Consider adding version information to the main header file

[alabuzhev]

To allow client code rertieve library version instead of hard-coding it somewhere.

Motivation:

• informational purposes / troubleshooting (e. g. about box or log file with detailed list of used libraries)
• validation that code is being compiled with compatible version (e. g. if source is pulled from somewhere)

Can be in form of preprocessor definitions for integral version components (major, minor etc.) or preformatted string, e. g. "3.0.0". For example, SQLite defines these macros:

#define SQLITE_VERSION        "3.15.0"
#define SQLITE_VERSION_NUMBER 3015000

[foonathan]

Good point.

@vitaut The version information is currently only available in CMake.
While it is easy to pass it to a C++ header, this requires an external CMake configuration step.
We could go the other way and parse the version from the header file, but I don't think the trouble is worth it compared to simply keeping two macros in sync.

[vitaut]

I am thinking of defining a single FMT_VERSION macro in the form

#define FMT_VERSION MMmmpp

as suggested for GCC here, where MM is a major version, mm is a minor version, and pp is a patch number, for example,

#define FMT_VERSION 030001

is version 3.0.1.

I think it is better than having separate major, minor, and patch macros because it requires awkward comparison:

/* Test for GCC > 3.2.0 */
          #if __GNUC__ > 3 || \
              (__GNUC__ == 3 && (__GNUC_MINOR__ > 2 || \
                                 (__GNUC_MINOR__ == 2 && \
                                  __GNUC_PATCHLEVEL__ > 0))

Major, minor, and patch version can be easily extracted from FMT_VERSION.

As for CMake, I think it's better to extract version from the header file to avoid duplication.

[vitaut]

Done in f5b1c16.