# ######################################################################################################################
# Specialized setup for GNU gcc compilers.
# ######################################################################################################################

# The settings and definitions here will apply to all projects. Specific project settings should be included in the
# relevant CMakeLists.txt file for that project.

# Set our own compiler version flag from the cmake one and export it globally
if(CMAKE_COMPILER_IS_GNUCXX)
  if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_EQUAL CMAKE_C_COMPILER_VERSION)
    message(
      FATAL_ERROR
        "gcc/g++ compiler version mismatch ( found gcc=${CMAKE_C_COMPILER_VERSION}, g++=${CMAKE_CXX_COMPILER_VERSION} ). Please ensure you use the same version of gcc and g++."
    )
  endif()
  set(GCC_COMPILER_VERSION
      ${CMAKE_CXX_COMPILER_VERSION}
      CACHE INTERNAL ""
  )
  message(STATUS "gcc version: ${GCC_COMPILER_VERSION}")
  if(NOT (GCC_COMPILER_VERSION VERSION_LESS "5.1.0"))
    # Add an option to use the old C++ ABI if gcc is 5 series
    option(USE_CXX98_ABI "If enabled, sets the _GLIBCXX_USE_CXX11_ABI=0 compiler flag" OFF)
    if(USE_CXX98_ABI)
      add_definitions(-D_GLIBCXX_USE_CXX11_ABI=0)
    endif()
  endif()
elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
  message(STATUS "clang version ${CMAKE_CXX_COMPILER_VERSION}")
endif()

# Global warning flags. Disable some warnings about deprecated headers and type conversions that we can't do anything
# about -Wno-deprecated: Do not warn about use of deprecated headers. -Wno-write-strings: Do not warn about deprecated
# conversions of char*->const char* -Wno-unused-result: Do not warn about unused return values in some C functions
add_compile_options(
  -Wall
  -Wextra
  -Wconversion
  -Winit-self
  -Wpointer-arith
  -Wcast-qual
  -Wcast-align
  -fno-common
  -Wno-deprecated
  -Wno-write-strings
  -Wno-unused-result
)
# C++-specific flags
add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Woverloaded-virtual> $<$<COMPILE_LANGUAGE:CXX>:-fno-operator-names>)

# Linking errors on Ubuntu 18.04 with --enable-new-dtags
if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
  string(APPEND CMAKE_MODULE_LINKER_FLAGS " -Wl,--disable-new-dtags")
  string(APPEND CMAKE_EXE_LINKER_FLAGS " -Wl,--disable-new-dtags")
  string(APPEND CMAKE_SHARED_LINKER_FLAGS " -Wl,--disable-new-dtags")
endif()

# Check if we have a new enough version for these flags
if(CMAKE_COMPILER_IS_GNUCXX)
  add_compile_options(-Wpedantic)
  if(NOT (GCC_COMPILER_VERSION VERSION_LESS "5.1"))
    add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Wsuggest-override>)
  endif()
  if(NOT (GCC_COMPILER_VERSION VERSION_LESS "7.1"))
    # Consider enabling once [[fallthrough]] is available on all platforms.
    # https://developers.redhat.com/blog/2017/03/10/wimplicit-fallthrough-in-gcc-7/
    add_compile_options(-Wimplicit-fallthrough=0)
  endif()
elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
  add_compile_options(-Wno-sign-conversion)
  # Conda uses its own newer compilers so these checks are not needed
  add_definitions(-D_LIBCPP_DISABLE_AVAILABILITY)
  # Keep C++14 alignment behaviour while older macOS C++ ABI does not contain the required symbols. Minimum=macos 10.14
  add_compile_options(-fno-aligned-new)
  add_compile_options(-fno-assume-unique-vtables)
endif()

# Add some options for debug build to help the Zoom profiler
add_compile_options($<$<OR:$<CONFIG:Debug>,$<CONFIG:RelWithDebInfo>>:-fno-omit-frame-pointer>)

# XCode isn't picking up the c++ standard by CMAKE_CXX_STANDARD
if(CMAKE_GENERATOR STREQUAL Xcode)
  set(CMAKE_XCODE_ATTRIBUTE_OTHER_CPLUSPLUSFLAGS "${GNUFLAGS} -Woverloaded-virtual -fno-operator-names")
  set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LANGUAGE_STANDARD "c++14")
  set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++")
endif()

if(CMAKE_COMPILER_IS_GNUCXX)
  # Define an option to statically link libstdc++
  option(STATIC_LIBSTDCXX "If ON then statically link with the C++ standard library" OFF)
  if(STATIC_LIBSTDCXX)
    add_compile_options(-static-libgcc $<$<COMPILE_LANGUAGE:CXX>:-static-libstdc++>)
    set(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "${CMAKE_SHARED_LIBRARY_LINK_C_FLAGS} -static-libgcc")
    set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "${CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS} -static-libgcc -static-libstdc++")
  endif()
endif()

option(COLORED_COMPILER_OUTPUT "Always produce ANSI-colored output (GNU/Clang only)." TRUE)

if(COLORED_COMPILER_OUTPUT)
  if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
    add_compile_options(-fdiagnostics-color=always)
  elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
    add_compile_options(-fcolor-diagnostics)
  endif()
else()
  # disables the color output on diagnostics
  if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
    add_compile_options(-fdiagnostics-color=never)
  elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
    add_compile_options(-fno-color-diagnostics)
  endif()
endif()