All non-`CMakePresets.json` builds broken

[pszenher]

Overview

This project's CMakeLists.txt unconditionally requires beman-install-library to be resolvable via find_package, but does not guarantee its own ./infra/cmake/beman-install-library-config.cmake file is resolvable.

optional/CMakeLists.txt

Line 61 in 4e2a094

find_package(beman-install-library REQUIRED)

Nothing in the CMakeLists.txt file takes steps to check/provide this before hard-erroring, and all README-described build steps are broken (except for the preset builds, see below).

Broken Build Output

[pszenher ~/src/optional]$ cmake -B .build -S . -DOPTIONAL_ENABLE_TESTING=OFF
-- The CXX compiler identification is GNU 15.2.0
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /nix/store/kbw2j1vag664b3sj3rjwz9v53cqx87sb-gcc-wrapper-15.2.0/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at CMakeLists.txt:61 (find_package):
  By not providing "Findbeman-install-library.cmake" in CMAKE_MODULE_PATH
  this project has asked CMake to find a package configuration file provided
  by "beman-install-library", but CMake did not find one.

  Could not find a package configuration file provided by
  "beman-install-library" with any of the following names:

    beman-install-libraryConfig.cmake
    beman-install-library-config.cmake

  Add the installation prefix of "beman-install-library" to CMAKE_PREFIX_PATH
  or set "beman-install-library_DIR" to a directory containing one of the
  above files.  If "beman-install-library" provides a separate development
  package or SDK, be sure it has been installed.

Details

I had originally drafted up an issue about incompatibility of this package being fetched/built via CMake FetchContent, but realized midway through that the primary build instructions are broken.

There are only three currently working build-flows:

1. Setting -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES=.infra/cmake/use-fetch-content.cmake at configure-time
   • note that this is not the readme-recommended cmake/use-fetch-content.cmake from the top-level cmake dir; build using the readme-suggested CMAKE_PROJECT_TOP_LEVEL_INCLUDES file are broken
2. Any of the CMake preset builds, which use the infra toolchain files, each of which call list(APPEND CMAKE_PREFIX_PATH "${CMAKE_CURRENT_LIST_DIR}")
   • note that these would work without the toolchain cmake files, as the _root-config base preset also sets CMAKE_PROJECT_TOP_LEVEL_INCLUDES to ./infra/cmake/use-fetch-content.cmake, reducing to the same case as above
3. Building on a system/in a context where beman-install-library is resolvable from CMAKE_PREFIX_PATH

It appears that all of the CI workflows explicitly inject "./infra/cmake" into CMAKE_PREFIX_PATH via the strategy matrix, which is why CI flows remain green.

Recommendation

This project's top-level CMakeLists.txt file should likely change:

optional/CMakeLists.txt

Line 61 in 4e2a094

find_package(beman-install-library REQUIRED)

to:

find_package(
    beman-install-library REQUIRED
    HINTS "${CMAKE_CURRENT_LIST_DIR}/infra/cmake"
)

[ednolan]

github.com/bemanproject/exemplar switched from find_package to include for this file in this commit: bemanproject/exemplar@df40a6d

We should address this by doing the same thing for optional.