* data/glr.c (yytnamerr): New function.

(yyreportSyntaxError): Use it to dequote most string literals.
* data/lalr1.c (yytname_): Renamed from yyname_, for compatibility
with other skeletons.  All uses changed.
(yytnameerr_): New function.
(yyreport_syntax_error): Use it to dequote most string literals.
* data/yacc.c (yytnamerr): New function.
(yyerrlab): Use it to decode most string literals.
* doc/bison.texinfo (Decl Summary, Calling Convention):
Clarify quoting convention of yytname.
* src/output.c (prepare_symbols): Quote all names.  This undoes
the 2005-04-17 change, which is now accomplished (mostly) via
changes in the parsers as described above.
* tests/regression.at (Token definitions, Web2c Actions):
Undo most 2005-04-17 change here, too.

data/glr.c

@@ -332,7 +332,7 @@ static const ]b4_int_type_for([b4_rline])[ yyrline[] =
 #endif
 
 #if (YYDEBUG) || YYERROR_VERBOSE
-/* YYTNME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
+/* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
    First, the terminals, then, starting at YYNTOKENS, nonterminals. */
 static const char *const yytname[] =
 {
@@ -600,6 +600,54 @@ yystpcpy (char *yydest, const char *yysrc)
 #  endif
 # endif
 
+# ifndef yytnamerr
+/* Copy to YYRES the contents of YYSTR after stripping away unnecessary
+   quotes and backslashes, so that it's suitable for yyerror.  The
+   heuristic is that double-quoting is unnecessary unless the string
+   contains an apostrophe, a comma, or backslash (other than
+   backslash-backslash).  YYSTR is taken from yytname.  If YYRES is
+   null, do not copy; instead, return the length of what the result
+   would have been.  */
+static size_t
+yytnamerr (char *yyres, const char *yystr)
+{
+  if (*yystr == '"')
+    {
+      size_t yyn = 0;
+      char const *yyp = yystr;
+
+      for (;;)
+	switch (*++yyp)
+	  {
+	  case '\'':
+	  case ',':
+	    goto do_not_strip_quotes;
+
+	  case '\\':
+	    if (*++yyp != '\\')
+	      goto do_not_strip_quotes;
+	    /* Fall through.  */
+	  default:
+	    if (yyres)
+	      yyres[yyn] = *yyp;
+	    yyn++;
+	    break;
+
+	  case '"':
+	    if (yyres)
+	      yyres[yyn] = '\0';
+	    return yyn;
+	  }
+    do_not_strip_quotes: ;
+    }
+
+  if (! yyres)
+    return strlen (yystr);
+
+  return yystpcpy (yyres, yystr) - yyres;
+}
+# endif
+
 #endif /* !YYERROR_VERBOSE */
 
 /** State numbers, as in LALR(1) machine */
@@ -1736,7 +1784,7 @@ yyreportSyntaxError (yyGLRStack* yystack,
       yyn = yypact[yystack->yytops.yystates[0]->yylrState];
       if (YYPACT_NINF < yyn && yyn < YYLAST)
 	{
-	  size_t yysize0 = strlen (yytokenName (*yytokenp));
+	  size_t yysize0 = yytnamerr (NULL, yytokenName (*yytokenp));
 	  size_t yysize = yysize0;
 	  size_t yysize1;
 	  yybool yysize_overflow = yyfalse;
@@ -1778,7 +1826,7 @@ yyreportSyntaxError (yyGLRStack* yystack,
 		    break;
 		  }
 		yyarg[yycount++] = yytokenName (yyx);
-		yysize1 = yysize + strlen (yytokenName (yyx));
+		yysize1 = yysize + yytnamerr (NULL, yytokenName (yyx));
 		yysize_overflow |= yysize1 < yysize;
 		yysize = yysize1;
 		yyfmt = yystpcpy (yyfmt, yyprefix);
@@ -1801,7 +1849,7 @@ yyreportSyntaxError (yyGLRStack* yystack,
 		{
 		  if (*yyp == '%' && yyf[1] == 's' && yyi < yycount)
 		    {
-		      yyp = yystpcpy (yyp, yyarg[yyi++]);
+		      yyp += yytnamerr (yyp, yyarg[yyi++]);
 		      yyf += 2;
 		    }
 		  else

data/lalr1.cc

@@ -323,7 +323,12 @@ namespace yy
 
 #if YYDEBUG || YYERROR_VERBOSE
     /// For a symbol, its name in clear.
-    static const char* const yyname_[];
+    static const char* const yytname_[];
+#endif
+
+#if YYERROR_VERBOSE
+    /// Convert the symbol name \a n to a form suitable for a diagnostic.
+    virtual std::string yytnamerr_ (const char *n);
 #endif
 
 #if YYDEBUG
@@ -471,6 +476,47 @@ do {					\
 #define YYABORT		goto yyabortlab
 #define YYERROR		goto yyerrorlab
 
+#if YYERROR_VERBOSE
+
+/* Return YYSTR after stripping away unnecessary quotes and
+   backslashes, so that it's suitable for yyerror.  The heuristic is
+   that double-quoting is unnecessary unless the string contains an
+   apostrophe, a comma, or backslash (other than backslash-backslash).
+   YYSTR is taken from yytname.  */
+std::string
+yy::]b4_parser_class_name[::yytnamerr_ (const char *yystr)
+{
+  if (*yystr == '"')
+    {
+      std::string yyr = "";
+      char const *yyp = yystr;
+
+      for (;;)
+	switch (*++yyp)
+	  {
+	  case '\'':
+	  case ',':
+	    goto do_not_strip_quotes;
+
+	  case '\\':
+	    if (*++yyp != '\\')
+	      goto do_not_strip_quotes;
+	    /* Fall through.  */
+	  default:
+	    yyr += *yyp;
+	    break;
+
+	  case '"':
+	    return yyr;
+	  }
+    do_not_strip_quotes: ;
+    }
+
+  return yystr;
+}
+
+#endif
+
 #if YYDEBUG
 /*--------------------------------.
 | Print this symbol on YYOUTPUT.  |
@@ -488,7 +534,7 @@ yy::]b4_parser_class_name[::yysymprint_ (int yytype,
   (void) cdebug_;
 
   *yycdebug_ << (yytype < yyntokens_ ? "token" : "nterm")
-	     << ' ' << yyname_[yytype] << " ("
+	     << ' ' << yytname_[yytype] << " ("
              << *yylocationp << ": ";
   switch (yytype)
     {
@@ -880,10 +926,10 @@ yy::]b4_parser_class_name[::yyreport_syntax_error_ ()
 	  // "syntax error, unexpected %s or %s or %s"
 	  // Then, invoke YY_ on this string.
 	  // Finally, use the string as a format to output
-	  // yyname_[yyilooka_], etc.
+	  // yytname_[yyilooka_], etc.
 	  // Until this gets fixed, this message appears in English only.
 	  message = "syntax error, unexpected ";
-	  message += yyname_[yyilooka_];
+	  message += yytnamerr_ (yytname_[yyilooka_]);
           if (count < 5)
             {
               count = 0;
@@ -891,7 +937,7 @@ yy::]b4_parser_class_name[::yyreport_syntax_error_ ()
                 if (yycheck_[x + yyn_] == x && x != yyterror_)
                   {
                     message += (!count++) ? ", expecting " : " or ";
-                    message += yyname_[x];
+		    message += yytnamerr_ (yytname_[x]);
  	          }
             }
 	}
@@ -988,7 +1034,7 @@ yy::]b4_parser_class_name[::yyr2_[] =
 /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
    First, the terminals, then, starting at \a yyntokens_, nonterminals. */
 const char*
-const yy::]b4_parser_class_name[::yyname_[] =
+const yy::]b4_parser_class_name[::yytname_[] =
 {
   ]b4_tname[
 };
@@ -1038,8 +1084,8 @@ yy::]b4_parser_class_name[::yyreduce_print_ (int yyrule)
              << " (line " << yylno << "), ";
   for (]b4_int_type_for([b4_prhs])[ i = yyprhs_[yyn_];
        0 <= yyrhs_[i]; ++i)
-    *yycdebug_ << yyname_[yyrhs_[i]] << ' ';
+    *yycdebug_ << yytname_[yyrhs_[i]] << ' ';
-  *yycdebug_ << "-> " << yyname_[yyr1_[yyn_]] << std::endl;
+  *yycdebug_ << "-> " << yytname_[yyr1_[yyn_]] << std::endl;
 }
 #endif // YYDEBUG
 

data/yacc.c

@@ -416,7 +416,7 @@ static const ]b4_int_type_for([b4_rline])[ yyrline[] =
 #endif
 
 #if YYDEBUG || YYERROR_VERBOSE
-/* YYTNME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
+/* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
    First, the terminals, then, starting at YYNTOKENS, nonterminals. */
 static const char *const yytname[] =
 {
@@ -645,8 +645,8 @@ do {								\
              yyrule - 1, yylno);
   /* Print the symbols being reduced, and their result.  */
   for (yyi = yyprhs[yyrule]; 0 <= yyrhs[yyi]; yyi++)
-    YYFPRINTF (stderr, "%s ", yytname [yyrhs[yyi]]);
+    YYFPRINTF (stderr, "%s ", yytname[yyrhs[yyi]]);
-  YYFPRINTF (stderr, "-> %s\n", yytname [yyr1[yyrule]]);
+  YYFPRINTF (stderr, "-> %s\n", yytname[yyr1[yyrule]]);
 }
 
 # define YY_REDUCE_PRINT(Rule)		\
@@ -735,7 +735,55 @@ yystpcpy (yydest, yysrc)
 #  endif
 # endif
 
-#endif /* !YYERROR_VERBOSE */
+# ifndef yytnamerr
+/* Copy to YYRES the contents of YYSTR after stripping away unnecessary
+   quotes and backslashes, so that it's suitable for yyerror.  The
+   heuristic is that double-quoting is unnecessary unless the string
+   contains an apostrophe, a comma, or backslash (other than
+   backslash-backslash).  YYSTR is taken from yytname.  If YYRES is
+   null, do not copy; instead, return the length of what the result
+   would have been.  */
+static YYSIZE_T
+yytnamerr (char *yyres, const char *yystr)
+{
+  if (*yystr == '"')
+    {
+      size_t yyn = 0;
+      char const *yyp = yystr;
+
+      for (;;)
+	switch (*++yyp)
+	  {
+	  case '\'':
+	  case ',':
+	    goto do_not_strip_quotes;
+
+	  case '\\':
+	    if (*++yyp != '\\')
+	      goto do_not_strip_quotes;
+	    /* Fall through.  */
+	  default:
+	    if (yyres)
+	      yyres[yyn] = *yyp;
+	    yyn++;
+	    break;
+
+	  case '"':
+	    if (yyres)
+	      yyres[yyn] = '\0';
+	    return yyn;
+	  }
+    do_not_strip_quotes: ;
+    }
+
+  if (! yyres)
+    return yystrlen (yystr);
+
+  return yystpcpy (yyres, yystr) - yyres;
+}
+# endif
+
+#endif /* YYERROR_VERBOSE */
 
 
 
@@ -1111,7 +1159,7 @@ yyerrlab:
       if (YYPACT_NINF < yyn && yyn < YYLAST)
 	{
 	  int yytype = YYTRANSLATE (yychar);
-	  YYSIZE_T yysize0 = yystrlen (yytname[yytype]);
+	  YYSIZE_T yysize0 = yytnamerr (0, yytname[yytype]);
 	  YYSIZE_T yysize = yysize0;
 	  YYSIZE_T yysize1;
 	  int yysize_overflow = 0;
@@ -1163,7 +1211,7 @@ yyerrlab:
 		    break;
 		  }
 		yyarg[yycount++] = yytname[yyx];
-		yysize1 = yysize + yystrlen (yytname[yyx]);
+		yysize1 = yysize + yytnamerr (0, yytname[yyx]);
 		yysize_overflow |= yysize1 < yysize;
 		yysize = yysize1;
 		yyfmt = yystpcpy (yyfmt, yyprefix);
@@ -1188,7 +1236,7 @@ yyerrlab:
 		{
 		  if (*yyp == '%' && yyf[1] == 's' && yyi < yycount)
 		    {
-		      yyp = yystpcpy (yyp, yyarg[yyi++]);
+		      yyp += yytnamerr (yyp, yyarg[yyi++]);
 		      yyf += 2;
 		    }
 		  else

doc/bison.texinfo

@@ -4164,15 +4164,14 @@ three elements of @code{yytname} correspond to the predefined tokens
 @code{"error"}, and @code{"$undefined"}; after these come the symbols
 defined in the grammar file.
 
-For single-character literal tokens and literal string tokens, the name
+The name in the table includes all the characters needed to represent
-in the table includes the single-quote or double-quote characters: for
+the token in Bison.  For single-character literals and literal
-example, @code{"'+'"} is a single-character literal and @code{"\"<=\""}
+strings, this includes the surrounding quoting characters and any
-is a literal string token.  All the characters of the literal string
+escape sequences.  For example, the Bison single-character literal
-token appear verbatim in the string found in the table; even
+@code{'+'} corresponds to a three-character name, represented in C as
-double-quote characters are not escaped.  For example, if the token
+@code{"'+'"}; and the Bison two-character literal string @code{"\\/"}
-consists of three characters @samp{*"*}, its string in @code{yytname}
+corresponds to a five-character name, represented in C as
-contains @samp{"*"*"}.  (In C, that would be written as
+@code{"\"\\\\/\""}.
-@code{"\"*\"*\""}).
 
 When you specify @code{%token-table}, Bison also generates macro
 definitions for macros @code{YYNTOKENS}, @code{YYNNTS}, and
@@ -4413,11 +4412,13 @@ the grammar file has no effect on @code{yylex}.
 table.  The index of the token in the table is the token type's code.
 The name of a multicharacter token is recorded in @code{yytname} with a
 double-quote, the token's characters, and another double-quote.  The
-token's characters are not escaped in any way; they appear verbatim in
+token's characters are escaped as necessary to be suitable as input
-the contents of the string in the table.
+to Bison.
 
-Here's code for looking up a token in @code{yytname}, assuming that the
+Here's code for looking up a multicharacter token in @code{yytname},
-characters of the token are stored in @code{token_buffer}.
+assuming that the characters of the token are stored in
+@code{token_buffer}, and assuming that the token does not contain any
+characters like @samp{"} that require escaping.
 
 @smallexample
 for (i = 0; i < YYNTOKENS; i++)

src/output.c

@@ -60,7 +60,7 @@ bool error_verbose = false;
 #define GENERATE_MUSCLE_INSERT_TABLE(Name, Type)			\
 									\
 static void								\
-Name (const char *name,							\
+Name (char const *name,							\
       Type *table_data,							\
       Type first,							\
       int begin,							\
@@ -162,10 +162,7 @@ prepare_symbols (void)
     int j = 2;
     for (i = 0; i < nsyms; i++)
       {
-	char const *tag = symbols[i]->tag;
+	char const *cp = quotearg_style (c_quoting_style, symbols[i]->tag);
-	char const *cp = (*tag == '"'
-			  ? tag
-			  : quotearg_style (c_quoting_style, tag));
 	/* Width of the next token, including the two quotes, the
 	   comma and the space.  */
 	int width = strlen (cp) + 2;

tests/regression.at

@@ -324,9 +324,9 @@ int yylex (void);
 %token B_TOKEN "b"
 %token C_TOKEN 'c'
 %token 'd' D_TOKEN
-%token SPECIAL "\\\'\?\"\n\t??!"
+%token SPECIAL "\\\'\?\"\a\b\f\n\r\t\v\001\377\x001\x0000ff??!"
 %%
-exp: "a" "\\\'\?\"\n\t??!";
+exp: "a" "\\\'\?\"\a\b\f\n\r\t\v\001\377\x001\x0000ff??!";
 %%
 void
 yyerror (char const *s)
@@ -350,8 +350,7 @@ main (void)
 AT_CHECK([bison -o input.c input.y])
 AT_COMPILE([input])
 AT_PARSER_CHECK([./input], 1, [],
-[syntax error, unexpected \'?"
+[syntax error, unexpected "\\'?\"\a\b\f\n\r\t\v\001\377\001\377?\?!", expecting a
-	??!, expecting a
 ])
 AT_CLEANUP
 
@@ -635,8 +634,8 @@ static const unsigned char yyrline[] =
 };
 static const char *const yytname[] =
 {
-  "$end", "error", "$undefined", "if", "const", "then", "else", "$accept",
+  "$end", "error", "$undefined", "\"if\"", "\"const\"", "\"then\"",
-  "statement", "struct_stat", "if", "else", 0
+  "\"else\"", "$accept", "statement", "struct_stat", "if", "else", 0
 };
 static const unsigned short int yytoknum[] =
 {