warnings: fix early exit of warnings treated as errors

Treating warnings as errors caused Bison to exit earlier than needed, making it
hide warnings that would have been printed had -Werror not been set.

Also, fix a bug that caused some context information of errors to not be
shown.

* src/complain.c (complaint_issued): Rename as...
(complaint_status): This, and change its type from boolean to
* src/complain.h (err_status): This, new enumeration.
* src/main.c (main): Adjust (only finish early if an actual complaint was
risen, not a mere warning treated an error).
* src/reader.c: Adjust.

src/complain.c

@@ -34,7 +34,7 @@ warnings warnings_flag =
 
 warnings errors_flag;
 
-bool complaint_issued;
+err_status complaint_status = status_none;
 static unsigned *indent_ptr = 0;
 
 void
@@ -129,8 +129,11 @@ complains (const location *loc, warnings flags, const char *message,
     : flags & (errors_flag | complaint) ? _("error")
     : _("warning");
 
-  complaint_issued |= flags & (complaint | errors_flag);
-  if (flags & (warnings_flag | silent | fatal | complaint))
+  if ((flags & complaint) && complaint_status < status_complaint)
+    complaint_status = status_complaint;
+  else if ((flags & (warnings_flag & errors_flag)) && ! complaint_status)
+    complaint_status = status_warning_as_error;
+  if (flags & (warnings_flag | fatal | complaint))
     error_message (loc, flags, prefix, message, args);
   if (flags & fatal)
     exit (EXIT_FAILURE);

src/complain.h

@@ -70,7 +70,18 @@ void complain_indent (location const *loc, warnings flags, unsigned *indent,
                       char const *message, ...)
   __attribute__ ((__format__ (__printf__, 4, 5)));
 
+
+/** Warnings treated as errors shouldn't stop the execution as regular errors
+    should (because due to their nature, it is safe to go on). Thus, there are
+    three possible execution statuses.  */
+typedef enum
+  {
+    status_none,
+    status_warning_as_error,
+    status_complaint
+  } err_status;
+
 /** Whether an error was reported.  */
-extern bool complaint_issued;
+extern err_status complaint_status;
 
 #endif /* !COMPLAIN_H_ */

src/main.c

@@ -94,7 +94,7 @@ main (int argc, char *argv[])
   reader ();
   timevar_pop (TV_READER);
 
-  if (complaint_issued)
+  if (complaint_status == status_complaint)
     goto finish;
 
   /* Find useless nonterminals and productions and reduce the grammar. */
@@ -173,7 +173,7 @@ main (int argc, char *argv[])
 
   /* Stop if there were errors, to avoid trashing previous output
      files.  */
-  if (complaint_issued)
+  if (complaint_status == status_complaint)
     goto finish;
 
   /* Lookahead tokens are no longer needed. */
@@ -215,5 +215,5 @@ main (int argc, char *argv[])
   timevar_stop (TV_TOTAL);
   timevar_print (stderr);
 
-  return complaint_issued ? EXIT_FAILURE : EXIT_SUCCESS;
+  return complaint_status ? EXIT_FAILURE : EXIT_SUCCESS;
 }

src/reader.c

@@ -631,7 +631,7 @@ reader (void)
   gram_parse ();
   prepare_percent_define_front_end_variables ();
 
-  if (! complaint_issued)
+  if (complaint_status  < status_complaint)
     check_and_convert_grammar ();
 
   xfclose (gram_in);