiler bug where `super` is incorrectly disallowed in lazy property closures. The fix likely involves modifying the Swift type checker in the `lib/Sema` directory to permit `super` in that context. Review the existing comments (12 comments) for any proposed solutions or constraints. The issue is assigned, so coordination with the assignee may be needed.
[SR-9795] Cannot use `super` in lazy property: 'super' cannot be used outside of class members · swiftlang/swift#52220 | Good First Issue