These modifications ensure enum.h can be used in a wider
selection of end user projects without triggering warnings.
GCC 4.9.2 was used with the following warning flags set:
-Wall -Wextra -Wshadow -Weffc++ -Wno-unused-parameter
-Wno-unused-local-typedefs -Wno-long-long -Wstrict-aliasing
-Werror -pedantic -std=c++1y -Wformat=2 -Wmissing-include-dirs
-Wsync-nand -Wuninitialized -Wconditionally-supported -Wconversion
-Wuseless-cast -Wzero-as-null-pointer-constant
This commit includes the modifications required to enable successful
use of enum.h via both the "test" and "example" directories.
enum.h tries to automatically detect whether it is running with C++11 support.
If not, it emits alternative code that is supposed to work on compilers
supporting C++98 and variadic macros. This code is largely interface-compatible
with the C++11 code, with the following semantic differences:
- No compile-time stringization. This is done upon first use of a function other
than to_integral.
- Implicit conversion to integral types. This is due to the lack of enum class
support.
- The values _name, _names, _values are replaced with functions _name_, _names_,
_values_.
Each Better Enum now has an internal enum class type to which it is convertible,
instead of being convertible to the regular enum that defines its constants.
switch statements are compiled at the enum class type. This comes at the price
of the user having to type +Enum::Constant instead of Enum::Constant in cases,
in order to trigger an explicit promotion of the pre-C++11 enum to Better Enum,
so it can then be implicitly converted to the enum class.
The remaining "hole" is that direct references to constants (Enum::Constant) are
still implicitly convertible to integral types, because they have naked
pre-C++11 enum type.
