glad not exported when built locally

[ryan0270]

Bug category

• [x ] bug - compilation error
• bug - compilation warning
• bug - runtime error
• bug - runtime warning
• bug - logic error

Describe the bug
When MATPLOTPP_BUILD_EXPERIMENTAL_OPENGL_BACKEND=ON I get the following error during cmake configure.

CMake Error: install(EXPORT "Matplot++Targets" ...) includes target "matplot_opengl" which requires target "glad" that is not in any export set.

In my case, find_package(GLAD) does not find anything so FetchContent is used to download glad. Cmake is complaining that matplot_opengl depends on a local target, glad, that won't be installed.

I suspect the solution is to append it to the TARGETS list if built locally, but there may be some other subtleties I'm not considering.

Steps to Reproduce

# This is part on Arch Linux AUR build() step
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX="$pkgdir/usr" \
      -DBUILD_SHARED_LIBS=ON \
      -DMATPLOTPP_BUILD_EXPERIMENTAL_OPENGL_BACKEND=ON \
      -DMATPLOTPP_BUILD_EXAMPLES=OFF \
      -DMATPLOTPP_BUILD_TESTS=OFF \

Output

CMake Error: install(EXPORT "Matplot++Targets" ...) includes target "matplot_opengl" which requires target "glad" that is not in any export set.

Platform

• [ x] cross-platform issue - linux
• cross-platform issue - windows
• cross-platform issue - macos

Environment Details:

• OS: Arch Linux
• OS Version: Jan 2024
• Compiler: gcc
• Compiler version: 13.2

Additional context