Require C++14 more consistently (#692)

Author: hcho3

CMakeLists.txt

@@ -204,10 +204,7 @@ else()
     target_compile_options(dmlc PRIVATE -O3)
   endif()
 
-  target_compile_definitions(dmlc PUBLIC -DDMLC_USE_CXX11=1)
-  if(SUPPORT_CXX14)
-    target_compile_definitions(dmlc PUBLIC -DDMLC_USE_CXX14=1)
-  endif()
+  target_compile_definitions(dmlc PUBLIC -DDMLC_USE_CXX11=1 -DDMLC_USE_CXX14=1)
 endif()
 
 

README.md

@@ -31,7 +31,7 @@ Contributing
 
 Contributing to dmlc-core is welcomed! dmlc-core follows google's C style guide. If you are interested in contributing, take a look at [feature wishlist](https://github.com/dmlc/dmlc-core/labels/feature%20wishlist) and open a new issue if you like to add something.
 
-* DMLC-Core uses C++11 standard. Ensure that your C++ compiler supports C++11.
+* DMLC-Core uses C++14 standard. Ensure that your C++ compiler supports C++14.
 * Try to introduce minimum dependency when possible
 
 ### CheckList before submit code