Enhance CMake files to set warning level high(er) and set C++14 flags

CMakeLists.txt

@@ -1,6 +1,62 @@
 cmake_minimum_required(VERSION 2.8)
 add_definitions("-std=c++1y")
 
+# Check if a supported compiler is used and add c++14 flag:
+if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+  if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9)
+    message(FATAL_ERROR "Need at least gcc 4.9 to compile.")
+  endif()
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
+elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+  if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19)
+    message(FATAL_ERROR "Visual Studio 2015 or newer is required.")
+  endif()
+elseif(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
+elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+  if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.4)
+    message(FATAL_ERROR "Clang below version 3.4 will most likely not work. Please upgrade your compiler.")
+  endif()
+
+  if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.6)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++1y")
+  else()
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
+  endif()
+else() # no GNU, no MSVC, no Clang
+  message(WARNING "You are using an unsupported compiler. Compilation has only been tested with MSVC, GCC and Clang.")
+
+  include(CheckCXXCompilerFlag)
+  check_cxx_compiler_flag(-std=c++14 HAS_CXX14_FLAG)
+  if(HAS_CXX14_FLAG)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
+  else()
+    message(FATAL_ERROR "Your compiler doesn't support the '-std=c++14' flag.")
+  endif()
+endif()
+
+
+if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang"
+    OR CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
+  set(warning_options -Weverything
+    -Wno-c++98-compat
+    -Wno-padded
+    -Wno-c++98-compat-pedantic
+    -Wno-exit-time-destructors
+    -Wno-missing-prototypes
+    -Wno-weak-vtables
+    -Wno-global-constructors
+    -Wno-format-nonliteral
+    -Wno-switch-enum
+    -Wno-missing-noreturn
+    -Wno-covered-switch-default
+    )
+elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+  set(warning_options -Wall -Wpedantic -Wextra)
+elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+  set(warning_options /WX /W4 /wd4503 /wd4512)
+endif()
+
 enable_testing()
 
 add_subdirectory(lint)

example/CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 2.8)
 include_directories(..)
-add_definitions("-std=c++1y")
+add_compile_options(${cxx11_options} ${warning_options})
 
 add_executable(calc calc.cc)
 target_link_libraries(calc pthread)

language/culebra/CMakeLists.txt

@@ -1,5 +1,4 @@
 cmake_minimum_required(VERSION 2.8)
 include_directories(../..)
-add_definitions("-std=c++1y")
 
 add_executable(culebra main.cc)

language/pl0/CMakeLists.txt

@@ -1,5 +1,4 @@
 cmake_minimum_required(VERSION 2.8)
 include_directories(../..)
-add_definitions("-std=c++1y")
 
 add_executable(pl0 pl0.cc)

lint/CMakeLists.txt

@@ -1,5 +1,4 @@
 cmake_minimum_required(VERSION 2.8)
 include_directories(..)
-add_definitions("-std=c++1y")
 
 add_executable(peglint peglint.cc server.cc)

test/CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 2.8)
 include_directories(..)
-add_definitions("-std=c++1y")
+add_compile_options(${cxx11_options} ${warning_options})
 
 add_executable(test-main test.cc)
 target_link_libraries(test-main pthread)