elog with automatic file, line, and function

It has been brought up that elog should be able to automatically fill in
the file, line, and perhaps the function name where it's called, to avoid
having to prefix each message with the function name by hand, which is
quite ugly.

This is doable, but it requires a C preprocessor that can handle varargs
macros.  Since this is required by C99 and has been available in GCC for a
while, it *might* be okay to rely on this.

Additionally, C99 (and GCC for a while) would allow filling in the
function name automatically.

Since these would be mostly developer features, how do people feel about
relying on modern tools for implementing these?  The bottom line seems to
be that without these tools it would simply not be possible.

-- 
Peter Eisentraut      peter_e@gmx.net       http://yi.org/peter-e/