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Clarify autom4te debugging tips.

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* doc/autoconf.texi (Debugging via autom4te): Fix example from
previous commit, and add clarification.

Signed-off-by: Eric Blake <ebb9@byu.net>
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Bruno Haible 2009-07-25 09:38:39 -06:00 committed by Eric Blake
parent de8a83c3e9
commit bd9c233305
2 changed files with 23 additions and 31 deletions
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@ -1,3 +1,9 @@
2009-07-25 Bruno Haible <bruno@clisp.org>
Clarify autom4te debugging tips.
* doc/autoconf.texi (Debugging via autom4te): Fix example from
previous commit, and add clarification.
2009-07-25 Eric Blake <ebb9@byu.net>
Document some autom4te debugging tips.

48
doc/autoconf.texi
View File

@ -12454,39 +12454,25 @@ $ @kbd{autoconf --trace='AC_INIT:version is $2'}
version is 2.63b.95-3963
@end example
Another trick is using @code{m4_errprintn} to output debugging messages
to standard error with no further m4 expansion, and without interfering
with the post-processing done to standard output. For example, contrast
these two attempts to learn how @code{m4_dquote} is implemented:
Another trick is to print out the expansion of various m4 expressions to
standard error or to an independent file, with no further m4 expansion,
and without interfering with diversion changes or the post-processing
done to standard output. @code{m4_errprintn} shows a given expression
on standard error. For example, if you want to see the expansion of an
autoconf primitive or of one of your autoconf macros, you can do it like
this:
@smallexample
$ @kbd{cat <<\EOF > foo.m4}
m4_init
try one: [m4_dquote is ]m4_defn([m4_dquote])
m4_divert([0])dnl
try two: [m4_dquote is ]m4_defn([m4_dquote])
m4_dquote([hi])
@example
$ @kbd{cat <<\EOF > configure.ac}
AC_INIT
m4_errprintn([The definition of AC_DEFINE_UNQUOTED:])
m4_errprintn(m4_defn([AC_DEFINE_UNQUOTED]))
AC_OUTPUT
EOF
$ @kbd{autom4te --language=m4sugar -o foo foo.m4}
foo.m4:2: error: possibly undefined macro: m4_dquote
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
$ @kbd{cat foo}
try two: m4_dquote is [$@@]
[hi]
$ @kbd{cat <<\EOF > foo.m4}
m4_init
m4_errprintn([try one: m4_dquote is ]m4_defn([m4_dquote]))
m4_divert([0])dnl
m4_errprintn([try two: m4_dquote is ]m4_defn([m4_dquote]))dnl
m4_dquote([hi])
EOF
$ @kbd{autom4te --language=m4sugar foo.m4}
try one: m4_dquote is [$@@]
try two: m4_dquote is [$@@]
$ @kbd{cat foo}
[hi]
@end smallexample
$ @kbd{autoconf}
@error{}The definition of AC_DEFINE_UNQUOTED:
@error{}_AC_DEFINE_Q([], $@@)
@end example
@node Programming in M4sh
@chapter Programming in M4sh