roc/BUILDING_FROM_SOURCE.md

Building the Roc compiler from source

Installing LLVM

To build the compiler, you need a particular version of LLVM installed on your system.

To see which version of LLVM you need, take a look at Cargo.toml, in particular the branch section of the inkwell dependency. It should have something like llvmX-Y where X and Y are the major and minor revisions of LLVM you need.

For Ubuntu, I used the Automatic installation script at apt.llvm.org - but there are plenty of alternative options at http://releases.llvm.org/download.html

You may run into an error like this:

    Updating git repository `https://github.com/TheDan64/inkwell`
error: failed to load source for a dependency on `inkwell`

Caused by:
  Unable to update https://github.com/TheDan64/inkwell?branch=llvm8-0#d0f5c1e1

Caused by:
  revspec 'd0f5c1e198853bc06d8427fbafb7b068032d1d1a' not found; class=Reference (4); code=NotFound (-3)

This seems to be caused by cargo being out of date (even if it's freshly installed), and can be fixed with cargo update.