doc: catch up with the current display of cex

[Akim Demaille]

commit 01a4ff244be85229f1a243c37a049f6670873f99
Author: Akim Demaille <akim.demaille@gmail.com>
Date:   Wed Jul 22 07:26:21 2020 +0200

    doc: catch up with the current display of cex
    
    Unfortunately I found no way to use the ↳ glyph in Texinfo, so I used
    @arrow{} instead, which has a different width, so we have to have all
    the examples doubled, once for TeX, another for the rest of the world.
    
    * doc/bison.texi: Use the current display in the examples.
    * doc/calc.y, doc/ids.y, doc/if-then-else.y, doc/sequence.y: New.

diff --git a/doc/bison.texi b/doc/bison.texi
index 5312cbe2..811ff0a6 100644
--- a/doc/bison.texi
+++ b/doc/bison.texi
@@ -9889,10 +9889,11 @@ initially developed by Chinawat Isradisaikul and Andrew 
Myers
 As a first example, see the example grammar of @ref{Shift/Reduce}, which
 features on shift/reduce conflict:
 
+@c see doc/if-then-else.y
 @example
 $ @kbd{bison if-then-else.y}
-if-then-else.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
-if-then-else.y: warning: rerun with option '-Wcounterexamples' to generate 
conflict counterexamples [-Wother]
+if-then-else.y: @dwarning{warning}: 1 shift/reduce conflict 
[@dwarning{-Wconflicts-sr}]
+if-then-else.y: @dnotice{note}: rerun with option '-Wcounterexamples' to 
generate conflict counterexamples
 @end example
 
 @noindent
@@ -9900,32 +9901,46 @@ Let's rerun @command{bison} with the option
 @option{-Wcex}/@option{-Wcounterexamples}@inlinefmt{info, (the following
 output is actually in color)}:
 
-@ifhtml
+@ifnottex
 @example
-Shift/reduce conflict on token "else":
+if-then-else.y: @dwarning{warning}: 1 shift/reduce conflict 
[@dwarning{-Wconflicts-sr}]
+if-then-else.y: @dwarning{warning}: shift/reduce conflict on token "else" 
[@dwarning{-Wcounterexamples}]
 @group
-  Example            @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} 
@red{•} @blue{"else" stmt}
-  Shift derivation   @yellow{if_stmt @arrow{} [ "if" expr "then"} @green{stmt 
@arrow{} [} @blue{if_stmt @arrow{} [ "if" expr "then" stmt} @red{•} 
@blue{"else" stmt ]} @green{]} @yellow{]}
-  Example            @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} 
@red{•} @yellow{"else" stmt}
-  Reduce derivation  @yellow{if_stmt @arrow{} [ "if" expr "then"} @green{stmt 
@arrow{} [} @blue{if_stmt @arrow{} [ "if" expr "then" stmt} @red{•} @blue{]} 
@green{]} @yellow{"else" stmt ]}
+  Example: @yellow{"if" expr "then"} "if" expr "then" stmt • "else" stmt
+  Shift derivation
+    @yellow{if_stmt}
+    @yellow{↳ "if" expr "then"} @green{stmt}
+                       @green{↳} @blue{if_stmt}
+                         @blue{↳ "if" expr "then" stmt} @red{•} @blue{"else" 
stmt}
+  Example: @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} 
@yellow{"else" stmt}
+  Reduce derivation
+    @yellow{if_stmt}
+    @yellow{↳ "if" expr "then"} @green{stmt}                        
@yellow{"else" stmt}
+                       @green{↳} @blue{if_stmt}
+                         @blue{↳ "if" expr "then" stmt} @red{•}
 @end group
 @end example
-@end ifhtml
-@ifnothtml
-@smallexample
-Shift/reduce conflict on token "else":
+@end ifnottex
+@iftex
+@example
+if-then-else.y: @dwarning{warning}: 1 shift/reduce conflict 
[@dwarning{-Wconflicts-sr}]
+if-then-else.y: @dwarning{warning}: shift/reduce conflict on token "else" 
[@dwarning{-Wcounterexamples}]
 @group
-  Example
-    @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} 
@blue{"else" stmt}
+  Example: @yellow{"if" expr "then"} "if" expr "then" stmt • "else" stmt
   Shift derivation
-    @yellow{if_stmt @arrow{} [ "if" expr "then"} @green{stmt @arrow{} [} 
@blue{if_stmt @arrow{} [ "if" expr "then" stmt} @red{•} @blue{"else" stmt ]} 
@green{]} @yellow{]}
-  Example
-    @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} 
@yellow{"else" stmt}
+    @yellow{if_stmt}
+    @yellow{@arrow{} "if" expr "then"} @green{stmt}
+                        @green{@arrow{}} @blue{if_stmt}
+                          @blue{@arrow{} "if" expr "then" stmt} @red{•} 
@blue{"else" stmt}
+  Example: @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} 
@yellow{"else" stmt}
   Reduce derivation
-    @yellow{if_stmt @arrow{} [ "if" expr "then"} @green{stmt @arrow{} [} 
@blue{if_stmt @arrow{} [ "if" expr "then" stmt} @red{•} @blue{]} @green{]} 
@yellow{"else" stmt ]}
+    @yellow{if_stmt}
+    @yellow{@arrow{} "if" expr "then"} @green{stmt}                        
@yellow{"else" stmt}
+                        @green{@arrow{}} @blue{if_stmt}
+                           @blue{@arrow{} "if" expr "then" stmt} @red{•}
 @end group
-@end smallexample
-@end ifnothtml
+@end example
+@end iftex
 
 This shows two different derivations for one single expression.  That
 demonstrates that the grammar is ambiguous.
@@ -9935,6 +9950,7 @@ demonstrates that the grammar is ambiguous.
 As a more delicate example, consider the example grammar of
 @ref{Reduce/Reduce}, which features a reduce/reduce conflict:
 
+@c doc/sequence.y
 @example
 %%
 sequence:
@@ -9950,32 +9966,112 @@ 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}]
-Shift/reduce conflict on token "word":
-  Example              @red{•} @green{"word"}
-  Shift derivation     @yellow{sequence @arrow{} [} @green{maybeword @arrow{} 
[} @red{•} @green{"word" ]} @yellow{]}
-  Example              @red{•} @yellow{"word"}
-  Reduce derivation    @yellow{sequence @arrow{} [} @green{sequence @arrow{} 
[} @red{•} @green{]} @yellow{"word" ]}
-
-Reduce/reduce conflict on tokens $end, "word":
-  Example              @red{•}
-  First derivation     @yellow{sequence @arrow{} [} @red{•} @yellow{]}
-  Example              @red{•}
-  Second derivation    @yellow{sequence @arrow{} [} @green{maybeword @arrow{} 
[} @red{•} @green{]} @yellow{]}
-
-Shift/reduce conflict on token "word":
-  Example              @red{•} @green{"word"}
-  Shift derivation     @yellow{sequence @arrow{} [} @green{maybeword @arrow{} 
[} @red{•} @green{"word" ]} @yellow{]}
-  Example              @red{•} @yellow{"word"}
-  Reduce derivation    @yellow{sequence @arrow{} [} @green{sequence @arrow{} 
[} @blue{maybeword @arrow{} [} @red{•} @blue{]} @green{]} @yellow{"word" ]}
-
+@end group
+@group
+sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" 
[@dwarning{-Wcounterexamples}]
+  Example: @red{•} @green{"word"}
+  Shift derivation
+    @yellow{sequence}
+    @yellow{↳} @green{maybeword}
+      @green{↳} @red{•} @green{"word"}
+  Example: @red{•} @yellow{"word"}
+  Reduce derivation
+    @yellow{sequence}
+    @yellow{↳} @green{sequence} @yellow{"word"}
+      @green{↳} @red{•}
+@end group
+@group
+sequence.y: @dwarning{warning}: reduce/reduce conflict on tokens $end, "word" 
[@dwarning{-Wcounterexamples}]
+  Example: @red{•}
+  First reduce derivation
+    @yellow{sequence}
+    @yellow{↳} @red{•}
+  Example: @red{•}
+  Second reduce derivation
+    @yellow{sequence}
+    @yellow{↳} @green{maybeword}
+      @green{↳} @red{•}
+@end group
+@group
+sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" 
[@dwarning{-Wcounterexamples}]
+  Example: @red{•} @green{"word"}
+  Shift derivation
+    @yellow{sequence}
+    @yellow{↳} @green{maybeword}
+      @green{↳} @red{•} @green{"word"}
+  Example: @red{•} @yellow{"word"}
+  Reduce derivation
+    @yellow{sequence}
+    @yellow{↳} @green{sequence}    @yellow{"word"}
+      @green{↳} @blue{maybeword}
+        @blue{↳} @red{•}
+@end group
+@group
 sequence.y:8.3-45: @dwarning{warning}: rule useless in parser due to conflicts 
[@dwarning{-Wother}]
     8 |   @dwarning{%empty    @{ printf ("empty maybeword\n"); @}}
       |   @dwarning{^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
+@end group
 @end example
+@end ifnottex
+@iftex
+@example
+@group
+$ @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"}
+  Shift derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{maybeword}
+       @green{@arrow{}} @red{•} @green{"word"}
+  Example: @red{•} @yellow{"word"}
+  Reduce derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{sequence} @yellow{"word"}
+       @green{@arrow{}} @red{•}
+@end group
+@group
+sequence.y: @dwarning{warning}: reduce/reduce conflict on tokens $end, "word" 
[@dwarning{-Wcounterexamples}]
+  Example: @red{•}
+  First reduce derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @red{•}
+  Example: @red{•}
+  Second reduce derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{maybeword}
+       @green{@arrow{}} @red{•}
+@end group
+@group
+sequence.y: @dwarning{warning}: shift/reduce conflict on token "word" 
[@dwarning{-Wcounterexamples}]
+  Example: @red{•} @green{"word"}
+  Shift derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{maybeword}
+       @green{@arrow{}} @red{•} @green{"word"}
+  Example: @red{•} @yellow{"word"}
+  Reduce derivation
+    @yellow{sequence}
+    @yellow{@arrow{}} @green{sequence}    @yellow{"word"}
+      @green{@arrow{}} @blue{maybeword}
+         @blue{@arrow{}} @red{•}
+@end group
+@group
+sequence.y:8.3-45: @dwarning{warning}: rule useless in parser due to conflicts 
[@dwarning{-Wother}]
+    8 |   @dwarning{%empty    @{ printf ("empty maybeword\n"); @}}
+      |   @dwarning{^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~}
+@end group
+@end example
+@end iftex
 
 Each of these three conflicts, again, prove that the grammar is ambiguous.
 For instance, the second conflict (the reduce/reduce one) shows that the
@@ -9989,6 +10085,7 @@ that are the same up until the dot.  Most notably, this 
will happen when
 your grammar requires a stronger parser (more lookahead, LR instead of
 LALR).  The following example isn't LR(1):
 
+@c doc/ids.y
 @example
 %token ID
 %%
@@ -9999,13 +10096,58 @@ expr: %empty | expr ID ','
 
 @command{bison} reports:
 
-@smallexample
-Shift/reduce conflict on token ID:
-  First example        @purple{expr} @red{•} @purple{ID ','} @green{ID} 
@yellow{$end}
-  Shift derivation     @yellow{$accept @arrow{} [} @green{s @arrow{} [} 
@blue{a @arrow{} [} @purple{expr @arrow{} [ expr} @red{•} @purple{ID ',' ]} 
@blue{]} @green{ID ]} @yellow{$end ]}
-  Second example       @blue{expr} @red{•} @green{ID} @yellow{$end}
-  Reduce derivation    @yellow{$accept @arrow{} [} @green{s @arrow{} [} 
@blue{a @arrow{} [ expr} @red{•} @blue{]} @green{ID ]} @yellow{$end ]}
-@end smallexample
+@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}]
+@group
+  First example: @purple{expr} @red{•} @purple{ID ','} @green{ID} @yellow{$end}
+  Shift derivation
+    @yellow{$accept}
+    @yellow{↳} @green{s}                      @yellow{$end}
+      @green{↳} @blue{a}                 @green{ID}
+        @blue{↳} @purple{expr}
+          @purple{↳ expr} @red{•} @purple{ID ','}
+  Second example: @blue{expr} @red{•} @green{ID} @yellow{$end}
+  Reduce derivation
+    @yellow{$accept}
+    @yellow{↳} @green{s}             @yellow{$end}
+      @green{↳} @blue{a}        @green{ID}
+        @blue{↳ expr} @red{•}
+@end group
+@group
+ids.y:4.4-7: @dwarning{warning}: rule useless in parser due to conflicts 
[@dwarning{-Wother}]
+    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{$end}
+  Shift derivation
+    @yellow{$accept}
+    @yellow{@arrow{}} @green{s}                      @yellow{$end}
+       @green{@arrow{}} @blue{a}                 @green{ID}
+          @blue{@arrow{}} @purple{expr}
+             @purple{@arrow{} expr} @red{•} @purple{ID ','}
+  Second example: @blue{expr} @red{•} @green{ID} @yellow{$end}
+  Reduce derivation
+    @yellow{$accept}
+    @yellow{@arrow{}} @green{s}             @yellow{$end}
+       @green{@arrow{}} @blue{a}        @green{ID}
+          @blue{@arrow{} expr} @red{•}
+@end group
+@group
+ids.y:4.4-7: @dwarning{warning}: rule useless in parser due to conflicts 
[@dwarning{-Wother}]
+    4 | a: expr
+      |    ^~~~
+@end group
+@end example
+@end iftex
 
 This conflict is caused by the parser not having enough information to know
 the difference between these two examples.  The parser would need an
@@ -10041,6 +10183,7 @@ by default.  As a consequence, the verbose output file 
is called
 
 The following grammar file, @file{calc.y}, will be used in the sequel:
 
+@c doc/calc.y
 @example
 @group
 %union
@@ -10084,7 +10227,7 @@ calc.y:19.1-7: @dwarning{warning}: nonterminal useless 
in grammar: useless [@dwa
    19 | @dwarning{useless: STR;}
       | @dwarning{^~~~~~~}
 calc.y: @dwarning{warning}: 7 shift/reduce conflicts 
[@dwarning{-Wconflicts-sr}]
-calc.y: @dwarning{warning}: rerun with option '-Wcounterexamples' to generate 
conflict counterexamples [@dwarning{-Wother}]
+calc.y: @dnotice{note}: rerun with option '-Wcounterexamples' to generate 
conflict counterexamples
 @end smallexample
 
 Going back to the calc example, when given @option{--report=state},
@@ -10396,15 +10539,44 @@ When given @option{--report=counterexamples}, 
@command{bison} will generate
 counterexamples within the report, augmented with the corresponding items
 (@pxref{Counterexamples}).
 
+@ifnottex
+@example
+shift/reduce conflict on token '/':
+    1 exp: exp '+' exp •
+    4 exp: exp • '/' exp
+@group
+  Example: exp '+' exp • '/' exp
+  Shift derivation
+    exp
+    ↳ exp '+' exp
+              ↳ exp • '/' exp
+  Example: exp '+' exp • '/' exp
+  Reduce derivation
+    exp
+    ↳ exp             '/' exp
+      ↳ exp '+' exp •
+@end group
+@end example
+@end ifnottex
+@iftex
 @example
-Shift/reduce conflict on token '/':
+shift/reduce conflict on token '/':
     1 exp: exp '+' exp •
     4 exp: exp • '/' exp
-  Example              @yellow{exp '+'} @green{exp} @red{•} @green{'/' exp}
-  Shift derivation     @yellow{exp @arrow{} [ exp '+'} @green{exp @arrow{} [ 
exp} @red{•} @green{'/' exp ]} @yellow{]}
-  Example              @green{exp '+' exp} @red{•} @yellow{'/' exp}
-  Reduce derivation    @yellow{exp @arrow{} [} @green{exp @arrow{} [ exp '+' 
exp} @red{•} @green{]} @yellow{'/' exp ]}
+@group
+  Example: exp '+' exp • '/' exp
+  Shift derivation
+    exp
+    @arrow{} exp '+' exp
+               @arrow{} exp • '/' exp
+  Example: exp '+' exp • '/' exp
+  Reduce derivation
+    exp
+    @arrow{} exp             '/' exp
+       @arrow{} exp '+' exp •
+@end group
 @end example
+@end iftex
 
 This shows two separate derivations in the grammar for the same @code{exp}:
 @samp{e1 + e2 / e3}.  The derivations show how your rules would parse the
diff --git a/doc/calc.y b/doc/calc.y
new file mode 100644
index 00000000..6f468b20
--- /dev/null
+++ b/doc/calc.y
@@ -0,0 +1,23 @@
+%union
+{
+  int ival;
+  const char *sval;
+}
+
+%token <ival> NUM
+%nterm <ival> exp
+%token <sval> STR
+%nterm <sval> useless
+
+%left '+' '-'
+%left '*'
+
+%%
+exp:
+  exp '+' exp
+| exp '-' exp
+| exp '*' exp
+| exp '/' exp
+| NUM
+;
+useless: STR;
diff --git a/doc/ids.y b/doc/ids.y
new file mode 100644
index 00000000..31a851ca
--- /dev/null
+++ b/doc/ids.y
@@ -0,0 +1,5 @@
+%token ID
+%%
+s: a ID
+a: expr
+expr: %empty | expr ID ','
diff --git a/doc/if-then-else.y b/doc/if-then-else.y
new file mode 100644
index 00000000..01e1f938
--- /dev/null
+++ b/doc/if-then-else.y
@@ -0,0 +1,13 @@
+%%
+stmt:
+  expr
+| if_stmt
+;
+
+if_stmt:
+  "if" expr "then" stmt
+| "if" expr "then" stmt "else" stmt
+;
+
+expr:
+  "identifier"
diff --git a/doc/sequence.y b/doc/sequence.y
new file mode 100644
index 00000000..2423759e
--- /dev/null
+++ b/doc/sequence.y
@@ -0,0 +1,10 @@
+%%
+sequence:
+  %empty
+| maybeword
+| sequence "word"
+;
+maybeword:
+  %empty
+| "word"
+;