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cex: display shifts before reductions

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When reporting counterexamples for s/r conflicts, put the shift first.
This is more natural, and displays the default resolution first, which
is also what happens for r/r conflicts where the smallest rule number
is displayed first, and "wins".

* src/counterexample.c (counterexample): Add a shift_reduce member.
(new_counterexample): Adjust.
Swap the derivations when this is a s/r conflict.
(print_counterexample): For s/r conflicts, prefer "Shift derivation"
and "Reduce derivation" rather than "First/Second derivation".

* tests/conflicts.at, tests/counterexample.at, tests/report.at: Adjust.
* NEWS, doc/bison.texi: Ditto.
This commit is contained in:
Akim Demaille
2020-07-12 18:53:30 +02:00
parent 78f72a4516
commit 4f9ae5de07
7 changed files with 146 additions and 128 deletions
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tests/report.at
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@@ -1539,8 +1539,8 @@ AT_CHECK([LC_ALL="$locale" bison -fno-caret -o input.cc -rall -Wcex --graph=inpu
input.y: warning: 3 reduce/reduce conflicts [-Wconflicts-rr]
Shift/reduce conflict on token "⊕":
Example exp "+" exp • "⊕" exp
First derivation exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
Second derivation exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
Shift derivation exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
Reduce derivation exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
Reduce/reduce conflict on tokens $end, "+", "⊕":
Example exp "+" exp •
@@ -1549,23 +1549,23 @@ Reduce/reduce conflict on tokens $end, "+", "⊕":
Shift/reduce conflict on token "⊕":
Example exp "+" exp • "⊕" exp
First derivation exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
Second derivation exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
Shift derivation exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
Reduce derivation exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
Shift/reduce conflict on token "⊕":
Example exp "⊕" exp • "⊕" exp
First derivation exp → [ exp → [ exp "⊕" exp • ] "⊕" exp ]
Second derivation exp → [ exp "⊕" exp → [ exp • "⊕" exp ] ]
Shift derivation exp → [ exp "⊕" exp → [ exp • "⊕" exp ] ]
Reduce derivation exp → [ exp → [ exp "⊕" exp • ] "⊕" exp ]
Shift/reduce conflict on token "+":
Example exp "⊕" exp • "+" exp
First derivation exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
Second derivation exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
Shift derivation exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
Reduce derivation exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
Shift/reduce conflict on token "+":
Example exp "⊕" exp • "+" exp
First derivation exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
Second derivation exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
Shift derivation exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
Reduce derivation exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
input.y:6.3-13: warning: rule useless in parser due to conflicts [-Wother]
]])
@@ -1714,8 +1714,8 @@ State 7
2 exp: exp "+" exp •
1 exp: exp • "⊕" exp
Example exp "+" exp • "⊕" exp
First derivation exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
Second derivation exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
Shift derivation exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
Reduce derivation exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
Reduce/reduce conflict on tokens $end, "+", "⊕":
2 exp: exp "+" exp •
@@ -1728,8 +1728,8 @@ State 7
3 exp: exp "+" exp •
1 exp: exp • "⊕" exp
Example exp "+" exp • "⊕" exp
First derivation exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
Second derivation exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
Shift derivation exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
Reduce derivation exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
@@ -1751,22 +1751,22 @@ State 8
1 exp: exp "⊕" exp •
1 exp: exp • "⊕" exp
Example exp "⊕" exp • "⊕" exp
First derivation exp → [ exp → [ exp "⊕" exp • ] "⊕" exp ]
Second derivation exp → [ exp "⊕" exp → [ exp • "⊕" exp ] ]
Shift derivation exp → [ exp "⊕" exp → [ exp • "⊕" exp ] ]
Reduce derivation exp → [ exp → [ exp "⊕" exp • ] "⊕" exp ]
Shift/reduce conflict on token "+":
1 exp: exp "⊕" exp •
2 exp: exp • "+" exp
Example exp "⊕" exp • "+" exp
First derivation exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
Second derivation exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
Shift derivation exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
Reduce derivation exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
Shift/reduce conflict on token "+":
1 exp: exp "⊕" exp •
3 exp: exp • "+" exp
Example exp "⊕" exp • "+" exp
First derivation exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
Second derivation exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
Shift derivation exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
Reduce derivation exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
]])