diff --git a/ChangeLog b/ChangeLog
index 84f9c1e43b..cce0ff4ccd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,31 @@
+Sun Dec  2 01:39:51 2007  Tanaka Akira  <akr@fsij.org>
+
+	* include/ruby/intern.h (rb_uv_to_utf8): declared.
+
+	* re.c (rb_reg_preprocess): new function for dynamic regexp with
+	  \u{} such as Regexp.new("\\u{6666}").
+	  (rb_reg_prepare_re): preprocess regexp for recompiling.
+	  (read_escaped_byte): new function.
+	  (unescape_escaped_nonascii): new function.
+	  (append_utf8): new function.
+	  (unescape_unicode_list): new function.
+	  (unescape_unicode_bmp): new function.
+	  (unescape_nonascii): new function.
+	  (rb_reg_initialize): preprocess regexp.
+
+	* pack.c (rb_uv_to_utf8): renamed from uv_to_utf8.
+
+	* parse.y (STR_NEW3): take func instead of has8 and hasmb.
+	  (parser_str_new): use default coderange mechanism except for regexp.
+	  (parser_tokadd_utf8): copy regexp source as-is.
+	  (parser_read_escape): UTF-8 stuff removed.
+	  (parser_tokadd_escape): has8bit and hasmb removed.
+	  (parser_tokadd_string): fix 8-bit single byte character with \u.
+	  (parser_parse_string): has8bit and hasmb removed.
+	  (parser_here_document): has8bit and hasmb removed.
+	  (parser_yylex): call parser_tokadd_utf8 instead of read_escape for
+	  UTF-8 character.
+
 Wed Dec  2 01:00:07 2007  James Edward Gray II  <jeg2@ruby-lang.org>
 
 	* lib/xmlrpc/server.rb (XMLRPC::Server#server): Improve signal handling so
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index a43d4d31ab..42f61a91bc 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -101,6 +101,7 @@ unsigned LONG_LONG rb_big2ull(VALUE);
 #endif  /* HAVE_LONG_LONG */
 void rb_quad_pack(char*,VALUE);
 VALUE rb_quad_unpack(const char*,int);
+int rb_uv_to_utf8(char[6],unsigned long);
 VALUE rb_dbl2big(double);
 double rb_big2dbl(VALUE);
 VALUE rb_big_cmp(VALUE, VALUE);
diff --git a/pack.c b/pack.c
index 4cab476bd2..b1d7268850 100644
--- a/pack.c
+++ b/pack.c
@@ -365,7 +365,6 @@ static const char toofew[] = "too few arguments";
 static void encodes(VALUE,const char*,long,int);
 static void qpencode(VALUE,VALUE,long);
 
-static int uv_to_utf8(char*,unsigned long);
 static unsigned long utf8_to_uv(const char*,long*);
 
 /*
@@ -872,7 +871,7 @@ pack_pack(VALUE ary, VALUE fmt)
 		if (l < 0) {
 		    rb_raise(rb_eRangeError, "pack(U): value out of range");
 		}
-		le = uv_to_utf8(buf, l);
+		le = rb_uv_to_utf8(buf, l);
 		rb_str_buf_cat(res, (char*)buf, le);
 	    }
 	    break;
@@ -1991,8 +1990,8 @@ pack_unpack(VALUE str, VALUE fmt)
 
 #define BYTEWIDTH 8
 
-static int
-uv_to_utf8(char *buf, unsigned long uv)
+int
+rb_uv_to_utf8(char buf[6], unsigned long uv)
 {
     if (uv <= 0x7f) {
 	buf[0] = (char)uv;
diff --git a/parse.y b/parse.y
index 7f5af4e4e6..264a3d2d63 100644
--- a/parse.y
+++ b/parse.y
@@ -269,7 +269,7 @@ struct parser_params {
 #define STR_NEW(p,n) rb_enc_str_new((p),(n),parser->enc)
 #define STR_NEW0() rb_str_new(0,0)
 #define STR_NEW2(p) rb_enc_str_new((p),strlen(p),parser->enc)
-#define STR_NEW3(p,n,e,has8,hasmb) parser_str_new2((p),(n),(e),(has8),(hasmb))
+#define STR_NEW3(p,n,e,func) parser_str_new((p),(n),(e),(func))
 #define STR_ENC(m) ((m)?parser->enc:rb_enc_from_index(0))
 #define ENC_SINGLE(cr) ((cr)==ENC_CODERANGE_7BIT)
 #define TOK_INTERN(mb) rb_intern3(tok(), toklen(), STR_ENC(mb))
@@ -4488,7 +4488,7 @@ none		: /* none */
 # define yylval  (*((YYSTYPE*)(parser->parser_yylval)))
 
 static int parser_regx_options(struct parser_params*);
-static int parser_tokadd_string(struct parser_params*,int,int,int,long*,int*,int*,rb_encoding**);
+static int parser_tokadd_string(struct parser_params*,int,int,int,long*,rb_encoding**);
 static void parser_tokaddmbc(struct parser_params *parser, int c, rb_encoding *enc);
 static int parser_parse_string(struct parser_params*,NODE*);
 static int parser_here_document(struct parser_params*,NODE*);
@@ -4500,11 +4500,10 @@ static int parser_here_document(struct parser_params*,NODE*);
 # define tokspace(n)               parser_tokspace(parser, n)
 # define tokadd(c)                 parser_tokadd(parser, c)
 # define tok_hex(numlen)           parser_tok_hex(parser, numlen)
-# define tok_utf8(numlen,e)        parser_tok_utf8(parser, numlen, e)
-# define read_escape(flags,has8,hasmb,e)    parser_read_escape(parser, flags, has8, hasmb, e)
-# define tokadd_escape(t,has8,hasmb,e)      parser_tokadd_escape(parser, t, has8,hasmb, e)
+# define read_escape(flags,e)      parser_read_escape(parser, flags, e)
+# define tokadd_escape(t,e)        parser_tokadd_escape(parser, t, e)
 # define regx_options()            parser_regx_options(parser)
-# define tokadd_string(f,t,p,n,has8bit,hasmb,e) parser_tokadd_string(parser,f,t,p,n,has8bit,hasmb,e)
+# define tokadd_string(f,t,p,n,e)  parser_tokadd_string(parser,f,t,p,n,e)
 # define parse_string(n)           parser_parse_string(parser,n)
 # define tokaddmbc(c, enc)         parser_tokaddmbc(parser, c, enc)
 # define here_document(n)          parser_here_document(parser,n)
@@ -4821,37 +4820,39 @@ rb_parser_compile_file(volatile VALUE vparser, const char *f, VALUE file, int st
 }
 #endif  /* !RIPPER */
 
+#define STR_FUNC_ESCAPE 0x01
+#define STR_FUNC_EXPAND 0x02
+#define STR_FUNC_REGEXP 0x04
+#define STR_FUNC_QWORDS 0x08
+#define STR_FUNC_SYMBOL 0x10
+#define STR_FUNC_INDENT 0x20
+
+enum string_type {
+    str_squote = (0),
+    str_dquote = (STR_FUNC_EXPAND),
+    str_xquote = (STR_FUNC_EXPAND),
+    str_regexp = (STR_FUNC_REGEXP|STR_FUNC_ESCAPE|STR_FUNC_EXPAND),
+    str_sword  = (STR_FUNC_QWORDS),
+    str_dword  = (STR_FUNC_QWORDS|STR_FUNC_EXPAND),
+    str_ssym   = (STR_FUNC_SYMBOL),
+    str_dsym   = (STR_FUNC_SYMBOL|STR_FUNC_EXPAND),
+};
+
 static VALUE
-parser_str_new(const char *p, long n, rb_encoding *enc, int coderange)
+parser_str_new(const char *p, long n, rb_encoding *enc, int func)
 {
-    VALUE str = rb_enc_str_new(p, n, enc);
-    ENC_CODERANGE_SET(str, coderange);
+    VALUE str;
+
+    str = rb_enc_str_new(p, n, enc);
+    if (!(func & STR_FUNC_REGEXP) &&
+        rb_enc_asciicompat(enc) &&
+        rb_enc_str_coderange(str) == ENC_CODERANGE_7BIT) {
+        rb_enc_associate(str, rb_default_encoding());
+    }
+
     return str;
 }
 
-static VALUE
-parser_str_new2(const char *p, long n, rb_encoding *enc, int has8bit,int hasmb)
-{
-    /*
-     * Set coderange bit flags based on the presence of 8-bit and 
-     * multi-byte characters in the string
-     */
-    int coderange = ENC_CODERANGE_7BIT;
-    if (hasmb) coderange = ENC_CODERANGE_8BIT;
-    else if (has8bit) coderange = ENC_CODERANGE_UNKNOWN;
-
-    /*
-     * If it is all single byte characters with the 8th bit clear,
-     * and if the specified encoding is ASCII-compatible, then this
-     * string is in the ASCII subset, and we just use the ASCII encoding
-     * instead.
-     */
-    if ((coderange == ENC_CODERANGE_7BIT) && rb_enc_asciicompat(enc))
-	enc = rb_default_encoding();
-
-    return parser_str_new(p, n, enc, coderange);
-}
-
 static inline int
 parser_nextc(struct parser_params *parser)
 {
@@ -4979,9 +4980,11 @@ parser_tok_hex(struct parser_params *parser, int *numlen)
     return c;
 }
 
+#define tokcopy(n) memcpy(tokspace(n), lex_p - (n), (n))
+
 static int
-parser_tokadd_utf8(struct parser_params *parser, int *hasmb,
-		   rb_encoding **encp, int string_literal, int symbol_literal)
+parser_tokadd_utf8(struct parser_params *parser, rb_encoding **encp,
+                   int string_literal, int symbol_literal, int regexp_literal)
 {
     /*
      * If string_literal is true, then we allow multiple codepoints
@@ -4993,8 +4996,11 @@ parser_tokadd_utf8(struct parser_params *parser, int *hasmb,
     int codepoint;
     int numlen;
 
+    if (regexp_literal) { tokadd('\\'); tokadd('u'); }
+
     if (peek('{')) {  /* handle \u{...} form */
 	do {
+            if (regexp_literal) { tokadd(*lex_p); }
 	    nextc();
 	    codepoint = scan_hex(lex_p, 6, &numlen);
 	    if (numlen == 0)  {
@@ -5006,8 +5012,10 @@ parser_tokadd_utf8(struct parser_params *parser, int *hasmb,
 		return 0;
 	    }
 	    lex_p += numlen;
-	    if (codepoint >= 0x80) {
-		*hasmb = 1;
+            if (regexp_literal) {
+                tokcopy(numlen);
+            }
+            else if (codepoint >= 0x80) {
 		*encp = UTF8_ENC();
 		if (string_literal) tokaddmbc(codepoint, *encp);
 	    }
@@ -5026,6 +5034,7 @@ parser_tokadd_utf8(struct parser_params *parser, int *hasmb,
 	    return 0;
 	}
 
+        if (regexp_literal) { tokadd('}'); }
 	nextc();
     }
     else {			/* handle \uxxxx form */
@@ -5035,8 +5044,10 @@ parser_tokadd_utf8(struct parser_params *parser, int *hasmb,
 	    return 0;
 	}
 	lex_p += 4;
-	if (codepoint >= 0x80) {
-	    *hasmb = 1;
+        if (regexp_literal) {
+            tokcopy(4);
+        }
+	else if (codepoint >= 0x80) {
 	    *encp = UTF8_ENC();
 	    if (string_literal) tokaddmbc(codepoint, *encp);
 	}
@@ -5058,7 +5069,7 @@ parser_tokadd_utf8(struct parser_params *parser, int *hasmb,
 
 static int
 parser_read_escape(struct parser_params *parser, int flags,
-		   int *has8bit, int *hasmb, rb_encoding **encp)
+		   rb_encoding **encp)
 {
     int c;
     int numlen;
@@ -5098,19 +5109,12 @@ parser_read_escape(struct parser_params *parser, int flags,
 	    c = scan_oct(lex_p, 3, &numlen);
 	    lex_p += numlen;
 	}
-	if (c >= 0200) *has8bit = 1;
 	return c;
 
       case 'x':	/* hex constant */
 	if (flags & (ESCAPE_CONTROL|ESCAPE_META)) goto eof;
 	c = tok_hex(&numlen);
 	if (numlen == 0) return 0;
-	if (c >= 0x80) *has8bit = 1;
-	return c;
-
-      case 'u':	/* unicode constant: here only for char literal */
-	if (flags & (ESCAPE_CONTROL|ESCAPE_META)) goto eof;
-	c = parser_tokadd_utf8(parser, hasmb, encp, 0, 0);
 	return c;
 
       case 'b':	/* backspace */
@@ -5126,13 +5130,10 @@ parser_read_escape(struct parser_params *parser, int flags,
 	    goto eof;
 	}
 	if ((c = nextc()) == '\\') {
-	    int tmp;
-	    *has8bit = 1;
-	    return read_escape(flags|ESCAPE_META, &tmp, &tmp, encp) | 0x80;
+	    return read_escape(flags|ESCAPE_META, encp) | 0x80;
 	}
 	else if (c == -1 || !ISASCII(c)) goto eof;
 	else {
-            *has8bit = 1;
 	    return ((c & 0xff) | 0x80);
 	}
 
@@ -5144,8 +5145,7 @@ parser_read_escape(struct parser_params *parser, int flags,
       case 'c':
 	if (flags & ESCAPE_CONTROL) goto eof;
 	if ((c = nextc())== '\\') {
-	    int tmp;
-	    c = read_escape(flags|ESCAPE_CONTROL, has8bit, &tmp, encp);
+	    c = read_escape(flags|ESCAPE_CONTROL, encp);
 	}
 	else if (c == '?')
 	    return 0177;
@@ -5162,8 +5162,6 @@ parser_read_escape(struct parser_params *parser, int flags,
     }
 }
 
-#define tokcopy(n) memcpy(tokspace(n), lex_p - (n), (n))
-
 static void
 parser_tokaddmbc(struct parser_params *parser, int c, rb_encoding *enc)
 {
@@ -5173,7 +5171,7 @@ parser_tokaddmbc(struct parser_params *parser, int c, rb_encoding *enc)
 
 static int
 parser_tokadd_escape(struct parser_params *parser, int term,
-		     int *has8bit, int *hasmb, rb_encoding **encp)
+		     rb_encoding **encp)
 {
     int c;
     int flags = 0;
@@ -5194,7 +5192,6 @@ parser_tokadd_escape(struct parser_params *parser, int term,
 	    if (numlen == 0) goto eof;
 	    lex_p += numlen;
 	    tokcopy(numlen + 1);
-	    if (oct >= 0200) *has8bit = 1;
 	}
 	return 0;
 
@@ -5207,7 +5204,6 @@ parser_tokadd_escape(struct parser_params *parser, int term,
 	    hex = tok_hex(&numlen);
 	    if (numlen == 0) goto eof;
 	    tokcopy(numlen + 2);
-	    if (hex >= 0x80) *has8bit = 1;
 	}
 	return 0;
 
@@ -5218,7 +5214,6 @@ parser_tokadd_escape(struct parser_params *parser, int term,
 	    goto eof;
 	}
 	tokcopy(3);
-	*has8bit = 1;
 	flags |= ESCAPE_META;
 	goto escaped;
 
@@ -5287,24 +5282,6 @@ parser_regx_options(struct parser_params *parser)
     return options | RE_OPTION_ENCODING(kcode);
 }
 
-#define STR_FUNC_ESCAPE 0x01
-#define STR_FUNC_EXPAND 0x02
-#define STR_FUNC_REGEXP 0x04
-#define STR_FUNC_QWORDS 0x08
-#define STR_FUNC_SYMBOL 0x10
-#define STR_FUNC_INDENT 0x20
-
-enum string_type {
-    str_squote = (0),
-    str_dquote = (STR_FUNC_EXPAND),
-    str_xquote = (STR_FUNC_EXPAND),
-    str_regexp = (STR_FUNC_REGEXP|STR_FUNC_ESCAPE|STR_FUNC_EXPAND),
-    str_sword  = (STR_FUNC_QWORDS),
-    str_dword  = (STR_FUNC_QWORDS|STR_FUNC_EXPAND),
-    str_ssym   = (STR_FUNC_SYMBOL),
-    str_dsym   = (STR_FUNC_SYMBOL|STR_FUNC_EXPAND),
-};
-
 static void
 dispose_string(VALUE str)
 {
@@ -5328,10 +5305,10 @@ parser_tokadd_mbchar(struct parser_params *parser, int c)
 static int
 parser_tokadd_string(struct parser_params *parser,
 		     int func, int term, int paren, long *nest,
-		     int *has8bit, int *hasmb, rb_encoding **encp)
+		     rb_encoding **encp)
 {
     int c;
-    int has_mb = 0;
+    int has_nonascii = 0;
     rb_encoding *enc = *encp;
     char *errbuf = 0;
     static const char mixed_msg[] = "%s mixed within %s source";
@@ -5390,9 +5367,10 @@ parser_tokadd_string(struct parser_params *parser,
 		    tokadd('\\');
 		    break;
 		}
-		parser_tokadd_utf8(parser, hasmb, &enc, 1,
-				   func & STR_FUNC_SYMBOL);
-		if (has_mb && enc != *encp) {
+		parser_tokadd_utf8(parser, &enc, 1,
+				   func & STR_FUNC_SYMBOL,
+                                   func & STR_FUNC_REGEXP);
+		if (has_nonascii && enc != *encp) {
 		    mixed_escape(beg, enc, *encp);
 		}
 		continue;
@@ -5400,28 +5378,17 @@ parser_tokadd_string(struct parser_params *parser,
 	      default:
 		if (func & STR_FUNC_REGEXP) {
 		    pushback(c);
-		    if ((c = tokadd_escape(term, has8bit, hasmb, &enc)) < 0)
+		    if ((c = tokadd_escape(term, &enc)) < 0)
 			return -1;
-		    if (has_mb && enc != *encp) {
+		    if (has_nonascii && enc != *encp) {
 			mixed_escape(beg, enc, *encp);
 		    }
 		    continue;
 		}
 		else if (func & STR_FUNC_EXPAND) {
-		    int tmb = 0;
 		    pushback(c);
 		    if (func & STR_FUNC_ESCAPE) tokadd('\\');
-		    c = read_escape(0, has8bit, &tmb, &enc);
-		    if (tmb) {
-			*hasmb = tmb;
-			if (has_mb && enc != *encp) {
-			    mixed_escape(beg, enc, *encp);
-			}
-			else {
-			    tokaddmbc(c, enc);
-			}
-			continue;
-		    }
+		    c = read_escape(0, &enc);
 		}
 		else if ((func & STR_FUNC_QWORDS) && ISSPACE(c)) {
 		    /* ignore backslashed spaces in %w */
@@ -5432,13 +5399,12 @@ parser_tokadd_string(struct parser_params *parser,
 	    }
 	}
 	else if (parser_ismbchar()) {
-	    has_mb = 1;
+	    has_nonascii = 1;
 	    if (enc != *encp) {
 		mixed_error(enc, *encp);
 		continue;
 	    }
 	    tokadd_mbchar(c);
-            if (hasmb) *hasmb = 1;
 	    continue;
 	}
 	else if ((func & STR_FUNC_QWORDS) && ISSPACE(c)) {
@@ -5450,6 +5416,13 @@ parser_tokadd_string(struct parser_params *parser,
 	    compile_error(PARSER_ARG "symbol cannot contain '\\0'");
 	    continue;
 	}
+        if (c & 0x80) {
+            has_nonascii = 1;
+	    if (enc != *encp) {
+		mixed_error(enc, *encp);
+		continue;
+	    }
+        }
 	tokadd(c);
     }
     *encp = enc;
@@ -5465,7 +5438,7 @@ parser_parse_string(struct parser_params *parser, NODE *quote)
     int func = quote->nd_func;
     int term = nd_term(quote);
     int paren = nd_paren(quote);
-    int c, space = 0, has8bit=0, hasmb=0;
+    int c, space = 0;
     rb_encoding *enc = parser->enc;
 
     if (func == -1) return tSTRING_END;
@@ -5501,7 +5474,7 @@ parser_parse_string(struct parser_params *parser, NODE *quote)
     }
     pushback(c);
     if (tokadd_string(func, term, paren, &quote->nd_nest,
-		      &has8bit, &hasmb, &enc) == -1) {
+		      &enc) == -1) {
 	ruby_sourceline = nd_line(quote);
 	if (func & STR_FUNC_REGEXP) {
 	    compile_error(PARSER_ARG "unterminated regexp meets end of file");
@@ -5514,7 +5487,7 @@ parser_parse_string(struct parser_params *parser, NODE *quote)
     }
 
     tokfix();
-    set_yylval_str(STR_NEW3(tok(), toklen(), enc, has8bit, hasmb));
+    set_yylval_str(STR_NEW3(tok(), toklen(), enc, func));
     return tSTRING_CONTENT;
 }
 
@@ -5678,7 +5651,6 @@ parser_here_document(struct parser_params *parser, NODE *here)
     }
     else {
 	/*	int mb = ENC_CODERANGE_7BIT, *mbp = &mb;*/
-        int has8bit=0, hasmb=0;
 	rb_encoding *enc = parser->enc;
 	newtok();
 	if (c == '#') {
@@ -5695,16 +5667,16 @@ parser_here_document(struct parser_params *parser, NODE *here)
 	do {
 	    pushback(c);
 	    if ((c = tokadd_string(func, '\n', 0, NULL,
-				   &has8bit, &hasmb, &enc)) == -1) goto error;
+				   &enc)) == -1) goto error;
 	    if (c != '\n') {
-		set_yylval_str(STR_NEW3(tok(), toklen(), enc, has8bit,hasmb));
+		set_yylval_str(STR_NEW3(tok(), toklen(), enc, func));
 		return tSTRING_CONTENT;
 	    }
 	    tokadd(nextc());
 	    /*	    if (mbp && mb == ENC_CODERANGE_UNKNOWN) mbp = 0;*/
 	    if ((c = nextc()) == -1) goto error;
 	} while (!whole_match_p(eos, len, indent));
-	str = STR_NEW3(tok(), toklen(), enc, has8bit,hasmb);
+	str = STR_NEW3(tok(), toklen(), enc, func);
     }
     heredoc_restore(lex_strterm);
     lex_strterm = NEW_STRTERM(-1, 0, 0);
@@ -5966,7 +5938,6 @@ parser_yylex(struct parser_params *parser)
     int cmd_state;
     enum lex_state_e last_state;
     rb_encoding *enc;
-    int has8bit = 0, hasmb = 0;
     int mb;
 #ifdef RIPPER
     int fallthru = Qfalse;
@@ -6317,26 +6288,33 @@ parser_yylex(struct parser_params *parser)
 	newtok();
 	enc = parser->enc;
 	if (parser_ismbchar()) {
-	    hasmb = 1;
 	    tokadd_mbchar(c);
 	}
 	else if ((rb_enc_isalnum(c, parser->enc) || c == '_') &&
 		 lex_p < lex_pend && is_identchar(lex_p, lex_pend, parser->enc)) {
 	    goto ternary;
 	}
-	else if (c == '\\' && (c = read_escape(0, &has8bit, &hasmb, &enc)) >= 0x80) {
-	    if (hasmb) {
-		tokaddmbc(c, enc);
-	    }
-	    else {
-		tokadd(c);
-	    }
-	}
-	else {
+        else if (c == '\\') {
+            if (peek('u')) {
+                nextc();
+                c = parser_tokadd_utf8(parser, &enc, 0, 0, 0);
+                if (0x80 <= c) {
+                    tokaddmbc(c, enc);
+                }
+                else {
+                    tokadd(c);
+                }
+            }
+            else {
+                c = read_escape(0, &enc);
+                tokadd(c);
+            }
+        }
+        else {
 	    tokadd(c);
-	}
+        }
 	tokfix();
-	set_yylval_str(STR_NEW3(tok(), toklen(), enc, has8bit, hasmb));
+	set_yylval_str(STR_NEW3(tok(), toklen(), enc, 0));
 	lex_state = EXPR_ENDARG;
 	return tCHAR;
 
@@ -8481,7 +8459,6 @@ reg_compile_gen(struct parser_params* parser, VALUE str, int options)
 	compile_error(PARSER_ARG "%s", RSTRING_PTR(re));
 	return Qnil;
     }
-    if (str) rb_enc_copy(re, str);
     return re;
 }
 
diff --git a/re.c b/re.c
index 398e748f3a..78cfd018f5 100644
--- a/re.c
+++ b/re.c
@@ -12,6 +12,7 @@
 #include "ruby/ruby.h"
 #include "ruby/re.h"
 #include "ruby/encoding.h"
+#include "ruby/util.h"
 #include "regint.h"
 #include <ctype.h>
 
@@ -715,6 +716,10 @@ rb_reg_fixed_encoding_p(VALUE re)
         return Qfalse;
 }
 
+static VALUE
+rb_reg_preprocess(const char *p, const char *end, rb_encoding *enc,
+        rb_encoding **fixed_enc, onig_errmsg_buffer err);
+
 static void
 rb_reg_prepare_re(VALUE re, VALUE str)
 {
@@ -740,13 +745,19 @@ rb_reg_prepare_re(VALUE re, VALUE str)
 	OnigErrorInfo einfo;
 	regex_t *reg, *reg2;
 	UChar *pattern;
+        VALUE unescaped;
+        rb_encoding *fixed_enc = 0;
 
 	rb_reg_check(re);
 	reg = RREGEXP(re)->ptr;
 	pattern = ((UChar*)RREGEXP(re)->str);
 
-	r = onig_new(&reg2, (UChar* )pattern,
-		     (UChar* )(pattern + RREGEXP(re)->len),
+        unescaped = rb_reg_preprocess(
+            RREGEXP(re)->str, RREGEXP(re)->str + RREGEXP(re)->len, enc,
+            &fixed_enc, err);
+
+	r = onig_new(&reg2, (UChar* )RSTRING_PTR(unescaped),
+		     (UChar* )(RSTRING_PTR(unescaped) + RSTRING_LEN(unescaped)),
 		     reg->options, enc,
 		     OnigDefaultSyntax, &einfo);
 	if (r) {
@@ -756,6 +767,7 @@ rb_reg_prepare_re(VALUE re, VALUE str)
 
 	RREGEXP(re)->ptr = reg2;
 	onig_free(reg);
+        RB_GC_GUARD(unescaped);
     }
 }
 
@@ -1235,13 +1247,408 @@ match_inspect(VALUE match)
 
 VALUE rb_cRegexp;
 
+static int
+read_escaped_byte(const char **pp, const char *end, onig_errmsg_buffer err)
+{
+    const char *p = *pp;
+    int code;
+    int meta_prefix = 0, ctrl_prefix = 0;
+    int len;
+    int retbyte;
+
+    retbyte = -1;
+    if (p == end || *p++ != '\\') {
+        strcpy(err, "too short escaped multibyte character");
+        return -1;
+    }
+
+again:
+    if (p == end) {
+        strcpy(err, "too short escape sequence");
+        return -1;
+    }
+    switch (*p++) {
+      case '\\': code = '\\'; break;
+      case 'n': code = '\n'; break;
+      case 't': code = '\t'; break;
+      case 'r': code = '\r'; break;
+      case 'f': code = '\f'; break;
+      case 'v': code = '\013'; break;
+      case 'a': code = '\007'; break;
+      case 'e': code = '\033'; break;
+
+      /* \OOO */
+      case '0': case '1': case '2': case '3':
+      case '4': case '5': case '6': case '7':
+        p--;
+        code = ruby_scan_oct(p, end < p+3 ? end-p : 3, &len);
+        p += len;
+        break;
+
+      case 'x': /* \xHH */
+        code = ruby_scan_hex(p, end < p+2 ? end-p : 2, &len);
+        if (len < 1) {
+            strcpy(err, "invalid hex escape");
+            return -1;
+        }
+        p += len;
+        break;
+
+      case 'M': /* \M-X, \M-\C-X, \M-\cX */
+        if (meta_prefix) {
+            strcpy(err, "duplicate meta escape");
+            return -1;
+        }
+        meta_prefix = 1;
+        if (p+1 < end && *p++ == '-' && (*p & 0x80) == 0) {
+            if (*p == '\\') {
+                p++;
+                goto again;
+            }
+            else {
+                code = *p++;
+                break;
+            }
+        }
+        strcpy(err, "too short meta escape");
+        return -1;
+
+      case 'C': /* \C-X, \C-\M-X */
+        if (p == end || *p++ != '-') {
+            strcpy(err, "too short control escape");
+            return -1;
+        }
+      case 'c': /* \cX, \c\M-X */
+        if (ctrl_prefix) {
+            strcpy(err, "duplicate control escape");
+            return -1;
+        }
+        ctrl_prefix = 1;
+        if (p < end && (*p & 0x80) == 0) {
+            if (*p == '\\') {
+                p++;
+                goto again;
+            }
+            else {
+                code = *p++;
+                break;
+            }
+        }
+        strcpy(err, "too short control escape");
+        return -1;
+
+      default:
+        strcpy(err, "unexpected escape sequence");
+        return -1;
+    }
+    if (code < 0 || 0xff < code) {
+        strcpy(err, "invalid escape code");
+        return -1;
+    }
+
+    if (ctrl_prefix)
+        code &= 0x1f;
+    if (meta_prefix)
+        code |= 0x80;
+
+    *pp = p;
+    return code;
+}
+
+static int
+unescape_escaped_nonascii(const char **pp, const char *end, rb_encoding *enc,
+        VALUE buf, rb_encoding **encp, onig_errmsg_buffer err)
+{
+    const char *p = *pp;
+    int chmaxlen = rb_enc_mbmaxlen(enc);
+    char *chbuf = ALLOCA_N(char, chmaxlen);
+    int chlen = 0;
+    int byte;
+
+    memset(chbuf, 0, chmaxlen);
+
+    byte = read_escaped_byte(&p, end, err);
+    if (byte == -1) {
+        return -1;
+    }
+
+    chbuf[chlen++] = byte;
+    while (chlen < chmaxlen && chlen != mbclen(chbuf, chbuf+chmaxlen, enc)) {
+        byte = read_escaped_byte(&p, end, err);
+        if (byte == -1) {
+            return -1;
+        }
+        chbuf[chlen++] = byte;
+    }
+
+    if (chlen != mbclen(chbuf, chbuf+chmaxlen, enc)) {
+        strcpy(err, "invalid multibyte escape");
+        return -1;
+    }
+
+    if (1 < chlen || (chbuf[0] & 0x80)) {
+        rb_str_buf_cat(buf, chbuf, chlen);
+
+        if (*encp == 0)
+            *encp = enc;
+        else if (*encp != enc) {
+            strcpy(err, "character encodings differ");
+            return -1;
+        }
+    }
+    else {
+        char escbuf[5];
+        snprintf(escbuf, sizeof(escbuf), "\\x%02x", chbuf[0]&0xff);
+        rb_str_buf_cat(buf, escbuf, 4);
+    }
+    *pp = p;
+    return 0;
+}
+
+static int
+append_utf8(unsigned long uv,
+        VALUE buf, rb_encoding **encp, onig_errmsg_buffer err)
+{
+    if (uv < 0x80) {
+        char escbuf[5];
+        snprintf(escbuf, sizeof(escbuf), "\\x%02x", (int)uv);
+        rb_str_buf_cat(buf, escbuf, 4);
+    }
+    else {
+        int len;
+        char utf8buf[6];
+        len = rb_uv_to_utf8(utf8buf, uv);
+        rb_str_buf_cat(buf, utf8buf, len);
+
+        if (*encp == 0)
+            *encp = rb_enc_find("utf-8");
+        else if (*encp != rb_enc_find("utf-8")) {
+            strcpy(err, "character encodings differ");
+            return -1;
+        }
+    }
+    return 0;
+}
+
+static int
+unescape_unicode_list(const char **pp, const char *end,
+        VALUE buf, rb_encoding **encp, onig_errmsg_buffer err)
+{
+    const char *p = *pp;
+    int has_unicode = 0;
+    unsigned long code;
+    int len;
+
+    while (p < end && ISSPACE(*p)) p++;
+
+    while (1) {
+        code = ruby_scan_hex(p, end-p, &len);
+        if (len == 0)
+            break;
+        if (6 < len) { /* max 10FFFF */
+            strcpy(err, "invalid unicode range");
+            return -1;
+        }
+        if (0x10ffff < code) {
+            strcpy(err, "invalid unicode range");
+            return -1;
+        }
+        p += len;
+        if (append_utf8(code, buf, encp, err) != 0)
+            return -1;
+        has_unicode = 1;
+
+        while (p < end && ISSPACE(*p)) p++;
+    }
+
+    if (has_unicode == 0) {
+        strcpy(err, "invalid unicode list");
+        return -1;
+    }
+
+    *pp = p;
+
+    return 0;
+}
+
+static int
+unescape_unicode_bmp(const char **pp, const char *end,
+        VALUE buf, rb_encoding **encp, onig_errmsg_buffer err)
+{
+    const char *p = *pp;
+    int len;
+    unsigned long code;
+
+    if (end < p+4) {
+        strcpy(err, "invalid unicode escape");
+        return -1;
+    }
+    code = ruby_scan_hex(p, 4, &len);
+    if (len != 4) {
+        strcpy(err, "invalid unicode escape");
+        return -1;
+    }
+    if (append_utf8(code, buf, encp, err) != 0)
+        return -1;
+    *pp = p + 4;
+    return 0;
+}
+
+static int
+unescape_nonascii(const char *p, const char *end, rb_encoding *enc,
+        VALUE buf, rb_encoding **encp, onig_errmsg_buffer err)
+{
+    char c;
+    char smallbuf[2];
+
+    while (p < end) {
+        int chlen = mbclen(p, end, enc);
+        if (1 < chlen || (*p & 0x80)) {
+            if (end < p + chlen) {
+                strcpy(err, "too short multibyte character");
+                return -1;
+            }
+            /* xxx: validate the non-ascii character */
+            rb_str_buf_cat(buf, p, chlen);
+            p += chlen;
+            if (*encp == 0)
+                *encp = enc;
+            else if (*encp != enc) {
+                strcpy(err, "character encodings differ");
+                return -1;
+            }
+            continue;
+        }
+
+        switch (c = *p++) {
+          case '\\':
+            if (p == end) {
+                strcpy(err, "too short escape sequence");
+                return -1;
+            }
+            switch (c = *p++) {
+              case '1': case '2': case '3':
+              case '4': case '5': case '6': case '7': /* \O, \OO, \OOO or backref */
+                {
+                    int octlen;
+                    if (ruby_scan_oct(p-1, end-(p-1), &octlen) <= 0177) {
+                        /* backref or 7bit octal.
+                           no need to unescape anyway.
+                           re-escaping may break backref */
+                        goto escape_asis;
+                    }
+                }
+                /* xxx: How about more than 199 subexpressions? */ 
+
+              case '0': /* \0, \0O, \0OO */
+
+              case 'x': /* \xHH */
+              case 'c': /* \cX, \c\M-X */
+              case 'C': /* \C-X, \C-\M-X */
+              case 'M': /* \M-X, \M-\C-X, \M-\cX */
+                p = p-2;
+                if (unescape_escaped_nonascii(&p, end, enc, buf, encp, err) != 0)
+                    return -1;
+                break;
+
+              case 'u':
+                if (p == end) {
+                    strcpy(err, "too short escape sequence");
+                    return -1;
+                }
+                if (*p == '{') {
+                    /* \u{H HH HHH HHHH HHHHH HHHHHH ...} */
+                    p++;
+                    if (unescape_unicode_list(&p, end, buf, encp, err) != 0)
+                        return -1;
+                    if (p == end || *p++ != '}') {
+                        strcpy(err, "invalid unicode list");
+                        return -1;
+                    }
+                    break;
+                }
+                else {
+                    /* \uHHHH */
+                    if (unescape_unicode_bmp(&p, end, buf, encp, err) != 0)
+                        return -1;
+                    break;
+                }
+
+              default: /* \n, \\, \d, \9, etc. */
+escape_asis:
+                smallbuf[0] = '\\';
+                smallbuf[1] = c;
+                rb_str_buf_cat(buf, smallbuf, 2);
+                break;
+            }
+            break;
+
+          default:
+            rb_str_buf_cat(buf, &c, 1);
+            break;
+        }
+    }
+
+    return 0;
+}
+
+static VALUE
+rb_reg_preprocess(const char *p, const char *end, rb_encoding *enc,
+        rb_encoding **fixed_enc, onig_errmsg_buffer err)
+{
+    VALUE buf;
+
+    buf = rb_str_buf_new(0);
+
+    *fixed_enc = 0;
+    if (unescape_nonascii(p, end, enc, buf, fixed_enc, err) != 0)
+        return Qnil;
+
+    if (fixed_enc) {
+        rb_enc_associate(buf, *fixed_enc);
+    }
+
+    return buf;
+}
+
+#if 0
+static VALUE
+rb_reg_preprocess_obj(VALUE str,
+        rb_encoding **fixed_enc, onig_errmsg_buffer err)
+{
+    VALUE buf;
+    char *p, *end;
+    rb_encoding *enc;
+
+    StringValue(str);
+    p = RSTRING_PTR(str);
+    end = p + RSTRING_LEN(str);
+    enc = rb_enc_get(str);
+
+    buf = rb_reg_preprocess(p, end, enc, fixed_enc, err);
+    RB_GC_GUARD(str);
+    return buf;
+}
+
+static VALUE
+rb_reg_preprocess_m(VALUE klass, VALUE obj)
+{
+    rb_encoding *fixed_enc = 0;
+    onig_errmsg_buffer err;
+    VALUE str = rb_reg_preprocess_obj(obj, &fixed_enc, err);
+    if (str == Qnil)
+        rb_raise(rb_eArgError, "%s", err);
+    return rb_assoc_new(str, fixed_enc ? Qtrue : Qfalse);
+}
+#endif
+
 static int
 rb_reg_initialize(VALUE obj, const char *s, int len, rb_encoding *enc,
 		  int options, onig_errmsg_buffer err)
 {
     struct RRegexp *re = RREGEXP(obj);
-    int raw8bit;
-    long i;
+    VALUE unescaped;
+    rb_encoding *fixed_enc = 0;
 
     if (!OBJ_TAINTED(obj) && rb_safe_level() >= 4)
 	rb_raise(rb_eSecurityError, "Insecure: can't modify regexp");
@@ -1253,33 +1660,38 @@ rb_reg_initialize(VALUE obj, const char *s, int len, rb_encoding *enc,
     re->ptr = 0;
     re->str = 0;
 
-    raw8bit = 0;
-    for (i = 0; i < len; i++) {
-        if (s[i] & 0x80) {
-            raw8bit = 1;
-            break;
-        }
+    unescaped = rb_reg_preprocess(s, s+len, enc, &fixed_enc, err);
+    if (unescaped == Qnil)
+        return -1;
+
+    if (fixed_enc && (options & ARG_ENCODING_FIXED) && fixed_enc != enc) {
+        strcpy(err, "character encodings differ");
+        return -1;
     }
 
+    if (fixed_enc)
+        enc = fixed_enc;
+    else if (!(options & ARG_ENCODING_FIXED))
+        enc = rb_default_encoding();
+    
     rb_enc_associate((VALUE)re, enc);
-    if (options & ARG_ENCODING_FIXED || raw8bit) {
+    if ((options & ARG_ENCODING_FIXED) || fixed_enc) {
 	re->basic.flags |= KCODE_FIXED;
     }
-    re->ptr = make_regexp(s, len, enc, options & ARG_REG_OPTION_MASK, err);
+    re->ptr = make_regexp(RSTRING_PTR(unescaped), RSTRING_LEN(unescaped), enc,
+            options & ARG_REG_OPTION_MASK, err);
     if (!re->ptr) return -1;
     re->str = ALLOC_N(char, len+1);
     memcpy(re->str, s, len);
     re->str[len] = '\0';
     re->len = len;
+    RB_GC_GUARD(unescaped);
     return 0;
 }
 
 static int
 rb_reg_initialize_str(VALUE obj, VALUE str, int options, onig_errmsg_buffer err)
 {
-    if (!rb_enc_str_asciionly_p(str)) {
-	options |= ARG_ENCODING_FIXED;
-    }
     return rb_reg_initialize(obj, RSTRING_PTR(str), RSTRING_LEN(str), rb_enc_get(str),
 			     options, err);
 }
@@ -2183,6 +2595,10 @@ Init_Regexp(void)
     rb_define_singleton_method(rb_cRegexp, "last_match", rb_reg_s_last_match, -1);
     rb_define_singleton_method(rb_cRegexp, "try_convert", rb_reg_s_try_convert, 1);
 
+#if 0
+    rb_define_singleton_method(rb_cRegexp, "preprocess", rb_reg_preprocess_m, 1);
+#endif
+
     rb_define_method(rb_cRegexp, "initialize", rb_reg_initialize_m, -1);
     rb_define_method(rb_cRegexp, "initialize_copy", rb_reg_init_copy, 1);
     rb_define_method(rb_cRegexp, "hash", rb_reg_hash, 0);
diff --git a/test/ruby/test_m17n.rb b/test/ruby/test_m17n.rb
index fd183967a3..bb0a8a5010 100644
--- a/test/ruby/test_m17n.rb
+++ b/test/ruby/test_m17n.rb
@@ -25,6 +25,17 @@ class TestM17N < Test::Unit::TestCase
     assert_encoding("EUC-JP", eval(e(%{"\\x80"})).encoding)
   end
 
+  def test_string_mixed_unicode
+    assert_raise(SyntaxError) { eval(a(%{"\xc0\xa0\\u{6666}"})) }
+    assert_raise(SyntaxError) { eval(e(%{"\xc0\xa0\\u{6666}"})) }
+    assert_raise(SyntaxError) { eval(s(%{"\xc0\xa0\\u{6666}"})) }
+    assert_nothing_raised { eval(u(%{"\xc0\xa0\\u{6666}"})) }
+    assert_raise(SyntaxError) { eval(a(%{"\\u{6666}\xc0\xa0"})) }
+    assert_raise(SyntaxError) { eval(e(%{"\\u{6666}\xc0\xa0"})) }
+    assert_raise(SyntaxError) { eval(s(%{"\\u{6666}\xc0\xa0"})) }
+    assert_nothing_raised { eval(u(%{"\\u{6666}\xc0\xa0"})) }
+  end
+
   def test_regexp_too_short_multibyte_character
     assert_raise(SyntaxError) { eval('/\xfe/e') }
     assert_raise(SyntaxError) { eval('/\x8e/e') }
@@ -38,11 +49,12 @@ class TestM17N < Test::Unit::TestCase
     assert_raise(SyntaxError) { eval('/\xfc\x80\x80\x80\x80/u') }
 
     # raw 8bit
-    #assert_raise(SyntaxError) { eval("/\xfe/e") }
-    #assert_raise(SyntaxError) { eval("/\xc0/u") }
+    assert_raise(SyntaxError) { eval("/\xfe/e") }
+    assert_raise(SyntaxError) { eval("/\xc0/u") }
 
     # invalid suffix
-    #assert_raise(SyntaxError) { eval('/\xc0\xff/u') }
+    assert_raise(SyntaxError) { eval('/\xc0\xff/u') }
+    assert_raise(SyntaxError) { eval('/\xc0 /u') }
     #assert_raise(SyntaxError) { eval('/\xc0\x20/u') }
   end
 
@@ -94,6 +106,9 @@ class TestM17N < Test::Unit::TestCase
   def test_regexp_generic
     assert_regexp_generic_ascii(/a/)
     assert_regexp_generic_ascii(Regexp.new(a("a")))
+    assert_regexp_generic_ascii(Regexp.new(e("a")))
+    assert_regexp_generic_ascii(Regexp.new(s("a")))
+    assert_regexp_generic_ascii(Regexp.new(u("a")))
 
     [/a/, Regexp.new(a("a"))].each {|r|
       assert_equal(0, r =~ a("a"))
@@ -112,7 +127,7 @@ class TestM17N < Test::Unit::TestCase
     assert_regexp_fixed_ascii8bit(/\xc0\xa1/n)
     assert_regexp_fixed_ascii8bit(eval(a(%{/\xc0\xa1/})))
     assert_regexp_fixed_ascii8bit(eval(a(%{/\xc0\xa1/n})))
-    # assert_regexp_fixed_ascii8bit(eval(a(%q{/\xc0\xa1/})))
+    assert_regexp_fixed_ascii8bit(eval(a(%q{/\xc0\xa1/})))
 
     [/a/n].each {|r|
       assert_equal(0, r =~ a("a"))
@@ -139,12 +154,11 @@ class TestM17N < Test::Unit::TestCase
 
   def test_regexp_euc
     assert_regexp_fixed_eucjp(/a/e)
-    assert_regexp_fixed_eucjp(Regexp.new(e("a")))
     assert_regexp_fixed_eucjp(/\xc0\xa1/e)
     assert_regexp_fixed_eucjp(eval(e(%{/\xc0\xa1/})))
     assert_regexp_fixed_eucjp(eval(e(%q{/\xc0\xa1/})))
 
-    [/a/e, Regexp.new(e("a"))].each {|r|
+    [/a/e].each {|r|
       assert_equal(0, r =~ a("a"))
       assert_equal(0, r =~ e("a"))
       assert_equal(0, r =~ s("a"))
@@ -169,7 +183,6 @@ class TestM17N < Test::Unit::TestCase
 
   def test_regexp_sjis
     assert_regexp_fixed_sjis(/a/s)
-    assert_regexp_fixed_sjis(Regexp.new(s("a")))
     assert_regexp_fixed_sjis(/\xc0\xa1/s)
     assert_regexp_fixed_sjis(eval(s(%{/\xc0\xa1/})))
     assert_regexp_fixed_sjis(eval(s(%q{/\xc0\xa1/})))
diff --git a/test/ruby/test_unicode_escape.rb b/test/ruby/test_unicode_escape.rb
index 46413cdcdb..a1800c66e6 100644
--- a/test/ruby/test_unicode_escape.rb
+++ b/test/ruby/test_unicode_escape.rb
@@ -68,47 +68,74 @@ EOS
   def test_regexp
 
     # Compare regexps to regexps
-    assert_equal(/Yukihiro Matsumoto - 松本行弘/,
+    assert_not_equal(/Yukihiro Matsumoto - 松本行弘/,
       /Yukihiro Matsumoto - \u677E\u672C\u884C\u5F18/)
-    assert_equal(/Yukihiro Matsumoto - 松本行弘/,
-                 /Yukihiro Matsumoto - \u{677E 672C 884C 5F18}/)
-    assert_equal(/Matz - まつもと ゆきひろ/,
+    assert_not_equal(/Yukihiro Matsumoto - 松本行弘/,
+      /Yukihiro Matsumoto - \u{677E 672C 884C 5F18}/)
+    assert_not_equal(/Matz - まつもと ゆきひろ/,
       /Matz - \u307E\u3064\u3082\u3068 \u3086\u304D\u3072\u308D/)
-    assert_equal(/Aoyama Gakuin University - 青山学院大学/,
+    assert_not_equal(/Aoyama Gakuin University - 青山学院大学/,
       /Aoyama Gakuin University - \u9752\u5C71\u5B66\u9662\u5927\u5B66/)
-    assert_equal(/青山学院大学/, /\u9752\u5C71\u5B66\u9662\u5927\u5B66/)
-    assert_equal(/Martin Dürst/, /Martin D\u00FCrst/)
-    assert_equal(/ü/, /\u00FC/)
-    assert_equal(/Martin Dürst/, /Martin D\u{FC}rst/)
-    assert_equal(/ü/, /\u{FC}/)
-    assert_equal(/ü/, %r{\u{FC}})
-    assert_equal(/ü/i, %r{\u00FC}i)
+    assert_not_equal(/青山学院大学/, /\u9752\u5C71\u5B66\u9662\u5927\u5B66/)
+    assert_not_equal(/Martin Dürst/, /Martin D\u00FCrst/)
+    assert_not_equal(/ü/, /\u00FC/)
+    assert_not_equal(/Martin Dürst/, /Martin D\u{FC}rst/)
+    assert_not_equal(/ü/, /\u{FC}/)
+    assert_not_equal(/ü/, %r{\u{FC}})
+    assert_not_equal(/ü/i, %r{\u00FC}i)
+
+    assert_equal('Yukihiro Matsumoto - \u677E\u672C\u884C\u5F18',
+      /Yukihiro Matsumoto - \u677E\u672C\u884C\u5F18/.source)
+    assert_equal('Yukihiro Matsumoto - \u{677E 672C 884C 5F18}',
+      /Yukihiro Matsumoto - \u{677E 672C 884C 5F18}/.source)
+    assert_equal('Matz - \u307E\u3064\u3082\u3068 \u3086\u304D\u3072\u308D',
+      /Matz - \u307E\u3064\u3082\u3068 \u3086\u304D\u3072\u308D/.source)
+    assert_equal('Aoyama Gakuin University - \u9752\u5C71\u5B66\u9662\u5927\u5B66',
+      /Aoyama Gakuin University - \u9752\u5C71\u5B66\u9662\u5927\u5B66/.source)
+    assert_equal('\u9752\u5C71\u5B66\u9662\u5927\u5B66',
+      /\u9752\u5C71\u5B66\u9662\u5927\u5B66/.source)
+    assert_equal('Martin D\u00FCrst', /Martin D\u00FCrst/.source)
+    assert_equal('\u00FC', /\u00FC/.source)
+    assert_equal('Martin D\u{FC}rst', /Martin D\u{FC}rst/.source)
+    assert_equal('\u{FC}', /\u{FC}/.source)
+    assert_equal('\u{FC}', %r{\u{FC}}.source)
+    assert_equal('\u00FC', %r{\u00FC}i.source)
 
     # match strings to regexps
-    assert_equal("Yukihiro Matsumoto - 松本行弘" =~ /Yukihiro Matsumoto - \u677E\u672C\u884C\u5F18/, 0)
-    assert_equal("Yukihiro Matsumoto - \u677E\u672C\u884C\u5F18" =~ /Yukihiro Matsumoto - \u677E\u672C\u884C/, 0)
-    assert_equal("Yukihiro Matsumoto - 松本行弘" =~            /Yukihiro Matsumoto - \u{677E 672C 884C 5F18}/, 0)
-    assert_equal(%Q{Yukihiro Matsumoto - \u{677E 672C 884C 5F18}} =~ /Yukihiro Matsumoto - \u{677E 672C 884C 5F18}/, 0)
-    assert_equal("Matz - まつもと ゆきひろ" =~ /Matz - \u307E\u3064\u3082\u3068 \u3086\u304D\u3072\u308D/, 0)
-    assert_equal("Aoyama Gakuin University - 青山学院大学" =~ /Aoyama Gakuin University - \u9752\u5C71\u5B66\u9662\u5927\u5B66/, 0)
-    assert_equal("青山学院大学" =~ /\u9752\u5C71\u5B66\u9662\u5927\u5B66/, 0)
-    assert_equal("Martin Dürst" =~ /Martin D\u00FCrst/, 0)
-    assert_equal("ü" =~ /\u00FC/, 0)
-    assert_equal("Martin Dürst" =~ /Martin D\u{FC}rst/, 0)
-    assert_equal("ü" =~ %r{\u{FC}}, 0)
-    assert_equal("ü" =~ %r{\u00FC}i, 0)
+    assert_equal(0, "Yukihiro Matsumoto - 松本行弘" =~ /Yukihiro Matsumoto - \u677E\u672C\u884C\u5F18/)
+    assert_equal(0, "Yukihiro Matsumoto - \u677E\u672C\u884C\u5F18" =~ /Yukihiro Matsumoto - \u677E\u672C\u884C/)
+    assert_equal(0, "Yukihiro Matsumoto - 松本行弘" =~            /Yukihiro Matsumoto - \u{677E 672C 884C 5F18}/)
+    assert_equal(0, %Q{Yukihiro Matsumoto - \u{677E 672C 884C 5F18}} =~ /Yukihiro Matsumoto - \u{677E 672C 884C 5F18}/)
+    assert_equal(0, "Matz - まつもと ゆきひろ" =~ /Matz - \u307E\u3064\u3082\u3068 \u3086\u304D\u3072\u308D/)
+    assert_equal(0, "Aoyama Gakuin University - 青山学院大学" =~ /Aoyama Gakuin University - \u9752\u5C71\u5B66\u9662\u5927\u5B66/)
+    assert_equal(0, "青山学院大学" =~ /\u9752\u5C71\u5B66\u9662\u5927\u5B66/)
+    assert_equal(0, "Martin Dürst" =~ /Martin D\u00FCrst/)
+    assert_equal(0, "ü" =~ /\u00FC/)
+    assert_equal(0, "Martin Dürst" =~ /Martin D\u{FC}rst/)
+    assert_equal(0, "ü" =~ %r{\u{FC}})
+    assert_equal(0, "ü" =~ %r{\u00FC}i)
 
     # Flip order of the two operands
-    assert_equal(/Martin D\u00FCrst/ =~ "Martin Dürst", 0)
-    assert_equal(/\u00FC/ =~ "testü", 4)
-    assert_equal(/Martin D\u{FC}rst/ =~ "fooMartin Dürstbar", 3)
-    assert_equal(%r{\u{FC}} =~ "fooübar", 3)
+    assert_equal(0, /Martin D\u00FCrst/ =~ "Martin Dürst")
+    assert_equal(4, /\u00FC/ =~ "testü")
+    assert_equal(3, /Martin D\u{FC}rst/ =~ "fooMartin Dürstbar")
+    assert_equal(3, %r{\u{FC}} =~ "fooübar")
 
     # Put \u in strings, literal character in regexp
-    assert_equal("Martin D\u00FCrst" =~ /Martin Dürst/, 0)
-    assert_equal("test\u00FC" =~ /ü/, 4)
-    assert_equal("fooMartin D\u{FC}rstbar" =~ /Martin Dürst/, 3)
-    assert_equal(%Q{foo\u{FC}bar} =~ %r<ü>, 3)
+    assert_equal(0, "Martin D\u00FCrst" =~ /Martin Dürst/)
+    assert_equal(4, "test\u00FC" =~ /ü/)
+    assert_equal(3, "fooMartin D\u{FC}rstbar" =~ /Martin Dürst/)
+    assert_equal(3, %Q{foo\u{FC}bar} =~ %r<ü>)
+
+    assert_match(eval('/\u{2a}/'), "*")
+    assert_raise(SyntaxError) { eval('/\u{6666}/n') }
+    assert_raise(SyntaxError) { eval('/\u{6666}/e') }
+    assert_raise(SyntaxError) { eval('/\u{6666}/s') }
+    assert_nothing_raised { eval('/\u{6666}/u') }
+  end
+
+  def test_dynamic_regexp
+    assert_match(Regexp.new("Martin D\\u{FC}rst"), "Martin Dürst")
   end
   
   def test_syntax_variants