Merge remote-tracking branch 'origin/maint'

[bison.git] / src / scan-code.l

diff --git a/src/scan-code.l b/src/scan-code.l
index 4c91fd1ac12782378d81c95794e3531364d76788..24ef5d920c280a35abea7ccfde6a01b7c2428f65 100644 (file)
--- a/src/scan-code.l
+++ b/src/scan-code.l
@@ -1,6 +1,6 @@
 /* Bison Action Scanner                             -*- C -*-
 
 /* Bison Action Scanner                             -*- C -*-
 

-   Copyright (C) 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2006-2012 Free Software Foundation, Inc.

 
    This file is part of Bison, the GNU Compiler Compiler.
 
 
    This file is part of Bison, the GNU Compiler Compiler.
 


@@ -17,7 +17,7 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 

-%option debug nodefault nounput noyywrap never-interactive
+%option debug nodefault noinput nounput noyywrap never-interactive

 %option prefix="code_" outfile="lex.yy.c"
 
 %{
 %option prefix="code_" outfile="lex.yy.c"
 
 %{


@@ -32,12 +32,14 @@
 #include <src/complain.h>
 #include <src/reader.h>
 #include <src/getargs.h>
 #include <src/complain.h>
 #include <src/reader.h>
 #include <src/getargs.h>

-#include <get-errno.h>
-#include <quote.h>

 #include <src/muscle-tab.h>
 #include <src/scan-code.h>
 #include <src/symlist.h>
 
 #include <src/muscle-tab.h>
 #include <src/scan-code.h>
 #include <src/symlist.h>
 

+#include <c-ctype.h>
+#include <get-errno.h>
+#include <quote.h>
+

 /* The current calling start condition: SC_RULE_ACTION or
    SC_SYMBOL_ACTION. */
 # define YY_DECL static char *code_lex (code_props *self, int sc_context)
 /* The current calling start condition: SC_RULE_ACTION or
    SC_SYMBOL_ACTION. */
 # define YY_DECL static char *code_lex (code_props *self, int sc_context)


@@ -46,10 +48,10 @@ YY_DECL;
 #define YY_USER_ACTION  location_compute (loc, &loc->end, yytext, yyleng);
 
 static void handle_action_dollar (symbol_list *rule, char *cp,
 #define YY_USER_ACTION  location_compute (loc, &loc->end, yytext, yyleng);
 
 static void handle_action_dollar (symbol_list *rule, char *cp,

-                                 location dollar_loc);
+                                  location dollar_loc);

 static void handle_action_at (symbol_list *rule, char *cp, location at_loc);
 
 static void handle_action_at (symbol_list *rule, char *cp, location at_loc);
 

-/* A string to be pushed to obstack after dollar/at has been handled */
+/* A string to be pushed to obstack after dollar/at has been handled. */

 static char *ref_tail_fields;
 
 static location the_location;
 static char *ref_tail_fields;
 
 static location the_location;


@@ -74,16 +76,17 @@ static bool untyped_var_seen;
 /* POSIX says that a tag must be both an id and a C union member, but
    historically almost any character is allowed in a tag.  We disallow
    NUL and newline, as this simplifies our implementation.  */
 /* POSIX says that a tag must be both an id and a C union member, but
    historically almost any character is allowed in a tag.  We disallow
    NUL and newline, as this simplifies our implementation.  */

-tag     [^\0\n>]+
+tag      [^\0\n>]+

 
 /* Zero or more instances of backslash-newline.  Following GCC, allow
    white space between the backslash and the newline.  */
 
 /* Zero or more instances of backslash-newline.  Following GCC, allow
    white space between the backslash and the newline.  */

-splice  (\\[ \f\t\v]*\n)*
+splice   (\\[ \f\t\v]*\n)*

 
 /* C style identifier. Must start with letter. Will be used for
 
 /* C style identifier. Must start with letter. Will be used for

-   named symbol references. */
-letter   [-.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
-id       {letter}({letter}|[0-9])*
+   named symbol references. Shall be kept synchronized with
+   scan-gram.l "letter" and "id". */
+letter    [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
+id        {letter}({letter}|[-0-9])*

 ref      -?[0-9]+|{id}|"["{id}"]"|"$"
 
 %%
 ref      -?[0-9]+|{id}|"["{id}"]"|"$"
 
 %%


@@ -93,10 +96,10 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
   int braces_level = 0;
 
   /* Whether a semicolon is probably needed.
   int braces_level = 0;
 
   /* Whether a semicolon is probably needed.

-     The heuristic is that a semicolon is not needed after `{', `}', `;',
+     The heuristic is that a semicolon is not needed after '{', '}', ';',

      or a C preprocessor directive, and that whitespaces and comments
      do not affect this flag.
      or a C preprocessor directive, and that whitespaces and comments
      do not affect this flag.

-     Note that `{' does not need a semicolon because of `{}'.
+     Note that '{' does not need a semicolon because of '{}'.

      A semicolon may be needed before a cpp direcive, but don't bother.  */
   bool need_semicolon = false;
 
      A semicolon may be needed before a cpp direcive, but don't bother.  */
   bool need_semicolon = false;
 


@@ -109,13 +112,13 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
      is expected to return only once.  This initialization is
      therefore done once per action to translate. */
   aver (sc_context == SC_SYMBOL_ACTION
      is expected to return only once.  This initialization is
      therefore done once per action to translate. */
   aver (sc_context == SC_SYMBOL_ACTION

-       || sc_context == SC_RULE_ACTION
-       || sc_context == INITIAL);
+        || sc_context == SC_RULE_ACTION
+        || sc_context == INITIAL);

   BEGIN sc_context;
 %}
 
   /*------------------------------------------------------------.
   BEGIN sc_context;
 %}
 
   /*------------------------------------------------------------.

-  | Scanning a C comment.  The initial `/ *' is already eaten.  |
+  | Scanning a C comment.  The initial '/ *' is already eaten.  |

   `------------------------------------------------------------*/
 
 <SC_COMMENT>
   `------------------------------------------------------------*/
 
 <SC_COMMENT>


@@ -125,13 +128,13 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
 
 
   /*--------------------------------------------------------------.
 
 
   /*--------------------------------------------------------------.

-  | Scanning a line comment.  The initial `//' is already eaten.  |
+  | Scanning a line comment.  The initial '//' is already eaten.  |

   `--------------------------------------------------------------*/
 
 <SC_LINE_COMMENT>
 {
   `--------------------------------------------------------------*/
 
 <SC_LINE_COMMENT>
 {

-  "\n"          STRING_GROW; BEGIN sc_context;
-  {splice}      STRING_GROW;
+  "\n"           STRING_GROW; BEGIN sc_context;
+  {splice}       STRING_GROW;

 }
 
 
 }
 
 


@@ -141,17 +144,17 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
 
 <SC_CHARACTER,SC_STRING>
 {
 
 <SC_CHARACTER,SC_STRING>
 {

-  {splice}|\\{splice}. STRING_GROW;
+  {splice}|\\{splice}.  STRING_GROW;

 }
 
 <SC_CHARACTER>
 {
 }
 
 <SC_CHARACTER>
 {

-  "'"          STRING_GROW; BEGIN sc_context;
+  "'"           STRING_GROW; BEGIN sc_context;

 }
 
 <SC_STRING>
 {
 }
 
 <SC_STRING>
 {

-  "\""         STRING_GROW; BEGIN sc_context;
+  "\""          STRING_GROW; BEGIN sc_context;

 }
 
 
 }
 
 


@@ -181,7 +184,7 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
   "$"("<"{tag}">")?{ref}  {
     ref_tail_fields = 0;
     handle_action_dollar (self->rule, yytext, *loc);
   "$"("<"{tag}">")?{ref}  {
     ref_tail_fields = 0;
     handle_action_dollar (self->rule, yytext, *loc);

-    if (ref_tail_fields != NULL) {
+    if (ref_tail_fields) {

       obstack_sgrow (&obstack_for_string, ref_tail_fields);
     }
     need_semicolon = true;
       obstack_sgrow (&obstack_for_string, ref_tail_fields);
     }
     need_semicolon = true;


@@ -189,18 +192,18 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
   "@"{ref} {
     ref_tail_fields = 0;
     handle_action_at (self->rule, yytext, *loc);
   "@"{ref} {
     ref_tail_fields = 0;
     handle_action_at (self->rule, yytext, *loc);

-    if (ref_tail_fields != NULL) {
+    if (ref_tail_fields) {

       obstack_sgrow (&obstack_for_string, ref_tail_fields);
     }
     need_semicolon = true;
   }
   "$"  {
       obstack_sgrow (&obstack_for_string, ref_tail_fields);
     }
     need_semicolon = true;
   }
   "$"  {

-    warn_at (*loc, _("stray `$'"));
+    complain_at (*loc, Wother, _("stray '$'"));

     obstack_sgrow (&obstack_for_string, "$][");
     need_semicolon = true;
   }
   "@"  {
     obstack_sgrow (&obstack_for_string, "$][");
     need_semicolon = true;
   }
   "@"  {

-    warn_at (*loc, _("stray `@'"));
+    complain_at (*loc, Wother, _("stray '@'"));

     obstack_sgrow (&obstack_for_string, "@@");
     need_semicolon = true;
   }
     obstack_sgrow (&obstack_for_string, "@@");
     need_semicolon = true;
   }


@@ -218,16 +221,18 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
   "}"  {
     bool outer_brace = --braces_level == 0;
 
   "}"  {
     bool outer_brace = --braces_level == 0;
 

-    /* As an undocumented Bison extension, append `;' before the last
+    /* As an undocumented Bison extension, append ';' before the last

        brace in braced code, so that the user code can omit trailing
        brace in braced code, so that the user code can omit trailing

-       `;'.  But do not append `;' if emulating Yacc, since Yacc does
+       ';'.  But do not append ';' if emulating Yacc, since Yacc does

        not append one.  */
     if (outer_brace && !yacc_flag && language_prio == default_prio
         && skeleton_prio == default_prio && need_semicolon && ! in_cpp)
       {
        not append one.  */
     if (outer_brace && !yacc_flag && language_prio == default_prio
         && skeleton_prio == default_prio && need_semicolon && ! in_cpp)
       {

-       warn_at (*loc, _("a `;' might be needed at the end of action code"));
-       warn_at (*loc, _("future versions of Bison will not add the `;'"));
-       obstack_1grow (&obstack_for_string, ';');
+        complain_at (*loc, Wother,
+                     _("a ';' might be needed at the end of action code"));
+        complain_at (*loc, Wother,
+                     _("future versions of Bison will not add the ';'"));
+        obstack_1grow (&obstack_for_string, ';');

       }
 
     STRING_GROW;
       }
 
     STRING_GROW;


@@ -236,14 +241,27 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
 
   /* Preprocessing directives should only be recognized at the beginning
      of lines, allowing whitespace including comments, but in C/C++,
 
   /* Preprocessing directives should only be recognized at the beginning
      of lines, allowing whitespace including comments, but in C/C++,

-     `#' can only be the start of preprocessor directives or within
-     `#define' directives anyway, so don't bother with begin of line.  */
+     '#' can only be the start of preprocessor directives or within
+     '#define' directives anyway, so don't bother with begin of line.  */

   "#"       STRING_GROW; in_cpp = true;
 
   {splice}  STRING_GROW;
   [\n\r]    STRING_GROW; if (in_cpp) in_cpp = need_semicolon = false;
   [ \t\f]   STRING_GROW;
   "#"       STRING_GROW; in_cpp = true;
 
   {splice}  STRING_GROW;
   [\n\r]    STRING_GROW; if (in_cpp) in_cpp = need_semicolon = false;
   [ \t\f]   STRING_GROW;

-  .         STRING_GROW; need_semicolon = true;
+
+  /* YYFAIL is undocumented and was formally deprecated in Bison
+     2.4.2.  */
+  YYFAIL {
+    STRING_GROW; need_semicolon = true;
+    complain_at (*loc, Wother,
+                 _("use of YYFAIL, which is deprecated and will be removed"));
+  }
+
+  /* The sole purpose of this is to make sure identifiers that merely
+     contain YYFAIL don't produce the above warning.  */
+  [A-Za-z_][0-9A-Za-z_]* STRING_GROW; need_semicolon = true;
+
+  . STRING_GROW; need_semicolon = true;

 }
 
 <SC_SYMBOL_ACTION>
 }
 
 <SC_SYMBOL_ACTION>


@@ -265,103 +283,105 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
 
 <*>
 {
 
 <*>
 {

-  \$   obstack_sgrow (&obstack_for_string, "$][");
-  \@   obstack_sgrow (&obstack_for_string, "@@");
-  \[   obstack_sgrow (&obstack_for_string, "@{");
-  \]   obstack_sgrow (&obstack_for_string, "@}");
+  \$    obstack_sgrow (&obstack_for_string, "$][");
+  \@    obstack_sgrow (&obstack_for_string, "@@");
+  \[    obstack_sgrow (&obstack_for_string, "@{");
+  \]    obstack_sgrow (&obstack_for_string, "@}");

 }
 
   /*-----------------------------------------------------.
   | By default, grow the string obstack with the input.  |
   `-----------------------------------------------------*/
 
 }
 
   /*-----------------------------------------------------.
   | By default, grow the string obstack with the input.  |
   `-----------------------------------------------------*/
 

-<*>.|\n        STRING_GROW;
+<*>.|\n STRING_GROW;

 
  /* End of processing. */
 
  /* End of processing. */

-<*><<EOF>>      {
+<*><<EOF>>       {

                    STRING_FINISH;
                    return last_string;
                  }
 
 %%
 
                    STRING_FINISH;
                    return last_string;
                  }
 
 %%
 

-

 static inline bool
 static inline bool

-symbol_list_null(symbol_list *l)
-{
-  if (l && !(l->content_type == SYMLIST_SYMBOL && l->content.sym == NULL))
-    return false;
-  else
-    return true;
-}
-
-static inline bool
-is_dot_or_dash(char ch)
+is_dot_or_dash (char ch)

 {
   return ch == '.' || ch == '-';
 }
 
 static inline bool
 {
   return ch == '.' || ch == '-';
 }
 
 static inline bool

-is_digit(char ch)
-{
-  return '0' <= ch && ch <= '9';
-}
-
-static inline bool
-contains_dot_or_dash(const char* str)
+contains_dot_or_dash (const char* p)

 {
 {

-  return strpbrk(str, ".-") != NULL;
+  for (; *p; ++p)
+    if (is_dot_or_dash (*p))
+      return true;
+  return false;

 }
 
 }
 

-#define VARIANT_HIDDEN (1 << 0)
-#define VARIANT_BAD_BRACKETING (1 << 1)
-#define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
-
+/* Defines a variant of a symbolic name resolution. */

 typedef struct
 {
   /* Index in symbol list. */
 typedef struct
 {
   /* Index in symbol list. */

-  long int ind;
+  unsigned symbol_index;

 
   /* Matched symbol id and loc. */
   uniqstr id;
   location loc;
 
 
   /* Matched symbol id and loc. */
   uniqstr id;
   location loc;
 

-  /* Hidding named reference. */
+  /* Hiding named reference. */

   named_ref* hidden_by;
 
   named_ref* hidden_by;
 

-  /* Error flags. */
+  /* Error flags. May contain zero (no errors) or
+     a combination of VARIANT_* values. */

   unsigned err;
 } variant;
 
   unsigned err;
 } variant;
 

+/* Set when the variant refers to a symbol hidden
+   by an explicit symbol reference. */
+#define VARIANT_HIDDEN (1 << 0)
+
+/* Set when the variant refers to a symbol containing
+   dots or dashes. Will require explicit bracketing. */
+#define VARIANT_BAD_BRACKETING (1 << 1)
+
+/* Set when the variant refers to a symbol which is
+   not visible from current midrule. */
+#define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
+

 static variant *variant_table = 0;
 static unsigned variant_table_size = 0;
 static unsigned variant_count = 0;
 
 static variant *
 static variant *variant_table = 0;
 static unsigned variant_table_size = 0;
 static unsigned variant_count = 0;
 
 static variant *

-variant_table_grow()
+variant_table_grow (void)

 {
   ++variant_count;
   if (variant_count > variant_table_size)
     {
       while (variant_count > variant_table_size)
 {
   ++variant_count;
   if (variant_count > variant_table_size)
     {
       while (variant_count > variant_table_size)

-       variant_table_size = 2 * variant_table_size + 3;
+        variant_table_size = 2 * variant_table_size + 3;

       variant_table = xnrealloc (variant_table, variant_table_size,
       variant_table = xnrealloc (variant_table, variant_table_size,

-                                sizeof *variant_table);
+                                 sizeof *variant_table);

     }
   return &variant_table[variant_count - 1];
 }
 
     }
   return &variant_table[variant_count - 1];
 }
 

+static void
+variant_table_free (void)
+{
+  free (variant_table);
+  variant_table = 0;
+  variant_table_size = variant_count = 0;
+}
+

 static char *
 static char *

-find_prefix_end(const char *prefix, char *begin, char *end)
+find_prefix_end (const char *prefix, char *begin, char *end)

 {
   char *ptr = begin;
 
 {
   char *ptr = begin;
 

-  while (*prefix && ptr != end)
-    {
-      if (*prefix != *ptr)
-       return 0;
-      ++prefix, ++ptr;
-    }
+  for (; *prefix && ptr != end; ++prefix, ++ptr)
+    if (*prefix != *ptr)
+      return 0;

 
   if (*prefix)
     return 0;
 
   if (*prefix)
     return 0;


@@ -370,20 +390,20 @@ find_prefix_end(const char *prefix, char *begin, char *end)
 }
 
 static variant *
 }
 
 static variant *

-variant_add(uniqstr id, location loc, long int ind,
-           char *cp, char *cp_end, bool exact_mode)
+variant_add (uniqstr id, location id_loc, unsigned symbol_index,
+             char *cp, char *cp_end, bool explicit_bracketing)

 {
   char *prefix_end;
 
 {
   char *prefix_end;
 

-  prefix_end = find_prefix_end(id, cp, cp_end);
+  prefix_end = find_prefix_end (id, cp, cp_end);

   if (prefix_end &&
       (prefix_end == cp_end ||
   if (prefix_end &&
       (prefix_end == cp_end ||

-       (!exact_mode && is_dot_or_dash(*prefix_end))))
+       (!explicit_bracketing && is_dot_or_dash (*prefix_end))))

     {
     {

-      variant *r = variant_table_grow();
-      r->ind = ind;
+      variant *r = variant_table_grow ();
+      r->symbol_index = symbol_index;

       r->id = id;
       r->id = id;

-      r->loc = loc;
+      r->loc = id_loc;

       r->hidden_by = NULL;
       r->err = 0;
       return r;
       r->hidden_by = NULL;
       r->err = 0;
       return r;


@@ -392,207 +412,279 @@ variant_add(uniqstr id, location loc, long int ind,
     return NULL;
 }
 
     return NULL;
 }
 

+static const char *
+get_at_spec(unsigned symbol_index)
+{
+  static char at_buf[20];
+  if (symbol_index == 0)
+    strcpy (at_buf, "$$");
+  else
+    snprintf (at_buf, sizeof at_buf, "$%u", symbol_index);
+  return at_buf;
+}
+
+static void
+show_sub_messages (const char* cp, bool explicit_bracketing,
+                   int midrule_rhs_index, char dollar_or_at,
+                   bool is_warning, unsigned indent)
+{
+  unsigned i;
+
+  for (i = 0; i < variant_count; ++i)
+    {
+      const variant *var = &variant_table[i];
+      const char *at_spec = get_at_spec (var->symbol_index);
+
+      if (var->err == 0)
+        {
+          if (is_warning)
+            complain_at_indent (var->loc, Wother, &indent,
+                                _("refers to: %c%s at %s"), dollar_or_at,
+                                var->id, at_spec);
+          else
+            complain_at_indent (var->loc, complaint, &indent,
+                                _("refers to: %c%s at %s"), dollar_or_at,
+                                var->id, at_spec);
+        }
+      else
+        {
+          static struct obstack msg_buf;
+          const char *tail = explicit_bracketing ? "" :
+            cp + strlen (var->id);
+          const char *id = var->hidden_by ? var->hidden_by->id :
+            var->id;
+          location id_loc = var->hidden_by ? var->hidden_by->loc :
+            var->loc;
+
+          /* Create the explanation message. */
+          obstack_init (&msg_buf);
+
+          obstack_fgrow1 (&msg_buf, _("possibly meant: %c"), dollar_or_at);
+          if (contains_dot_or_dash (id))
+            obstack_fgrow1 (&msg_buf, "[%s]", id);
+          else
+            obstack_sgrow (&msg_buf, id);
+          obstack_sgrow (&msg_buf, tail);
+
+          if (var->err & VARIANT_HIDDEN)
+            {
+              obstack_fgrow1 (&msg_buf, _(", hiding %c"), dollar_or_at);
+              if (contains_dot_or_dash (var->id))
+                obstack_fgrow1 (&msg_buf, "[%s]", var->id);
+              else
+                obstack_sgrow (&msg_buf, var->id);
+              obstack_sgrow (&msg_buf, tail);
+            }
+
+          obstack_fgrow1 (&msg_buf, _(" at %s"), at_spec);
+
+          if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
+            {
+              const char *format =
+                _(", cannot be accessed from mid-rule action at $%d");
+              obstack_fgrow1 (&msg_buf, format, midrule_rhs_index);
+            }
+
+          obstack_1grow (&msg_buf, '\0');
+          if (is_warning)
+            complain_at_indent (id_loc, Wother, &indent, "%s",
+                                (char *) obstack_finish (&msg_buf));
+          else
+            complain_at_indent (id_loc, complaint, &indent, "%s",
+                                (char *) obstack_finish (&msg_buf));
+          obstack_free (&msg_buf, 0);
+        }
+    }
+}
+
+/* Returned from "parse_ref" when the reference
+   is inappropriate. */

 #define INVALID_REF (INT_MIN)
 #define INVALID_REF (INT_MIN)

+
+/* Returned from "parse_ref" when the reference
+   points to LHS ($$) of the current rule or midrule. */

 #define LHS_REF (INT_MIN + 1)
 
 #define LHS_REF (INT_MIN + 1)
 

+/* Sub-messages indent. */
+#define SUB_INDENT (4)
+
+/* Parse named or positional reference. In case of positional
+   references, can return negative values for $-n "deep" stack
+   accesses. */

 static long int
 static long int

-parse_named_ref(char *cp, symbol_list *rule, int rule_length,
-               int midrule_rhs_index, char *text, location loc,
-               char dollar_or_at)
+parse_ref (char *cp, symbol_list *rule, int rule_length,
+           int midrule_rhs_index, char *text, location text_loc,
+           char dollar_or_at)

 {
   symbol_list *l;
   char *cp_end;
 {
   symbol_list *l;
   char *cp_end;

-  bool exact_mode;
-  bool has_error;
-  bool has_valid;
-  long int ind, i;
-  variant* variant;
-  char* p;
+  bool explicit_bracketing;
+  unsigned i;
+  unsigned valid_variants = 0;
+  unsigned valid_variant_index = 0;

 
   if ('$' == *cp)
     return LHS_REF;
 
 
   if ('$' == *cp)
     return LHS_REF;
 

-  if (is_digit (*cp) || (*cp == '-' && is_digit (* (cp + 1))))
+  if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))

     {
       long int num = strtol (cp, &cp, 10);
       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
     {
       long int num = strtol (cp, &cp, 10);
       if (1 - INT_MAX + rule_length <= num && num <= rule_length)

-       return num;
+        return num;

       else
       else

-       {
-         complain_at (loc, _("integer out of range: %s"), quote (text));
-         return INVALID_REF;
-       }
+        {
+          complain_at (text_loc, complaint, _("integer out of range: %s"),
+                       quote (text));
+          return INVALID_REF;
+        }

     }
 
   if ('[' == *cp)
     {
     }
 
   if ('[' == *cp)
     {

-      exact_mode = true;
-

       /* Ignore the brackets. */
       /* Ignore the brackets. */

-      ++cp;
-      for (p = cp; *p != ']'; ++p);
+      char *p;
+      for (p = ++cp; *p != ']'; ++p)
+        continue;

       cp_end = p;
       cp_end = p;

+
+      explicit_bracketing = true;

     }
   else
     {
     }
   else
     {

-      exact_mode = false;
-

       /* Take all characters of the name. */
       /* Take all characters of the name. */

+      char* p;
+      for (p = cp; *p; ++p)
+        if (is_dot_or_dash (*p))
+          {
+            ref_tail_fields = p;
+            break;
+          }

       for (p = cp; *p; ++p)
       for (p = cp; *p; ++p)

-       if (is_dot_or_dash(*p))
-         {
-           ref_tail_fields = p;
-           break;
-         }
-      for (p = cp; *p; ++p);
+        continue;

       cp_end = p;
       cp_end = p;

+
+      explicit_bracketing = false;

     }
 
   /* Add all relevant variants. */
     }
 
   /* Add all relevant variants. */

-  variant_count = 0;
-  for (ind = 0, l = rule; !symbol_list_null(l); ++ind, l = l->next)
-    {
-      if (l->content_type != SYMLIST_SYMBOL)
-       continue;
-
-      variant = variant_add(l->content.sym->tag, l->sym_loc, ind,
-                           cp, cp_end, exact_mode);
-
-      if (variant && l->named_ref)
-       variant->hidden_by = l->named_ref;
-
-      if (l->named_ref)
-       variant_add(l->named_ref->id, l->named_ref->loc, ind,
-                   cp, cp_end, exact_mode);
-    }
+  {
+    unsigned symbol_index;
+    variant_count = 0;
+    for (symbol_index = 0, l = rule; !symbol_list_null (l);
+         ++symbol_index, l = l->next)
+      {
+        variant *var;
+        if (l->content_type != SYMLIST_SYMBOL)
+          continue;
+
+        var = variant_add (l->content.sym->tag, l->sym_loc,
+                           symbol_index, cp, cp_end, explicit_bracketing);
+        if (var && l->named_ref)
+          var->hidden_by = l->named_ref;
+
+        if (l->named_ref)
+          variant_add (l->named_ref->id, l->named_ref->loc,
+                       symbol_index, cp, cp_end, explicit_bracketing);
+      }
+  }

 
   /* Check errors. */
 
   /* Check errors. */

-  has_error = false;
-  has_valid = false;

   for (i = 0; i < variant_count; ++i)
     {
   for (i = 0; i < variant_count; ++i)
     {

-      variant = &variant_table[i];
-      ind = variant->ind;
+      variant *var = &variant_table[i];
+      unsigned symbol_index = var->symbol_index;

 
       /* Check visibility from mid-rule actions. */
 
       /* Check visibility from mid-rule actions. */

-      if (midrule_rhs_index != 0 &&
-         (ind == 0 || ind > midrule_rhs_index))
-       {
-         variant->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
-         has_error = true;
-       }
+      if (midrule_rhs_index != 0
+          && (symbol_index == 0 || midrule_rhs_index < symbol_index))
+        var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;

 
       /* Check correct bracketing. */
 
       /* Check correct bracketing. */

-      if (!exact_mode && contains_dot_or_dash(variant->id))
-       {
-         variant->err |= VARIANT_BAD_BRACKETING;
-         has_error = true;
-       }
+      if (!explicit_bracketing && contains_dot_or_dash (var->id))
+        var->err |= VARIANT_BAD_BRACKETING;

 
       /* Check using of hidden symbols. */
 
       /* Check using of hidden symbols. */

-      if (variant->hidden_by != NULL)
-       {
-         variant->err |= VARIANT_HIDDEN;
-         has_error = true;
-       }
-
-      if (!variant->err)
-       has_valid = true;
+      if (var->hidden_by)
+        var->err |= VARIANT_HIDDEN;
+
+      if (!var->err)
+        {
+          valid_variant_index = i;
+          ++valid_variants;
+        }

     }
 
     }
 

-  if (variant_count == 1 && has_valid)
+  switch (valid_variants)

     {
     {

-      /* The only "good" case is here. */
-      ind = variant_table[0].ind;
-      if (ind == midrule_rhs_index)
-       return LHS_REF;
-      else
-       return ind;
-    }
-
-  /* Start complaining. */
-
-  if (variant_count == 0)
-    complain_at (loc, _("reference is invalid: %s, symbol not found"),
-                quote (text));
-  else if (variant_count > 1 && !has_error)
-    complain_at (loc, _("reference is ambiguous: %s"),
-                quote (text));
-  else if (variant_count > 1 && has_valid && has_error)
-    complain_at (loc, _("reference is misleading: %s"),
-                quote (text));
-  else
-    complain_at (loc, _("reference is invalid: %s"),
-                quote (text));
-
-  for (i = 0; i < variant_count; ++i)
-    {
-      static char at_buf[20];
-
-      variant = &variant_table[i];
-
-      if (variant->ind == 0)
-       strcpy(at_buf, "$$");
-      else
-       snprintf(at_buf, sizeof(at_buf), "$%d", variant->ind);
-
-      if (variant->err == 0)
-       complain_at (variant->loc, _("  refers to: %c%s at %s"),
-                    dollar_or_at, variant->id, at_buf);
-      else
-       {
-         static struct obstack msg_buf;
-         const char *tail = "";
-         const char *id;
-         location loc;
-
-         if (!exact_mode)
-           tail = cp + strlen(variant->id);
-
-         if (variant->hidden_by)
-           {
-             id = variant->hidden_by->id;
-             loc = variant->hidden_by->loc;
-           }
-         else
-           {
-             id = variant->id;
-             loc = variant->loc;
-           }
-
-         /* Create the explanation message. */
-
-         obstack_init (&msg_buf);
-
-         obstack_fgrow1 (&msg_buf, "  possibly meant: %c", dollar_or_at);
-         if (contains_dot_or_dash (id))
-           obstack_fgrow1 (&msg_buf, "[%s]", id);
-         else
-           obstack_sgrow (&msg_buf, id);
-         obstack_sgrow (&msg_buf, tail);
-
-         if (variant->err & VARIANT_HIDDEN)
-           {
-             obstack_fgrow1 (&msg_buf, ", hiding %c", dollar_or_at);
-             if (contains_dot_or_dash (variant->id))
-               obstack_fgrow1 (&msg_buf, "[%s]", variant->id);
-             else
-               obstack_sgrow (&msg_buf, variant->id);
-             obstack_sgrow (&msg_buf, tail);
-           }
-
-         obstack_fgrow1 (&msg_buf, " at %s", at_buf);
-
-         if (variant->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
-           obstack_fgrow1 (&msg_buf, ", cannot be accessed from "
-                           "mid-rule action at $%d", midrule_rhs_index);
-
-         obstack_1grow (&msg_buf, '\0');
-         complain_at (loc, _("%s"), obstack_finish (&msg_buf));
-         obstack_free (&msg_buf, 0);
-       }
+    case 0:
+      {
+        unsigned len = (explicit_bracketing || !ref_tail_fields) ?
+          cp_end - cp : ref_tail_fields - cp;
+        unsigned indent = 0;
+
+        complain_at_indent (text_loc, complaint, &indent,
+                            _("invalid reference: %s"), quote (text));
+        indent += SUB_INDENT;
+        if (len == 0)
+          {
+            location sym_loc = text_loc;
+            sym_loc.start.column += 1;
+            sym_loc.end = sym_loc.start;
+            const char *format =
+              _("syntax error after '%c', expecting integer, letter,"
+                " '_', '[', or '$'");
+            complain_at_indent (sym_loc, complaint, &indent, format,
+                                dollar_or_at);
+          }
+        else if (midrule_rhs_index)
+          {
+            const char *format =
+              _("symbol not found in production before $%d: %.*s");
+            complain_at_indent (rule->location, complaint, &indent, format,
+                                midrule_rhs_index, len, cp);
+          }
+        else
+          {
+            const char *format =
+              _("symbol not found in production: %.*s");
+            complain_at_indent (rule->location, complaint, &indent, format,
+                                len, cp);
+          }
+
+        if (variant_count > 0)
+          show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
+                             dollar_or_at, false, indent);
+        return INVALID_REF;
+      }
+    case 1:
+      {
+        unsigned indent = 0;
+        if (variant_count > 1)
+          {
+            complain_at_indent (text_loc, Wother, &indent,
+                                _("misleading reference: %s"), quote (text));
+            show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
+                               dollar_or_at, true, indent + SUB_INDENT);
+          }
+        {
+          unsigned symbol_index =
+            variant_table[valid_variant_index].symbol_index;
+          return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
+        }
+      }
+    case 2:
+    default:
+      {
+        unsigned indent = 0;
+        complain_at_indent (text_loc, complaint, &indent,
+                            _("ambiguous reference: %s"), quote (text));
+        show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
+                           dollar_or_at, false, indent + SUB_INDENT);
+        return INVALID_REF;
+      }

     }
 
     }
 

+  /* Not reachable. */

   return INVALID_REF;
 }
 
   return INVALID_REF;
 }
 


@@ -603,7 +695,7 @@ int max_left_semantic_context = 0;
 
 
 /*------------------------------------------------------------------.
 
 
 /*------------------------------------------------------------------.

-| TEXT is pointing to a wannabee semantic value (i.e., a `$').      |
+| TEXT is pointing to a wannabee semantic value (i.e., a '$').      |

 |                                                                   |
 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 |                                                                   |
 |                                                                   |
 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 |                                                                   |


@@ -617,7 +709,8 @@ handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
   char *cp = text + 1;
   char *gt_ptr = 0;
   symbol_list *effective_rule;
   char *cp = text + 1;
   char *gt_ptr = 0;
   symbol_list *effective_rule;

-  int effective_rule_length, n;
+  int effective_rule_length;
+  int n;

 
   if (rule->midrule_parent_rule)
     {
 
   if (rule->midrule_parent_rule)
     {


@@ -635,19 +728,20 @@ handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
     {
       type_name = ++cp;
       while (*cp != '>')
     {
       type_name = ++cp;
       while (*cp != '>')

-       ++cp;
+        ++cp;

 
       /* The '>' symbol will be later replaced by '\0'. Original
 
       /* The '>' symbol will be later replaced by '\0'. Original

-        'text' is needed for error messages. */
+         'text' is needed for error messages. */

       gt_ptr = cp;
       ++cp;
       if (untyped_var_seen)
       gt_ptr = cp;
       ++cp;
       if (untyped_var_seen)

-       complain_at (dollar_loc, _("explicit type given in untyped grammar"));
+        complain_at (dollar_loc, complaint,
+                  _("explicit type given in untyped grammar"));

       tag_seen = true;
     }
 
       tag_seen = true;
     }
 

-  n = parse_named_ref (cp, effective_rule, effective_rule_length,
-                      rule->midrule_parent_rhs_index, text, dollar_loc, '$');
+  n = parse_ref (cp, effective_rule, effective_rule_length,
+                 rule->midrule_parent_rhs_index, text, dollar_loc, '$');

 
   if (gt_ptr)
     *gt_ptr = '\0';
 
   if (gt_ptr)
     *gt_ptr = '\0';


@@ -659,61 +753,63 @@ handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 
     case LHS_REF:
       if (!type_name)
 
     case LHS_REF:
       if (!type_name)

-       type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
+        type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);

 
       if (!type_name)
 
       if (!type_name)

-       {
-         if (union_seen | tag_seen)
-           {
-             if (rule->midrule_parent_rule)
-               complain_at (dollar_loc,
-                            _("$$ for the midrule at $%d of `%s'"
-                              " has no declared type"),
-                            rule->midrule_parent_rhs_index,
-                            effective_rule->content.sym->tag);
-             else
-               complain_at (dollar_loc, _("$$ of `%s' has no declared type"),
-                            rule->content.sym->tag);
-           }
-         else
-           untyped_var_seen = true;
-         type_name = "";
-       }
+        {
+          if (union_seen | tag_seen)
+            {
+              if (rule->midrule_parent_rule)
+                complain_at (dollar_loc, complaint,
+                             _("$$ for the midrule at $%d of %s"
+                               " has no declared type"),
+                             rule->midrule_parent_rhs_index,
+                             quote (effective_rule->content.sym->tag));
+              else
+                complain_at (dollar_loc, complaint,
+                             _("$$ of %s has no declared type"),
+                             quote (rule->content.sym->tag));
+            }
+          else
+            untyped_var_seen = true;
+          type_name = "";
+        }

 
       obstack_fgrow1 (&obstack_for_string,
 
       obstack_fgrow1 (&obstack_for_string,

-                     "]b4_lhs_value([%s])[", type_name);
+                      "]b4_lhs_value([%s])[", type_name);

       rule->action_props.is_value_used = true;
       break;
 
     default:
       if (max_left_semantic_context < 1 - n)
       rule->action_props.is_value_used = true;
       break;
 
     default:
       if (max_left_semantic_context < 1 - n)

-       max_left_semantic_context = 1 - n;
+        max_left_semantic_context = 1 - n;

       if (!type_name && 0 < n)
       if (!type_name && 0 < n)

-       type_name =
-         symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
+        type_name =
+          symbol_list_n_type_name_get (effective_rule, dollar_loc, n);

       if (!type_name)
       if (!type_name)

-       {
-         if (union_seen | tag_seen)
-           complain_at (dollar_loc, _("$%s of `%s' has no declared type"),
-                        cp, effective_rule->content.sym->tag);
-         else
-           untyped_var_seen = true;
-         type_name = "";
-       }
+        {
+          if (union_seen | tag_seen)
+            complain_at (dollar_loc, complaint,
+                         _("$%s of %s has no declared type"), cp,
+                         quote (effective_rule->content.sym->tag));
+          else
+            untyped_var_seen = true;
+          type_name = "";
+        }

 
       obstack_fgrow3 (&obstack_for_string,
 
       obstack_fgrow3 (&obstack_for_string,

-                     "]b4_rhs_value(%d, %d, [%s])[",
-                     effective_rule_length, n, type_name);
+                      "]b4_rhs_value(%d, %d, [%s])[",
+                      effective_rule_length, n, type_name);

       if (n > 0)
       if (n > 0)

-       symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
-         true;
+        symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
+          true;

       break;
     }
 }
 
 
 /*------------------------------------------------------.
       break;
     }
 }
 
 
 /*------------------------------------------------------.

-| TEXT is a location token (i.e., a `@...').  Output to |
+| TEXT is a location token (i.e., a '@...').  Output to |

 | OBSTACK_FOR_STRING a reference to this location.      |
 `------------------------------------------------------*/
 
 | OBSTACK_FOR_STRING a reference to this location.      |
 `------------------------------------------------------*/
 


@@ -722,7 +818,8 @@ handle_action_at (symbol_list *rule, char *text, location at_loc)
 {
   char *cp = text + 1;
   symbol_list *effective_rule;
 {
   char *cp = text + 1;
   symbol_list *effective_rule;

-  int effective_rule_length, n;
+  int effective_rule_length;
+  int n;

 
   if (rule->midrule_parent_rule)
     {
 
   if (rule->midrule_parent_rule)
     {


@@ -737,8 +834,8 @@ handle_action_at (symbol_list *rule, char *text, location at_loc)
 
   muscle_percent_define_ensure("locations", at_loc, true);
 
 
   muscle_percent_define_ensure("locations", at_loc, true);
 

-  n = parse_named_ref (cp, effective_rule, effective_rule_length,
-                      rule->midrule_parent_rhs_index, text, at_loc, '@');
+  n = parse_ref (cp, effective_rule, effective_rule_length,
+                       rule->midrule_parent_rhs_index, text, at_loc, '@');

   switch (n)
     {
     case INVALID_REF:
   switch (n)
     {
     case INVALID_REF:


@@ -750,7 +847,7 @@ handle_action_at (symbol_list *rule, char *text, location at_loc)
 
     default:
       obstack_fgrow2 (&obstack_for_string, "]b4_rhs_location(%d, %d)[",
 
     default:
       obstack_fgrow2 (&obstack_for_string, "]b4_rhs_location(%d, %d)[",

-                     effective_rule_length, n);
+                      effective_rule_length, n);

       break;
     }
 }
       break;
     }
 }


@@ -796,39 +893,37 @@ code_props_none_init (code_props *self)
 code_props const code_props_none = CODE_PROPS_NONE_INIT;
 
 void
 code_props const code_props_none = CODE_PROPS_NONE_INIT;
 
 void

-code_props_plain_init (code_props *self, char const *code, location code_loc)
+code_props_plain_init (code_props *self, char const *code,
+                       location code_loc)

 {
 {

+  code_props_none_init (self);

   self->kind = CODE_PROPS_PLAIN;
   self->code = code;
   self->location = code_loc;
   self->kind = CODE_PROPS_PLAIN;
   self->code = code;
   self->location = code_loc;

-  self->is_value_used = false;
-  self->rule = NULL;
-  self->named_ref = NULL;

 }
 
 void
 code_props_symbol_action_init (code_props *self, char const *code,
                                location code_loc)
 {
 }
 
 void
 code_props_symbol_action_init (code_props *self, char const *code,
                                location code_loc)
 {

+  code_props_none_init (self);

   self->kind = CODE_PROPS_SYMBOL_ACTION;
   self->code = code;
   self->location = code_loc;
   self->kind = CODE_PROPS_SYMBOL_ACTION;
   self->code = code;
   self->location = code_loc;

-  self->is_value_used = false;
-  self->rule = NULL;
-  self->named_ref = NULL;

 }
 
 void
 code_props_rule_action_init (code_props *self, char const *code,
                              location code_loc, symbol_list *rule,
 }
 
 void
 code_props_rule_action_init (code_props *self, char const *code,
                              location code_loc, symbol_list *rule,

-                            named_ref *named_ref)
+                             named_ref *name, bool is_predicate)

 {
 {

+  code_props_none_init (self);

   self->kind = CODE_PROPS_RULE_ACTION;
   self->code = code;
   self->location = code_loc;
   self->kind = CODE_PROPS_RULE_ACTION;
   self->code = code;
   self->location = code_loc;

-  self->is_value_used = false;

   self->rule = rule;
   self->rule = rule;

-  self->named_ref = named_ref;
+  self->named_ref = name;
+  self->is_predicate = is_predicate;

 }
 
 void
 }
 
 void


@@ -860,6 +955,8 @@ void
 code_scanner_free (void)
 {
   obstack_free (&obstack_for_string, 0);
 code_scanner_free (void)
 {
   obstack_free (&obstack_for_string, 0);

+  variant_table_free ();
+

   /* Reclaim Flex's buffers.  */
   yylex_destroy ();
 }
   /* Reclaim Flex's buffers.  */
   yylex_destroy ();
 }