* src/reduce.c (reduce_grammar): When the language is empty,

[bison.git] / tests / conflicts.at

# Exercising Bison on conflicts.                         -*- Autotest -*-
# Copyright (C) 2002 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., 59 Temple Place - Suite 330, Boston, MA
# 02111-1307, USA.

AT_BANNER([[Conflicts.]])


## ---------------- ##
## S/R in initial.  ##
## ---------------- ##

# I once hacked Bison in such a way that it lost its reductions on the
# initial state (because it was confusing it with the last state).  It
# took me a while to strip down my failures to this simple case.  So
# make sure it finds the s/r conflict below.

AT_SETUP([S/R in initial])

AT_DATA([[input.y]],
[[%expect 1
%%
exp: e 'e';
e: 'e' | /* Nothing. */;
]])

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

AT_CLEANUP


## ------------------- ##
## %nonassoc and eof.  ##
## ------------------- ##

AT_SETUP([%nonassoc and eof])

AT_DATA([input.y],
[[
%{
#include <config.h>
/* We don't need a perfect malloc for these tests. */
#undef malloc
#include <stdio.h>

#if STDC_HEADERS
# include <stdlib.h>
#endif

#define YYERROR_VERBOSE 1
static void
yyerror (const char *msg)
{
  fprintf (stderr, "%s\n", msg);
  exit (1);
}

/* The current argument. */
static const char *input = NULL;

static int
yylex (void)
{
  /* No token stands for end of file. */
  if (input && *input)
    return *input++;
  else
    return 0;
}

%}

%nonassoc '<' '>'

%%
expr: expr '<' expr
    | expr '>' expr
    | '0'
    ;
%%
int
main (int argc, const char *argv[])
{
  if (argc > 1)
    input = argv[1];
  return yyparse ();
}
]])

# Specify the output files to avoid problems on different file systems.
AT_CHECK([bison input.y -o input.c])
AT_COMPILE([input])

AT_PARSER_CHECK([./input '0<0'])
# FIXME: This is an actual bug, but a new one, in the sense that
# no one has ever spotted it!  The messages are *wrong*: there should
# be nothing there, it should be expected eof.
AT_PARSER_CHECK([./input '0<0<0'], [1], [],
         [parse error, unexpected '<', expecting '<' or '>'
])

AT_PARSER_CHECK([./input '0>0'])
AT_PARSER_CHECK([./input '0>0>0'], [1], [],
         [parse error, unexpected '>', expecting '<' or '>'
])

AT_PARSER_CHECK([./input '0<0>0'], [1], [],
         [parse error, unexpected '>', expecting '<' or '>'
])

AT_CLEANUP



## ------------------------- ##
## Unresolved SR Conflicts.  ##
## ------------------------- ##

AT_SETUP([Unresolved SR Conflicts])

AT_KEYWORDS([report])

AT_DATA([input.y],
[[%token NUM OP
%%
exp: exp OP exp | NUM;
]])

AT_CHECK([bison input.y -o input.c --report=all], 0, [],
[input.y contains 1 shift/reduce conflict.
])

# Check the contents of the report.
AT_CHECK([cat input.output], [],
[[State 5 contains 1 shift/reduce conflict.


Grammar

    0 $axiom: exp $

    1 exp: exp OP exp
    2    | NUM


Terminals, with rules where they appear

$ (0) 0
error (256)
NUM (258) 2
OP (259) 1


Nonterminals, with rules where they appear

$axiom (5)
    on left: 0
exp (6)
    on left: 1 2, on right: 0 1


state 0

    0 $axiom: . exp $
    1 exp: . exp OP exp
    2    | . NUM

    NUM  shift, and go to state 1

    exp  go to state 2


state 1

    2 exp: NUM .

    $default  reduce using rule 2 (exp)


state 2

    0 $axiom: exp . $
    1 exp: exp . OP exp

    $   shift, and go to state 3
    OP  shift, and go to state 4


state 3

    0 $axiom: exp $ .

    $default	accept


state 4

    1 exp: . exp OP exp
    1    | exp OP . exp
    2    | . NUM

    NUM  shift, and go to state 1

    exp  go to state 5


state 5

    1 exp: exp . OP exp  [$, OP]
    1    | exp OP exp .  [$, OP]

    OP  shift, and go to state 4

    OP        [reduce using rule 1 (exp)]
    $default  reduce using rule 1 (exp)
]])

AT_CLEANUP



## ----------------------- ##
## Resolved SR Conflicts.  ##
## ----------------------- ##

AT_SETUP([Resolved SR Conflicts])

AT_KEYWORDS([report])

AT_DATA([input.y],
[[%token NUM OP
%left OP
%%
exp: exp OP exp | NUM;
]])

AT_CHECK([bison input.y -o input.c --report=all])

# Check the contents of the report.
AT_CHECK([cat input.output], [],
[[Grammar

    0 $axiom: exp $

    1 exp: exp OP exp
    2    | NUM


Terminals, with rules where they appear

$ (0) 0
error (256)
NUM (258) 2
OP (259) 1


Nonterminals, with rules where they appear

$axiom (5)
    on left: 0
exp (6)
    on left: 1 2, on right: 0 1


state 0

    0 $axiom: . exp $
    1 exp: . exp OP exp
    2    | . NUM

    NUM  shift, and go to state 1

    exp  go to state 2


state 1

    2 exp: NUM .

    $default  reduce using rule 2 (exp)


state 2

    0 $axiom: exp . $
    1 exp: exp . OP exp

    $   shift, and go to state 3
    OP  shift, and go to state 4


state 3

    0 $axiom: exp $ .

    $default	accept


state 4

    1 exp: . exp OP exp
    1    | exp OP . exp
    2    | . NUM

    NUM  shift, and go to state 1

    exp  go to state 5


state 5

    1 exp: exp . OP exp  [$, OP]
    1    | exp OP exp .  [$, OP]

    $default  reduce using rule 1 (exp)
    Conflict between rule 1 and token OP resolved as reduce (%left OP).
]])

AT_CLEANUP


## -------------------------------- ##
## Defaulted Conflicted Reduction.  ##
## -------------------------------- ##

# When there are RR conflicts, some rules are disabled.  Usually it is
# simply displayed as:
#
#    $           reduce using rule 3 (num)
#    $           [reduce using rule 4 (id)]
#
# But when `reduce 3' is the default action, we'd produce:
#
#    $           [reduce using rule 4 (id)]
#    $default    reduce using rule 3 (num)
#
# In this precise case (a reduction is masked by the default
# reduction), we make the `reduce 3' explicit:
#
#    $           reduce using rule 3 (num)
#    $           [reduce using rule 4 (id)]
#    $default    reduce using rule 3 (num)
#
# Maybe that's not the best display, but then, please propose something
# else.

AT_SETUP([Defaulted Conflicted Reduction])
AT_KEYWORDS([report])

AT_DATA([input.y],
[[%%
exp: num | id;
num: '0';
id : '0';
%%
]])

AT_CHECK([bison input.y -o input.c --report=all], 0, [],
[input.y contains 1 reduce/reduce conflict.
])

# Check the contents of the report.
AT_CHECK([cat input.output], [],
[[State 1 contains 1 reduce/reduce conflict.


Grammar

    0 $axiom: exp $

    1 exp: num
    2    | id

    3 num: '0'

    4 id: '0'


Terminals, with rules where they appear

$ (0) 0
'0' (48) 3 4
error (256)


Nonterminals, with rules where they appear

$axiom (4)
    on left: 0
exp (5)
    on left: 1 2, on right: 0
num (6)
    on left: 3, on right: 1
id (7)
    on left: 4, on right: 2


state 0

    0 $axiom: . exp $
    1 exp: . num
    2    | . id
    3 num: . '0'
    4 id: . '0'

    '0'  shift, and go to state 1

    exp  go to state 2
    num  go to state 3
    id   go to state 4


state 1

    3 num: '0' .  [$]
    4 id: '0' .  [$]

    $         reduce using rule 3 (num)
    $         [reduce using rule 4 (id)]
    $default  reduce using rule 3 (num)


state 2

    0 $axiom: exp . $

    $  shift, and go to state 5


state 3

    1 exp: num .

    $default  reduce using rule 1 (exp)


state 4

    2 exp: id .

    $default  reduce using rule 2 (exp)


state 5

    0 $axiom: exp $ .

    $default	accept
]])

AT_CLEANUP




## -------------------- ##
## %expect not enough.  ##
## -------------------- ##

AT_SETUP([%expect not enough])

AT_DATA([input.y],
[[%token NUM OP
%expect 0
%%
exp: exp OP exp | NUM;
]])

AT_CHECK([bison input.y -o input.c], 1, [],
[input.y contains 1 shift/reduce conflict.
expected 0 shift/reduce conflicts
])
AT_CLEANUP


## --------------- ##
## %expect right.  ##
## --------------- ##

AT_SETUP([%expect right])

AT_DATA([input.y],
[[%token NUM OP
%expect 1
%%
exp: exp OP exp | NUM;
]])

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


## ------------------ ##
## %expect too much.  ##
## ------------------ ##

AT_SETUP([%expect too much])

AT_DATA([input.y],
[[%token NUM OP
%expect 2
%%
exp: exp OP exp | NUM;
]])

AT_CHECK([bison input.y -o input.c], 1, [],
[input.y contains 1 shift/reduce conflict.
expected 2 shift/reduce conflicts
])
AT_CLEANUP