[Flex-devel] Bootstrapping flex

[Mighty Jo <mig...@gm...>]

First up: that rc1 version number, lol.  The FLEX_BETA test in flex.skl
near line 90 does not like that.

I noticed because I've been working on bootstrapping.

Will noticed a quirk in my recent pull requests in which it was necessary
to bootstrap flex by compiling scan.l with the installed f/lex first, then
again with the flex built by the first stage. I'm summarizing some of that
conversation here.

Best practices for testing the build process including starting from a
source tree prepared by

$ git clean -xdf

which removes everything that isn't known to version control.

Then run

$ ./autogen.sh && ./configure && make && make check && make distcheck

If all that works you're in pretty good shape. (If your shell complains
that configure doesn't exist, change the '&&' after autogen.sh to a
semicolon or run the commands separately.)

Bootstrapping is needed whenever scan.l changes. It's also needed when the
skeleton changes, since that's involved in compiling scan.l. I haven't
worked out whether that means a second bootstrap stage is needed but I
don't think it is since flex.skl is independent of scan.l.

I've been playing with techniques for performing a bootstrap via automake
and I'm getting close.  -local extensions and suffix rule games get you
most of the way. I got sidetracked trying to understand how the VERSION
variable in src/Makefile.am gets set.  It from AC_INIT, semi-obviously, but
the autoconf manual says the variable is called PACKAGE_VERSION.  Turns out
it also sets the VERSION variable to the same value but doesn't mention
this in its manual.

That's all the brain dump I have for tonight.

-Joe