Re: Words in configure.ac that look like macros forbidden or merely discouraged?

[Eric Blake]

On 06/12/2016 05:25 AM, Gavin Smith wrote:
> Hello,

Apologies for just now noticing this thread.

> 
> In the Autoconf manual we read:

Any reason you mailed this to the automake list, and not autoconf, then?

> 
> ====
> 
> When you use the same text in a macro argument, you must therefore
> have an extra quotation level (since one is stripped away by the macro
> substitution). In general, then, it is a good idea to use double
> quoting for all literal string arguments, either around just the
> problematic portions, or over the entire argument:
> 
>      AC_MSG_WARN([[AC_DC] stinks  --Iron Maiden])
>      AC_MSG_WARN([[AC_DC stinks  --Iron Maiden]])
> 

> 
> Note what it says: "triggers a warning". However, it seems in some
> cases, using a word that looks like it could be a macro triggers a
> hard error, not just a warning:
> 
> $ autoreconf -iv
> autoreconf: Entering directory `.'
> autoreconf: configure.ac: not using Gettext
> autoreconf: running: aclocal
> configure.ac:4: warning: macro 'AM_DC' not found in library

AM_DC is not the name used in the example, but falls into the namespace
reserved by automake, so I guess I see why you are testing it instead of
AC_DC.

> autoreconf: configure.ac: tracing
> autoreconf: configure.ac: not using Libtool
> autoreconf: running: /usr/bin/autoconf
> configure.ac:4: error: possibly undefined macro: AM_DC
>       If this token and others are legitimate, please use m4_pattern_allow.
>       See the Autoconf documentation.
> autoreconf: /usr/bin/autoconf failed with exit status: 1

However, the error message says that it is autoconf (not automake) that
is failing, so I don't see how this is applicable to automake.

> 
> Any ideas which it is: is it actually forbidden, or should it be just a 
> warning?

So I guess you are pointing out a documentation error in the autoconf
manual, and that the manual should call it an error, not a warning?
Sure, I can do that.

> 
> I intend to put information about this here:
> http://buildsystem-manual.sourceforge.net/Macro-name-quoting.html#Macro-name-quoting
> , which I've adapted from the test in the automake manual.
> 
> Contents of files:
> 
> $ cat configure.ac
> AC_INIT([helloprog], [1.0])
> AM_INIT_AUTOMAKE
> 
> echo AM_DC rocks
> 
> AC_CONFIG_FILES([Makefile])
> AC_OUTPUT
> $ cat Makefile.am
> AUTOMAKE_OPTIONS=foreign dist-xz
> $
> 
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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