cex: prefer → to ::=

It does not make a lot of sense to use ::= in our counterexamples,
that's not something that belongs to the Bison "vocabulary".  Using
the colon makes sense, but it's too discreet.  Let's use the arrow,
which we already use in some reports (HTML and Dot).

* src/gram.h (print_dot_fallback): Generalize into...
(print_fallback): this.
(print_arrow): New.
* src/derivation.c: Use it.

* NEWS, tests/conflicts.at, tests/counterexample.at,
* tests/diagnostics.at, tests/report.at: Adjust.
* doc/bison.texi: Ditto.
Unfortunately the literal `→` is output as `↦`.  So we need to use
@arrow.

NEWS

@@ -45,8 +45,8 @@ GNU Bison NEWS
   conflict.  For example:
 
     Example              exp '+' exp • '/' exp
-    First derivation     exp ::=[ exp ::=[ exp '+' exp • ] '/' exp ]
+    First derivation     exp → [ exp → [ exp '+' exp • ] '/' exp ]
-    Second derivation    exp ::=[ exp '+' exp ::=[ exp • '/' exp ] ]
+    Second derivation    exp → [ exp '+' exp → [ exp • '/' exp ] ]
 
   When Bison is installed with text styling enabled, the example is actually
   shown twice, with colors highlighting the ambiguity.
@@ -57,9 +57,9 @@ GNU Bison NEWS
   generates two examples that are the same up until the dot:
 
     First example        expr • ID $end
-    First derivation     $accept ::=[ s ::=[ a ::=[ expr • ] ID ] $end ]
+    First derivation     $accept → [ s → [ a → [ expr • ] ID ] $end ]
     Second example       expr • ID ',' ID $end
-    Second derivation    $accept ::=[ s ::=[ a ::=[ expr ::=[ expr • ID ',' ] ] ID ] $end ]
+    Second derivation    $accept → [ s → [ a → [ expr → [ expr • ID ',' ] ] ID ] $end ]
 
   In these cases, the parser usually doesn't have enough lookahead to
   differentiate the two given examples.

doc/bison.texi

@@ -9937,9 +9937,9 @@ output is actually in color)}:
 Shift/reduce conflict on token "else":
 @group
   Example            @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} @yellow{"else" stmt}
-  First derivation   @yellow{if_stmt ::=[ "if" expr "then"} @green{stmt ::=[} @blue{if_stmt ::=[ "if" expr "then" stmt} @red{•} @blue{]} @green{]} @yellow{"else" stmt ]}
+  First 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"} @blue{"if" expr "then" stmt} @red{•} @blue{"else" stmt}
-  Second derivation  @yellow{if_stmt ::=[ "if" expr "then"} @green{stmt ::=[} @blue{if_stmt ::=[ "if" expr "then" stmt} @red{•} @blue{"else" stmt ]} @green{]} @yellow{]}
+  Second 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{]}
 @end group
 @end example
 @end ifhtml
@@ -9950,11 +9950,11 @@ Shift/reduce conflict on token "else":
   Example
     @yellow{"if" expr "then"} @blue{"if" expr "then" stmt} @red{•} @yellow{"else" stmt}
   First derivation
-    @yellow{if_stmt ::=[ "if" expr "then"} @green{stmt ::=[} @blue{if_stmt ::=[ "if" expr "then" stmt} @red{•} @blue{]} @green{]} @yellow{"else" stmt ]}
+    @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"} @blue{"if" expr "then" stmt} @red{•} @blue{"else" stmt}
   Second derivation
-    @yellow{if_stmt ::=[ "if" expr "then"} @green{stmt ::=[} @blue{if_stmt ::=[ "if" expr "then" stmt} @red{•} @blue{"else" stmt ]} @green{]} @yellow{]}
+    @yellow{if_stmt @arrow [ "if" expr "then"} @green{stmt @arrow [} @blue{if_stmt @arrow [ "if" expr "then" stmt} @red{•} @blue{"else" stmt ]} @green{]} @yellow{]}
 @end group
 @end smallexample
 @end ifnothtml
@@ -9988,21 +9988,21 @@ sequence.y: @dwarning{warning}: 1 shift/reduce conflict [@dwarning{-Wconflicts-s
 sequence.y: @dwarning{warning}: 2 reduce/reduce conflicts [@dwarning{-Wconflicts-rr}]
 Shift/reduce conflict on token "word":
   Example              @red{•} @yellow{"word"}
-  First derivation     @yellow{sequence ::=[} @green{sequence ::=[} @red{•} @green{]} @yellow{"word" ]}
+  First derivation     @yellow{sequence @arrow [} @green{sequence @arrow [} @red{•} @green{]} @yellow{"word" ]}
   Example              @red{•} @green{"word"}
-  Second derivation    @yellow{sequence ::=[} @green{maybeword ::=[} @red{•} @green{"word" ]} @yellow{]}
+  Second derivation    @yellow{sequence @arrow [} @green{maybeword @arrow [} @red{•} @green{"word" ]} @yellow{]}
 
 Reduce/reduce conflict on tokens $end, "word":
   Example              @red{•}
-  First derivation     @yellow{sequence ::=[} @red{•} @yellow{]}
+  First derivation     @yellow{sequence @arrow [} @red{•} @yellow{]}
   Example              @red{•}
-  Second derivation    @yellow{sequence ::=[} @green{maybeword ::=[} @red{•} @green{]} @yellow{]}
+  Second derivation    @yellow{sequence @arrow [} @green{maybeword @arrow [} @red{•} @green{]} @yellow{]}
 
 Shift/reduce conflict on token "word":
   Example              @red{•} @yellow{"word"}
-  First derivation     @yellow{sequence ::=[} @green{sequence ::=[} @blue{maybeword ::=[} @red{•} @blue{]} @green{]} @yellow{"word" ]}
+  First derivation     @yellow{sequence @arrow [} @green{sequence @arrow [} @blue{maybeword @arrow [} @red{•} @blue{]} @green{]} @yellow{"word" ]}
   Example              @red{•} @green{"word"}
-  Second derivation    @yellow{sequence ::=[} @green{maybeword ::=[} @red{•} @green{"word" ]} @yellow{]}
+  Second derivation    @yellow{sequence @arrow [} @green{maybeword @arrow [} @red{•} @green{"word" ]} @yellow{]}
 
 sequence.y:8.3-45: @dwarning{warning}: rule useless in parser due to conflicts [@dwarning{-Wother}]
     8 |   @dwarning{%empty    @{ printf ("empty maybeword\n"); @}}
@@ -10034,9 +10034,9 @@ expr: %empty | expr ID ','
 @smallexample
 Shift/reduce conflict on token ID:
   First example        @blue{expr} @red{•} @green{ID} @yellow{$end}
-  First derivation     @yellow{$accept ::=[} @green{s ::=[} @blue{a ::=[ expr} @red{•} @blue{]} @green{ID ]} @yellow{$end ]}
+  First derivation     @yellow{$accept @arrow [} @green{s @arrow [} @blue{a @arrow [ expr} @red{•} @blue{]} @green{ID ]} @yellow{$end ]}
   Second example       @purple{expr} @red{•} @purple{ID ','} @green{ID} @yellow{$end}
-  Second derivation    @yellow{$accept ::=[} @green{s ::=[} @blue{a ::=[} @purple{expr ::=[ expr} @red{•} @purple{ID ',' ]} @blue{]} @green{ID ]} @yellow{$end ]}
+  Second derivation    @yellow{$accept @arrow [} @green{s @arrow [} @blue{a @arrow [} @purple{expr @arrow [ expr} @red{•} @purple{ID ',' ]} @blue{]} @green{ID ]} @yellow{$end ]}
 @end smallexample
 
 This conflict is caused by the parser not having enough information to know
@@ -10433,9 +10433,9 @@ Shift/reduce conflict on token '/':
     1 exp: exp '+' exp •
     4 exp: exp • '/' exp
   Example              @green{exp '+' exp} @red{•} @yellow{'/' exp}
-  First derivation     @yellow{exp ::=[} @green{exp ::=[ exp '+' exp} @red{•} @green{]} @yellow{'/' exp ]}
+  First derivation     @yellow{exp @arrow [} @green{exp @arrow [ exp '+' exp} @red{•} @green{]} @yellow{'/' exp ]}
   Example              @yellow{exp '+'} @green{exp} @red{•} @green{'/' exp}
-  Second derivation    @yellow{exp ::=[ exp '+'} @green{exp ::=[ exp} @red{•} @green{'/' exp ]} @yellow{]}
+  Second derivation    @yellow{exp @arrow [ exp '+'} @green{exp @arrow [ exp} @red{•} @green{'/' exp ]} @yellow{]}
 @end example
 
 This shows two separate derivations in the grammar for the same @code{exp}:

src/derivation.c

@@ -145,7 +145,9 @@ derivation_print_impl (const derivation *deriv, FILE *f,
         {
           fputs (prefix, f);
           begin_use_class ("cex-step", f);
-          fprintf (f, "%s ::=[ ", sym->tag);
+          fprintf (f, "%s ", sym->tag);
+          print_arrow (f);
+          fprintf (f, " [ ");
           end_use_class ("cex-step", f);
           prefix = "";
         }

src/gram.h

@@ -217,23 +217,41 @@ typedef struct
 extern rule *rules;
 extern rule_number nrules;
 
-/* Fallback in case we can't print "•".  */
+/* Fallback in case we can't print "•" or "→".  */
 static inline long
-print_dot_fallback (unsigned int code _GL_UNUSED,
+print_fallback (unsigned int code _GL_UNUSED,
-                    const char *msg _GL_UNUSED,
+                const char *msg _GL_UNUSED,
-                    void *callback_arg)
+                void *callback_arg)
 {
   FILE *out = (FILE *) callback_arg;
-  putc ('.', out);
+  switch (code)
+    {
+    case 0x2022:
+      putc ('.', out);
+      break;
+    case 0x2192:
+      fputs ("->", out);
+      break;
+    default:
+      abort ();
+    }
   return -1;
 }
 
+/* Print "→", the symbol used to separate the lhs of a rule from its
+   rhs.  */
+static inline void
+print_arrow (FILE *out)
+{
+  unicode_to_mb (0x2192, fwrite_success_callback, print_fallback, out);
+}
+
 /* Print "•", the symbol used to represent a point in an item (aka, a
    dotted rule).  */
 static inline void
 print_dot (FILE *out)
 {
-  unicode_to_mb (0x2022, fwrite_success_callback, print_dot_fallback, out);
+  unicode_to_mb (0x2022, fwrite_success_callback, print_fallback, out);
 }
 
 /* Get the rule associated to this item.  ITEM points inside RITEM.  */

tests/conflicts.at

@@ -865,8 +865,8 @@ State 5
         1 exp: exp OP exp .
         1 exp: exp . OP exp
       Example                  exp OP exp . OP exp
-      First derivation         exp ::=[ exp ::=[ exp OP exp . ] OP exp ]
+      First derivation         exp -> [ exp -> [ exp OP exp . ] OP exp ]
-      Second derivation        exp ::=[ exp OP exp ::=[ exp . OP exp ] ]
+      Second derivation        exp -> [ exp OP exp -> [ exp . OP exp ] ]
 
 ]])
 
@@ -1207,8 +1207,8 @@ State 1
         3 num: '0' .
         4 id: '0' .
       Example                  '0' .
-      First derivation         exp ::=[ num ::=[ '0' . ] ]
+      First derivation         exp -> [ num -> [ '0' . ] ]
-      Second derivation        exp ::=[ id ::=[ '0' . ] ]
+      Second derivation        exp -> [ id -> [ '0' . ] ]
 
 
 
@@ -1754,17 +1754,17 @@ State 4
        10 reported_conflicts: . %empty
         8 reported_conflicts: . 'a'
       First example            resolved_conflict . 'a'
-      First derivation         start ::=[ resolved_conflict reported_conflicts ::=[ . ] 'a' ]
+      First derivation         start -> [ resolved_conflict reported_conflicts -> [ . ] 'a' ]
       Second example           resolved_conflict . 'a' 'a'
-      Second derivation        start ::=[ resolved_conflict reported_conflicts ::=[ . 'a' ] 'a' ]
+      Second derivation        start -> [ resolved_conflict reported_conflicts -> [ . 'a' ] 'a' ]
 
     Shift/reduce conflict on token 'a':
        10 reported_conflicts: . %empty
         9 reported_conflicts: . 'a'
       First example            resolved_conflict . 'a'
-      First derivation         start ::=[ resolved_conflict reported_conflicts ::=[ . ] 'a' ]
+      First derivation         start -> [ resolved_conflict reported_conflicts -> [ . ] 'a' ]
       Second example           resolved_conflict . 'a' 'a'
-      Second derivation        start ::=[ resolved_conflict reported_conflicts ::=[ . 'a' ] 'a' ]
+      Second derivation        start -> [ resolved_conflict reported_conflicts -> [ . 'a' ] 'a' ]
 
 
 
@@ -1781,8 +1781,8 @@ State 5
         8 reported_conflicts: 'a' .
         9 reported_conflicts: 'a' .
       Example                  'a' .
-      First derivation         reported_conflicts ::=[ 'a' . ]
+      First derivation         reported_conflicts -> [ 'a' . ]
-      Second derivation        reported_conflicts ::=[ 'a' . ]
+      Second derivation        reported_conflicts -> [ 'a' . ]
 
 
 
@@ -1965,8 +1965,8 @@ AT_CHECK([[cat input.output | sed -n '/^State 0$/,/^State 1$/p']], 0,
        12 empty_c2: . %empty
        13 empty_c3: . %empty
       Example                  . 'c'
-      First derivation         start ::=[ empty_c2 ::=[ . ] 'c' ]
+      First derivation         start -> [ empty_c2 -> [ . ] 'c' ]
-      Second derivation        start ::=[ empty_c3 ::=[ . ] 'c' ]
+      Second derivation        start -> [ empty_c3 -> [ . ] 'c' ]
 
 
 

tests/counterexample.at

@@ -47,8 +47,8 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 Shift/reduce conflict on token B:
   Example              A . B C
-  First derivation     s ::=[ a ::=[ A . ] x ::=[ B C ] ]
+  First derivation     s -> [ a -> [ A . ] x -> [ B C ] ]
-  Second derivation    s ::=[ y ::=[ A . B ] c ::=[ C ] ]
+  Second derivation    s -> [ y -> [ A . B ] c -> [ C ] ]
 
 input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -76,13 +76,13 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 Shift/reduce conflict on token B:
   Example              A . B C
-  First derivation     s ::=[ a ::=[ A . ] bc ::=[ B C ] ]
+  First derivation     s -> [ a -> [ A . ] bc -> [ B C ] ]
-  Second derivation    s ::=[ ac ::=[ A ac ::=[ b ::=[ . B ] ] C ] ]
+  Second derivation    s -> [ ac -> [ A ac -> [ b -> [ . B ] ] C ] ]
 
 Shift/reduce conflict on token B:
   Example              A A . B B C C
-  First derivation     s ::=[ a ::=[ A a ::=[ A . ] ] bc ::=[ B bc ::=[ B C ] C ] ]
+  First derivation     s -> [ a -> [ A a -> [ A . ] ] bc -> [ B bc -> [ B C ] C ] ]
-  Second derivation    s ::=[ ac ::=[ A ac ::=[ A ac ::=[ b ::=[ . b ::=[ B B ] ] ] C ] C ] ]
+  Second derivation    s -> [ ac -> [ A ac -> [ A ac -> [ b -> [ . b -> [ B B ] ] ] C ] C ] ]
 
 input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -111,14 +111,14 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
 Shift/reduce conflict on token B:
   Example              A . B
-  First derivation     s ::=[ ax ::=[ A x ::=[ . ] ] by ::=[ B y ::=[ ] ] ]
+  First derivation     s -> [ ax -> [ A x -> [ . ] ] by -> [ B y -> [ ] ] ]
-  Second derivation    s ::=[ A xby ::=[ . B ] ]
+  Second derivation    s -> [ A xby -> [ . B ] ]
 
 Shift/reduce conflict on token B:
   First example        A X . B y $end
-  First derivation     $accept ::=[ s ::=[ ax ::=[ A x ::=[ X x ::=[ . ] ] ] by ::=[ B y ] ] $end ]
+  First derivation     $accept -> [ s -> [ ax -> [ A x -> [ X x -> [ . ] ] ] by -> [ B y ] ] $end ]
   Second example       A X . B Y $end
-  Second derivation    $accept ::=[ s ::=[ A xby ::=[ X xby ::=[ . B ] Y ] ] $end ]
+  Second derivation    $accept -> [ s -> [ A xby -> [ X xby -> [ . B ] Y ] ] $end ]
 
 input.y:5.4-9: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -147,9 +147,9 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 Shift/reduce conflict on token C:
   First example        B . C D $end
-  First derivation     $accept ::=[ g ::=[ x ::=[ b ::=[ B . ] cd ::=[ C D ] ] ] $end ]
+  First derivation     $accept -> [ g -> [ x -> [ b -> [ B . ] cd -> [ C D ] ] ] $end ]
   Second example       B . C $end
-  Second derivation    $accept ::=[ g ::=[ x ::=[ bc ::=[ B . C ] ] ] $end ]
+  Second derivation    $accept -> [ g -> [ x -> [ bc -> [ B . C ] ] ] $end ]
 
 input.y:6.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -176,9 +176,9 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 Shift/reduce conflict on token A:
   First example        A . A $end
-  First derivation     $accept ::=[ s ::=[ s ::=[ t ::=[ x ::=[ A . ] ] ] t ::=[ x ::=[ A ] ] ] $end ]
+  First derivation     $accept -> [ s -> [ s -> [ t -> [ x -> [ A . ] ] ] t -> [ x -> [ A ] ] ] $end ]
   Second example       A . A B $end
-  Second derivation    $accept ::=[ s ::=[ t ::=[ y ::=[ A . A B ] ] ] $end ]
+  Second derivation    $accept -> [ s -> [ t -> [ y -> [ A . A B ] ] ] $end ]
 
 ]])
 
@@ -209,14 +209,14 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 2 shift/reduce conflicts [-Wconflicts-sr]
 Shift/reduce conflict on token A:
   Example              b . A X X Y
-  First derivation     a ::=[ r ::=[ b . ] t ::=[ A x ::=[ X ] xy ::=[ X Y ] ] ]
+  First derivation     a -> [ r -> [ b . ] t -> [ A x -> [ X ] xy -> [ X Y ] ] ]
-  Second derivation    a ::=[ s ::=[ b . xx ::=[ A X X ] y ::=[ Y ] ] ]
+  Second derivation    a -> [ s -> [ b . xx -> [ A X X ] y -> [ Y ] ] ]
 
 Shift/reduce conflict on token X:
   First example        X . X xy
-  First derivation     a ::=[ x ::=[ X . ] t ::=[ X xy ] ]
+  First derivation     a -> [ x -> [ X . ] t -> [ X xy ] ]
   Second example       A X . X
-  Second derivation    a ::=[ t ::=[ A xx ::=[ X . X ] ] ]
+  Second derivation    a -> [ t -> [ A xx -> [ X . X ] ] ]
 
 input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
 input.y:8.4: warning: rule useless in parser due to conflicts [-Wother]
@@ -242,8 +242,8 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 reduce/reduce conflict [-Wconflicts-rr]
 Reduce/reduce conflict on token $end:
   Example              A b .
-  First derivation     a ::=[ A b . ]
+  First derivation     a -> [ A b . ]
-  Second derivation    a ::=[ A b ::=[ b . ] ]
+  Second derivation    a -> [ A b -> [ b . ] ]
 
 input.y:4.9: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -269,9 +269,9 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 2 reduce/reduce conflicts [-Wconflicts-rr]
 Reduce/reduce conflict on tokens A, C:
   First example        D . A $end
-  First derivation     $accept ::=[ s ::=[ a ::=[ D . ] A ] $end ]
+  First derivation     $accept -> [ s -> [ a -> [ D . ] A ] $end ]
   Second example       B D . A $end
-  Second derivation    $accept ::=[ s ::=[ B b ::=[ D . ] A ] $end ]
+  Second derivation    $accept -> [ s -> [ B b -> [ D . ] A ] $end ]
 
 input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -298,9 +298,9 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 Shift/reduce conflict on token J:
 time limit exceeded: XXX
   First example        H i . J $end
-  First derivation     $accept ::=[ s ::=[ a ::=[ H i . ] J ] $end ]
+  First derivation     $accept -> [ s -> [ a -> [ H i . ] J ] $end ]
   Second example       H i . J K $end
-  Second derivation    $accept ::=[ a ::=[ H i ::=[ i . J K ] ] $end ]
+  Second derivation    $accept -> [ a -> [ H i -> [ i . J K ] ] $end ]
 
 input.y:4.4-6: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -330,13 +330,13 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 Shift/reduce conflict on token B:
   Example              N A . B C
-  First derivation     s ::=[ n ::=[ N a ::=[ A . ] B ] C ]
+  First derivation     s -> [ n -> [ N a -> [ A . ] B ] C ]
-  Second derivation    s ::=[ n ::=[ N b ::=[ A . B C ] ] ]
+  Second derivation    s -> [ n -> [ N b -> [ A . B C ] ] ]
 
 Shift/reduce conflict on token B:
   Example              N N A . B D C
-  First derivation     s ::=[ n ::=[ N n ::=[ N a ::=[ A . ] B ] D ] C ]
+  First derivation     s -> [ n -> [ N n -> [ N a -> [ A . ] B ] D ] C ]
-  Second derivation    s ::=[ n ::=[ N n ::=[ N b ::=[ A . B D ] ] C ] ]
+  Second derivation    s -> [ n -> [ N n -> [ N b -> [ A . B D ] ] C ] ]
 
 input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -367,13 +367,13 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 4 reduce/reduce conflicts [-Wconflicts-rr]
 Reduce/reduce conflict on tokens b, c:
   Example              B . b c
-  First derivation     S ::=[ B ::=[ A ::=[ B . ] b A ::=[ ] ] C ::=[ A ::=[ ] c A ::=[ ] ] ]
+  First derivation     S -> [ B -> [ A -> [ B . ] b A -> [ ] ] C -> [ A -> [ ] c A -> [ ] ] ]
-  Second derivation    S ::=[ B C ::=[ A ::=[ B ::=[ A ::=[ . ] b A ::=[ ] ] ] c A ::=[ ] ] ]
+  Second derivation    S -> [ B C -> [ A -> [ B -> [ A -> [ . ] b A -> [ ] ] ] c A -> [ ] ] ]
 
 Reduce/reduce conflict on tokens b, c:
   Example              C . c b
-  First derivation     S ::=[ C ::=[ A ::=[ C . ] c A ::=[ ] ] B ::=[ A ::=[ ] b A ::=[ ] ] ]
+  First derivation     S -> [ C -> [ A -> [ C . ] c A -> [ ] ] B -> [ A -> [ ] b A -> [ ] ] ]
-  Second derivation    S ::=[ C B ::=[ A ::=[ C ::=[ A ::=[ . ] c A ::=[ ] ] ] b A ::=[ ] ] ]
+  Second derivation    S -> [ C B -> [ A -> [ C -> [ A -> [ . ] c A -> [ ] ] ] b A -> [ ] ] ]
 
 ]])
 
@@ -400,52 +400,52 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 input.y: warning: 6 reduce/reduce conflicts [-Wconflicts-rr]
 Reduce/reduce conflict on token A:
   First example        . c A A $end
-  First derivation     $accept ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] $end ]
+  First derivation     $accept -> [ a -> [ b -> [ . ] d -> [ c A A ] ] $end ]
   Second example       . c A A $end
-  Second derivation    $accept ::=[ a ::=[ c ::=[ . ] d ::=[ c A A ] ] $end ]
+  Second derivation    $accept -> [ a -> [ c -> [ . ] d -> [ c A A ] ] $end ]
 
 Reduce/reduce conflict on token A:
 time limit exceeded: XXX
   First example        b . c A A $end
-  First derivation     $accept ::=[ a ::=[ b d ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] ] ] $end ]
+  First derivation     $accept -> [ a -> [ b d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] $end ]
   Second example       b . A $end
-  Second derivation    $accept ::=[ a ::=[ b d ::=[ c ::=[ . ] A ] ] $end ]
+  Second derivation    $accept -> [ a -> [ b d -> [ c -> [ . ] A ] ] $end ]
 
 Reduce/reduce conflict on token A:
 time limit exceeded: XXX
   First example        c . c A A $end
-  First derivation     $accept ::=[ a ::=[ c d ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] ] ] $end ]
+  First derivation     $accept -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] $end ]
   Second example       c . A $end
-  Second derivation    $accept ::=[ a ::=[ c d ::=[ c ::=[ . ] A ] ] $end ]
+  Second derivation    $accept -> [ a -> [ c d -> [ c -> [ . ] A ] ] $end ]
 
 Shift/reduce conflict on token A:
 time limit exceeded: XXX
   First example        b c . c A A $end
-  First derivation     $accept ::=[ a ::=[ b d ::=[ a ::=[ c d ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] ] ] ] ] $end ]
+  First derivation     $accept -> [ a -> [ b d -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] ] ] $end ]
   Second example       b c . A
-  Second derivation    a ::=[ b d ::=[ c . A ] ]
+  Second derivation    a -> [ b d -> [ c . A ] ]
 
 Reduce/reduce conflict on token A:
   First example        b c . c A A $end
-  First derivation     $accept ::=[ a ::=[ b d ::=[ a ::=[ c d ::=[ a ::=[ b ::=[ . ] d ::=[ c A A ] ] ] ] ] ] $end ]
+  First derivation     $accept -> [ a -> [ b d -> [ a -> [ c d -> [ a -> [ b -> [ . ] d -> [ c A A ] ] ] ] ] ] $end ]
   Second example       b c . A $end
-  Second derivation    $accept ::=[ a ::=[ b d ::=[ a ::=[ c d ::=[ c ::=[ . ] A ] ] ] ] $end ]
+  Second derivation    $accept -> [ a -> [ b d -> [ a -> [ c d -> [ c -> [ . ] A ] ] ] ] $end ]
 
 Shift/reduce conflict on token A:
   First example        b c . A $end
-  First derivation     $accept ::=[ a ::=[ b d ::=[ a ::=[ c d ::=[ c ::=[ . ] A ] ] ] ] $end ]
+  First derivation     $accept -> [ a -> [ b d -> [ a -> [ c d -> [ c -> [ . ] A ] ] ] ] $end ]
   Second example       b c . A
-  Second derivation    a ::=[ b d ::=[ c . A ] ]
+  Second derivation    a -> [ b d -> [ c . A ] ]
 
 Reduce/reduce conflict on token $end:
   Example              b d .
-  First derivation     a ::=[ b d . ]
+  First derivation     a -> [ b d . ]
-  Second derivation    a ::=[ b d ::=[ d . ] ]
+  Second derivation    a -> [ b d -> [ d . ] ]
 
 Reduce/reduce conflict on token $end:
   Example              c d .
-  First derivation     a ::=[ c d . ]
+  First derivation     a -> [ c d . ]
-  Second derivation    a ::=[ c d ::=[ d . ] ]
+  Second derivation    a -> [ c d -> [ d . ] ]
 
 input.y:5.4: warning: rule useless in parser due to conflicts [-Wother]
 input.y:6.15: warning: rule useless in parser due to conflicts [-Wother]
@@ -475,8 +475,8 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 Shift/reduce conflict on token J:
   Example              H i J . J J
-  First derivation     s ::=[ a ::=[ H i ::=[ i J . ] J J ] ]
+  First derivation     s -> [ a -> [ H i -> [ i J . ] J J ] ]
-  Second derivation    s ::=[ a ::=[ H i J . J ] J ]
+  Second derivation    s -> [ a -> [ H i J . J ] J ]
 
 input.y:5.13-15: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -507,8 +507,8 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 Shift/reduce conflict on token D:
   Example              A a . D
-  First derivation     s ::=[ A a a ::=[ b ::=[ c ::=[ . ] ] ] d ::=[ D ] ]
+  First derivation     s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] ]
-  Second derivation    s ::=[ A a d ::=[ . D ] ]
+  Second derivation    s -> [ A a d -> [ . D ] ]
 
 ]])
 
@@ -537,9 +537,9 @@ AT_BISON_CHECK_CEX([input.y], [], [],
 [[input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
 Shift/reduce conflict on token D:
   First example        A a . D E $end
-  First derivation     $accept ::=[ s ::=[ A a a ::=[ b ::=[ c ::=[ . ] ] ] d ::=[ D ] E ] $end ]
+  First derivation     $accept -> [ s -> [ A a a -> [ b -> [ c -> [ . ] ] ] d -> [ D ] E ] $end ]
   Second example       A a . D $end
-  Second derivation    $accept ::=[ s ::=[ A a d ::=[ . D ] ] $end ]
+  Second derivation    $accept -> [ s -> [ A a d -> [ . D ] ] $end ]
 
 ]])
 

tests/diagnostics.at

@@ -376,10 +376,12 @@ exp:^M
 ]],
 [0],
 [[input.y:11.9-11: <warning>warning:</warning> symbol FOO redeclared [<warning>-Wother</warning>]
-   11 | %token 
+   11 | %token 
+ <warning>FOO</warning>
       |         <warning>^~~</warning>
 input.y:10.9-11: <note>note:</note> previous declaration
-input.y:10.9-11: <note>note:</note> previous declaration
+   10 | %token 
+ <note>FOO</note>
       |         <note>^~~</note>
 input.y:13.5: <warning>warning:</warning> empty rule without %empty [<warning>-Wempty-rule</warning>]
    13 | exp:
@@ -535,27 +537,27 @@ exp
 [[input.y: <error>error:</error> shift/reduce conflicts: 4 found, 0 expected
 Shift/reduce conflict on token "+":
   Example              <cex-0><cex-1><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
-Shift/reduce conflict on token "+":
+  First derivation     <cex-0><cex-step>exp → [ </cex-step><cex-1><cex-step>exp → [ </cex-step><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot><cex-step> ]</cex-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
   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>
-  First derivation     <cex-0><cex-step>exp ::=[ </cex-step><cex-1><cex-step>exp ::=[ </cex-step><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot><cex-step> ]</cex-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
+  Second derivation    <cex-0><cex-step>exp → [ </cex-step><cex-leaf>exp</cex-leaf> <cex-leaf>"+"</cex-leaf><cex-1> <cex-step>exp → [ </cex-step><cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-1><cex-step> ]</cex-step></cex-0>
 
 Shift/reduce conflict on token "else":
   Example              <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><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>"else"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
-Shift/reduce conflict on token "else":
+  First derivation     <cex-0><cex-step>exp → [ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-step>exp → [ </cex-step><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-step></cex-1> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
   Example              <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><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-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-1></cex-0>
-  First derivation     <cex-0><cex-step>exp ::=[ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-step>exp ::=[ </cex-step><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-step></cex-1> <cex-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
+  Second derivation    <cex-0><cex-step>exp → [ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-step>exp → [ </cex-step><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-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-1><cex-step> ]</cex-step></cex-0>
 
 Shift/reduce conflict on token "+":
   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>
-Shift/reduce conflict on token "+":
+  First derivation     <cex-0><cex-step>exp → [ </cex-step><cex-1><cex-step>exp → [ </cex-step><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-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
   Example              <cex-0><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</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>
-  First derivation     <cex-0><cex-step>exp ::=[ </cex-step><cex-1><cex-step>exp ::=[ </cex-step><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-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
+  Second derivation    <cex-0><cex-step>exp → [ </cex-step><cex-leaf>"if"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-leaf>"then"</cex-leaf><cex-1> <cex-step>exp → [ </cex-step><cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-1><cex-step> ]</cex-step></cex-0>
 
 Shift/reduce conflict on token "+":
   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-leaf>"else"</cex-leaf> <cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf></cex-0>
-Shift/reduce conflict on token "+":
+  First derivation     <cex-0><cex-step>exp → [ </cex-step><cex-1><cex-step>exp → [ </cex-step><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-leaf>exp</cex-leaf> <cex-dot>•</cex-dot><cex-step> ]</cex-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
   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>
-  First derivation     <cex-0><cex-step>exp ::=[ </cex-step><cex-1><cex-step>exp ::=[ </cex-step><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-leaf>exp</cex-leaf> <cex-dot>•</cex-dot><cex-step> ]</cex-step></cex-1> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-0>
+  Second derivation    <cex-0><cex-step>exp → [ </cex-step><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-step>exp → [ </cex-step><cex-leaf>exp</cex-leaf> <cex-dot>•</cex-dot> <cex-leaf>"+"</cex-leaf> <cex-leaf>exp</cex-leaf><cex-step> ]</cex-step></cex-1><cex-step> ]</cex-step></cex-0>
 
 ]])
 

tests/report.at

@@ -1539,33 +1539,33 @@ AT_CHECK([LC_ALL="$locale" bison -fno-caret -o input.cc -rall -Wcex --graph=inpu
 input.y: warning: 3 reduce/reduce conflicts [-Wconflicts-rr]
 Shift/reduce conflict on token "⊕":
   Example              exp "+" exp • "⊕" exp
-  First derivation     exp ::=[ exp ::=[ exp "+" exp • ] "⊕" exp ]
+  First derivation     exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
-  Second derivation    exp ::=[ exp "+" exp ::=[ exp • "⊕" exp ] ]
+  Second derivation    exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
 
 Reduce/reduce conflict on tokens $end, "+", "⊕":
   Example              exp "+" exp •
-  First derivation     exp ::=[ exp "+" exp • ]
+  First derivation     exp → [ exp "+" exp • ]
-  Second derivation    exp ::=[ exp "+" exp • ]
+  Second derivation    exp → [ exp "+" exp • ]
 
 Shift/reduce conflict on token "⊕":
   Example              exp "+" exp • "⊕" exp
-  First derivation     exp ::=[ exp ::=[ exp "+" exp • ] "⊕" exp ]
+  First derivation     exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
-  Second derivation    exp ::=[ exp "+" exp ::=[ exp • "⊕" exp ] ]
+  Second derivation    exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
 
 Shift/reduce conflict on token "⊕":
   Example              exp "⊕" exp • "⊕" exp
-  First derivation     exp ::=[ exp ::=[ exp "⊕" exp • ] "⊕" exp ]
+  First derivation     exp → [ exp → [ exp "⊕" exp • ] "⊕" exp ]
-  Second derivation    exp ::=[ exp "⊕" exp ::=[ exp • "⊕" exp ] ]
+  Second derivation    exp → [ exp "⊕" exp → [ exp • "⊕" exp ] ]
 
 Shift/reduce conflict on token "+":
   Example              exp "⊕" exp • "+" exp
-  First derivation     exp ::=[ exp ::=[ exp "⊕" exp • ] "+" exp ]
+  First derivation     exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
-  Second derivation    exp ::=[ exp "⊕" exp ::=[ exp • "+" exp ] ]
+  Second derivation    exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
 
 Shift/reduce conflict on token "+":
   Example              exp "⊕" exp • "+" exp
-  First derivation     exp ::=[ exp ::=[ exp "⊕" exp • ] "+" exp ]
+  First derivation     exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
-  Second derivation    exp ::=[ exp "⊕" exp ::=[ exp • "+" exp ] ]
+  Second derivation    exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
 
 input.y:6.3-13: warning: rule useless in parser due to conflicts [-Wother]
 ]])
@@ -1714,22 +1714,22 @@ State 7
         2 exp: exp "+" exp •
         1 exp: exp • "⊕" exp
       Example                  exp "+" exp • "⊕" exp
-      First derivation         exp ::=[ exp ::=[ exp "+" exp • ] "⊕" exp ]
+      First derivation         exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
-      Second derivation        exp ::=[ exp "+" exp ::=[ exp • "⊕" exp ] ]
+      Second derivation        exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
 
     Reduce/reduce conflict on tokens $end, "+", "⊕":
         2 exp: exp "+" exp •
         3 exp: exp "+" exp •
       Example                  exp "+" exp •
-      First derivation         exp ::=[ exp "+" exp • ]
+      First derivation         exp → [ exp "+" exp • ]
-      Second derivation        exp ::=[ exp "+" exp • ]
+      Second derivation        exp → [ exp "+" exp • ]
 
     Shift/reduce conflict on token "⊕":
         3 exp: exp "+" exp •
         1 exp: exp • "⊕" exp
       Example                  exp "+" exp • "⊕" exp
-      First derivation         exp ::=[ exp ::=[ exp "+" exp • ] "⊕" exp ]
+      First derivation         exp → [ exp → [ exp "+" exp • ] "⊕" exp ]
-      Second derivation        exp ::=[ exp "+" exp ::=[ exp • "⊕" exp ] ]
+      Second derivation        exp → [ exp "+" exp → [ exp • "⊕" exp ] ]
 
 
 
@@ -1751,22 +1751,22 @@ State 8
         1 exp: exp "⊕" exp •
         1 exp: exp • "⊕" exp
       Example                  exp "⊕" exp • "⊕" exp
-      First derivation         exp ::=[ exp ::=[ exp "⊕" exp • ] "⊕" exp ]
+      First derivation         exp → [ exp → [ exp "⊕" exp • ] "⊕" exp ]
-      Second derivation        exp ::=[ exp "⊕" exp ::=[ exp • "⊕" exp ] ]
+      Second derivation        exp → [ exp "⊕" exp → [ exp • "⊕" exp ] ]
 
     Shift/reduce conflict on token "+":
         1 exp: exp "⊕" exp •
         2 exp: exp • "+" exp
       Example                  exp "⊕" exp • "+" exp
-      First derivation         exp ::=[ exp ::=[ exp "⊕" exp • ] "+" exp ]
+      First derivation         exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
-      Second derivation        exp ::=[ exp "⊕" exp ::=[ exp • "+" exp ] ]
+      Second derivation        exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
 
     Shift/reduce conflict on token "+":
         1 exp: exp "⊕" exp •
         3 exp: exp • "+" exp
       Example                  exp "⊕" exp • "+" exp
-      First derivation         exp ::=[ exp ::=[ exp "⊕" exp • ] "+" exp ]
+      First derivation         exp → [ exp → [ exp "⊕" exp • ] "+" exp ]
-      Second derivation        exp ::=[ exp "⊕" exp ::=[ exp • "+" exp ] ]
+      Second derivation        exp → [ exp "⊕" exp → [ exp • "+" exp ] ]
 
 ]])