Cmake issue

[p-selini]

I am trying to use this lib in our project, but when I add the following to my CMake it compalins about in-source build not supported.

FetchContent_Declare(
  glaze
  GIT_REPOSITORY https://github.com/stephenberry/glaze.git
  GIT_TAG v2.9.5
  GIT_SHALLOW TRUE
)

FetchContent_MakeAvailable(glaze)

but when I ran cmake I see this error:

In-source builds are not supported. Please read the BUILDING document before trying to build this project. You may need to delete 'CMakeCache.txt' and 'CMakeFiles/' first.

A little bit google search shows me to do cmake -H. -Bbuild but it did not help. Any ideas?

[stephenberry]

I'd probably have to see more of your CMake to determine what is going on. Are you doing the following?

include(FetchContent)

FetchContent_Declare(
  glaze
  GIT_REPOSITORY https://github.com/stephenberry/glaze.git
  GIT_TAG v2.9.5
  GIT_SHALLOW TRUE
)

FetchContent_MakeAvailable(glaze)

add_executable(${PROJECT_NAME} ${srcs})
target_link_libraries(${PROJECT_NAME} PRIVATE glaze::glaze)

[stephenberry]

Hmm, I wouldn't think CMakePresets.json would be the problem. The in source build error message comes from here:

glaze/cmake/prelude.cmake

Line 5 in e0b7ea2

FATAL_ERROR

I don't understand why if(CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR) would be true in your use case.

[p-selini]

ah, you solved issue. I think our project (predates me) might set this to equal and dependency lib is within our include I think. So anyway we can disable it through some variable trick (or save it and restore after your project with some sort of post trick)? I can't change my current project config of those since I did not own it. Also if you do add a variable anyway you can do it for earlier version since we are still c++20 not c++23 yet.

[stephenberry]

Okay, that makes sense. I'm glad the issue has been discovered. A lot of Glaze's cmake files are structured to follow https://github.com/friendlyanon/cmake-init, which has nice templates

[p-selini]

Like I said I don't control our cmake it is much larger effort, so I can't change theirs. Anyway for you to add a flag to selectively disable this check if I pass that flag on build commandline?

[stephenberry]

Yes, I should be able to add an option to disable the check. But, I think it may have larger CMake implications for you, as cmake-init always requires this behavior and is used by a lot of projects. I think it can cause issues with CMake itself, but I can look into it.