swiftlang/swift

[SR-7230] Improve error message for statement that begins with open brace

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#49,778 opened on Mar 19, 2018

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Description
Previous ID SR-7230
Radar None
Original Reporter @jckarter
Type Bug
Votes 0
Component/s Compiler
Labels Bug, DiagnosticsQoI, StarterBug
Assignee None
Priority Medium

md5: 809fd159923a9a4b4bcf2169a9eb2a66

Issue Description:

Swift doesn't allow a statement to begin with an open brace, and the error message you get when you do is hostile to beginners, talking about "unused closures" rather than the syntactic issue:

https://twitter.com/twostraws/status/975740708601593857

This is likely to come up when a user is moving code around, so the error and associated fixits could be greatly improved.

Contributor guide

Research direction
Find the part of the Swift compiler that emits the error for statements beginning with an open brace. Improve the diagnostic message to suggest a possible fix (e.g., adding a semicolon or wrapping in parentheses) and consider providing a fix it.
Tech stack
swift
Domain
compilers
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Swiftcompiler concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85