Building with with LLVM's libc++ (and general cmake configuration)

[jmarrec]

Describe the bug

This should never be done like this:

ssc/ssc/CMakeLists.txt

Line 253 in 9d76d0c

target_link_libraries(ssc -lpthread -lm -ldl -lstdc++)

Please remove the lstdc++. Side note but the rest is also supoptimal:

-target_link_libraries(ssc -lpthread -lm -ldl -lstdc++)
+find_package(Threads REQUIRED)
+target_link_libraries(ssc PUBLIC Threads::Threads ${CMAKE_DL_LIBS}) 
+find_library(MATH_LIBRARY m)
+if(MATH_LIBRARY)
+    target_link_libraries(ssc PUBLIC ${MATH_LIBRARY})
+endif()

CMAKE_DL_LIBS

That bit below defines CMAKE_CXX_STANDARD twice (and it does it globally... which is frowned upon). The CMAKE_C_COMPILER block is super strange and should be removed. The projectcommand should use the LANGUAGES CXX which would take care of linking to a C++ std lib, and defining the C/CXX compilers as needed.

ssc/CMakeLists.txt

Lines 28 to 48 in 9d76d0c

	if (UNIX AND NOT CMAKE_C_COMPILER)
	set(CMAKE_C_COMPILER gcc)
	set(CMAKE_CXX_COMPILER g++)
	endif()
	set(CMAKE_CXX_STANDARD 11)
	if ( NOT APPLE)
	set(CURL_DIR build_resources/libcurl_ssl_x64)
	endif()
	Project(sam_simulation_core VERSION 1.0.0)
	#####################################################################################################################
	#
	# Compile Options per Platform
	#
	#####################################################################################################################
	set(CMAKE_VERBOSE_MAKEFILE ON)
	set(CMAKE_POSITION_INDEPENDENT_CODE ON)
	set(CMAKE_CXX_STANDARD 11)

Generally speaking, the project could benefit from a deep cleaning and modernization of the CMake config (eg: avoid polluting the global space and use target specific compilation flags). I know that's probably not a priority and not a sexy task, just saying.

Additional context

I noticed some issues while trying to build EnergyPlus with clang-17 on macOS M1.

[brtietz]

Thank you for flagging this! We have some pending CMakeLists changes coming with #1035, we'll see if we can bundle these fixes in with those changes.