mirror of
https://git.savannah.gnu.org/git/bison.git
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b0bb4cde2e
Suggesting -Wcounterexamples when there are conflicts is probably not
what the user wants. If she knows her conflicts and has set
%expect/%expect-rr appropriately, we shouldn't warn.
The commit also swaps the counterexamples and the report of conflicts,
into, IMHO, a more natural order: from
Shift/reduce conflict on token B:
1: 3 a: A .
1: 8 y: A . B
Example A • B C
First derivation s ::=[ a ::=[ A • ] x ::=[ B C ] ]
Example A • B C
Second derivation s ::=[ y ::=[ A • B ] c ::=[ C ] ]
input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
to
input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token B:
1: 3 a: A .
1: 8 y: A . B
Example A • B C
First derivation s ::=[ a ::=[ A • ] x ::=[ B C ] ]
Example A • B C
Second derivation s ::=[ y ::=[ A • B ] c ::=[ C ] ]
input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
* src/conflicts.c (rule_conflicts_print): Rename as...
(report_rule_expectation_mismatches): this.
Move the handling of report_counterexamples to...
(conflicts_print): Here.
Display this warning when applicable.
471 lines
9.6 KiB
Plaintext
471 lines
9.6 KiB
Plaintext
# Exercising Bison Grammar Sets. -*- Autotest -*-
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# Copyright (C) 2001-2002, 2005, 2007, 2009-2015, 2018-2020 Free
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# Software Foundation, Inc.
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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AT_BANNER([[Grammar Sets (Firsts etc.).]])
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## ---------- ##
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## Nullable. ##
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## ---------- ##
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AT_SETUP([Nullable])
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# At some point, nullable had been smoking grass, and managed to say:
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#
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# Entering set_nullable
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# NULLABLE
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# 'e': yes
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# (null): no
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# ...
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AT_DATA([[input.y]],
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[[%%
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e: 'e' | /* Nothing */;
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]])
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AT_BISON_CHECK([[--trace=sets input.y]], [], [], [stderr])
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AT_SETS_CHECK([stderr], [[DERIVES], [NULLABLE], [FIRSTS], [FDERIVES]],
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[[DERIVES
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$accept derives
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0 e $end
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e derives
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1 'e'
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2 %empty
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NULLABLE
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$accept: no
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e: yes
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FIRSTS
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$accept firsts
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$accept
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e
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e firsts
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e
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FDERIVES
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$accept derives
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0 e $end
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1 'e'
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2 %empty
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e derives
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1 'e'
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2 %empty
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]])
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AT_CLEANUP
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## ---------------- ##
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## Broken Closure. ##
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## ---------------- ##
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# TC was once broken during a massive 'simplification' of the code.
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# It resulted in bison dumping core on the following grammar (the
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# computation of FIRSTS uses TC). It managed to produce a pretty
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# exotic closure:
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#
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# TC: Input
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#
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# 01234567
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# +--------+
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# 0| 1 |
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# 1| 1 |
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# 2| 1 |
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# 3| 1 |
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# 4| 1 |
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# 5| 1 |
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# 6| 1|
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# 7| |
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# +--------+
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#
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# TC: Output
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#
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# 01234567
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# +--------+
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# 0| 1 |
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# 1| 111 |
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# 2| 111 |
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# 3| 1111 |
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# 4| 111 1 |
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# 5| 111 1 |
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# 6| 111 1|
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# 7| 111 |
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# +--------+
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#
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# instead of that below.
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AT_SETUP([Broken Closure])
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AT_DATA([input.y],
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[[%%
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a: b;
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b: c;
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c: d;
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d: e;
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e: f;
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f: g;
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g: h;
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h: 'h';
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]])
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AT_BISON_CHECK([[--trace=sets input.y]], [], [], [stderr])
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AT_CHECK([[sed -n 's/[ ]*$//;/^RTC: Firsts Output BEGIN/,/^RTC: Firsts Output END/p' stderr]], [],
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[[RTC: Firsts Output BEGIN
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012345678
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.---------.
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0|111111111|
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1| 11111111|
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2| 1111111|
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3| 111111|
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4| 11111|
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5| 1111|
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6| 111|
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7| 11|
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8| 1|
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`---------'
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RTC: Firsts Output END
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]])
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AT_CLEANUP
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## -------- ##
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## Firsts. ##
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## -------- ##
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AT_SETUP([Firsts])
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AT_DATA([input.y],
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[[%nonassoc '<' '>'
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%left '+' '-'
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%right '^' '='
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%%
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exp:
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exp '<' exp
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| exp '>' exp
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| exp '+' exp
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| exp '-' exp
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| exp '^' exp
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| exp '=' exp
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| "exp"
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;
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]])
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AT_BISON_CHECK([[--trace=sets input.y]], [], [], [stderr])
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AT_SETS_CHECK([stderr], [[DERIVES], [NULLABLE], [FIRSTS], [FDERIVES]],
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[[DERIVES
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$accept derives
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0 exp $end
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exp derives
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1 exp '<' exp
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2 exp '>' exp
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3 exp '+' exp
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4 exp '-' exp
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5 exp '^' exp
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6 exp '=' exp
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7 "exp"
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NULLABLE
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$accept: no
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exp: no
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FIRSTS
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$accept firsts
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$accept
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exp
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exp firsts
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exp
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FDERIVES
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$accept derives
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0 exp $end
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1 exp '<' exp
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2 exp '>' exp
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3 exp '+' exp
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4 exp '-' exp
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5 exp '^' exp
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6 exp '=' exp
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7 "exp"
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exp derives
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1 exp '<' exp
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2 exp '>' exp
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3 exp '+' exp
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4 exp '-' exp
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5 exp '^' exp
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6 exp '=' exp
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7 "exp"
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]])
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AT_CLEANUP
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## -------- ##
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## Accept. ##
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## -------- ##
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# In some weird cases Bison could compute an incorrect final state
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# number. This happens only if the $end token is used in the user
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# grammar, which is a very suspicious accidental feature introduced as
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# a side effect of allowing the user to name $end using '%token END 0
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# "end of file"'.
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AT_SETUP([Accept])
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AT_DATA([input.y],
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[[%token END 0
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%%
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input:
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'a'
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| '(' input ')'
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| '(' error END
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;
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]])
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AT_BISON_CHECK([[-v -o input.c input.y]])
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# Get the final state in the parser.
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AT_CHECK([[sed -n 's/.*define YYFINAL *\([0-9][0-9]*\)/final state \1/p' input.c]],
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0, [stdout])
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mv stdout expout
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# Get the final state in the report, from the "accept" action..
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AT_CHECK([sed -n '
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/^State \(.*\)/{
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s//final state \1/
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x
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}
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/ accept/{
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x
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p
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q
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}
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' input.output],
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0, [expout])
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AT_CLEANUP
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## ----------------- ##
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## Build relations. ##
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## ----------------- ##
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AT_SETUP([Build relations])
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# The "includes" relation [DeRemer 1982] is between gotos, so of
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# course, for a given goto, there cannot be more that ngotos (number
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# of gotos) images. But we manipulate the set of images of a goto as
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# a list, without checking that an image was not already introduced.
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# So we can "register" way more images than ngotos, leading to a crash
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# (heap buffer overflow).
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#
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# http://lists.gnu.org/archive/html/bug-bison/2019-03/msg00007.html
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AT_DATA([input.y],
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[[%%
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expr: term | term | term | term | term | term
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term: 'n'
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]])
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AT_BISON_CHECK([[-fcaret input.y]], [], [],
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[[input.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
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input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
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input.y:2.14-17: warning: rule useless in parser due to conflicts [-Wother]
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2 | expr: term | term | term | term | term | term
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| ^~~~
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input.y:2.21-24: warning: rule useless in parser due to conflicts [-Wother]
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2 | expr: term | term | term | term | term | term
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| ^~~~
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input.y:2.28-31: warning: rule useless in parser due to conflicts [-Wother]
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2 | expr: term | term | term | term | term | term
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| ^~~~
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input.y:2.35-38: warning: rule useless in parser due to conflicts [-Wother]
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2 | expr: term | term | term | term | term | term
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| ^~~~
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input.y:2.42-45: warning: rule useless in parser due to conflicts [-Wother]
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2 | expr: term | term | term | term | term | term
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| ^~~~
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]])
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AT_CLEANUP
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## ----------------- ##
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## Reduced Grammar. ##
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## ----------------- ##
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# Check information about the grammar, once reduced.
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AT_SETUP([Reduced Grammar])
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AT_DATA([input.y],
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[[%%
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expr: expr "+" term | term
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term: term "*" fact | fact
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useless: "useless"
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fact: "num"
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]])
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AT_BISON_CHECK([[--trace=grammar -o input.c input.y]], [], [],
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[[input.y: warning: 1 nonterminal useless in grammar [-Wother]
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input.y: warning: 1 rule useless in grammar [-Wother]
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input.y:4.1-7: warning: nonterminal useless in grammar: useless [-Wother]
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Reduced Grammar
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ntokens = 7, nvars = 4, nsyms = 11, nrules = 6, nritems = 17
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Tokens
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------
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Value Sprec Sassoc Tag
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0 0 0 $end
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1 0 0 error
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2 0 0 $undefined
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3 0 0 "+"
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4 0 0 "*"
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5 0 0 "useless"
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6 0 0 "num"
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Non terminals
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-------------
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Value Tag
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7 $accept
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8 expr
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9 term
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10 fact
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Rules
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-----
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Num (Prec, Assoc, Useful, UselessChain) Lhs -> (Ritem Range) Rhs
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0 ( 0, 0, t, f) 7 -> ( 0- 1) 8 0
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1 ( 0, 0, t, f) 8 -> ( 3- 5) 8 3 9
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2 ( 0, 0, t, t) 8 -> ( 7- 7) 9
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3 ( 0, 0, t, f) 9 -> ( 9-11) 9 4 10
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4 ( 0, 0, t, t) 9 -> (13-13) 10
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5 ( 0, 0, t, t) 10 -> (17-17) 6
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6 ( 0, 0, f, t) 11 -> (15-15) 5
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Rules interpreted
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-----------------
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0 $accept: expr $end
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1 expr: expr "+" term
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2 expr: term
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3 term: term "*" fact
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4 term: fact
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5 fact: "num"
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6 useless: "useless"
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reduced input.y defines 7 terminals, 4 nonterminals, and 6 productions.
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]])
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AT_CLEANUP
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## ------------------------------------- ##
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## Reduced Grammar with prec and assoc. ##
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## ------------------------------------- ##
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# Check information about the grammar, once reduced.
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AT_SETUP([Reduced Grammar with prec and assoc])
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AT_DATA([input.y],
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[[%nonassoc '<' '>'
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%left '+' '-'
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%right '^' '='
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%%
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exp:
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exp '<' exp
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| exp '>' exp
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| exp '+' exp
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| exp '-' exp
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| exp '^' exp
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| exp '=' exp
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| "exp"
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;
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]])
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AT_BISON_CHECK([[--trace=grammar -o input.c input.y]], [], [],
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[[Reduced Grammar
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ntokens = 10, nvars = 2, nsyms = 12, nrules = 8, nritems = 29
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Tokens
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------
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Value Sprec Sassoc Tag
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0 0 0 $end
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1 0 0 error
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2 0 0 $undefined
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3 1 3 '<'
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4 1 3 '>'
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5 2 2 '+'
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6 2 2 '-'
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7 3 1 '^'
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8 3 1 '='
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9 0 0 "exp"
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Non terminals
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-------------
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Value Tag
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10 $accept
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11 exp
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Rules
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-----
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Num (Prec, Assoc, Useful, UselessChain) Lhs -> (Ritem Range) Rhs
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0 ( 0, 0, t, f) 10 -> ( 0- 1) 11 0
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1 ( 1, 3, t, f) 11 -> ( 3- 5) 11 3 11
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2 ( 1, 3, t, f) 11 -> ( 7- 9) 11 4 11
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3 ( 2, 2, t, f) 11 -> (11-13) 11 5 11
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4 ( 2, 2, t, f) 11 -> (15-17) 11 6 11
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5 ( 3, 1, t, f) 11 -> (19-21) 11 7 11
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6 ( 3, 1, t, f) 11 -> (23-25) 11 8 11
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7 ( 0, 0, t, t) 11 -> (27-27) 9
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Rules interpreted
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-----------------
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0 $accept: exp $end
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1 exp: exp '<' exp
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2 exp: exp '>' exp
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3 exp: exp '+' exp
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4 exp: exp '-' exp
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5 exp: exp '^' exp
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6 exp: exp '=' exp
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7 exp: "exp"
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reduced input.y defines 10 terminals, 2 nonterminals, and 8 productions.
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]])
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AT_CLEANUP
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