Future/bison
1
0
Fork 0
mirror of https://git.savannah.gnu.org/git/bison.git synced 2026-03-18 08:43:03 +00:00
Code Issues Packages Projects Releases Wiki Activity

cex: always show ε/%empty in counterexamples

Browse Source 
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

11
NEWS
View File

@@ -19,17 +19,18 @@ GNU Bison NEWS
*** Counterexamples *** Counterexamples
Counterexamples now show the rule numbers: Counterexamples now show the rule numbers, and always show ε for rules
with an empty right-hand side. For instance
exp exp
↳ 1: "if" exp "then" exp ↳ 1: e1 e2 "a"
↳ 2: "if" exp "then" exp • "else" exp ↳ 3: ε • ↳ 1: ε
instead of instead of
exp exp
↳ "if" exp "then" exp ↳ e1 e2 "a"
↳ "if" exp "then" exp • "else" exp ↳ • ↳ ε
* Noteworthy changes in release 3.7.1 (2020-08-02) [stable] * Noteworthy changes in release 3.7.1 (2020-08-02) [stable]

4
doc/bison.texi
View File

@@ -10605,8 +10605,8 @@ This shows two separate derivations in the grammar for the same @code{exp}:
given example. Here, the first derivation completes a reduction when seeing given example. Here, the first derivation completes a reduction when seeing
@samp{/}, causing @samp{e1 + e2} to be grouped as an @code{exp}. The second @samp{/}, causing @samp{e1 + e2} to be grouped as an @code{exp}. The second
derivation shifts on @samp{/}, resulting in @samp{e2 / e3} being grouped as derivation shifts on @samp{/}, resulting in @samp{e2 / e3} being grouped as
an @code{exp}. Therefore, it is easy to see that adding @code{%precedence} an @code{exp}. Therefore, it is easy to see that adding
directives would fix this conflict. precedence/associativity directives would fix this conflict.
The remaining states are similar: The remaining states are similar:

14
src/derivation.c
View File

@@ -245,6 +245,13 @@ derivation_width (const derivation *deriv)
children_width += empty_width; children_width += empty_width;
else else
{ {
if (gl_list_size (deriv->children) == 1
&& gl_list_get_first (deriv->children) == &d_dot)
{
children_width += empty_width;
children_width += derivation_separator_width;
}
derivation *child; derivation *child;
for (gl_list_iterator_t it = gl_list_iterator (deriv->children); for (gl_list_iterator_t it = gl_list_iterator (deriv->children);
derivation_list_next (&it, &child); derivation_list_next (&it, &child);
@@ -310,6 +317,13 @@ derivation_print_tree_impl (const derivation *deriv, FILE *out,
res += fputs_if (depth == 1, out, padding, empty); res += fputs_if (depth == 1, out, padding, empty);
else else
{ {
if (gl_list_size (deriv->children) == 1
&& gl_list_get_first (deriv->children) == &d_dot)
{
res += fputs_if (depth == 1, out, padding, empty);
res += fputs_if (depth == 1, out, padding, derivation_separator);
}
bool first = true; bool first = true;
derivation *child; derivation *child;
for (gl_list_iterator_t it = gl_list_iterator (deriv->children); for (gl_list_iterator_t it = gl_list_iterator (deriv->children);

12
tests/conflicts.at
View File

@@ -1776,7 +1776,7 @@ State 4
Reduce derivation Reduce derivation
start start
`-> 1: resolved_conflict reported_conflicts 'a' `-> 1: resolved_conflict reported_conflicts 'a'
`-> 10: . `-> 10: %empty .
shift/reduce conflict on token 'a': shift/reduce conflict on token 'a':
10 reported_conflicts: . %empty 10 reported_conflicts: . %empty
@@ -1790,7 +1790,7 @@ State 4
Reduce derivation Reduce derivation
start start
`-> 1: resolved_conflict reported_conflicts 'a' `-> 1: resolved_conflict reported_conflicts 'a'
`-> 10: . `-> 10: %empty .
@@ -1999,12 +1999,12 @@ AT_CHECK([[cat input.output | sed -n '/^State 0$/,/^State 1$/p']], 0,
Example: . 'c' Example: . 'c'
First reduce derivation First reduce derivation
start start
`-> 7: empty_c2 'c' `-> 7: empty_c2 'c'
`-> 12: . `-> 12: %empty .
Second reduce derivation Second reduce derivation
start start
`-> 8: empty_c3 'c' `-> 8: empty_c3 'c'
`-> 13: . `-> 13: %empty .

104
tests/counterexample.at
View File

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

62
tests/diagnostics.at
View File

@@ -532,9 +532,58 @@ exp
exp exp
: "if" exp "then" exp : "if" exp "then" exp
| "if" exp "then" exp "else" exp | "if" exp "then" exp "else" exp
| exp "+" exp
| "num"
| empty "a"
| "a" empty
empty empty
: %empty : %empty
]], ]],
[1],
[[input.y: <error>error:</error> shift/reduce conflicts: 9 found, 0 expected
input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
Shift derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
Reduce derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
Shift derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
Reduce derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
Shift derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
Reduce derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
Shift derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
Reduce derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0> <cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1> <cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>] input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>]
@@ -568,6 +617,17 @@ input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warnin
Example: <cex-0><cex-1><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0> Example: <cex-0><cex-1><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
Reduce derivation Reduce derivation
<cex-0><cex-step>exp</cex-step></cex-0> <cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 3: <cex-1><cex-step>exp</cex-step></cex-1><cex-leaf> "+"</cex-leaf><cex-leaf> exp</cex-leaf></cex-step></cex-0>
<cex-1><cex-step> ↳ 1: <cex-leaf>"if"</cex-leaf><cex-leaf> exp</cex-leaf><cex-leaf> "then"</cex-leaf><cex-leaf> exp</cex-leaf><cex-dot> •</cex-dot></cex-step></cex-1>
input.y: <warning>warning:</warning> shift/reduce conflict on token "a" [<warning>-Wcounterexamples</warning>]
Example: <cex-0><cex-dot>•</cex-dot> <cex-leaf>"a"</cex-leaf><cex-1></cex-1></cex-0>
Shift derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 6: <cex-dot>•</cex-dot><cex-leaf> "a"</cex-leaf><cex-1><cex-step> empty</cex-step></cex-1></cex-step></cex-0>
<cex-1><cex-step> ↳ 6: ε</cex-step></cex-1>
Example: <cex-0><cex-1><cex-dot>•</cex-dot></cex-1> <cex-leaf>"a"</cex-leaf></cex-0>
Reduce derivation
<cex-0><cex-step>exp</cex-step></cex-0>
<cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0> <cex-0><cex-step>↳ 5: <cex-1><cex-step>empty</cex-step></cex-1><cex-leaf> "a"</cex-leaf></cex-step></cex-0>
<cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1> <cex-1><cex-step> ↳ 7: ε<cex-dot> •</cex-dot></cex-step></cex-1>
input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>] input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warning>-Wcounterexamples</warning>]