+# Don't include xalloc.h unless you use one of its functions.
+# Consider these symbols:
+# perl -lne '/^# *define (\w+)\(/ and print $1' lib/xalloc.h|grep -v '^__';
+# perl -lne '/^(?:extern )?(?:void|char) \*?(\w+) \(/ and print $1' lib/xalloc.h
+# Divide into two sets on case, and filter each through this:
+# | sort | perl -MRegexp::Assemble -le \
+# 'print Regexp::Assemble->new(file => "/dev/stdin")->as_string'|sed 's/\?://g'
+# Note this was produced by the above:
+# _xa1 = \
+#x(((2n?)?re|c(har)?|n(re|m)|z)alloc|alloc_(oversized|die)|m(alloc|emdup)|strdup)
+# But we can do better, in at least two ways:
+# 1) take advantage of two "dup"-suffixed strings:
+# x(((2n?)?re|c(har)?|n(re|m)|[mz])alloc|alloc_(oversized|die)|(mem|str)dup)
+# 2) notice that "c(har)?|[mz]" is equivalent to the shorter and more readable
+# "char|[cmz]"
+# x(((2n?)?re|char|n(re|m)|[cmz])alloc|alloc_(oversized|die)|(mem|str)dup)
+_xa1 = x(((2n?)?re|char|n(re|m)|[cmz])alloc|alloc_(oversized|die)|(mem|str)dup)
+_xa2 = X([CZ]|N?M)ALLOC
+sc_prohibit_xalloc_without_use:
+ @h='"xalloc.h"' \
+ re='\<($(_xa1)|$(_xa2)) *\('\
+ $(_header_without_use)
+