Stop github action matrix case - yaml

Question

I want to use a github action matrix for different build types, but there's one case of the matrix that I'm not interested in supporting. How do I stop this case from running but still get the build to marked successfully.
In this particular case I want to build Windows and Ubuntu, 32bit and 64bit but I'm not interested in supporting 32bit on Ubuntu. So my matrix would be:
strategy:
fail-fast: false
matrix:
os: [windows-latest, ubuntu-latest]
platform: ['x64', 'x86']
My current solution is to stop each action running by adding an if expression:
- name: Build Native
if: ${{ ! (matrix.os == 'ubuntu-18.04' && matrix.platform == 'x86') }}
While this works okay, I feel there ought to be a more elegant way of solving this. Can anyone help make my yaml script more beautiful?

Answer 1

Perhaps the strategy.matrix.exclude directive is suitable?
From the documentation:
You can remove a specific configurations defined in the build matrix
using the exclude option. Using exclude removes a job defined by the
build matrix.
So in your case, probably something like this:
strategy:
matrix:
os: [windows-latest, ubuntu-latest]
platform: ['x64', 'x86']
exclude:
- os: ubuntu-latest
platform: x86

Answer 2

There are situations where one wants to include or exclude specific matrix coordinates so as not to run some of them, yet (stretching the question a bit) also still want the job to run for a couple of these coordinates, so as to track the evolution of it across commits, while not blocking the whole process.
In that situation, continue-on-error at the job level, combined with matrix include and exclude is very useful:
Prevents a workflow run from failing when a job fails. Set to true to allow a workflow run to pass when this job fails.
This is similar to GitLab CI's allow_failure, although at time of writing GitHub Actions UI only has two states (red failed and green passed) whereas GitLab introduces a third one (orange warning) in that case.
Here is a real-life workflow example:
jobs:
linux:
continue-on-error: ${{ matrix.experimental }}
strategy:
fail-fast: false
matrix:
os:
- ubuntu-20.04
container:
- 'ruby:2.0'
- 'ruby:2.1'
- 'ruby:2.2'
- 'ruby:2.3'
- 'ruby:2.4'
- 'ruby:2.5'
- 'ruby:2.6'
- 'ruby:2.7'
- 'ruby:3.0'
- 'ruby:2.1-alpine'
- 'ruby:2.2-alpine'
- 'ruby:2.3-alpine'
- 'ruby:2.4-alpine'
- 'ruby:2.5-alpine'
- 'ruby:2.6-alpine'
- 'ruby:2.7-alpine'
- 'jruby:9.2-jdk'
experimental:
- false
include:
- os: ubuntu-20.04
container: 'ruby:3.0.0-preview2'
experimental: true
- os: ubuntu-20.04
container: 'ruby:3.0.0-preview2-alpine'
experimental: true