I am on Manjaro 20.2 and installed the new Intel(R) oneAPI DPC++ Compiler 2021.1 (2020.10.0.1113) which is now called "icx" for C and "icpx" for C++ (formerly known as: "icc" and "icpc").

I tried to compile some projects which use meson with makepkg from AUR and albeit having the compiler setup correctly, meson errors out with:

Using 'PKG_CONFIG_PATH' from environment with value: '/opt/intel/oneapi/mkl/latest/tools/pkgconfig'
Using 'PKG_CONFIG_PATH' from environment with value: '/opt/intel/oneapi/mkl/latest/tools/pkgconfig'
The Meson build system
Version: 0.56.0
Source dir: /home/marcus/Downloads/mesa-git/src/mesa
Build dir: /home/marcus/Downloads/mesa-git/src/_build
Build type: native build
Program python found: YES (/usr/bin/python)
Project name: mesa
Project version: 21.0.0-devel
Using 'CC' from environment with value: 'icx'

mesa/meson.build:21:0: ERROR: Unknown compiler(s): [['icx']]

I've used both methods described here (altered for the new 2021 edition) to setup the compiler with the same results as seen above: https://wiki.archlinux.org/index.php/Intel_C%2B%2B

I've also tried to modify the PKGBUILD file with adding CC, CXX and CC_LD options as described here: https://mesonbuild.com/howtox.html

The issue persists though.

I've found a pull request which seems to be related to the underlying issue, but I am not an expert: #6827