Whether the default %destructor/%printer applies to a particular symbol

[bison.git] / tests / actions.at

# Executing Actions.                               -*- Autotest -*-
# Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.

AT_BANNER([[User Actions.]])

## ------------------ ##
## Mid-rule actions.  ##
## ------------------ ##

AT_SETUP([Mid-rule actions])

# Bison once forgot the mid-rule actions.  It was because the action
# was attached to the host rule (the one with the mid-rule action),
# instead of being attached to the empty rule dedicated to this
# action.

AT_DATA_GRAMMAR([[input.y]],
[[%error-verbose
%debug
%{
# include <stdio.h>
# include <stdlib.h>
  static void yyerror (const char *msg);
  static int yylex (void);
%}
%%
exp:     { putchar ('0'); }
     '1' { putchar ('1'); }
     '2' { putchar ('2'); }
     '3' { putchar ('3'); }
     '4' { putchar ('4'); }
     '5' { putchar ('5'); }
     '6' { putchar ('6'); }
     '7' { putchar ('7'); }
     '8' { putchar ('8'); }
     '9' { putchar ('9'); }
         { putchar ('\n'); }
   ;
%%
static int
yylex (void)
{
  static const char *input = "123456789";
  return *input++;
}

static void
yyerror (const char *msg)
{
  fprintf (stderr, "%s\n", msg);
}

int
main (void)
{
  return yyparse ();
}
]])

AT_CHECK([bison -d -v -o input.c input.y])
AT_COMPILE([input])
AT_PARSER_CHECK([./input], 0,
[[0123456789
]])

AT_CLEANUP





## ---------------- ##
## Exotic Dollars.  ##
## ---------------- ##

AT_SETUP([Exotic Dollars])

AT_DATA_GRAMMAR([[input.y]],
[[%error-verbose
%debug
%{
# include <stdio.h>
# include <stdlib.h>
  static void yyerror (const char *msg);
  static int yylex (void);
# define USE(Var)
%}

%union
{
  int val;
};

%type <val> a_1 a_2 a_5
            sum_of_the_five_previous_values

%%
exp: a_1 a_2 { $<val>$ = 3; } { $<val>$ = $<val>3 + 1; } a_5
     sum_of_the_five_previous_values
    {
       USE (($1, $2, $<foo>3, $<foo>4, $5));
       printf ("%d\n", $6);
    }
;
a_1: { $$ = 1; };
a_2: { $$ = 2; };
a_5: { $$ = 5; };

sum_of_the_five_previous_values:
    {
       $$ = $<val>0 + $<val>-1 + $<val>-2 + $<val>-3 + $<val>-4;
    }
;

%%
static int
yylex (void)
{
  return EOF;
}

static void
yyerror (const char *msg)
{
  fprintf (stderr, "%s\n", msg);
}

int
main (void)
{
  return yyparse ();
}
]])

AT_CHECK([bison -d -v -o input.c input.y], 0)
AT_COMPILE([input])
AT_PARSER_CHECK([./input], 0,
[[15
]])

AT_CLEANUP



## -------------------------- ##
## Printers and Destructors.  ##
## -------------------------- ##

# _AT_CHECK_PRINTER_AND_DESTRUCTOR($1, $2, $3, $4, BISON-DIRECTIVE, UNION-FLAG)
# -----------------------------------------------------------------------------
m4_define([_AT_CHECK_PRINTER_AND_DESTRUCTOR],
[# Make sure complex $n work.
m4_if([$1$2$3], $[1]$[2]$[3], [],
       [m4_fatal([$0: Invalid arguments: $@])])dnl

# Be sure to pass all the %directives to this macro to have correct
# helping macros.  So don't put any directly in the Bison file.
AT_BISON_OPTION_PUSHDEFS([$5])
AT_DATA_GRAMMAR([[input.y]],
[[%start-header {
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#define YYINITDEPTH 10
#define YYMAXDEPTH 10
]AT_LALR1_CC_IF(
  [#define RANGE(Location) (Location).begin.line, (Location).end.line],
  [#define RANGE(Location) (Location).first_line, (Location).last_line])
[}

$5]
m4_ifval([$6], [%union
{
  int ival;
}])
AT_LALR1_CC_IF([%define "global_tokens_and_yystype"])
m4_ifval([$6], [[%end-header {]], [[%start-header {]])
AT_LALR1_CC_IF([typedef yy::location YYLTYPE;
                m4_ifval([$6], , [#define YYSTYPE int])])
[static int yylex (]AT_LEX_FORMALS[);
]AT_LALR1_CC_IF([], [static void yyerror (const char *msg);])
[}

]m4_ifval([$6], [%type <ival> '(' 'x' 'y' ')' ';' thing line input END])[

/* FIXME: This %printer isn't actually tested.  */
%printer
  {
    ]AT_LALR1_CC_IF([debug_stream () << $$;],
                    [fprintf (yyoutput, "%d", $$)])[;
  }
  input line thing 'x' 'y'

%destructor
  { printf ("Freeing nterm input (%d@%d-%d)\n", $$, RANGE (@$)); }
  input

%destructor
  { printf ("Freeing nterm line (%d@%d-%d)\n", $$, RANGE (@$)); }
  line

%destructor
  { printf ("Freeing nterm thing (%d@%d-%d)\n", $$, RANGE (@$)); }
  thing

%destructor
  { printf ("Freeing token 'x' (%d@%d-%d)\n", $$, RANGE (@$)); }
  'x'

%destructor
  { printf ("Freeing token 'y' (%d@%d-%d)\n", $$, RANGE (@$)); }
  'y'

%token END 0
%destructor
  { printf ("Freeing token END (%d@%d-%d)\n", $$, RANGE (@$)); }
  END

%%
/*
   This grammar is made to exercise error recovery.
   "Lines" starting with `(' support error recovery, with
   ')' as synchronizing token.  Lines starting with 'x' can never
   be recovered from if in error.
*/

input:
  /* Nothing. */
    {
      $$ = 0;
      printf ("input (%d@%d-%d): /* Nothing */\n", $$, RANGE (@$));
    }
| line input /* Right recursive to load the stack so that popping at
		END can	be exercised.  */
    {
      $$ = 2;
      printf ("input (%d@%d-%d): line (%d@%d-%d) input (%d@%d-%d)\n",
	      $$, RANGE (@$), $1, RANGE (@1), $2, RANGE (@2));
    }
;

line:
  thing thing thing ';'
    {
      $$ = $1;
      printf ("line (%d@%d-%d): thing (%d@%d-%d) thing (%d@%d-%d) thing (%d@%d-%d) ';' (%d@%d-%d)\n",
              $$, RANGE (@$), $1, RANGE (@1), $2, RANGE (@2),
              $3, RANGE (@3), $4, RANGE (@4));
    }
| '(' thing thing ')'
    {
      $$ = $1;
      printf ("line (%d@%d-%d): '(' (%d@%d-%d) thing (%d@%d-%d) thing (%d@%d-%d) ')' (%d@%d-%d)\n",
              $$, RANGE (@$), $1, RANGE (@1), $2, RANGE (@2),
              $3, RANGE (@3), $4, RANGE (@4));
    }
| '(' thing ')'
    {
      $$ = $1;
      printf ("line (%d@%d-%d): '(' (%d@%d-%d) thing (%d@%d-%d) ')' (%d@%d-%d)\n",
              $$, RANGE (@$), $1, RANGE (@1), $2, RANGE (@2), $3, RANGE (@3));
    }
| '(' error ')'
    {
      $$ = -1;
      printf ("line (%d@%d-%d): '(' (%d@%d-%d) error (@%d-%d) ')' (%d@%d-%d)\n",
              $$, RANGE (@$), $1, RANGE (@1), RANGE (@2), $3, RANGE (@3));
    }
;

thing:
  'x'
    {
      $$ = $1;
      printf ("thing (%d@%d-%d): 'x' (%d@%d-%d)\n",
              $$, RANGE (@$), $1, RANGE (@1));
    }
;
%%
/* Alias to ARGV[1]. */
const char *source = 0;

static int
yylex (]AT_LEX_FORMALS[)
{
  static unsigned int counter = 0;

  int c = ]AT_VAL[]m4_ifval([$6], [.ival])[ = counter++;
  /* As in BASIC, line numbers go from 10 to 10.  */
]AT_LALR1_CC_IF(
[ AT_LOC.begin.line = AT_LOC.begin.column = 10 * c;
  AT_LOC.end.line = AT_LOC.end.column = AT_LOC.begin.line + 9;
],
[ AT_LOC.first_line = AT_LOC.first_column = 10 * c;
  AT_LOC.last_line = AT_LOC.last_column = AT_LOC.first_line + 9;
])[

  if (source[c])
    printf ("sending: '%c'", source[c]);
  else
    printf ("sending: END");
  printf (" (%d@%d-%d)\n", c, RANGE (]AT_LOC[));
  return source[c];
}

]AT_LALR1_CC_IF(
[/* A C++ error reporting function. */
void
yy::parser::error (const location& l, const std::string& m)
{
  printf ("%d-%d: %s\n", RANGE (l), m.c_str());
}

static bool yydebug;
int
yyparse ()
{
  yy::parser parser;
  parser.set_debug_level (yydebug);
  return parser.parse ();
}
],
[static void
yyerror (const char *msg)
{
  printf ("%d-%d: %s\n", RANGE (yylloc), msg);
}])[

int
main (int argc, const char *argv[])
{
  int status;
  yydebug = !!getenv ("YYDEBUG");
  assert (argc == 2);
  source = argv[1];
  status = yyparse ();
  switch (status)
    {
      case 0: printf ("Successful parse.\n"); break;
      case 1: printf ("Parsing FAILED.\n"); break;
      default: printf ("Parsing FAILED (status %d).\n", status); break;
    }
  return status;
}
]])

AT_LALR1_CC_IF(
  [AT_CHECK([bison -o input.cc input.y])
   AT_COMPILE_CXX([input])],
  [AT_CHECK([bison -o input.c input.y])
   AT_COMPILE([input])])


# Check the location of "empty"
# -----------------------------
# I.e., epsilon-reductions, as in "(x)" which ends by reducing
# an empty "line" nterm.
# FIXME: This location is not satisfying.  Depend on the lookahead?
AT_PARSER_CHECK([./input '(x)'], 0,
[[sending: '(' (0@0-9)
sending: 'x' (1@10-19)
thing (1@10-19): 'x' (1@10-19)
sending: ')' (2@20-29)
line (0@0-29): '(' (0@0-9) thing (1@10-19) ')' (2@20-29)
sending: END (3@30-39)
input (0@29-29): /* Nothing */
input (2@0-29): line (0@0-29) input (0@29-29)
Freeing token END (3@30-39)
Freeing nterm input (2@0-29)
Successful parse.
]])


# Check locations in error recovery
# ---------------------------------
# '(y)' is an error, but can be recovered from.  But what's the location
# of the error itself ('y'), and of the resulting reduction ('(error)').
AT_PARSER_CHECK([./input '(y)'], 0,
[[sending: '(' (0@0-9)
sending: 'y' (1@10-19)
10-19: syntax error, unexpected 'y', expecting 'x'
Freeing token 'y' (1@10-19)
sending: ')' (2@20-29)
line (-1@0-29): '(' (0@0-9) error (@10-19) ')' (2@20-29)
sending: END (3@30-39)
input (0@29-29): /* Nothing */
input (2@0-29): line (-1@0-29) input (0@29-29)
Freeing token END (3@30-39)
Freeing nterm input (2@0-29)
Successful parse.
]])


# Syntax errors caught by the parser
# ----------------------------------
# Exercise the discarding of stack top and input until `error'
# can be reduced.
#
#     '(', 'x', 'x', 'x', 'x', 'x', ')',
#
# Load the stack and provoke an error that cannot be caught by the
# grammar, to check that the stack is cleared.  And make sure the
# lookahead is freed.
#
#     '(', 'x', ')',
#     '(', 'x', ')',
#     'y'
AT_PARSER_CHECK([./input '(xxxxx)(x)(x)y'], 1,
[[sending: '(' (0@0-9)
sending: 'x' (1@10-19)
thing (1@10-19): 'x' (1@10-19)
sending: 'x' (2@20-29)
thing (2@20-29): 'x' (2@20-29)
sending: 'x' (3@30-39)
30-39: syntax error, unexpected 'x', expecting ')'
Freeing nterm thing (2@20-29)
Freeing nterm thing (1@10-19)
Freeing token 'x' (3@30-39)
sending: 'x' (4@40-49)
Freeing token 'x' (4@40-49)
sending: 'x' (5@50-59)
Freeing token 'x' (5@50-59)
sending: ')' (6@60-69)
line (-1@0-69): '(' (0@0-9) error (@10-59) ')' (6@60-69)
sending: '(' (7@70-79)
sending: 'x' (8@80-89)
thing (8@80-89): 'x' (8@80-89)
sending: ')' (9@90-99)
line (7@70-99): '(' (7@70-79) thing (8@80-89) ')' (9@90-99)
sending: '(' (10@100-109)
sending: 'x' (11@110-119)
thing (11@110-119): 'x' (11@110-119)
sending: ')' (12@120-129)
line (10@100-129): '(' (10@100-109) thing (11@110-119) ')' (12@120-129)
sending: 'y' (13@130-139)
input (0@129-129): /* Nothing */
input (2@100-129): line (10@100-129) input (0@129-129)
input (2@70-129): line (7@70-99) input (2@100-129)
input (2@0-129): line (-1@0-69) input (2@70-129)
130-139: syntax error, unexpected 'y', expecting END
Freeing nterm input (2@0-129)
Freeing token 'y' (13@130-139)
Parsing FAILED.
]])


# Syntax error caught by the parser where lookahead = END
# --------------------------------------------------------
# Load the stack and provoke an error that cannot be caught by the
# grammar, to check that the stack is cleared.  And make sure the
# lookahead is freed.
#
#     '(', 'x', ')',
#     '(', 'x', ')',
#     'x'
AT_PARSER_CHECK([./input '(x)(x)x'], 1,
[[sending: '(' (0@0-9)
sending: 'x' (1@10-19)
thing (1@10-19): 'x' (1@10-19)
sending: ')' (2@20-29)
line (0@0-29): '(' (0@0-9) thing (1@10-19) ')' (2@20-29)
sending: '(' (3@30-39)
sending: 'x' (4@40-49)
thing (4@40-49): 'x' (4@40-49)
sending: ')' (5@50-59)
line (3@30-59): '(' (3@30-39) thing (4@40-49) ')' (5@50-59)
sending: 'x' (6@60-69)
thing (6@60-69): 'x' (6@60-69)
sending: END (7@70-79)
70-79: syntax error, unexpected END, expecting 'x'
Freeing nterm thing (6@60-69)
Freeing nterm line (3@30-59)
Freeing nterm line (0@0-29)
Freeing token END (7@70-79)
Parsing FAILED.
]])


# Check destruction upon stack overflow
# -------------------------------------
# Upon stack overflow, all symbols on the stack should be destroyed.
# Only check for yacc.c.
AT_YACC_IF([
AT_PARSER_CHECK([./input '(x)(x)(x)(x)(x)(x)(x)'], 2,
[[sending: '(' (0@0-9)
sending: 'x' (1@10-19)
thing (1@10-19): 'x' (1@10-19)
sending: ')' (2@20-29)
line (0@0-29): '(' (0@0-9) thing (1@10-19) ')' (2@20-29)
sending: '(' (3@30-39)
sending: 'x' (4@40-49)
thing (4@40-49): 'x' (4@40-49)
sending: ')' (5@50-59)
line (3@30-59): '(' (3@30-39) thing (4@40-49) ')' (5@50-59)
sending: '(' (6@60-69)
sending: 'x' (7@70-79)
thing (7@70-79): 'x' (7@70-79)
sending: ')' (8@80-89)
line (6@60-89): '(' (6@60-69) thing (7@70-79) ')' (8@80-89)
sending: '(' (9@90-99)
sending: 'x' (10@100-109)
thing (10@100-109): 'x' (10@100-109)
sending: ')' (11@110-119)
line (9@90-119): '(' (9@90-99) thing (10@100-109) ')' (11@110-119)
sending: '(' (12@120-129)
sending: 'x' (13@130-139)
thing (13@130-139): 'x' (13@130-139)
sending: ')' (14@140-149)
line (12@120-149): '(' (12@120-129) thing (13@130-139) ')' (14@140-149)
sending: '(' (15@150-159)
sending: 'x' (16@160-169)
thing (16@160-169): 'x' (16@160-169)
sending: ')' (17@170-179)
line (15@150-179): '(' (15@150-159) thing (16@160-169) ')' (17@170-179)
sending: '(' (18@180-189)
sending: 'x' (19@190-199)
thing (19@190-199): 'x' (19@190-199)
sending: ')' (20@200-209)
200-209: memory exhausted
Freeing nterm thing (19@190-199)
Freeing nterm line (15@150-179)
Freeing nterm line (12@120-149)
Freeing nterm line (9@90-119)
Freeing nterm line (6@60-89)
Freeing nterm line (3@30-59)
Freeing nterm line (0@0-29)
Parsing FAILED (status 2).
]])
])

])


# AT_CHECK_PRINTER_AND_DESTRUCTOR([BISON-OPTIONS], [UNION-FLAG], [SKIP_FLAG])
# ---------------------------------------------------------------------------
m4_define([AT_CHECK_PRINTER_AND_DESTRUCTOR],
[AT_SETUP([Printers and Destructors $2: $1])

$3
_AT_CHECK_PRINTER_AND_DESTRUCTOR($[1], $[2], $[3], $[4],
[%error-verbose
%debug
%verbose
%locations
$1], [$2])

AT_CLEANUP
])


AT_CHECK_PRINTER_AND_DESTRUCTOR([])
AT_CHECK_PRINTER_AND_DESTRUCTOR([], [with union])

# These tests currently fail on a Debian GNU/Linux 3.0r2 x86 host,
# but the 2nd test succeeds on a Solaris 9 sparc hosts (Forte 7 cc).
# Skip them until we figure out what the problem is.
AT_CHECK_PRINTER_AND_DESTRUCTOR([%defines %skeleton "lalr1.cc"])
AT_CHECK_PRINTER_AND_DESTRUCTOR([%defines %skeleton "lalr1.cc"], [with union])

AT_CHECK_PRINTER_AND_DESTRUCTOR([%glr-parser])
AT_CHECK_PRINTER_AND_DESTRUCTOR([%glr-parser], [with union])



## --------------------------------- ##
## Default %printer and %destructor. ##
## --------------------------------- ##

# Check that the right %printer and %destructor are called, that they're not
# called for $end, and that $$ and @$ work correctly.

AT_SETUP([Default %printer and %destructor])

AT_DATA_GRAMMAR([[input.y]],
[[%error-verbose
%debug
%locations
%initial-action {
  @$.first_line = @$.last_line = 1;
  @$.first_column = @$.last_column = 1;
}

%{
# include <stdio.h>
# include <stdlib.h>
  static void yyerror (const char *msg);
  static int yylex (void);
# define USE(SYM)
%}

%printer {
  fprintf (yyoutput, "Default printer for '%c' @ %d", $$, @$.first_column);
}
%destructor {
  fprintf (stdout, "Default destructor for '%c' @ %d.\n", $$, @$.first_column);
}

%printer {
  fprintf (yyoutput, "'b'/'c' printer for '%c' @ %d", $$, @$.first_column);
} 'b' 'c'
%destructor {
  fprintf (stdout, "'b'/'c' destructor for '%c' @ %d.\n", $$, @$.first_column);
} 'b' 'c'

%%

start: 'a' 'b' 'c' 'd' 'e' { $$ = 'S'; USE(($1, $2, $3, $4, $5)); } ;

%%

static int
yylex (void)
{
  static const char *input = "abcd";
  static int column = 1;
  yylval = *input++;
  yylloc.first_line = yylloc.last_line = 1;
  yylloc.first_column = yylloc.last_column = column++;
  return yylval;
}

static void
yyerror (const char *msg)
{
  fprintf (stderr, "%s\n", msg);
}

int
main (void)
{
  yydebug = 1;
  return yyparse ();
}
]])

AT_CHECK([bison -o input.c input.y])
AT_COMPILE([input])
AT_PARSER_CHECK([./input], 1,
[[Default destructor for 'd' @ 4.
'b'/'c' destructor for 'c' @ 3.
'b'/'c' destructor for 'b' @ 2.
Default destructor for 'a' @ 1.
]],
[[Starting parse
Entering state 0
Reading a token: Next token is token 'a' (1.1-1.1: Default printer for 'a' @ 1)
Shifting token 'a' (1.1-1.1: Default printer for 'a' @ 1)
Entering state 1
Reading a token: Next token is token 'b' (1.2-1.2: 'b'/'c' printer for 'b' @ 2)
Shifting token 'b' (1.2-1.2: 'b'/'c' printer for 'b' @ 2)
Entering state 3
Reading a token: Next token is token 'c' (1.3-1.3: 'b'/'c' printer for 'c' @ 3)
Shifting token 'c' (1.3-1.3: 'b'/'c' printer for 'c' @ 3)
Entering state 5
Reading a token: Next token is token 'd' (1.4-1.4: Default printer for 'd' @ 4)
Shifting token 'd' (1.4-1.4: Default printer for 'd' @ 4)
Entering state 6
Reading a token: Now at end of input.
syntax error, unexpected $end, expecting 'e'
Error: popping token 'd' (1.4-1.4: Default printer for 'd' @ 4)
Stack now 0 1 3 5
Error: popping token 'c' (1.3-1.3: 'b'/'c' printer for 'c' @ 3)
Stack now 0 1 3
Error: popping token 'b' (1.2-1.2: 'b'/'c' printer for 'b' @ 2)
Stack now 0 1
Error: popping token 'a' (1.1-1.1: Default printer for 'a' @ 1)
Stack now 0
Cleanup: discarding lookahead token $end (1.5-1.5: )
Stack now 0
]])

AT_CLEANUP



## ------------------------------------------------------------- ##
## Default %printer and %destructor for user-defined end token. ##
## ------------------------------------------------------------- ##

AT_SETUP([Default %printer and %destructor for user-defined end token])

AT_DATA_GRAMMAR([[input.y]],
[[%error-verbose
%debug
%locations
%initial-action {
  @$.first_line = @$.last_line = 1;
  @$.first_column = @$.last_column = 1;
}

%{
# include <stdio.h>
# include <stdlib.h>
  static void yyerror (const char *msg);
  static int yylex (void);
# define USE(SYM)
%}

%token END 0
%printer {
  fprintf (yyoutput, "Default printer for '%c' @ %d", $$, @$.first_column);
}
%destructor {
  fprintf (stdout, "Default destructor for '%c' @ %d.\n", $$, @$.first_column);
}

%%

start: { $$ = 'S'; } ;

%%

static int
yylex (void)
{
  yylval = 'E';
  yylloc.first_line = yylloc.last_line = 1;
  yylloc.first_column = yylloc.last_column = 1;
  return 0;
}

static void
yyerror (const char *msg)
{
  fprintf (stderr, "%s\n", msg);
}

int
main (void)
{
  yydebug = 1;
  return yyparse ();
}
]])

AT_CHECK([bison -o input.c input.y])
AT_COMPILE([input])
AT_PARSER_CHECK([./input], 0,
[[Default destructor for 'E' @ 1.
Default destructor for 'S' @ 1.
]],
[[Starting parse
Entering state 0
Reducing stack by rule 1 (line 37):
-> $$ = nterm start (1.1-1.1: Default printer for 'S' @ 1)
Stack now 0
Entering state 1
Reading a token: Now at end of input.
Shifting token END (1.1-1.1: Default printer for 'E' @ 1)
Entering state 2
Stack now 0 1 2
Cleanup: popping token END (1.1-1.1: Default printer for 'E' @ 1)
Cleanup: popping nterm start (1.1-1.1: Default printer for 'S' @ 1)
]])

AT_CLEANUP



## ------------------------------------------------------------------ ##
## Default %printer and %destructor are not for error or $undefined.  ##
## ------------------------------------------------------------------ ##

AT_SETUP([Default %printer and %destructor are not for error or \$undefined])

# If Bison were to apply the default %printer and %destructor to the error
# token or to $undefined:
#   - For the error token:
#     - It would generate warnings for unused $n.
#     - It would invoke the %printer and %destructor on the error token's
#       semantic value, which would be initialized from the lookahead, which
#       would be destroyed separately.
#   - For $undefined, who knows what the semantic value would be.

AT_DATA_GRAMMAR([[input.y]],
[[%debug

%{
# include <stdio.h>
  static void yyerror (const char *msg);
  static int yylex (void);
# define USE(SYM)
%}

%printer {
  fprintf (yyoutput, "'%c'", $$);
}
%destructor {
  fprintf (stderr, "DESTROY '%c'\n", $$);
}

%%

start:
  { $$ = 'S'; }
  /* In order to reveal the problems that this bug caused during parsing, add
   * $2 to USE.  */
  | 'a' error 'b' 'c' { USE(($1, $3, $4)); $$ = 'S'; }
  ;

%%

static int
yylex (void)
{
  static const char *input = "abd";
  yylval = *input++;
  return yylval;
}

static void
yyerror (const char *msg)
{
  fprintf (stderr, "%s\n", msg);
}

int
main (void)
{
  yydebug = 1;
  return yyparse ();
}
]])

AT_CHECK([bison -o input.c input.y])
AT_COMPILE([input])
AT_PARSER_CHECK([./input], [1], [],
[[Starting parse
Entering state 0
Reading a token: Next token is token 'a' ('a')
Shifting token 'a' ('a')
Entering state 1
Reading a token: Next token is token 'b' ('b')
syntax error
Shifting token error ()
Entering state 3
Next token is token 'b' ('b')
Shifting token 'b' ('b')
Entering state 5
Reading a token: Next token is token $undefined ()
Error: popping token 'b' ('b')
DESTROY 'b'
Stack now 0 1 3
Error: popping token error ()
Stack now 0 1
Shifting token error ()
Entering state 3
Next token is token $undefined ()
Error: discarding token $undefined ()
Error: popping token error ()
Stack now 0 1
Shifting token error ()
Entering state 3
Reading a token: Now at end of input.
Cleanup: discarding lookahead token $end ()
Stack now 0 1 3
Cleanup: popping token error ()
Cleanup: popping token 'a' ('a')
DESTROY 'a'
]])

AT_CLEANUP



## ------------------------------------------------------ ##
## Default %printer and %destructor are not for $accept.  ##
## ------------------------------------------------------ ##

AT_SETUP([Default %printer and %destructor are not for \$accept])

# If YYSTYPE is a union and Bison were to apply the default %printer and
# %destructor to $accept:
#   - The %printer and %destructor code generated for $accept would always be
#     dead code because $accept is currently never shifted onto the stack.
#   - $$ for $accept would always be of type YYSTYPE because it's not possible
#     to declare `%type <field> $accept'.  (Also true for $undefined.)
#   - Thus, the compiler might complain that the user code assumes the wrong
#     type for $$ since the code might assume the type associated with a
#     specific union field, which is especially reasonable in C++ since that
#     type may be a base type.  This test case checks for this problem.  (Also
#     true for $undefined and the error token, so there are three warnings for
#     %printer and three for %destructor.)

AT_DATA_GRAMMAR([[input.y]],
[[%debug /* So that %printer is actually compiled.  */

%{
# include <stdio.h>
  static void yyerror (const char *msg);
  static int yylex (void);
# define USE(SYM)
%}

%printer {
  char chr = $$;
  fprintf (yyoutput, "'%c'", chr);
}
%destructor {
  char chr = $$;
  fprintf (stderr, "DESTROY '%c'\n", chr);
}

%union { char chr; }
%type <chr> start

%%

start: { USE($$); } ;

%%

static int
yylex (void)
{
  return 0;
}

static void
yyerror (const char *msg)
{
  fprintf (stderr, "%s\n", msg);
}

int
main (void)
{
  return yyparse ();
}
]])

AT_CHECK([bison -o input.c input.y])
AT_COMPILE([input])

AT_CLEANUP