nobu	2010-04-21 12:15:49 +0900 (Wed, 21 Apr 2010)

  New Revision: 27429

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=27429

  Log:
    * parse.y (parser_yylex): warn confusing binary operators after
      local variable.

  Modified files:
    trunk/ChangeLog
    trunk/parse.y

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 27428)
+++ ChangeLog	(revision 27429)
@@ -1,3 +1,8 @@
+Wed Apr 21 12:15:46 2010  Nobuyoshi Nakada  <nobu@r...>
+
+	* parse.y (parser_yylex): warn confusing binary operators after
+	  local variable.
+
 Wed Apr 21 11:53:47 2010  Eric Hodel  <drbrain@s...>
 
 	* lib/rdoc:  Update to RDoc 2.5.5.  Fixes bugs in ri, Darkfish and
Index: parse.y
===================================================================
--- parse.y	(revision 27428)
+++ parse.y	(revision 27429)
@@ -6418,6 +6418,15 @@
 #define IS_BEG() (lex_state == EXPR_BEG || lex_state == EXPR_MID || lex_state == EXPR_VALUE || lex_state == EXPR_CLASS)
 #define IS_SPCARG(c) (IS_ARG() && space_seen && !ISSPACE(c))
 
+#ifndef RIPPER
+#define ambiguous_operator(op, syn) ( \
+    rb_warning0("`"op"' after local variable is interpreted as binary operator"), \
+    rb_warning0("even though it seems like "syn""))
+#else
+#define ambiguous_operator(op, syn) dispatch2(operator_ambiguous, ripper_intern(op), rb_str_new_cstr(syn))
+#endif
+#define warn_balanced(op, syn) (space_seen && !ISSPACE(c) && (ambiguous_operator(op, syn), 0))
+
 static int
 parser_yylex(struct parser_params *parser)
 {
@@ -6463,7 +6472,7 @@
 	/* white spaces */
       case ' ': case '\t': case '\f': case '\r':
       case '\13': /* '\v' */
-	space_seen++;
+	space_seen = 1;
 #ifdef RIPPER
 	while ((c = nextc())) {
 	    switch (c) {
@@ -6514,7 +6523,7 @@
 	    switch (c) {
 	      case ' ': case '\t': case '\f': case '\r':
 	      case '\13': /* '\v' */
-		space_seen++;
+		space_seen = 1;
 		break;
 	      case '.': {
 		  if ((c = nextc()) != '.') {
@@ -6566,6 +6575,7 @@
 		c = tSTAR;
 	    }
 	    else {
+		warn_balanced("*", "argument prefix");
 		c = '*';
 	    }
 	}
@@ -6686,6 +6696,7 @@
 		return tOP_ASGN;
 	    }
 	    pushback(c);
+	    warn_balanced("<<", "here document");
 	    return tLSHFT;
 	}
 	pushback(c);
@@ -6836,6 +6847,7 @@
 	    c = tAMPER;
 	}
 	else {
+	    warn_balanced("&", "argument prefix");
 	    c = '&';
 	}
 	switch (lex_state) {
@@ -6897,6 +6909,7 @@
 	}
 	lex_state = EXPR_BEG;
 	pushback(c);
+	warn_balanced("+", "unary operator");
 	return '+';
 
       case '-':
@@ -6928,6 +6941,7 @@
 	}
 	lex_state = EXPR_BEG;
 	pushback(c);
+	warn_balanced("-", "unary operator");
 	return '-';
 
       case '.':
@@ -7230,6 +7244,7 @@
 	  default:
 	    lex_state = EXPR_BEG; break;
 	}
+	warn_balanced("/", "regexp literal");
 	return '/';
 
       case '^':
@@ -7422,6 +7437,7 @@
 	    lex_state = EXPR_BEG; break;
 	}
 	pushback(c);
+	warn_balanced("%%", "string literal");
 	return '%';
 
       case '$':

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