[PATCH 1/3] errors: introduce the -Werror=CATEGORY option

[Theophile Ranquet]

This new option is a lot more flexible than the previous one. Its
details will be discussed in the NEWS and info file, in a forthcoming
change.

If no category is specified (ie: used as simply "-Werror"), the
functionality is the same as before.

* src/complain.c (errors_flag): New variable.
(set_warning_issued): Accept warning categories as an argument.
* src/complain.h (Wall): Better definition.
* src/getargs.c (flags_argmatch): Support for the new format.
(usage): Update -Werror to -Werror[=CATEGORY] format.

* src/complain.c (errors_flag): New variable.
(set_warning_issued): Accept warning categories as an argument.
* src/complain.h (Wall): Better definition.
* src/getargs.c (flags_argmatch): Support for the new format.
(usage): Update -Werror to -Werror=[CATEGORY] format.
---
 NEWS           |  9 ++++-----
 src/complain.c | 10 ++++++----
 src/complain.h | 12 +++++++++---
 src/getargs.c  | 39 ++++++++++++++++++++++++++-------------
 4 files changed, 45 insertions(+), 25 deletions(-)

diff --git a/NEWS b/NEWS
index a70c23d..7e5bda2 100644
--- a/NEWS
+++ b/NEWS
@@ -90,9 +90,8 @@ GNU Bison NEWS
     foo.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
     foo.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
     $ bison -Werror foo.y
-    bison: warnings being treated as errors
-    foo.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-    foo.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
+    foo.y: error: 1 shift/reduce conflict [-Werror=conflicts-sr]
+    foo.y: error: 2 reduce/reduce conflicts [-Werror=conflicts-rr]
 
   When %expect or %expect-rr is used, such as with bar.y:
 
@@ -111,8 +110,8 @@ GNU Bison NEWS
   New one:
 
     $ bison bar.y
-    bar.y: shift/reduce conflicts: 1 found, 0 expected
-    bar.y: reduce/reduce conflicts: 2 found, 0 expected
+    bar.y: error: shift/reduce conflicts: 1 found, 0 expected
+    bar.y: error: reduce/reduce conflicts: 2 found, 0 expected
 
 ** Additional yylex/yyparse arguments
 
diff --git a/src/complain.c b/src/complain.c
index 1834120..849a71c 100644
--- a/src/complain.c
+++ b/src/complain.c
@@ -32,6 +32,8 @@
 warnings warnings_flag =
   Wconflicts_sr | Wconflicts_rr | Wdeprecated  | Wother;
 
+warnings errors_flag;
+
 bool complaint_issued;
 static unsigned *indent_ptr = 0;
 
@@ -141,7 +143,7 @@ complains (const location *loc, warnings flags, const char 
*message,
         }
       else if (warnings_flag & Wyacc)
         {
-          set_warning_issued ();
+          set_warning_issued (Wyacc);
           error_message (loc, flags,
                          indent_ptr && *indent_ptr ? NULL : _("warning"),
                          message, args);
@@ -149,7 +151,7 @@ complains (const location *loc, warnings flags, const char 
*message,
     }
   else if (warnings_flag & flags)
     {
-      set_warning_issued ();
+      set_warning_issued (flags);
       error_message (loc, flags,
                      indent_ptr && *indent_ptr ? NULL : _("warning"),
                      message, args);
@@ -191,10 +193,10 @@ void complain_at_indent (location loc, warnings flags, 
unsigned *indent,
 `--------------------------------*/
 
 void
-set_warning_issued (void)
+set_warning_issued (warnings warning)
 {
   static bool warning_issued = false;
-  if (!warning_issued && (warnings_flag & Werror))
+  if (!warning_issued && (warning & warnings_flag & errors_flag))
     {
       fprintf (stderr, "%s: warnings being treated as errors\n", program_name);
       complaint_issued = true;
diff --git a/src/complain.h b/src/complain.h
index 452508e..840e736 100644
--- a/src/complain.h
+++ b/src/complain.h
@@ -35,16 +35,22 @@ typedef enum
     Wdeprecated       = 1 << 4,  /**< Obsolete constructs.  */
     Wother            = 1 << 5,  /**< All other warnings.  */
 
-    Werror            = 1 << 10, /**< Warnings are treated as errors.  */
+    Werror            = 1 << 10, /** This bit is no longer used. */
+
     complaint         = 1 << 11, /**< All complaints.  */
     fatal             = 1 << 12, /**< All fatal errors.  */
     silent            = 1 << 13, /**< Do not display the warning type.  */
-    Wall              = ~Werror  /**< All above warnings.  */
+
+    /**< All above warnings.  */
+    Wall              = ~complaint & ~fatal & ~silent
   } warnings;
 
 /** What warnings are issued.  */
 extern warnings warnings_flag;
 
+/** What warnings are made errors.  */
+extern warnings errors_flag;
+
 /** Display a "[-Wyacc]" like message on stderr.  */
 void warnings_print_categories (warnings warn_flags);
 
@@ -56,7 +62,7 @@ void warnings_print_categories (warnings warn_flags);
     only for the sake of Yacc-compatible conflict reports in conflicts.c.
     All other warnings should be implemented in complain.c and should use
     the normal warning format.  */
-void set_warning_issued (void);
+void set_warning_issued (warnings warning);
 
 /** Make a complaint, but don't specify any location.  */
 void complain (warnings flags, char const *message, ...)
diff --git a/src/getargs.c b/src/getargs.c
index 97f061f..90b2655 100644
--- a/src/getargs.c
+++ b/src/getargs.c
@@ -87,9 +87,17 @@ flags_argmatch (const char *option,
       args = strtok (args, ",");
       while (args)
         {
+          int value = all;
+          int *save_flags = flags;
           int no = STRPREFIX_LIT ("no-", args) ? 3 : 0;
-          int value = XARGMATCH (option, args + no, keys, values);
-          if (value == 0)
+          int err = STRPREFIX_LIT ("error", args + no) ? 5 : 0;
+
+          if (err)
+            flags = &errors_flag;
+          if (!err || args[no + err++] != '\0')
+            value = XARGMATCH (option, args + no + err, keys, values);
+
+          if (!value)
             {
               if (no)
                 *flags |= all;
@@ -101,8 +109,13 @@ flags_argmatch (const char *option,
               if (no)
                 *flags &= ~value;
               else
-                *flags |= value;
+                {
+                  if (err)
+                    warnings_flag |= value;
+                  *flags |= value;
+                }
             }
+          flags = save_flags;
           args = strtok (NULL, ",");
         }
     }
@@ -322,16 +335,16 @@ Output:\n\
 
       fputs (_("\
 Warning categories include:\n\
-  `midrule-values'  unset or unused midrule values\n\
-  `yacc'            incompatibilities with POSIX Yacc\n\
-  `conflicts-sr'    S/R conflicts (enabled by default)\n\
-  `conflicts-rr'    R/R conflicts (enabled by default)\n\
-  `deprecated'      obsolete constructs\n\
-  `other'           all other warnings (enabled by default)\n\
-  `all'             all the warnings\n\
-  `no-CATEGORY'     turn off warnings in CATEGORY\n\
-  `none'            turn off all the warnings\n\
-  `error'           treat warnings as errors\n\
+  `midrule-values'    unset or unused midrule values\n\
+  `yacc'              incompatibilities with POSIX Yacc\n\
+  `conflicts-sr'      S/R conflicts (enabled by default)\n\
+  `conflicts-rr'      R/R conflicts (enabled by default)\n\
+  `deprecated'        obsolete constructs\n\
+  `other'             all other warnings (enabled by default)\n\
+  `all'               all the warnings\n\
+  `no-CATEGORY'       turn off warnings in CATEGORY\n\
+  `none'              turn off all the warnings\n\
+  `error[=CATEGORY]'  treat warnings as errors\n\
 "), stdout);
       putc ('\n', stdout);
 
-- 
1.7.11.4