# Exercising Bison on counterexamples.                         -*- Autotest -*-

# Copyright (C) 2020 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.

AT_BANNER([[Counterexamples.]])

# AT_BISON_CHECK_CEX(TREE, FLAT)
# ------------------------------
m4_define([AT_BISON_CHECK_CEX],
[AT_KEYWORDS([cex])

AT_BISON_CHECK([-Wcounterexamples input.y], [0], [], [stderr])
# FIXME: Avoid trailing white spaces.
AT_CHECK([[sed -e 's/time limit exceeded: [0-9][.0-9]*/time limit exceeded: XXX/g;s/ *$//;' stderr]],
         [], [$1])

m4_pushdef([AT_SET_ENV_IF],
           [[YYFLAT=1; export YYFLAT;]]m4_defn([AT_SET_ENV_IF]))
AT_BISON_CHECK([-Wcounterexamples input.y], [0], [], [stderr])
AT_CHECK([[sed -e 's/time limit exceeded: [0-9][.0-9]*/time limit exceeded: XXX/g' stderr]],
         [], [$2])
m4_popdef([AT_SET_ENV_IF])

])

## --------------------- ##
## Simple Unifying S/R.  ##
## --------------------- ##

AT_SETUP([Unifying S/R])

AT_DATA([[input.y]],
[[%token A B C
%%
s: a x | y c;
a: A;
c: C;
x: B | B C;
y: A | A B;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example: A . B C
  Shift derivation
    s
    `-> y         c
        `-> A . B `-> C
  Reduce derivation
    s
    `-> a       x
        `-> A . `-> B C
input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example           A . B C
  Shift derivation  s -> [ y -> [ A . B ] c -> [ C ] ]
  Reduce derivation s -> [ a -> [ A . ] x -> [ B C ] ]
input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## ------------------- ##
## Deep Unifying S/R.  ##
## ------------------- ##

AT_SETUP([Deep Unifying S/R])

AT_DATA([[input.y]],
[[%token A B C
%%
s: ac | a bc;
ac: A ac C | b;
b: B | B b;
a: A | A a;
bc: B bc C | B C;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example: A . B C
  Shift derivation
    s
    `-> ac
        `-> A ac          C
              `-> b
                  `-> . B
  Reduce derivation
    s
    `-> a       bc
        `-> A . `-> B C
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example: A A . B B C C
  Shift derivation
    s
    `-> ac
        `-> A ac                        C
              `-> A ac                C
                    `-> b
                        `-> . b
                              `-> B B
  Reduce derivation
    s
    `-> a             bc
        `-> A a       `-> B bc      C
              `-> A .       `-> B C
input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example           A . B C
  Shift derivation  s -> [ ac -> [ A ac -> [ b -> [ . B ] ] C ] ]
  Reduce derivation s -> [ a -> [ A . ] bc -> [ B C ] ]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example           A A . B B C C
  Shift derivation  s -> [ ac -> [ A ac -> [ A ac -> [ b -> [ . b -> [ B B ] ] ] C ] C ] ]
  Reduce derivation s -> [ a -> [ A a -> [ A . ] ] bc -> [ B bc -> [ B C ] C ] ]
input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## ------------------------------------ ##
## S/R Conflict with Nullable Symbols.  ##
## ------------------------------------ ##

AT_SETUP([S/R Conflict with Nullable Symbols])

AT_DATA([[input.y]],
[[%token A B X Y
%%
s: ax by | A xby;
ax: A x;
x: %empty | X x;
by: B y;
y: %empty | Y y;
xby: B | X xby Y;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example: A . B
  Shift derivation
    s
    `-> A xby
          `-> . B
  Reduce derivation
    s
    `-> ax          by
        `-> A x     `-> B y
              `-> .       `-> %empty
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  First example: A X . B Y $end
  Shift derivation
    $accept
    `-> s                     $end
        `-> A xby
              `-> X xby     Y
                    `-> . B
  Second example: A X . B y $end
  Reduce derivation
    $accept
    `-> s                             $end
        `-> ax                by
            `-> A x           `-> B y
                  `-> X x
                        `-> .
input.y:5.4-9: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example           A . B
  Shift derivation  s -> [ A xby -> [ . B ] ]
  Reduce derivation s -> [ ax -> [ A x -> [ . ] ] by -> [ B y -> [ ] ] ]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  First example     A X . B Y $end
  Shift derivation  $accept -> [ s -> [ A xby -> [ X xby -> [ . B ] Y ] ] $end ]
  Second example    A X . B y $end
  Reduce derivation $accept -> [ s -> [ ax -> [ A x -> [ X x -> [ . ] ] ] by -> [ B y ] ] $end ]
input.y:5.4-9: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## ---------------------------- ##
## Non-unifying Ambiguous S/R.  ##
## ---------------------------- ##

AT_SETUP([Non-unifying Ambiguous S/R])

AT_DATA([[input.y]],
[[%token A B C D E
%%
g: s | x;
s: A x E | A x D E;
x: b cd | bc;
b: B;
cd: C D;
bc: B C;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token C [-Wcounterexamples]
  First example: B . C $end
  Shift derivation
    $accept
    `-> g                 $end
        `-> x
            `-> bc
                `-> B . C
  Second example: B . C D $end
  Reduce derivation
    $accept
    `-> g                       $end
        `-> x
            `-> b       cd
                `-> B . `-> C D
input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token C [-Wcounterexamples]
  First example     B . C $end
  Shift derivation  $accept -> [ g -> [ x -> [ bc -> [ B . C ] ] ] $end ]
  Second example    B . C D $end
  Reduce derivation $accept -> [ g -> [ x -> [ b -> [ B . ] cd -> [ C D ] ] ] $end ]
input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## ------------------------------ ##
## Non-unifying Unambiguous S/R.  ##
## ------------------------------ ##

AT_SETUP([Non-unifying Unambiguous S/R])

AT_DATA([[input.y]],
[[%token A B
%%
s: t | s t;
t: x | y;
x: A;
y: A A B;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
  First example: A . A B $end
  Shift derivation
    $accept
    `-> s                   $end
        `-> t
            `-> y
                `-> A . A B
  Second example: A . A $end
  Reduce derivation
    $accept
    `-> s                             $end
        `-> s               t
            `-> t           `-> x
                `-> x           `-> A
                    `-> A .
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
  First example     A . A B $end
  Shift derivation  $accept -> [ s -> [ t -> [ y -> [ A . A B ] ] ] $end ]
  Second example    A . A $end
  Reduce derivation $accept -> [ s -> [ s -> [ t -> [ x -> [ A . ] ] ] t -> [ x -> [ A ] ] ] $end ]
]])

AT_CLEANUP

## ----------------------- ##
## S/R after first token.  ##
## ----------------------- ##

AT_SETUP([S/R after first token])

AT_DATA([[input.y]],
[[%token A B X Y
%%
a: r t | s;
r: b;
b: B;
t: A xx | A x xy;
s: b A xx y;
x: X;
xx: X X;
xy: X Y;
y: Y;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
  Example: b . A X X Y
  Shift derivation
    a
    `-> s
        `-> b . xx        y
                `-> A X X `-> Y
  Reduce derivation
    a
    `-> r       t
        `-> b . `-> A x     xy
                      `-> X `-> X Y
input.y: warning: shift/reduce conflict on token X [-Wcounterexamples]
  First example: A X . X
  Shift derivation
    a
    `-> t
        `-> A xx
              `-> X . X
  Second example: X . X xy
  Reduce derivation
    a
    `-> x       t
        `-> X . `-> X xy
input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
input.y:8.4: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
  Example           b . A X X Y
  Shift derivation  a -> [ s -> [ b . xx -> [ A X X ] y -> [ Y ] ] ]
  Reduce derivation a -> [ r -> [ b . ] t -> [ A x -> [ X ] xy -> [ X Y ] ] ]
input.y: warning: shift/reduce conflict on token X [-Wcounterexamples]
  First example     A X . X
  Shift derivation  a -> [ t -> [ A xx -> [ X . X ] ] ]
  Second example    X . X xy
  Reduce derivation a -> [ x -> [ X . ] t -> [ X xy ] ]
input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
input.y:8.4: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## ----------------------------- ##
## Unifying R/R counterexample.  ##
## ----------------------------- ##

AT_SETUP([Unifying R/R counterexample])

AT_DATA([[input.y]],
[[%token A
%%
a : A b ;
b : A | b;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
  Example: A b .
  First reduce derivation
    a
    `-> A b .
  Second reduce derivation
    a
    `-> A b
          `-> b .
input.y:4.9: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
  Example                  A b .
  First reduce derivation  a -> [ A b . ]
  Second reduce derivation a -> [ A b -> [ b . ] ]
input.y:4.9: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## --------------------------------- ##
## Non-unifying R/R LR(1) conflict.  ##
## --------------------------------- ##

AT_SETUP([Non-unifying R/R LR(1) conflict])

AT_DATA([[input.y]],
[[%token A B C D
%%
s: a A | B a C | b C | B b A;
a: D;
b: D;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on tokens A, C [-Wcounterexamples]
  First example: D . A $end
  First reduce derivation
    $accept
    `-> s             $end
        `-> a       A
            `-> D .
  Second example: B D . A $end
  Second reduce derivation
    $accept
    `-> s               $end
        `-> B b       A
              `-> D .
input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on tokens A, C [-Wcounterexamples]
  First example            D . A $end
  First reduce derivation  $accept -> [ s -> [ a -> [ D . ] A ] $end ]
  Second example           B D . A $end
  Second reduce derivation $accept -> [ s -> [ B b -> [ D . ] A ] $end ]
input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## --------------------------------- ##
## Non-unifying R/R LR(2) conflict.  ##
## --------------------------------- ##

AT_SETUP([Non-unifying R/R LR(2) conflict])

AT_DATA([[input.y]],
[[%token H J K X
%%
s: a J;
a: H i;
i: X | i J K;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token J [-Wcounterexamples]
time limit exceeded: XXX
  First example: H i . J K $end
  Shift derivation
    $accept
    `-> a                 $end
        `-> H i
              `-> i . J K
  Second example: H i . J $end
  Reduce derivation
    $accept
    `-> s               $end
        `-> a         J
            `-> H i .
input.y:4.4-6: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token J [-Wcounterexamples]
time limit exceeded: XXX
  First example     H i . J K $end
  Shift derivation  $accept -> [ a -> [ H i -> [ i . J K ] ] $end ]
  Second example    H i . J $end
  Reduce derivation $accept -> [ s -> [ a -> [ H i . ] J ] $end ]
input.y:4.4-6: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## -------------------- ##
## Cex Search Prepend.  ##
## -------------------- ##

# Tests prepend steps in uniying counterexample
# graph search

AT_SETUP([Cex Search Prepend])

AT_DATA([[input.y]],
[[%token N A B C D
%%
s: n | n C;
n: N n D | N n C | N a B | N b;
a: A;
b: A B C | A B D;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example: N A . B C
  Shift derivation
    s
    `-> n
        `-> N b
              `-> A . B C
  Reduce derivation
    s
    `-> n               C
        `-> N a       B
              `-> A .
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example: N N A . B D C
  Shift derivation
    s
    `-> n
        `-> N n                 C
              `-> N b
                    `-> A . B D
  Reduce derivation
    s
    `-> n                       C
        `-> N n               D
              `-> N a       B
                    `-> A .
input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example           N A . B C
  Shift derivation  s -> [ n -> [ N b -> [ A . B C ] ] ]
  Reduce derivation s -> [ n -> [ N a -> [ A . ] B ] C ]
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
  Example           N N A . B D C
  Shift derivation  s -> [ n -> [ N n -> [ N b -> [ A . B D ] ] C ] ]
  Reduce derivation s -> [ n -> [ N n -> [ N a -> [ A . ] B ] D ] C ]
input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## ------------------- ##
## R/R cex with prec.  ##
## ------------------- ##

# Tests that counterexamples containing rules using
# precedence/associativity directives work.

AT_SETUP([R/R cex with prec])

AT_DATA([[input.y]],
[[%left b
%right c
%%
S: B C | C B;
A : B  | C  | %empty;
B : A b A;
C : A c A;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 4 reduce/reduce conflicts [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
  Example: B . b c
  First reduce derivation
    S
    `-> B                        C
        `-> A       b A          `-> A          c A
            `-> B .   `-> %empty     `-> %empty   `-> %empty
  Second reduce derivation
    S
    `-> B C
          `-> A                          c A
              `-> B                        `-> %empty
                  `-> A     b A
                      `-> .   `-> %empty
input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
  Example: C . c b
  First reduce derivation
    S
    `-> C                        B
        `-> A       c A          `-> A          b A
            `-> C .   `-> %empty     `-> %empty   `-> %empty
  Second reduce derivation
    S
    `-> C B
          `-> A                          b A
              `-> C                        `-> %empty
                  `-> A     c A
                      `-> .   `-> %empty
]],
[[input.y: warning: 4 reduce/reduce conflicts [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
  Example                  B . b c
  First reduce derivation  S -> [ B -> [ A -> [ B . ] b A -> [ ] ] C -> [ A -> [ ] c A -> [ ] ] ]
  Second reduce derivation S -> [ B C -> [ A -> [ B -> [ A -> [ . ] b A -> [ ] ] ] c A -> [ ] ] ]
input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
  Example                  C . c b
  First reduce derivation  S -> [ C -> [ A -> [ C . ] c A -> [ ] ] B -> [ A -> [ ] b A -> [ ] ] ]
  Second reduce derivation S -> [ C B -> [ A -> [ C -> [ A -> [ . ] c A -> [ ] ] ] b A -> [ ] ] ]
]])

AT_CLEANUP

## ------------------- ##
## Null nonterminals.  ##
## ------------------- ##

AT_SETUP([Null nonterminals])

AT_DATA([[input.y]],
[[%token A
%%
a : b d | c d ;
b : ;
c : ;
d : a | c A | d;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: 6 reduce/reduce conflicts [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
  First example: . c A A $end
  First reduce derivation
    $accept
    `-> a                   $end
        `-> b     d
            `-> . `-> c A A
  Second example: . c A A $end
  Second reduce derivation
    $accept
    `-> a                   $end
        `-> c     d
            `-> . `-> c A A
input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
time limit exceeded: XXX
  First example: b . c A A $end
  First reduce derivation
    $accept
    `-> a                             $end
        `-> b d
              `-> a
                  `-> b     d
                      `-> . `-> c A A
  Second example: b . A $end
  Second reduce derivation
    $accept
    `-> a                 $end
        `-> b d
              `-> c     A
                  `-> .
input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
time limit exceeded: XXX
  First example: c . c A A $end
  First reduce derivation
    $accept
    `-> a                             $end
        `-> c d
              `-> a
                  `-> b     d
                      `-> . `-> c A A
  Second example: c . A $end
  Second reduce derivation
    $accept
    `-> a                 $end
        `-> c d
              `-> c     A
                  `-> .
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
time limit exceeded: XXX
  First example: b c . A
  Shift derivation
    a
    `-> b d
          `-> c . A
  Second example: b c . c A A $end
  Reduce derivation
    $accept
    `-> a                                       $end
        `-> b d
              `-> a
                  `-> c d
                        `-> a
                            `-> b     d
                                `-> . `-> c A A
input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
  First example: b c . c A A $end
  First reduce derivation
    $accept
    `-> a                                       $end
        `-> b d
              `-> a
                  `-> c d
                        `-> a
                            `-> b     d
                                `-> . `-> c A A
  Second example: b c . A $end
  Second reduce derivation
    $accept
    `-> a                           $end
        `-> b d
              `-> a
                  `-> c d
                        `-> c     A
                            `-> .
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
  First example: b c . A
  Shift derivation
    a
    `-> b d
          `-> c . A
  Second example: b c . A $end
  Reduce derivation
    $accept
    `-> a                           $end
        `-> b d
              `-> a
                  `-> c d
                        `-> c     A
                            `-> .
input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
  Example: b d .
  First reduce derivation
    a
    `-> b d .
  Second reduce derivation
    a
    `-> b d
          `-> d .
input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
  Example: c d .
  First reduce derivation
    a
    `-> c d .
  Second reduce derivation
    a
    `-> c d
          `-> d .
input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
input.y:6.15: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: 6 reduce/reduce conflicts [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
  First example            . c A A $end
  First reduce derivation  $accept -> [ a -> [ b -> [ . ] d -> [ c A A ] ] $end ]
  Second example           . c A A $end
  Second reduce derivation $accept -> [ a -> [ c -> [ . ] d -> [ c A A ] ] $end ]
input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
time limit exceeded: XXX
  First example            b . c A A $end
  First reduce derivation  $accept -> [ a -> [ b d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] $end ]
  Second example           b . A $end
  Second reduce derivation $accept -> [ a -> [ b d -> [ c -> [ . ] A ] ] $end ]
input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
time limit exceeded: XXX
  First example            c . c A A $end
  First reduce derivation  $accept -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] $end ]
  Second example           c . A $end
  Second reduce derivation $accept -> [ a -> [ c d -> [ c -> [ . ] A ] ] $end ]
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
time limit exceeded: XXX
  First example     b c . A
  Shift derivation  a -> [ b d -> [ c . A ] ]
  Second example    b c . c A A $end
  Reduce derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] ] ] $end ]
input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
  First example            b c . c A A $end
  First reduce derivation  $accept -> [ a -> [ b d -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] ] ] $end ]
  Second example           b c . A $end
  Second reduce derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ c -> [ . ] A ] ] ] ] $end ]
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
  First example     b c . A
  Shift derivation  a -> [ b d -> [ c . A ] ]
  Second example    b c . A $end
  Reduce derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ c -> [ . ] A ] ] ] ] $end ]
input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
  Example                  b d .
  First reduce derivation  a -> [ b d . ]
  Second reduce derivation a -> [ b d -> [ d . ] ]
input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
  Example                  c d .
  First reduce derivation  a -> [ c d . ]
  Second reduce derivation a -> [ c d -> [ d . ] ]
input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
input.y:6.15: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## --------------------------- ##
## Non-unifying Prefix Share.  ##
## --------------------------- ##

AT_SETUP([Non-unifying Prefix Share])

# Tests for a counterexample which should start its derivation
# at a shared symbol rather than the start symbol.

AT_DATA([[input.y]],
[[%token H J
%%
s: a | a J;
a: H i J J
i: %empty | i J;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token J [-Wcounterexamples]
  Example: H i J . J J
  Shift derivation
    s
    `-> a             J
        `-> H i J . J
  Reduce derivation
    s
    `-> a
        `-> H i         J J
              `-> i J .
input.y:5.13-15: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token J [-Wcounterexamples]
  Example           H i J . J J
  Shift derivation  s -> [ a -> [ H i J . J ] J ]
  Reduce derivation s -> [ a -> [ H i -> [ i J . ] J J ] ]
input.y:5.13-15: warning: rule useless in parser due to conflicts [-Wother]
]])

AT_CLEANUP

## -------------------- ##
## Deep Null Unifying.  ##
## ---------------------##

# Tests that nested nullable nonterminals
# are derived correctly.

AT_SETUP([Deep Null Unifying])

AT_DATA([[input.y]],
[[%token A D
%%
s: A a d | A a a d;
a: b;
b: c
c: %empty
d: D;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
  Example: A a . D
  Shift derivation
    s
    `-> A a d
            `-> . D
  Reduce derivation
    s
    `-> A a a             d
            `-> b         `-> D
                `-> c
                    `-> .
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
  Example           A a . D
  Shift derivation  s -> [ A a d -> [ . D ] ]
  Reduce derivation s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] ]
]])

AT_CLEANUP

## ------------------------ ##
## Deep Null Non-unifying.  ##
## -------------------------##

# Tests that expand_to_conflict works with nullable sybols

AT_SETUP([Deep Null Non-unifying])

AT_DATA([[input.y]],
[[%token A D E
%%
s: A a d | A a a d E;
a: b;
b: c
c: %empty
d: D;
]])

AT_BISON_CHECK_CEX(
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
  First example: A a . D $end
  Shift derivation
    $accept
    `-> s               $end
        `-> A a d
                `-> . D
  Second example: A a . D E $end
  Reduce derivation
    $accept
    `-> s                             $end
        `-> A a a             d     E
                `-> b         `-> D
                    `-> c
                        `-> .
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
  First example     A a . D $end
  Shift derivation  $accept -> [ s -> [ A a d -> [ . D ] ] $end ]
  Second example    A a . D E $end
  Reduce derivation $accept -> [ s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] E ] $end ]
]])

AT_CLEANUP