Xcode 9: Comment on Last Active Line of Code in a File Hangs Xcode

Originator:alexceleste
Number:rdar://33500159 Date Originated:July 24, 2017
Status:Duplicate/33406496/Closed Resolved:
Product:Developer Tools Product Version:9.0/9M189t
Classification:Bug Reproducible:Always
 
Summary:
Writing a comment at the end of the last line of active code in a file in Xcode will eventually cause the editor to hang, with the beachball cursor. Generally this causes you to need to force quit Xcode, or you can (slowly) delete back over the comment and Xcode will get faster with each deleted character. This occurs in both files in projects, as well as in playgrounds.

Steps to Reproduce:
1. Create a new playground
2. Start adding a comment to the last line (in new playgrounds this would be this line: var str = "Hello, playground")
3. Notice the editor getting hung up eventually as you type. On faster Macs you can go longer than on slower Macs, but every Mac will get hung up on this.

Expected Results:
The editor to let you add a comment as usual.

Observed Results:
The editor begins to get hung as you type further characters in the comment.

Version:
Xcode: 9.0/9M189t
macOS: 10.12.6/16G29

Notes:
We first noticed this in a project, but tested it in a playground as well. Since it appears in playgrounds we offer that as the steps to reproduce since that is simpler. The playground we used to test this is attached to this bug report.

Configuration:
We tested this on both a slower 2011 iMac as well as a faster 2013 iMac.

Comments

When later asked I provided sysdiagnose from my iMac, as well as from a MacBook Pro with High Sierra beta.

By alexceleste at July 27, 2017, 9:58 p.m. (reply...)

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