Question

I’d like to use AC_PREREQ to state the minimum version my configure.ac requires. Neither the chapter Versioning nor the alphabetical index of available macros in the autoconf manual tell me when the specific macros where introduced (at least the chapter on Obsolete Macros tells me what not to use).

Is there an easier way than comparing old versions of the manual or browsing the changelog to deduce the required version for a macro like AC_PROG_SED?

Answer 1

The NEWS file in the source, possibly installed somewhere under /usr/share/doc/ for you, will tell you.

That said, you probably don’t need it. If all you are worried about is whether a macro exists, autoconf will tell you about it when you run it. (Using AC_PREREQ here would be exactly contrary to what Autoconf is all about, namely testing features, not version numbers.) You could argue that it might save your codevelopers from surprises, but are you really willing to dig up all those version numbers and maintain that carefully?

The case where you might want to test the version is when a macro was changed incompatibly or broken in some version. But then you probably already know what version that is.