Problems with Swift 3 dev toolchain

Question

I have installed Swift from the dev downloads and am currently using

swift-DEVELOPMENT-SNAPSHOT-2016-04-12-a-ubuntu14.04

When I run

swift build

I get this terse message:

error: invalid inferred toolchain

I have had this configuration running earlier this week, but I seem to have broken something. Any suggestions on how to proceed?

Answer 1

Did you install the required dependencies?

sudo apt-get install clang libicu-dev