Can't install; multiple compilation error messages about ranger

[mnwright]

Your gcc version is too old to support C++11. You will need to upgrade to 4.7 or newer.

@ALL: Any idea how to check for this and throw an error?

[mnwright]

This works, but:

Found the following file(s) containing GNU extensions:
src/Makevars
Portable Makefiles do not use GNU extensions such as +=, :=, $(shell),
$(wildcard), ifeq ... endif. See section ‘Writing portable packages’ in
the ‘Writing R Extensions’ manual.

[mnwright]

New approach: Use std=c++11 flag instead of CXX_STD = CXX11, should work on gcc >=4.7 and throw an error on earlier versions. But this time:

Non-portable flags in variable 'PKG_CPPFLAGS':
-std=c++11

[mnwright]

And one more approach: Created a cpp file checking for the preprocessor directive "__cplusplus". Seems to work.