Here is a comment in a forthcoming commit to groff's doc/doc.am file.
# Generating *.me from *.me.in is, surprisingly, a challenge.
# 1. A pattern rule ("%.me: %.me.in") is not portable to NetBSD or
# OpenBSD make.
# 2. A double-suffix rule won't work because the semantics of the rule
# are that the suffix is replaced, not removed.
# 3. A single-suffix rule works in an isolated Makefile, but _only_
# with the .SUFFIXES special target, not with the SUFFIXES macro.
# (Is the latter a bug?)
# .SUFFIXES: .in
# .in:
# $(DOC_SED) $< >$@
#
# (One can raise a valid complaint that the above may be too general.)
#
# But...
#
# 4. GNU Automake insists that we use the SUFFIXES macro and not the
# special target.
# error: use variable 'SUFFIXES', not target '.SUFFIXES'
# 5. So we have to use target rules, and explicitly write the first
# dependency name in the rule commands because NetBSD make (and
# reportedly OpenBSD) refuses to honor the $< variable in target
# rules.
#
# Yuck!
#
# Yes, I could work around this by renaming the depended upon files to
# destroy information, or to use confusing sigils instead of periods.
# But I won't--the meaning of, for instance, "meintro.me.in", is clear.
#
# This rigamarole by itself justifies to me the worth of pattern rules
# (which require neither '.SUFFIXES' nor 'SUFFIXES') and establishing
# semantics for $< in target rules. But I won't hold my breath waiting
# on make(1) implementors to agree.Regards, Branden
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