LLVM toolchain for bazel
// readme
LLVM toolchain for Bazel 
Quickstart
See notes on the release for how to get started.
NOTE: For releases prior to 0.10.1, please also see these notes.
Basic Usage
The toolchain can automatically detect your OS and arch type, and use the right pre-built binary LLVM distribution. See the section on “Bring Your Own LLVM” below for more options.
See in-code documentation in rules.bzl for available
attributes to llvm_toolchain.
Advanced Usage
Per host architecture LLVM version
LLVM does not come with distributions for all host architectures in each version. In particular patch versions often come with few prebuilt packages. This means that a single version probably is not enough to address all hosts one wants to support.
This can be solved by providing a target/version map with a default version.
The example below selects 15.0.6 as the default version for all targets not
specified…