How do I embed Mercurial tags into my C/C++ code?

Question

I would like to know if there is a way to embed Mercurial tags into my C/C++ code.

Basically I would like the tag string, which will end up being a release number (

Answer 1

We use a macro for this

#define CVS(a) static const volatile char *rcsid = a;

....
CVS("$Id$")

CVS automagically expands $Id$. I assume this is what mercurial tags work as well.

Then we can use the strings command to find the exact version of each file in the executable / library etc.

You could use something similar.

static const volatile char *rcsid = "$Id"; //or whatever mercurial tag you want

int main() {

    .....
    std::cout << "Version is " << rcsid << std::endl;
}

Answer 2

You will need the keyword extension to allow expansion of keyword entries, it is bundled with mercurial.

For instance to get support for $Id$ you could edit hgrc for you repo (.hg/hgrc) and add:

[extensions]
keyword =

[keyword]
# Enable expansion for the specific files
myfile.cpp =
# Enable for all .h files
**.h =

Then run

hg kwexpand

to expand keywords the relevant files, or

hg kwshrink

to shrink keywords. You can even create your own keywords by adding the [keywordmaps] entry, e.g.

[keywordmaps]
User = {author|user}

Note: This disables the builtin keywords

More details on the extension can be found in the wiki.