Multiple sources of project's version

[louis-langholtz]

Expected/Desired Behavior or Experience:

There's only a single source for what the project's version is or is supposed to be.

Actual Behavior:

There are multiple sources of the project's version:

1. CMakeLists.txt.
2. Documentation/Doxyfile.
3. PlayRho/Common/Version.cpp.
4. UnitTests/Version.cpp.
5. git itself is also a source of the version via git tags.

This obviously complicates versioning which in turn complicates making new releases.

[louis-langholtz]

Regarding git, I'm interested in Google benchmark's mechanism for getting version information from git. Their top-level CMakeLists.txt does:

# Read the git tags to determine the project version
include(GetGitVersion)
get_git_version(GIT_VERSION)

# Tell the user what versions we are using
string(REGEX MATCH "[0-9]+\\.[0-9]+\\.[0-9]+" VERSION ${GIT_VERSION})
message(STATUS "Version: ${VERSION}")

[louis-langholtz]

Remaining after merging Updates 20201105...

1. CMakeLists.txt.
2. git itself is also a source of the version via git tags.

Could take the version from git but then I'm wondering where non-git distributions get the version from. Keeping this issue open for now and marking with help-wanted.