Allow debugmode control over whether defn(undef) warns.

* ltdl/m4/gnulib-cache.m4: Import verify module.
* m4/m4module.h (M4_DEBUG_TRACE_DEREF, M4_DEBUG_TRACE_INITIAL):
New values.
(M4_DEBUG_TRACE_VERBOSE, M4_DEBUG_TRACE_DEFAULT): Adjust.
* m4/m4.c (m4_create): Start with debugmode = d.
* src/main.c (usage): Mention this.
(main): Let -E impact debug mode.
* m4/utility.c (m4_symbol_value_lookup): Squelch undefined warning
if flag is clear.
* modules/gnu.c (builtin, inder): Likewise.
* m4/debug.c (m4_debug_decode): Parse new mode.
* src/freeze.c (produce_debugmode_state): Accomodate new mode.
* doc/m4.texinfo (Debugging options): Mention change in the
default behavior.
(Debugmode): Mention new flag d.
(Operation modes): Mention interaction with -E.
(Undefine, Defn, Pushdef, Indir, Builtin, Dumpdef): Document and
test its effect.
* tests/options.at (--debugmode): Update tests.
* tests/freeze.at (reloading debugmode): Likewise.
* NEWS: Document this.
Reported by Ralf Wildenhues; without this patch, M4 1.6+ would be
incompatible with Autoconf 2.62.

Signed-off-by: Eric Blake <ebb9@byu.net>

1 files changed, 14 insertions, 8 deletions

diff --git a/modules/gnu.c b/modules/gnu.c
index 2e960305..74e1c4a7 100644
--- a/modules/gnu.c
+++ b/modules/gnu.c
@@ -424,14 +424,14 @@ M4BUILTIN_HANDLER (builtin)
 	  len = M4ARGLEN (2);
 	  if (len == strlen (name))
 	    value = m4_builtin_find_by_name (NULL, name);
-	  if (value == NULL)
-	    m4_warn (context, 0, me, _("undefined builtin %s"),
-		     quotearg_style_mem (locale_quoting_style, name, len));
-	  else
+	  if (value)
 	    {
 	      m4_push_builtin (context, obs, value);
 	      free (value);
 	    }
+	  else if (m4_is_debug_bit (context, M4_DEBUG_TRACE_DEREF))
+	    m4_warn (context, 0, me, _("undefined builtin %s"),
+		     quotearg_style_mem (locale_quoting_style, name, len));
 	}
       else
 	m4_warn (context, 0, me, _("invalid macro name ignored"));
@@ -443,8 +443,11 @@ M4BUILTIN_HANDLER (builtin)
       if (len == strlen (name))
 	value = m4_builtin_find_by_name (NULL, name);
       if (value == NULL)
-	m4_warn (context, 0, me, _("undefined builtin %s"),
-		 quotearg_style_mem (locale_quoting_style, name, len));
+	{
+	  if (m4_is_debug_bit (context, M4_DEBUG_TRACE_DEREF))
+	    m4_warn (context, 0, me, _("undefined builtin %s"),
+		     quotearg_style_mem (locale_quoting_style, name, len));
+	}
       else
 	{
 	  const m4_builtin *bp = m4_get_symbol_value_builtin (value);
@@ -692,8 +695,11 @@ M4BUILTIN_HANDLER (indir)
       m4_symbol *symbol = m4_symbol_lookup (M4SYMTAB, name, len);
 
       if (symbol == NULL)
-	m4_warn (context, 0, me, _("undefined macro %s"),
-		 quotearg_style_mem (locale_quoting_style, name, len));
+	{
+	  if (m4_is_debug_bit (context, M4_DEBUG_TRACE_DEREF))
+	    m4_warn (context, 0, me, _("undefined macro %s"),
+		     quotearg_style_mem (locale_quoting_style, name, len));
+	}
       else
 	{
 	  m4_macro_args *new_argv;