swiftlang/swift

[SR-7113] `try` on closures needs a clearer error message

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#49,661 opened on Mar 3, 2018

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Description
Previous ID SR-7113
Radar None
Original Reporter designatednerd (JIRA User)
Type Bug

Attachment: Download

Xcode Version 9.2 (9C40b)

OS X Version 10.12.6 (16G1212)

swift --version output:

Apple Swift version 4.0.3 (swiftlang-900.0.74.1 clang-900.0.39.2)
Votes 0
Component/s Compiler
Labels Bug, DiagnosticsQoI, StarterBug
Assignee None
Priority Medium

md5: 0de4d3bda4791cbb582db3d2e00a5ef2

Issue Description:

When trying to add a try to a closure, the warning received is confusing if there is something within the closure which also needs a try. See attached screenshot for an example.

Per @jckarter, this is something which probably needs a clearer message: https://twitter.com/jckarter/status/969774890373996544

My personal suggestion for a message would be "try outside of a closure does not affect the code within the closure", but feel free to bikeshed that as much as you'd like.

Contributor guide

Tech stack
swift
Domain
developer experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Swiftcompiler build setup
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
Locate the diagnostic for 'try' on closures in the Swift compiler source (likely in the type checker). Modify the error message to be clearer, as suggested. The issue has a Twitter link with additional discussion. Ensure changes pass existing tests.
[SR-7113] `try` on closures needs a clearer error message · swiftlang/swift#49661 | Good First Issue