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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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100
tests/counterexample.at
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@@ -47,8 +47,8 @@ AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token B:
Example A . B C
First derivation s -> [ a -> [ A . ] x -> [ B C ] ]
Second derivation s -> [ y -> [ A . B ] c -> [ 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]
]])
@@ -76,13 +76,13 @@ AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token B:
Example A . B C
First derivation s -> [ a -> [ A . ] bc -> [ B C ] ]
Second derivation s -> [ ac -> [ A ac -> [ b -> [ . B ] ] C ] ]
Shift derivation s -> [ ac -> [ A ac -> [ b -> [ . B ] ] C ] ]
Reduce derivation s -> [ a -> [ A . ] bc -> [ B C ] ]
Shift/reduce conflict on token B:
Example A A . B B C C
First derivation s -> [ a -> [ A a -> [ A . ] ] bc -> [ B bc -> [ B C ] C ] ]
Second derivation s -> [ ac -> [ A ac -> [ A ac -> [ b -> [ . b -> [ 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]
]])
@@ -111,14 +111,14 @@ AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
Shift/reduce conflict on token B:
Example A . B
First derivation s -> [ ax -> [ A x -> [ . ] ] by -> [ B y -> [ ] ] ]
Second derivation s -> [ A xby -> [ . B ] ]
Shift derivation s -> [ A xby -> [ . B ] ]
Reduce derivation s -> [ ax -> [ A x -> [ . ] ] by -> [ B y -> [ ] ] ]
Shift/reduce conflict on token B:
First example A X . B y $end
First derivation $accept -> [ s -> [ ax -> [ A x -> [ X x -> [ . ] ] ] by -> [ B y ] ] $end ]
Second example A X . B Y $end
Second derivation $accept -> [ s -> [ A xby -> [ X xby -> [ . B ] Y ] ] $end ]
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]
]])
@@ -146,10 +146,10 @@ bc: B C;
AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token C:
First example B . C D $end
First derivation $accept -> [ g -> [ x -> [ b -> [ B . ] cd -> [ C D ] ] ] $end ]
Second example B . C $end
Second derivation $accept -> [ g -> [ x -> [ bc -> [ B . C ] ] ] $end ]
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]
]])
@@ -175,10 +175,10 @@ y: A A B;
AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token A:
First example A . A $end
First derivation $accept -> [ s -> [ s -> [ t -> [ x -> [ A . ] ] ] t -> [ x -> [ A ] ] ] $end ]
Second example A . A B $end
Second derivation $accept -> [ s -> [ t -> [ y -> [ A . A B ] ] ] $end ]
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 ]
]])
@@ -209,14 +209,14 @@ AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
Shift/reduce conflict on token A:
Example b . A X X Y
First derivation a -> [ r -> [ b . ] t -> [ A x -> [ X ] xy -> [ X Y ] ] ]
Second derivation a -> [ s -> [ b . xx -> [ A X X ] y -> [ Y ] ] ]
Shift derivation a -> [ s -> [ b . xx -> [ A X X ] y -> [ Y ] ] ]
Reduce derivation a -> [ r -> [ b . ] t -> [ A x -> [ X ] xy -> [ X Y ] ] ]
Shift/reduce conflict on token X:
First example X . X xy
First derivation a -> [ x -> [ X . ] t -> [ X xy ] ]
Second example A X . X
Second derivation a -> [ t -> [ A xx -> [ X . X ] ] ]
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]
@@ -297,10 +297,10 @@ AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token J:
time limit exceeded: XXX
First example H i . J $end
First derivation $accept -> [ s -> [ a -> [ H i . ] J ] $end ]
Second example H i . J K $end
Second derivation $accept -> [ a -> [ H i -> [ i . J K ] ] $end ]
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]
]])
@@ -330,13 +330,13 @@ AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token B:
Example N A . B C
First derivation s -> [ n -> [ N a -> [ A . ] B ] C ]
Second derivation s -> [ n -> [ N b -> [ A . B C ] ] ]
Shift derivation s -> [ n -> [ N b -> [ A . B C ] ] ]
Reduce derivation s -> [ n -> [ N a -> [ A . ] B ] C ]
Shift/reduce conflict on token B:
Example N N A . B D C
First derivation s -> [ n -> [ N n -> [ N a -> [ A . ] B ] D ] C ]
Second derivation s -> [ n -> [ N n -> [ N b -> [ 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]
]])
@@ -420,10 +420,10 @@ time limit exceeded: XXX
Shift/reduce conflict on token A:
time limit exceeded: XXX
First example b c . c A A $end
First derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] ] ] $end ]
Second example b c . A
Second derivation a -> [ b d -> [ c . A ] ]
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 ]
Reduce/reduce conflict on token A:
First example b c . c A A $end
@@ -432,10 +432,10 @@ Reduce/reduce conflict on token A:
Second derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ c -> [ . ] A ] ] ] ] $end ]
Shift/reduce conflict on token A:
First example b c . A $end
First derivation $accept -> [ a -> [ b d -> [ a -> [ c d -> [ c -> [ . ] A ] ] ] ] $end ]
Second example b c . A
Second derivation a -> [ b d -> [ c . A ] ]
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 ]
Reduce/reduce conflict on token $end:
Example b d .
@@ -475,8 +475,8 @@ AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token J:
Example H i J . J J
First derivation s -> [ a -> [ H i -> [ i J . ] J J ] ]
Second derivation s -> [ a -> [ 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]
]])
@@ -507,8 +507,8 @@ AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token D:
Example A a . D
First derivation s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] ]
Second derivation s -> [ A a d -> [ . D ] ]
Shift derivation s -> [ A a d -> [ . D ] ]
Reduce derivation s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] ]
]])
@@ -536,10 +536,10 @@ d: D;
AT_BISON_CHECK_CEX([input.y], [], [],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token D:
First example A a . D E $end
First derivation $accept -> [ s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] E ] $end ]
Second example A a . D $end
Second derivation $accept -> [ s -> [ A a d -> [ . D ] ] $end ]
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 ]
]])