It may be useful to add one mixin to use fortified versions of some standard functions.
Source: https://developers.redhat.com/blog/2018/03/21/compiler-and-linker-flags-gcc

Certain projects such as NAV2 enable warnings as errors, not just in CI, but also for local development.
There are good reasons for doing this because NAV2 has contributions by many new developers that might ignore compile warnings.

Currently, to disable this, on Ubuntu 22, there is nothing to change except temporarily the source code,which is easy to accidentally commit.

When I build nav2 on rolling, due to it always changing, a newly introduced deprecation warning will now trigger a build failure, which defeats the purpose of a deprecation warning allowing smooth transitions away from unused features.

In new versions of CMake (3.24+), there is a new feature: compile-no-warning-as-error: https://cmake.org/cmake/help/latest/manual/cmake.1.html#cmdoption-cmake-compile-no-warning-as-error

With Kitware's apt repository, it's easy to install newer versions of CMake on the OS.

Would colcon-mixin accept a contribution for this as a mixin, or would it be prohibited because it doesn't work on LTS platforms?

I am trying to understand how mixin are structured and have been unable to find any documentation on this. Taking compile-commands.mixin as an example, I understand that build is the verb to which this mixin applies and that cmake-args refers to the CMake build system, but what does compile-commands refer to? Is this the name of a specific package?

{
    "build": {
        "compile-commands": {
            "cmake-args": [
                "-DCMAKE_EXPORT_COMPILE_COMMANDS=ON",
                "--no-warn-unused-cli"
            ]
        }
    }
}

It would be great if a couple notes on this could be added to the README.md or over at readthedocs.

--coverage
This option is used to compile and link code instrumented for coverage analysis. The option is a synonym for -fprofile-arcs -ftest-coverage (when compiling) and -lgcov (when linking).
https://stackoverflow.com/questions/28840261/gcov-what-is-the-difference-between-coverage-and-ftest-coverage-when-buildi

Was there a particular reason why -lgcov (when linking) was not included in this .mixin?

I'm unsure if this was deliberate, or a accidental omission in #8 .
Would switching the coverage.mixin to use --coverage be more obvious for gcc users?

Request

Can you document how to add the mixin verb to colcon? I've installed ros-dev-tools per the ROS Ubuntu installation, but colcon does not come with mixin.

Logs

$ colcon mixin add default https://raw.githubusercontent.com/colcon/colcon-mixin-repository/master/index.yaml
usage: colcon [-h] [--log-base LOG_BASE] [--log-level LOG_LEVEL] {build,extension-points,extensions,graph,info,list,metadata,test,test-result,version-check} ...
colcon: error: argument verb_name: invalid choice: 'mixin' (choose from 'build', 'extension-points', 'extensions', 'graph', 'info', 'list', 'metadata', 'test', 'test-result', 'version-check')

System Info

ROS version: Humble
Install method: Binaries

$ apt info ros-dev-tools
Package: ros-dev-tools
Version: 1.0.0
Priority: optional
Section: misc
Maintainer: Steven! Ragnarök <[email protected]>
Installed-Size: 9,216 B
Depends: ros-build-essential, python3-bloom, python3-colcon-common-extensions, python3-rosdep, python3-vcstool, wget
Homepage: https://github.com/ros-infrastructure/infra-variants
Download-Size: 1,748 B
APT-Manual-Installed: yes
APT-Sources: http://packages.ros.org/ros2/ubuntu jammy/main amd64 Packages
Description: Developer Tools for ROS
 Variant which includes packages generally useful during ROS development.

Suggestion

Add something to the README such as

sudo apt install python3-colcon-mixin