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doc: factor ifnottex/iftex examples

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* doc/bison.texi: Factor the common bits out of ifnottex/iftex.
This commit is contained in:
Akim Demaille
2020-07-28 07:40:45 +02:00
parent fa390dc311
commit e63f22703e
1 changed files with 4 additions and 15 deletions
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19
doc/bison.texi
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@@ -9973,13 +9973,13 @@ maybeword:
Bison generates the following counterexamples:
@ifnottex
@example
@group
$ @kbd{bison -Wcex sequence.y}
sequence.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
sequence.y: @dwarning{warning}: 2 reduce/reduce conflicts [@dwarning{-Wconflicts-rr}]
@end group
@ifnottex
@group
sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" [@dwarning{-Wcounterexamples}]
Example: @red{•} @green{"word"}
@@ -10024,15 +10024,8 @@ sequence.y:8.3-45: @dwarning{warning}: rule useless in parser due to conflicts [
8 | @dwarning{%empty @{ printf ("empty maybeword\n"); @}}
| @dwarning{^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
@end group
@end example
@end ifnottex
@iftex
@example
@group
$ @kbd{bison -Wcex sequence.y}
sequence.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
sequence.y: @dwarning{warning}: 2 reduce/reduce conflicts [@dwarning{-Wconflicts-rr}]
@end group
@group
sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" [@dwarning{-Wcounterexamples}]
Example: @red{•} @green{"word"}
@@ -10077,8 +10070,8 @@ sequence.y:8.3-45: @dwarning{warning}: rule useless in parser due to conflicts [
8 | @dwarning{%empty @{ printf ("empty maybeword\n"); @}}
| @dwarning{^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
@end group
@end example
@end iftex
@end example
Each of these three conflicts, again, prove that the grammar is ambiguous.
For instance, the second conflict (the reduce/reduce one) shows that the
@@ -10103,10 +10096,10 @@ expr: %empty | expr ID ','
@command{bison} reports:
@ifnottex
@example
ids.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
ids.y: @dwarning{warning}: shift/reduce conflict on token ID [@dwarning{-Wcounterexamples}]
@ifnottex
@group
First example: @purple{expr} @red{•} @purple{ID ','} @green{ID} @yellow{$end}
Shift derivation
@@ -10127,12 +10120,8 @@ ids.y:4.4-7: @dwarning{warning}: rule useless in parser due to conflicts [@dwarn
4 | a: expr
| ^~~~
@end group
@end example
@end ifnottex
@iftex
@example
ids.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-sr}]
ids.y: @dwarning{warning}: shift/reduce conflict on token ID [@dwarning{-Wcounterexamples}]
@group
First example: @purple{expr} @red{•} @purple{ID ','} @green{ID} @yellow{$end}
Shift derivation
@@ -10153,8 +10142,8 @@ ids.y:4.4-7: @dwarning{warning}: rule useless in parser due to conflicts [@dwarn
4 | a: expr
| ^~~~
@end group
@end example
@end iftex
@end example
This conflict is caused by the parser not having enough information to know
the difference between these two examples. The parser would need an