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cex: always show ε/%empty in counterexamples

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On a case such as
    %%
    exp
    : empty "a"
    | "a" empty

    empty
    : %empty

we used to display

    warning: shift/reduce conflict on token "a" [-Wcounterexamples]
    Example: • "a"
    Shift derivation
      exp
      ↳ 2: • "a" empty
                 ↳ 2: ε
    Example: • "a"
    Reduce derivation
      exp
      ↳ 1: empty  "a"
           ↳ 3: •

where the shift derivation shows an item "2: empty → ε", with an
explicit "ε", but the reduce derivation shows "3: empty → •", without
"ε".

For consistency, let's always show ε/%empty in rules with an empty
rhs:

    Reduce derivation
      exp
      ↳ 1: empty    "a"
           ↳ 3: ε •

* src/derivation.c (derivation_width, derivation_print_tree_impl):
Always show ε/%empty in counterexamples.
* tests/diagnostics.at: Check that case.
* tests/conflicts.at, tests/counterexample.at: Adjust.
This commit is contained in:
Akim Demaille
2020-08-31 07:22:17 +02:00
parent 82d913741b
commit 325ec7d324
6 changed files with 141 additions and 66 deletions
Download Patch File Download Diff File Expand all files Collapse all files

104
tests/counterexample.at
View File

@@ -164,9 +164,9 @@ input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
`-> 9: . B
Reduce derivation
s
`-> 1: ax by
`-> 3: A x `-> 6: B y
`-> 4: . `-> 6: %empty
`-> 1: ax by
`-> 3: A x `-> 6: B y
`-> 4: %empty . `-> 6: %empty
input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
First example: A X . B Y $end
Shift derivation
@@ -178,11 +178,11 @@ input.y: warning: shift/reduce conflict on token B [-Wcounterexamples]
Second example: A X . B y $end
Reduce derivation
$accept
`-> 0: s $end
`-> 1: ax by
`-> 3: A x `-> 6: B y
`-> 0: s $end
`-> 1: ax by
`-> 3: A x `-> 6: B y
`-> 5: X x
`-> 4: .
`-> 4: %empty .
input.y:5.4-9: warning: rule useless in parser due to conflicts [-Wother]
]],
[[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
@@ -571,10 +571,10 @@ input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
Second reduce derivation
S
`-> 1: B C
`-> 7: A c A
`-> 3: B `-> 7: %empty
`-> 6: A b A
`-> 5: . `-> 6: %empty
`-> 7: A c A
`-> 3: B `-> 7: %empty
`-> 6: A b A
`-> 5: %empty . `-> 6: %empty
input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
Example: C . c b
First reduce derivation
@@ -585,10 +585,10 @@ input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
Second reduce derivation
S
`-> 2: C B
`-> 6: A b A
`-> 4: C `-> 6: %empty
`-> 7: A c A
`-> 5: . `-> 7: %empty
`-> 6: A b A
`-> 4: C `-> 6: %empty
`-> 7: A c A
`-> 5: %empty . `-> 7: %empty
]],
[[input.y: warning: 4 reduce/reduce conflicts [-Wconflicts-rr]
input.y: warning: reduce/reduce conflict on tokens b, c [-Wcounterexamples]
@@ -625,49 +625,49 @@ input.y: warning: reduce/reduce conflict on token A [-Wcounterexamples]
First example: . c A A $end
First reduce derivation
$accept
`-> 0: a $end
`-> 1: b d
`-> 3: . `-> 6: c A A
`-> 0: a $end
`-> 1: b d
`-> 3: %empty . `-> 6: c A A
Second example: . c A A $end
Second reduce derivation
$accept
`-> 0: a $end
`-> 2: c d
`-> 4: . `-> 6: c A A
`-> 0: a $end
`-> 2: c d
`-> 4: %empty . `-> 6: 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
`-> 0: a $end
`-> 0: a $end
`-> 1: b d
`-> 5: a
`-> 1: b d
`-> 3: . `-> 6: c A A
`-> 1: b d
`-> 3: %empty . `-> 6: c A A
Second example: b . A $end
Second reduce derivation
$accept
`-> 0: a $end
`-> 0: a $end
`-> 1: b d
`-> 6: c A
`-> 4: .
`-> 6: c A
`-> 4: %empty .
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
`-> 0: a $end
`-> 0: a $end
`-> 2: c d
`-> 5: a
`-> 1: b d
`-> 3: . `-> 6: c A A
`-> 1: b d
`-> 3: %empty . `-> 6: c A A
Second example: c . A $end
Second reduce derivation
$accept
`-> 0: a $end
`-> 0: a $end
`-> 2: c d
`-> 6: c A
`-> 4: .
`-> 6: c A
`-> 4: %empty .
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
time limit exceeded: XXX
First example: b c . A
@@ -678,33 +678,33 @@ time limit exceeded: XXX
Second example: b c . c A A $end
Reduce derivation
$accept
`-> 0: a $end
`-> 0: a $end
`-> 1: b d
`-> 5: a
`-> 2: c d
`-> 5: a
`-> 1: b d
`-> 3: . `-> 6: c A A
`-> 1: b d
`-> 3: %empty . `-> 6: 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
`-> 0: a $end
`-> 0: a $end
`-> 1: b d
`-> 5: a
`-> 2: c d
`-> 5: a
`-> 1: b d
`-> 3: . `-> 6: c A A
`-> 1: b d
`-> 3: %empty . `-> 6: c A A
Second example: b c . A $end
Second reduce derivation
$accept
`-> 0: a $end
`-> 0: a $end
`-> 1: b d
`-> 5: a
`-> 2: c d
`-> 6: c A
`-> 4: .
`-> 6: c A
`-> 4: %empty .
input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
First example: b c . A
Shift derivation
@@ -714,12 +714,12 @@ input.y: warning: shift/reduce conflict on token A [-Wcounterexamples]
Second example: b c . A $end
Reduce derivation
$accept
`-> 0: a $end
`-> 0: a $end
`-> 1: b d
`-> 5: a
`-> 2: c d
`-> 6: c A
`-> 4: .
`-> 6: c A
`-> 4: %empty .
input.y: warning: reduce/reduce conflict on token $end [-Wcounterexamples]
Example: b d .
First reduce derivation
@@ -861,10 +861,10 @@ input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
`-> 6: . D
Reduce derivation
s
`-> 2: A a a d
`-> 3: b `-> 6: D
`-> 2: A a a d
`-> 3: b `-> 6: D
`-> 4: c
`-> 5: .
`-> 5: %empty .
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
@@ -905,11 +905,11 @@ input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]
Second example: A a . D E $end
Reduce derivation
$accept
`-> 0: s $end
`-> 2: A a a d E
`-> 3: b `-> 6: D
`-> 0: s $end
`-> 2: A a a d E
`-> 3: b `-> 6: D
`-> 4: c
`-> 5: .
`-> 5: %empty .
]],
[[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y: warning: shift/reduce conflict on token D [-Wcounterexamples]