# Clang 4.0 required for Ubuntu 16.04 after updating llvm-project (master-rebranch)

**URL:** <https://forums.swift.org/t/clang-4-0-required-for-ubuntu-16-04-after-updating-llvm-project-master-rebranch/39684>\
**Category:** Announcements\
**Created:** [August 25, 2020, 3:06am UTC](https://forums.swift.org/t/clang-4-0-required-for-ubuntu-16-04-after-updating-llvm-project-master-rebranch/39684 "2020-08-25T03:06:13Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![mishal\_shah](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/mishal_shah/32/247_2.png) [@mishal\_shah](https://forums.swift.org/u/mishal_shah)\
**Post date:** [August 25, 2020, 3:06am UTC](https://forums.swift.org/t/clang-4-0-required-for-ubuntu-16-04-after-updating-llvm-project-master-rebranch/39684/1 "2020-08-25T03:06:13Z")

</div>

We are updating the Clang version on Ubuntu 16.04 bots to 4.0, because Clang \< 4.0 is incompatible with libstdc++ 5.4 for at least LLVM’s usage of `std::function`. This will be required after we update the llvm-project branch. ([Updating llvm-project swift/master branch](https://forums.swift.org/t/updating-llvm-project-swift-master-branch/38484))

How to install Clang-4.0 on Ubuntu 16.04:

```swift
$ apt install clang-4.0
$ update-alternatives --install /usr/bin/clang clang /usr/bin/clang-4.0 100
$ update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-4.0 100

```

Verify Clang version:

```swift
$ clang --version
$ clang++ --version

```