[SR-3393] assertion failure during autocomplete

[swift-ci]

Previous ID	SR-3393
Radar	None
Original Reporter	mgritter (JIRA User)
Type	Bug

Environment

Swift version 3.0.1 (swift-3.0.1-RELEASE)
Target: x86_64-unknown-linux-gnu
Ubuntu 16.04.1

Additional Detail from JIRA

Votes	0
Component/s	CodeCompletion, LLDB for Swift
Labels	Bug, CompilerCrash, Linux, REPL
Assignee	None
Priority	Medium

md5: c836560b86f8334f556345cc216c57cb

Issue Description:

Hitting 'tab' to autocomplete in the REPL environment produced an assertion error after I had filled in the first argument to String.insert. I was hoping that I would get a list of argument labels.

1> var y = ["a", "b", "c"]
y: [String] = 3 values {
[0] = "a"
[1] = "b"
[2] = "c"
}
2> y.insert( "quux", lldb: /home/buildnode/disk2/workspace/oss-swift-3.0-package-linux-ubuntu-16_04/swift/lib/AST/Type.cpp:862: SmallVector<swift::CallArgParam, 4> swift::decomposeArgType(swift::Type, ArrayRef<swift::Identifier>): Assertion `argumentLabels.size() == 1' failed.
Aborted (core dumped)