style: comment and formatting changes

[Akim Demaille]

Some refactoring before a more important change that follows.
This is a 'diff -w', to avoid useless diffs in the indentation
changes because of the new braces in scan-code.l.

commit e40db8976c9448ee99a6c01d780bcda2e046478c
Author: Akim Demaille <address@hidden>
Date:   Sun Dec 2 08:32:01 2018 +0100

    style: comment and formatting changes
    
    * data/bison.m4, data/c++.m4, data/glr.c, data/java.m4, data/lalr1.cc,
    * data/yacc.c, src/scan-code.l:
    Fix comments.
    Prefer POS to denote the position of a symbol in a rule, since NUM
    is also used to denote symbol numbers.

diff --git a/data/bison.m4 b/data/bison.m4
index d2db2c86..4be8e696 100644
--- a/data/bison.m4
+++ b/data/bison.m4
@@ -391,7 +391,7 @@ b4_define_flag_if([yacc])               # Whether POSIX 
Yacc is emulated.
 #   If has_id, the id.  Guaranteed to be usable as a C identifier.
 #   Prefixed by api.token.prefix if defined.
 # - tag: string.
-#   A representat of the symbol.  Can be 'foo', 'foo.id', '"foo"' etc.
+#   A representation of the symbol.  Can be 'foo', 'foo.id', '"foo"' etc.
 # - user_number: integer
 #   The assigned (external) number as used by yylex.
 # - is_token: 0 or 1
@@ -497,7 +497,7 @@ m4_define([b4_symbol_actions],
 m4_ifval(m4_defn([b4_actions_]),
 [switch (m4_default([$2], [yytype]))
     {
-      m4_defn([b4_actions_])
+m4_defn([b4_actions_])[]dnl
       default:
         break;
     }dnl
@@ -569,7 +569,7 @@ m4_define([b4_token_format],
 # Run actions for the symbol NUMS that all have the same type-name.
 # Skip NUMS that have no type-name.
 #
-# To specify the action to run, define b4_dollar_dollar(NUMBER,
+# To specify the action to run, define b4_dollar_dollar(SYMBOL-NUM,
 # TAG, TYPE).
 m4_define([_b4_type_action],
 [b4_symbol_if([$1], [has_type],
diff --git a/data/c++.m4 b/data/c++.m4
index 3701525a..e3993edc 100644
--- a/data/c++.m4
+++ b/data/c++.m4
@@ -528,10 +528,11 @@ m4_define([b4_lhs_value],
 [b4_symbol_value([yyval], [$1])])
 
 
-# b4_rhs_value(RULE-LENGTH, NUM, [TYPE])
+# b4_rhs_value(RULE-LENGTH, POS, [TYPE])
 # --------------------------------------
-# Expansion of $<TYPE>NUM, where the current rule has RULE-LENGTH
+# Expansion of $<TYPE>POS, where the current rule has RULE-LENGTH
 # symbols on RHS.
+# FIXME: Dead code.
 m4_define([b4_rhs_value],
 [b4_symbol_value(address@hidden($1) - ($2)@}], [$3])])
 
@@ -543,9 +544,9 @@ m4_define([b4_lhs_location],
 [(yyloc)])
 
 
-# b4_rhs_location(RULE-LENGTH, NUM)
+# b4_rhs_location(RULE-LENGTH, POS)
 # ---------------------------------
-# Expansion of @NUM, where the current rule has RULE-LENGTH symbols
+# Expansion of @POS, where the current rule has RULE-LENGTH symbols
 # on RHS.
 m4_define([b4_rhs_location],
 [(address@hidden($1) - ($2)@})])
diff --git a/data/glr.c b/data/glr.c
index 437677d8..4c0c0165 100644
--- a/data/glr.c
+++ b/data/glr.c
@@ -119,10 +119,10 @@ m4_define([b4_lhs_value],
 [b4_symbol_value([(*yyvalp)], [$1])])
 
 
-# b4_rhs_data(RULE-LENGTH, NUM)
+# b4_rhs_data(RULE-LENGTH, POS)
 # -----------------------------
 # Expand to the semantic stack place that contains value and location
-# of symbol number NUM in a rule of length RULE-LENGTH.
+# of symbol number POS in a rule of length RULE-LENGTH.
 m4_define([b4_rhs_data],
 [((yyGLRStackItem const *)yyvsp)@{YYFILL (b4_subtract([$2], [$1]))@}.yystate])
 
diff --git a/data/java.m4 b/data/java.m4
index 5ac145c4..12491fd4 100644
--- a/data/java.m4
+++ b/data/java.m4
@@ -242,9 +242,9 @@ m4_define([b4_lhs_location],
 [(yyloc)])
 
 
-# b4_rhs_location(RULE-LENGTH, NUM)
+# b4_rhs_location(RULE-LENGTH, POS)
 # ---------------------------------
-# Expansion of @NUM, where the current rule has RULE-LENGTH symbols
+# Expansion of @POS, where the current rule has RULE-LENGTH symbols
 # on RHS.
 m4_define([b4_rhs_location],
 [yystack.locationAt ($1-($2))])
diff --git a/data/lalr1.cc b/data/lalr1.cc
index 322971bf..b66846b4 100644
--- a/data/lalr1.cc
+++ b/data/lalr1.cc
@@ -64,17 +64,17 @@ m4_define([b4_lhs_location],
 [yylhs.location])
 
 
-# b4_rhs_data(RULE-LENGTH, NUM)
+# b4_rhs_data(RULE-LENGTH, POS)
 # -----------------------------
-# Return the data corresponding to the symbol #NUM, where the current
+# Return the data corresponding to the symbol #POS, where the current
 # rule has RULE-LENGTH symbols on RHS.
 m4_define([b4_rhs_data],
 address@hidden($@)@}])
 
 
-# b4_rhs_state(RULE-LENGTH, NUM)
+# b4_rhs_state(RULE-LENGTH, POS)
 # ------------------------------
-# The state corresponding to the symbol #NUM, where the current
+# The state corresponding to the symbol #POS, where the current
 # rule has RULE-LENGTH symbols on RHS.
 m4_define([b4_rhs_state],
 [b4_rhs_data([$1], [$2]).state])
@@ -93,9 +93,9 @@ m4_define([b4_rhs_value],
                          [_b4_rhs_value($@)])])
 
 
-# b4_rhs_location(RULE-LENGTH, NUM)
+# b4_rhs_location(RULE-LENGTH, POS)
 # ---------------------------------
-# Expansion of @NUM, where the current rule has RULE-LENGTH symbols
+# Expansion of @POS, where the current rule has RULE-LENGTH symbols
 # on RHS.
 m4_define([b4_rhs_location],
 [b4_rhs_data([$1], [$2]).location])
diff --git a/data/yacc.c b/data/yacc.c
index ee0acd5b..ff023e88 100644
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -154,9 +154,9 @@ m4_define([b4_lhs_location],
 [(yyloc)])
 
 
-# b4_rhs_location(RULE-LENGTH, NUM)
+# b4_rhs_location(RULE-LENGTH, POS)
 # ---------------------------------
-# Expansion of @NUM, where the current rule has RULE-LENGTH symbols
+# Expansion of @POS, where the current rule has RULE-LENGTH symbols
 # on RHS.
 m4_define([b4_rhs_location],
 [(address@hidden([$2], [$1])@})])
diff --git a/src/scan-code.l b/src/scan-code.l
index ed21d547..a58ab4be 100644
--- a/src/scan-code.l
+++ b/src/scan-code.l
@@ -611,14 +611,12 @@ handle_action_dollar (symbol_list *rule, char *text, 
location dollar_loc)
       effective_rule_length = symbol_list_length (rule->next);
     }
 
-  /* Get the type name if explicit. */
+  /* The type name if explicit, otherwise left null. */
   char const *type_name = NULL;
   char *cp = fetch_type_name (text + 1, &type_name, dollar_loc);
-
   int n = parse_ref (cp, effective_rule, effective_rule_length,
                      rule->midrule_parent_rhs_index, text, dollar_loc, '$');
-
-  /* End type_name. */
+  /* End type_name.  Don't do it ealier: parse_ref depends on TEXT.  */
   if (type_name)
     cp[-1] = '\0';
 
@@ -628,6 +626,7 @@ handle_action_dollar (symbol_list *rule, char *text, 
location dollar_loc)
       break;
 
     case LHS_REF:
+      {
         if (!type_name)
           type_name = symbol_list_n_type_name_get (rule, 0);
 
@@ -654,9 +653,12 @@ handle_action_dollar (symbol_list *rule, char *text, 
location dollar_loc)
         obstack_quote (&obstack_for_string, type_name);
         obstack_sgrow (&obstack_for_string, ")[");
         rule->action_props.is_value_used = true;
+      }
       break;
 
+      /* Reference to a RHS symbol.  */
     default:
+      {
         if (max_left_semantic_context < 1 - n)
           max_left_semantic_context = 1 - n;
         if (!type_name && 0 < n)
@@ -685,6 +687,7 @@ handle_action_dollar (symbol_list *rule, char *text, 
location dollar_loc)
                         n);
             sym->action_props.is_value_used = true;
           }
+      }
       break;
     }
 }