Further improvements in `mail'.

* NEWS: Update.
* mail/mail.h (MOPTF_UNSET): New constant.
* mail/mailvar.c (MAILVAR_TYPEMASK): New define.
(struct mailvar_symbol): Remove `type'. Add `handler'.
The latter supplies special handling for certain variables.
(mailvar_tab): Update accordingly.
Implement "debug" variable.
(mailvar_set): Enforce correct variable type in variable-strict mode.
Handle MOPTF_UNSET flag.
Remove kludgy special handling for some attributes, use sym->handler
instead.
(set_decode_fallback, set_replyregex)
(set_screen, set_mailbox_debug_level, set_debug): New functions.
(describe_symbol): Handle alternative symbol types.
* mail/set.c: Use MOPTF_UNSET when unsetting the variable.
* mail/source.c: Set correct locus. This allows to display
locations along with error messages.

@@ -48,6 +48,13 @@ In addition, the form
 
 is also allowed.  
 
+** error locations
+
+Diagnostic messages issued while processing `source' command
+include file locations, in compliance with the GNU standards. This
+also includes diagnostics issued during processing of the
+system or user configuration file.
+
 ** envelope command
 
 The env[elope] command displays the SMTP envelopes of the messages

@@ -344,6 +344,7 @@ extern void mailvar_variable_format (FILE *fp,
 
 #define MOPTF_OVERWRITE 0x001
 #define MOPTF_QUIET     0x002
+#define MOPTF_UNSET     0x004
 extern int mailvar_set (const char *name, void *value,
 		      enum mailvar_type type, int flags);
 extern int util_isdeleted (size_t msgno);

@@ -48,7 +48,8 @@ mail_set (int argc, char **argv)
 	  
 	  if (!strncmp ("no", argv[i], 2) && !value)
 	    {
-	      mailvar_set (&argv[i][2], NULL, mailvar_type_boolean, flags);
+	      mailvar_set (&argv[i][2], NULL, mailvar_type_boolean,
+			   flags | MOPTF_UNSET);
 	    }
 	  else if (value)
 	    {

@@ -18,21 +18,25 @@
 
 #include "mail.h"
 
-
 static char *
 source_readline (void *closure, int cont MU_ARG_UNUSED)
 {
   FILE *fp = closure;
   size_t s = 0;
   char *buf = NULL;
+  mu_debug_t debug;
+  struct mu_debug_locus locus;
   
   if (getline (&buf, &s, fp) >= 0)
     {
-      int len = strlen (buf);
-      if (buf[len-1] == '\n')
-	buf[len-1] = '\0';
+      mu_rtrim_class (buf, MU_CTYPE_SPACE);
+
+      mu_diag_get_debug (&debug);
+      mu_debug_get_locus (debug, &locus);
+      mu_debug_set_locus (debug, locus.file, locus.line + 1);
       return buf;
     }
+  
   return NULL;
 }
   
@@ -45,11 +49,12 @@ mail_source (int argc, char **argv)
 {
   FILE *fp;
   int save_term;
+  mu_debug_t debug;
   
   if (argc != 2)
     {
       /* TRANSLATORS: 'source' is a command name. Do not translate it! */
-      util_error (_("source requires an argument"));
+      util_error (_("source requires a single argument"));
       return 1;
     }
   
@@ -63,8 +68,11 @@ mail_source (int argc, char **argv)
 
   save_term = interactive;
   interactive = 0;
-  mail_mainloop(source_readline, fp, 0);
+  mu_diag_get_debug (&debug);
+  mu_debug_set_locus (debug, argv[1], 0);
+  mail_mainloop (source_readline, fp, 0);
   interactive = save_term;
+  mu_debug_set_locus (debug, NULL, 0);
   fclose (fp);
   return 0;
 }