[SR-155] REPL: Summary string not being displayed for all struct names

[swift-ci]

Previous ID	SR-155
Radar	None
Original Reporter	MatiMax (JIRA User)
Type	Bug
Status	Closed
Resolution	Done

Environment

Linux 4.2.0-18-generic #22-Ubuntu SMP Fri Nov 6 18:25:50 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

Additional Detail from JIRA

Votes	0
Component/s	LLDB for Swift
Labels	Bug, Linux, REPL
Assignee	granataenrico (JIRA)
Priority	Medium

md5: 8bd91f558571b08051eea978d5766f67

Issue Description:

While in the Swift REPL defining a struct and creating a new value the evaluation of the value results in an error.

1> struct Point {
2.    var x: Float, y: Float 
3.    var d: Float { return y - x } 
4. }
5> var p = Point(x: -2.0, y: 3.0)
p: Point = error: summary string parsing error
6> print(p)
Point(x: -2.0, y: 3.0)

[swift-ci]

Comment by Matthias M. Schneider (JIRA)

If you rename Point to, for example, Pnt then the stuct will be evaluated correctly and printed without producing the error.

[swift-ci]

Comment by Enrico Granata (JIRA)

Hi,
I am one of the engineers that work on the Swift REPL

I can reproduce the issue you're presenting and it is an issue with the LLDB data formatters subsystem

We have a set of builtin data formatters that help us pretty print different data types (for instance, the elements in a Swift array, or the contents of an NSString, ...)
One of those data formatters is for a type named 'Point' that comes from some old Mac OS X framework
It is defined thusly: `(v=${var.v}, h=${var.h})`
In the LLDB formatters syntax, this means that your point shall be printed as the string "(v=" followed by the value of the member "v" of your Point variable, the string ", h=" the value of your Point variable's "h" member, and then a closed parenthesis

In your example, the Point type you defined has neither a ".v" nor a ".h" member, so the LLDB formatter gets confused, and emits a print error instead of just falling back to normal printing

The workaround is to - before defining your Point structure - type at the REPL prompt:

:type summary delete -l objc Point

I can see a few ways to improve this experience here, and I am going to hold on to this issue so that I can actively track these possible avenues

Thanks for your report!

[swift-ci]

Comment by Matthias M. Schneider (JIRA)

Hi Enrico,

thanks for looking into this and the workaround. I would never have thought along those lines given that a newly started REPL session explicitly tells me that Point is an "unresolved identifier" and as such I was happily playing along with the struct using this name. 😉

Your explanation is clear to me and I hope you and the team can fix this issue in the near future.

Cheers,

Mati

[swift-ci]

Comment by Matthias M. Schneider (JIRA)

The issue seems to be solved in snapshot 2016-01-11-a on Ubuntu 15.10.

[swift-ci]

Comment by Matthias M. Schneider (JIRA)

The issue seems to be fixed in current builds of Swift 2.2 and Swift 3.0.