warnings: introduce -Wprecedence

The new warning category "precedence" flags useless precedence and
associativity.  -Wprecedence can now be used, it is disabled by default.
The warnings about precedence and associativity are grouped into one, and
the testsuite was corrected accordingly.

* src/complain.h (warnings): Introduce "precedence".
* src/complain.c (warnings_print_categories): Adjust.
* src/getargs.c (warnings_args, warning_types): Likewise.
* src/symtab.h, src/symtab.c (print_associativity_warnings): Remove.
* src/symtab.h (register_assoc): Correct arguments.
* src/symtab.c (print_precedence_warnings): Print both warnings together.
* doc/bison.texi (Bison options): Document the warnings and provide an
example.
* tests/conflicts.at, tests/existing.at, tests/local.at,
* tests/regression.at: Adapt the testsuite for the new category
(-Wprecedence instead of -Wother where appropriate).

src/complain.c

@@ -50,6 +50,7 @@ warnings_print_categories (warnings warn_flags)
           "conflicts-sr",
           "conflicts-rr",
           "deprecated",
+          "precedence",
           "other"
         };
 

src/complain.h

@@ -36,7 +36,9 @@ typedef enum
     Wconflicts_sr     = 1 << 2,  /**< S/R conflicts.  */
     Wconflicts_rr     = 1 << 3,  /**< R/R conflicts.  */
     Wdeprecated       = 1 << 4,  /**< Obsolete constructs.  */
-    Wother            = 1 << 5,  /**< All other warnings.  */
+    Wprecedence       = 1 << 5,  /**< Useless precedence and associativity.  */
+
+    Wother            = 1 << 6,  /**< All other warnings.  */
 
     Werror            = 1 << 10, /** This bit is no longer used. */
 

src/getargs.c

@@ -252,6 +252,7 @@ static const char * const warnings_args[] =
   "conflicts-sr    - S/R conflicts",
   "conflicts-rr    - R/R conflicts",
   "deprecated      - obsolete constructs",
+  "precedence      - useless precedence and associativity",
   "other           - all other warnings",
   "all             - all of the above",
   "error           - warnings are errors",
@@ -266,6 +267,7 @@ static const int warnings_types[] =
   Wconflicts_sr,
   Wconflicts_rr,
   Wdeprecated,
+  Wprecedence,
   Wother,
   Wall,
   Werror
@@ -381,6 +383,7 @@ Warning categories include:\n\
   `conflicts-sr'      S/R conflicts (enabled by default)\n\
   `conflicts-rr'      R/R conflicts (enabled by default)\n\
   `deprecated'        obsolete constructs\n\
+  `precedence'        useless precedence and associativity\n\
   `other'             all other warnings (enabled by default)\n\
   `all'               all the warnings\n\
   `no-CATEGORY'       turn off warnings in CATEGORY\n\

src/main.c

@@ -146,8 +146,6 @@ main (int argc, char *argv[])
 
   print_precedence_warnings ();
 
-  print_assoc_warnings ();
-
   /* Output file names. */
   compute_output_file_names ();
 

src/symtab.c

@@ -1057,29 +1057,6 @@ register_precedence (graphid first, graphid snd)
 }
 
 
-/*--------------------------------------------------.
-| Print a warning for unused precedence relations.  |
-`--------------------------------------------------*/
-
-void
-print_precedence_warnings (void)
-{
-  int i;
-  if (!prec_nodes)
-    init_prec_nodes ();
-  for (i = 0; i < nsyms; ++i)
-    {
-      symbol *s = symbols[i];
-      if (s
-          && s->prec != 0
-          && !prec_nodes[i]->pred
-          && !prec_nodes[i]->succ
-          && s->assoc == precedence_assoc)
-        complain (&s->location, Wother,
-                  _("useless precedence for %s"), s->tag);
-    }
-}
-
 /*---------------------------------------.
 | Initialize association tracking table. |
 `---------------------------------------*/
@@ -1119,21 +1096,35 @@ register_assoc (graphid i, graphid j)
   used_assoc[j] = true;
 }
 
-/*------------------------------------------------------.
-| Print a warning for each unused symbol associativity. |
-`------------------------------------------------------*/
+/*--------------------------------------------------.
+| Print a warning for unused precedence relations.  |
+`--------------------------------------------------*/
 
 void
-print_assoc_warnings (void)
+print_precedence_warnings (void)
 {
-  graphid i;
+  int i;
+  if (!prec_nodes)
+    init_prec_nodes ();
   if (!used_assoc)
     init_assoc ();
   for (i = 0; i < nsyms; ++i)
     {
       symbol *s = symbols[i];
-      if (is_assoc_useless (s))
-        complain (&s->location, Wother,
-                  _("useless associativity for %s"), s->tag);
+      if (s
+          && s->prec != 0
+          && !prec_nodes[i]->pred
+          && !prec_nodes[i]->succ)
+        {
+          if (is_assoc_useless (s))
+            complain (&s->location, Wprecedence,
+                      _("useless precedence and associativity for %s"), s->tag);
+          else if (s->assoc == precedence_assoc)
+            complain (&s->location, Wprecedence,
+                      _("useless precedence for %s"), s->tag);
+        }
+      else if (is_assoc_useless (s))
+        complain (&s->location, Wprecedence,
+                  _("useless associativity for %s, use %%precedence"), s->tag);
     }
 }

src/symtab.h

@@ -266,7 +266,8 @@ struct symgraph
 
 void register_precedence (graphid first, graphid snd);
 
-/** Print a warning for each symbol whose precedence is useless. */
+/** Print a warning for each symbol whose precedence and/or associativity
+ * is useless. */
 
 void print_precedence_warnings (void);
 
@@ -274,9 +275,7 @@ void print_precedence_warnings (void);
 | Symbol associativity  |
 `----------------------*/
 
-void register_assoc (int i, int j);
-
-void print_assoc_warnings (void);
+void register_assoc (graphid i, graphid j);
 
 /*-----------------.
 | Semantic types.  |