Open Radar

 
Summary:
When editing a Swift source file in Xcode, option- or command-clicking on certain variables inside generic functions causes the SourceKit Service to crash, which results in a loss of semantic source highlighting in Xcode.

Steps to Reproduce:
1. Install and launch Xcode
2. Start a new project, e.g. an iOS framework, fill in details, etc.
3. Add a new Swift file to the project and paste the following snippet in to it: func foo<T>() -> T? { let bar: T? = nil; return bar }
4. Option- or command-click on the last occurrence of the word ‘bar’ in the snippet.

Expected Results:
A tooltip should pop up displaying the variable’s declaration signature (let bar: T?), and the location of its declaration (the name of the Swift source file).

Actual Results:
SourceKit Service crashes (can be seen in Console.app), which in Xcode tends to result in a loss of semantic source highlighting (i.e. all source code turns black). When after a while highlighting recovers, and step 4. is repeated, SourceKit Service crashes again, and Xcode shows the yellow-font “An internal error occurred…” bar along the top of the editor.

Version:
OS X 10.11.4 (15E65), Xcode 7.3 (7D175).

Notes:
The crash log backtrace points to a EXC_BAD_ACCESS in “com.apple.SourceKitService.703.0.18.1 0x0000000108a45311 (anonymous namespace)::PrintAST::printGenericParams(swift::GenericParamList*) + 209”.

Configuration:
Retina MacBook Pro (MacBookPro11,2), no external hardware attached.