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cex: suggest -Wcounterexamples when there are unexpected conflicts

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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.
This commit is contained in:
Akim Demaille
2020-06-10 08:11:56 +02:00
parent d2acc4b401
commit b0bb4cde2e
8 changed files with 112 additions and 56 deletions
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1
tests/sets.at
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@@ -285,6 +285,7 @@ term: 'n'
AT_BISON_CHECK([[-fcaret input.y]], [], [],
[[input.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
input.y: warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
input.y:2.14-17: warning: rule useless in parser due to conflicts [-Wother]
2 | expr: term | term | term | term | term | term
| ^~~~