What's the right way to put `dnl' in the body of AT_CONFIGURE_AC text?

[Zack Weinberg]

I'm trying to write a test case and autom4te doesn't like it ...

AT_CONFIGURE_AC([[
m4_define([fn_bar],[fn_quux])
AC_CHECK_FUNCS([fn_foo dnl
                fn_bar dnl Ordinary comment
                fn_blurf dnl Apos'trophed comment
])
]])

=>

autom4te_perllibdir='..'/lib AUTOM4TE_CFG='lib/autom4te.cfg'
./bin/autom4te -B '.'/lib -B '..'/lib         --language=autotest -I
tests -I ../tests suite.at -o tests/testsuite.tmp
tests/testsuite.tmp:69094: error: possibly undefined macro: dnl
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
make[2]: *** [Makefile:2143: tests/testsuite] Error 1

m4_pattern_allow([dnl]) would affect the whole test suite and that's
far too drastic, but I really do want those dnl's in there to be
processed by the autoconf under test and I am not having any luck
finding a way to exempt them locally.  (For instance, writing
`dn@&t@l` does not change anything.)  Any ideas?

zw