yui-knk	2018-06-10 15:22:15 +0900 (Sun, 10 Jun 2018)

  New Revision: 63623

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=63623

  Log:
    parse.y: Fix locations of none and mid-rule actions
    
    When an empty rule or a mid-rule action is reduced,
    `YYLLOC_DEFAULT` is called with the third parameter to be zero.
    If we use `RUBY_SET_YYLLOC_OF_NONE` to set their locations,
    sometimes the end position of NODE indicates a blank.
    For example, `a.b ;` generates `NODE_CALL (line: 1, location: (1,0)-(1,4))*`,
    whose end position indicates a blank.
    
    This is because of the following reasons:
    
    * `NODE_CALL` is created when `primary_value call_op operation2 opt_paren_args` is
      reduced to `method_call`.
    * `opt_paren_args` is `none`.
    * `yylex` is called and `lex.pbeg` moves before `none` is reduced, so
      the beginning position of `none` does not match with the end position of `operation2`.
    
    To fix locations, use `YYRHSLOC(Rhs, 0)` in `YYLLOC_DEFAULT`
    (0 "refers to the symbol just before the reduction").
    
    By this change, the bottom of the location stack would be referenced,
    so initialize the bottom with `RUBY_SET_YYLLOC_OF_NONE` in `%initial-action`.
    
    Ref: https://www.gnu.org/software/bison/manual/html_node/Location-Default-Action.html#Location-Default-Action

  Modified files:
    trunk/parse.y
Index: parse.y
===================================================================
--- parse.y	(revision 63622)
+++ parse.y	(revision 63623)
@@ -59,7 +59,10 @@ https://github.com/ruby/ruby/blob/trunk/parse.y#L59
 	  (Current).end_pos = YYRHSLOC(Rhs, N).end_pos;			\
 	}								\
       else								\
-	RUBY_SET_YYLLOC_OF_NONE(Current);				\
+        {                                                               \
+          (Current).beg_pos = YYRHSLOC(Rhs, 0).end_pos;                 \
+          (Current).end_pos = YYRHSLOC(Rhs, 0).end_pos;                 \
+        }                                                               \
     while (0)
 
 #define RUBY_SET_YYLLOC_FROM_STRTERM_HEREDOC(Current)			\
@@ -747,6 +750,10 @@ static void token_info_warn(struct parse https://github.com/ruby/ruby/blob/trunk/parse.y#L750
 %pure-parser
 %lex-param {struct parser_params *p}
 %parse-param {struct parser_params *p}
+%initial-action
+{
+    RUBY_SET_YYLLOC_OF_NONE(@$);
+};
 
 %union {
     VALUE val;

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