FlatBuffers CMake does not contain version information

[dominiklohmann]

FlatBuffers installed via Homebrew does not set the version information in the bundled CMake package configuration file as expected, causing find_package(Flatbuffers 1.12) to fail.

❯ cat /usr/local/lib/cmake/flatbuffers/FlatbuffersConfigVersion.cmake

set(PACKAGE_VERSION "..")

# Check whether the requested PACKAGE_FIND_VERSION is compatible
if("${PACKAGE_VERSION}" VERSION_LESS "${PACKAGE_FIND_VERSION}")
  set(PACKAGE_VERSION_COMPATIBLE FALSE)
else()
  set(PACKAGE_VERSION_COMPATIBLE TRUE)
  if ("${PACKAGE_VERSION}" VERSION_EQUAL "${PACKAGE_FIND_VERSION}")
    set(PACKAGE_VERSION_EXACT TRUE)
  endif()
endif()

This happens because FlatBuffers uses git describe to generate the version components.

There are two ways to fix this:

• Submit a patch to FlatBuffers, and wait for 1.13 to be released.
• Submit a patch to homebrew-core, that adds git fetch --all --tags in the install section of the formula.

I'd strongly prefer to do the latter, but is that even allowed? I couldn't find much information on this and could not find any other formula running git fetch.

[gromgit]

Patching the source independent of upstream is generally discouraged, but I don't think your solution would work anyway, since the formula is built with the release tarball, which has zero Git metadata.

Better to submit a patch to upstream, and let them fix it for everyone.