Vendor CLI11 library inside ignition-utils

[mjcarroll]

Depends on: gazebosim/gz-cmake#143

Signed-off-by: Michael Carroll [email protected]

[caguero]

It looks good to me assuming that we're convinced that we want to vendor this library. My only suggestion would be to create a basic example to show how to use it in a very basic way.

[mjcarroll]

From @scpeters homebrew has a package: https://github.com/Homebrew/homebrew-core/blob/master/Formula/cli11.rb

[scpeters]

looks like it's in vcpkg as well: https://repology.org/project/cli11/versions

[mjcarroll]

@scpeters and I discussed this with @j-rivero offline. Since this will only be used in executables, is header only, and has no existing Debian package, it makes sense to include the CLI11 headers as part of the ign-utils install.

Additionally, rather than using the packaged versions for vcpkg and homebrew via cmake logic, we can use the same set of headers across all platforms for consistency.

This is still pending me developing a prototype for using this with ign-tools

[chapulina]

Closing and reopening to see if DCO takes effect

[azeey]

How do we deal with side-by-side installs in the future? We have used inline namespaces for this in our other packages, but CLI will have its own namespace. This could potentially be a problem down the road if we want to update the version of CLI we vendor.

[scpeters]

How do we deal with side-by-side installs in the future? We have used inline namespaces for this in our other packages, but CLI will have its own namespace. This could potentially be a problem down the road if we want to update the version of CLI we vendor.

are you concerned about conflicting header file locations or conflicting symbols? I would expect CLI11 to only be used in executables, so I wouldn't expect problems with symbols

[azeey]

Yeah, I think you're right. If we limit its usage only to executables, we shouldn't have a problem.

[scpeters]

this seems to be working well enough with gazebosim/gz-transport#216

let's go ahead and merge and make a prerelease

[chapulina]

let's go ahead and merge and make a prerelease

We could also use a nightly

[scpeters]

we don't have to wait a day if we make a prerelease now