cex: always show ε/%empty in counterexamples
Akim Demaille <[email protected]>
| Newsgroups | gmane.comp.parsers.bison.patches |
|---|---|
| Message-ID | <[email protected]> |
This is for master, not maint. commit 325ec7d32414d3b732d22387bb54da6918ec2ffc Author: Akim Demaille <[email protected]> Date: Mon Aug 31 07:22:17 2020 +0200 cex: always show ε/%empty in counterexamples 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. diff --git a/NEWS b/NEWS index c14d17f2..5f869f12 100644 --- a/NEWS +++ b/NEWS @@ -19,17 +19,18 @@ GNU Bison NEWS *** 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 - ↳ 1: "if" exp "then" exp - ↳ 2: "if" exp "then" exp • "else" exp + ↳ 1: e1 e2 "a" + ↳ 3: ε • ↳ 1: ε instead of exp - ↳ "if" exp "then" exp - ↳ "if" exp "then" exp • "else" exp + ↳ e1 e2 "a" + ↳ • ↳ ε * Noteworthy changes in release 3.7.1 (2020-08-02) [stable] diff --git a/doc/bison.texi b/doc/bison.texi index e36f8a38..f9aaf343 100644 --- a/doc/bison.texi +++ b/doc/bison.texi @@ -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 @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 -an @code{exp}. Therefore, it is easy to see that adding @code{%precedence} -directives would fix this conflict. +an @code{exp}. Therefore, it is easy to see that adding +precedence/associativity directives would fix this conflict. The remaining states are similar: diff --git a/src/derivation.c b/src/derivation.c index 382dc458..433f504e 100644 --- a/src/derivation.c +++ b/src/derivation.c @@ -245,6 +245,13 @@ derivation_width (const derivation *deriv) children_width += empty_width; 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; for (gl_list_iterator_t it = gl_list_iterator (deriv->children); 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); 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; derivation *child; for (gl_list_iterator_t it = gl_list_iterator (deriv->children); diff --git a/tests/conflicts.at b/tests/conflicts.at index d68f03aa..de0a993e 100644 --- a/tests/conflicts.at +++ b/tests/conflicts.at @@ -1776,7 +1776,7 @@ State 4 Reduce derivation start `-> 1: resolved_conflict reported_conflicts 'a' - `-> 10: . + `-> 10: %empty . shift/reduce conflict on token 'a': 10 reported_conflicts: . %empty @@ -1790,7 +1790,7 @@ State 4 Reduce derivation start `-> 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' First reduce derivation start - `-> 7: empty_c2 'c' - `-> 12: . + `-> 7: empty_c2 'c' + `-> 12: %empty . Second reduce derivation start - `-> 8: empty_c3 'c' - `-> 13: . + `-> 8: empty_c3 'c' + `-> 13: %empty . diff --git a/tests/counterexample.at b/tests/counterexample.at index bd9c1e96..fcc239bb 100644 --- a/tests/counterexample.at +++ b/tests/counterexample.at @@ -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] diff --git a/tests/diagnostics.at b/tests/diagnostics.at index faf4c9a7..42b6d3a8 100644 --- a/tests/diagnostics.at +++ b/tests/diagnostics.at @@ -532,9 +532,58 @@ exp | "if" exp "then" exp "else" exp | exp "+" exp | "num" +| empty "a" +| "a" empty + +empty +: %empty ]], [1], -[[input.y: <error>error:</error> shift/reduce conflicts: 4 found, 0 expected +[[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-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>] Example: <cex-0><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf><cex-1> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0> Shift derivation @@ -568,6 +617,17 @@ input.y: <warning>warning:</warning> shift/reduce conflict on token "+" [<warnin <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-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>] Example: <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"else"</cex-leaf><cex-1> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0> Shift derivation