Meson does not allow strings like X.Y.Z+META to be used as the library version

[DieTime]

Describe the bug
I am passing the version using the meson options from the rpm spec file.

When using the Sailfish OS build system, the version has metadata at the end, which also gets into the meson build script.

$ meson -Dversion=0.1.0+master.20220705111300.6e4b184 builddir

Previously, I used cmake, which allowed you to specify strings of this format as the version of the library. Meson throws an error that the version must be X.Y.Z. However, Semantic Versioning 2.0 assumes the use of metadata in the version, see this.

This makes it difficult to write meson scripts, as it is very common to write something like this:

version_parts = get_option('version').replace('+', '.').split('.')
assert(version_parts.length() >= 3,
       'The version does not contain major, minor and patch')

major = version_parts[0]
minor = version_parts[1]
patch = version_parts[2]

version = f'@major@.@minor@.@patch@'

To Reproduce

project('libexample', 'c')

version = '0.1.0+master.20220705111300.6e4b184'

# ERROR:
# Invalid Shared library version "0.1.0+master.20220705111300.6e4b184".
# Must be of the form X.Y.Z where all three are numbers.
lib = shared_library('example', 'main.c', version: version)

Expected behavior
Behavior similar to cmake: output library libexample.so.0.1.0+master.20220705111300.6e4b184

system parameters

• Is this a cross build or just a plain native build (for the same computer)? native build
• what operating system (e.g. MacOS Catalina, Windows 10, CentOS 8.0, Ubuntu 18.04, etc.): Ubuntu 20.04
• what Python version are you using e.g. 3.8.0: 3.8.10
• what meson --version: 0.62.2
• what ninja --version if it's a Ninja build: 1.10.0

[eli-schwartz]

However, Semantic Versioning 2.0 assumes the use of metadata in the version, see this.

It doesn't assume it, it permits it. :)

And I honestly don't think I've ever seen this in a library version before. :) Considering e.g. the libtool versioning convention, I wouldn't even assume library versions follow a 3-part semver, let alone one with optional metadata, regardless of what project versions do.

This makes it difficult to write meson scripts, as it is very common to write something like this:

I wouldn't say that's difficult. Or common. If someone is replacing a plus with a period, then they are specifically trying to handle this uncommon use case.

It will always trigger the assert and fail, but if the version is used for something other than a library version, you could handle the library version much more simply: use .split('+') instead, and only keep the first half.