Unknown CMake command "add_compile_definitions".

[linas]

While refreshing on an Ubuntu bionic (18.04 LTS) system, I got the error

CMake Error at opencog/util/CMakeLists.txt:72 (add_compile_definitions):
  Unknown CMake command "add_compile_definitions".

Apparently, this requires a newer version of CMake? Which version? Currently, the very first line of CMakeLists.txt is

CMAKE_MINIMUM_REQUIRED(VERSION 2.8.12.2)

but apparently, this is not enough? Looking at the blame log, this shows that pull req #240 added this code, and it was provided by @ntoxeg and merged by me (apparently, without checking if it worked on bionic ...)

Any clue for what it would take to get this to work on bionic?

[linas]

Apparently, this first appears in cmake version 3.12 while ubuntu 18.04 has only cmake version 3.10

[ntoxeg]

The older way of doing this is to use add_compile_options and explicitly state the option. Another way is to have newer CMake installed - besides obvious (and undesirable I’m assuming) installation from source it should also be installable with Snap like this: sudo snap install cmake —classic.

[amebel]

See https://apt.kitware.com/ for installing the latest cmake version on ubuntu.

[linas]

fixed in #246