Comment by DonHopkins

https://en.wikipedia.org/wiki/Poul-Henning_Kamp

[...]

Today's Unix/Posix-like operating systems, even including IBM's z/OS mainframe version, as seen with 1980 eyes are identical; yet the 31,085 lines of configure for libtool still check if <sys/stat.h> and <stdlib.h> exist, even though the Unixen, which lacked them, had neither sufficient memory to execute libtool nor disks big enough for its 16-MB source code.

How did that happen?

Well, autoconf, for reasons that have never made sense, was written in the obscure M4 macro language, which means that the actual tests look like this:

  ## Whether `make' supports order-only prerequisites.
  AC_CACHE_CHECK([whether ${MAKE-make} supports order-only prerequisites],
    [lt_cv_make_order_only],
    [mkdir conftest.dir
     cd conftest.dir
     touch b
     touch a
  cat >confmk << 'END'
  a: b | c
  a b c:
         touch $[]@
  END
    touch c
    if ${MAKE-make} -s -q -f confmk >/dev/null 2>&1; then
      lt_cv_make_order_only=yes
    else
      lt_cv_make_order_only=no
    fi
    cd ..
    rm -rf conftest.dir
  ])
  if test $lt_cv_make_order_only = yes; then
    ORDER='|'
  else
    ORDER=''
  fi
  AC_SUBST([ORDER])

Needless to say, this is more than most programmers would ever want to put up with, even if they had the skill, so the input files for autoconf happen by copy and paste, often hiding behind increasingly bloated standard macros covering "standard tests" such as those mentioned earlier, which look for compatibility problems not seen in the past 20 years.

This is probably also why libtool's configure probes no fewer than 26 different names for the Fortran compiler my system does not have, and then spends another 26 tests to find out if each of these nonexistent Fortran compilers supports the -g option.

That is the sorry reality of the bazaar Raymond praised in his book: a pile of old festering hacks, endlessly copied and pasted by a clueless generation of IT "professionals" who wouldn't recognize sound IT architecture if you hit them over the head with it. It is hard to believe today, but under this embarrassing mess lies the ruins of the beautiful cathedral of Unix, deservedly famous for its simplicity of design, its economy of features, and its elegance of execution. (Sic transit gloria mundi, etc.)

[...]

Poul-Henning Kamp (phk@FreeBSD.org) has programmed computers for 26 years and is the inspiration behind https://bikeshed.org . His software has been widely adopted as under-the-hood building blocks in both open source and commercial products. His most recent project is the Varnish HTTP accelerator, which is used to speed up large Web sites such as Facebook.