# based on https://github.com/bluescarni/yacma

include(CheckCXXCompilerFlag)

macro(CHECK_ENABLE_CXX_FLAG flag)
  set(CMAKE_REQUIRED_QUIET TRUE)
  check_cxx_compiler_flag("${flag}" CHECK_CXX_FLAG)
  unset(CMAKE_REQUIRED_QUIET)

  if(CHECK_CXX_FLAG)
    message(STATUS "'${flag}': flag is enabled.")
    add_compile_options("${flag}")
  else()
    message(STATUS "'${flag}': flag is NOT supported.")
  endif()
  # NOTE: check_cxx_compiler stores variables in the cache.
  unset(CHECK_CXX_FLAG CACHE)
endmacro()

# Common configuration for GCC, clang and Intel.
if(CMAKE_CXX_COMPILER_IS_CLANG OR CMAKE_CXX_COMPILER_IS_INTEL OR CMAKE_CXX_COMPILER_IS_GCC)
  set(CMAKE_CXX_STANDARD 11)
  set(CMAKE_CXX_STANDARD_REQUIRED YES)
  set(CMAKE_CXX_EXTENSIONS YES)

  if(CMAKE_BUILD_TYPE STREQUAL "Debug")
    CHECK_ENABLE_CXX_FLAG(-Wall)
    CHECK_ENABLE_CXX_FLAG(-Wextra)
    CHECK_ENABLE_CXX_FLAG(-Wnon-virtual-dtor)
    CHECK_ENABLE_CXX_FLAG(-Wnoexcept)
    CHECK_ENABLE_CXX_FLAG(-Wlogical-op)
    CHECK_ENABLE_CXX_FLAG(-Wconversion)
    CHECK_ENABLE_CXX_FLAG(-Wdeprecated)
    # This limit is supposed to be at least 1024 in C++11, but for some reason
    # clang sets this to 256, and gcc to 900.
    CHECK_ENABLE_CXX_FLAG(-ftemplate-depth=1024)
    CHECK_ENABLE_CXX_FLAG(-Wold-style-cast)
    CHECK_ENABLE_CXX_FLAG(-Wdisabled-optimization)
    # This is useful when the compiler decides the template backtrace is too verbose.
    CHECK_ENABLE_CXX_FLAG(-ftemplate-backtrace-limit=0)
    CHECK_ENABLE_CXX_FLAG(-fstack-protector-all)
    # A few suggestion flags.
    CHECK_ENABLE_CXX_FLAG(-Wsuggest-attribute=pure)
    CHECK_ENABLE_CXX_FLAG(-Wsuggest-attribute=const)
    CHECK_ENABLE_CXX_FLAG(-Wsuggest-attribute=noreturn)
    CHECK_ENABLE_CXX_FLAG(-Wsuggest-attribute=format)
    # From GCC 5.
    CHECK_ENABLE_CXX_FLAG(-Wodr)
    CHECK_ENABLE_CXX_FLAG(-Wsuggest-final-types)
    CHECK_ENABLE_CXX_FLAG(-Wsuggest-final-methods)
    CHECK_ENABLE_CXX_FLAG(-Wsuggest-override)
    # From GCC 6.
    CHECK_ENABLE_CXX_FLAG(-Wshift-negative-value)
    CHECK_ENABLE_CXX_FLAG(-Wshift-overflow=2)
    CHECK_ENABLE_CXX_FLAG(-Wduplicated-cond)
    CHECK_ENABLE_CXX_FLAG(-Wnull-dereference)
    # From GCC 7.
    CHECK_ENABLE_CXX_FLAG(-Wrestrict)
    CHECK_ENABLE_CXX_FLAG(-Waligned-new)
    # From GCC 8.
    CHECK_ENABLE_CXX_FLAG(-Wcast-align=strict)
    # This is supposed to produce a nice graphical visualization
    # of mismatching template errors.
    CHECK_ENABLE_CXX_FLAG(-fdiagnostics-show-template-tree)
    CHECK_ENABLE_CXX_FLAG(-fdiagnostics-show-option)

    CHECK_ENABLE_CXX_FLAG(-pedantic)
    CHECK_ENABLE_CXX_FLAG(-Wcast-align)
    CHECK_ENABLE_CXX_FLAG(-Wcast-qual)
    CHECK_ENABLE_CXX_FLAG(-Wctor-dtor-privacy)
    CHECK_ENABLE_CXX_FLAG(-Wdisabled-optimization)
    CHECK_ENABLE_CXX_FLAG(-Wformat=2)
    CHECK_ENABLE_CXX_FLAG(-Winit-self)
    CHECK_ENABLE_CXX_FLAG(-Wmissing-include-dirs)
    CHECK_ENABLE_CXX_FLAG(-Woverloaded-virtual)
    CHECK_ENABLE_CXX_FLAG(-Wredundant-decls)
    CHECK_ENABLE_CXX_FLAG(-Wsign-promo)
    CHECK_ENABLE_CXX_FLAG(-Wstrict-overflow=5)
    CHECK_ENABLE_CXX_FLAG(-Wundef)
    CHECK_ENABLE_CXX_FLAG(-Wno-unused)
    CHECK_ENABLE_CXX_FLAG(-Wno-variadic-macros)
    CHECK_ENABLE_CXX_FLAG(-Wno-parentheses)
    CHECK_ENABLE_CXX_FLAG(-Wstrict-null-sentinel)
    CHECK_ENABLE_CXX_FLAG(-Wshadow)
    CHECK_ENABLE_CXX_FLAG(-Wshadow-all)
  endif()

  if(CMAKE_BUILD_TYPE STREQUAL "Release")
    CHECK_ENABLE_CXX_FLAG(-flto)
    if(CMAKE_CXX_COMPILER_IS_GCC AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER "4.8")
      # Doesn't work with GCC 4.7.2 in Astra Linux 1.5
      CHECK_ENABLE_CXX_FLAG(-fno-fat-lto-objects)
    endif()
  endif()
endif()

if (CMAKE_CXX_COMPILER_IS_GCC)
  CHECK_ENABLE_CXX_FLAG(-fdiagnostics-color=auto)
  # The -Wmaybe-uninitialized flag is enabled by -Wall, but it is known
  # to emit a lot of possibly spurious warnings. Let's just disable it.
  CHECK_ENABLE_CXX_FLAG(-Wno-maybe-uninitialized)
  if(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER "5.999")
    # NOTE: GCC >= 6 seems to be wrongly warning about visibility attributes
    # in some situations:
    # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80947
    # Let's just disable the warning for now.
    CHECK_ENABLE_CXX_FLAG(-Wno-attributes)
  endif()
endif()

if(CMAKE_SYSTEM_PROCESSOR STREQUAL "e2k")
  add_definitions(-DQT_NO_VERSION_TAGGING)
  list(APPEND CMAKE_LIBRARY_PATH "/usr/lib/e2k-linux-gnu")
endif()