Enable character hex escapes by default

R6RS character hex escapes do not conflict with legacy Guile octal
character escapes, so they can be enabled by default.

* libguile/read.c (scm_read_character): modified
* test-suite/tests/reader.test: modify character escape tests
* doc/ref/api-data.texi: modified
* doc/ref/api-options.texi: modified

doc/ref/api-data.texi

@@ -1763,17 +1763,9 @@ Characters may also be written using their code point values.  They can
 be written with as an octal number, such as @code{#\10} for
 @code{#\bs} or @code{#\177} for @code{#\del}.
 
-When the @code{r6rs-hex-escapes} reader option is enabled, there is an
-additional syntax for character escapes: @code{#\xHHHH} -- the letter 'x'
-followed by a hexadecimal number of one to eight digits.
-
-@lisp
-(read-enable 'r6rs-hex-escapes)
-@end lisp
-
-Enabling this option will also change the hex escape format for strings.  More
-on string escapes can be found at (@pxref{String Syntax}).  More on reader
-options in general can be found at (@pxref{Reader options}).
+If one prefers hex to octal, there is an additional syntax for character
+escapes: @code{#\xHHHH} -- the letter 'x' followed by a hexadecimal
+number of one to eight digits.
 
 @rnindex char?
 @deffn {Scheme Procedure} char? x
@@ -2698,9 +2690,8 @@ it can be enabled with the reader option @code{r6rs-hex-escapes}.
 (read-enable 'r6rs-hex-escapes)
 @end lisp
 
-Enabling this option will also change the hex escape format for characters.
-More on character escapes can be found at (@pxref{Characters}).  More on
-reader options in general can be found at (@pxref{Reader options}).
+More on reader options in general can be found at (@pxref{Reader
+options}).
 
 @node String Predicates
 @subsubsection String Predicates

doc/ref/api-options.texi

@@ -509,7 +509,7 @@ keywords         #f      Style of keyword recognition: #f, 'prefix or 'postfix
 case-insensitive no      Convert symbols to lower case.
 positions        yes     Record positions of source code expressions.
 copy             no      Copy source code expressions.
-r6rs-hex-escapes no      Use R6RS-style string and character hex escapes
+r6rs-hex-escapes no      Use R6RS-style string hex escapes
 @end smalllisp
 
 Notice that while Standard Scheme is case insensitive, to ease
@@ -523,7 +523,7 @@ To make Guile case insensitive, you can type
 @end lisp
 
 For more information on the effect of the @code{r6rs-hex-escapes} option, see
-(@pxref{Characters}) and (@pxref{String Syntax}).
+(@pxref{String Syntax}).
 
 @node Printing options
 @subsubsection Printing options

libguile/read.c

@@ -966,16 +966,16 @@ scm_read_character (scm_t_wchar chr, SCM port)
           if (SCM_IS_UNICODE_CHAR (c))
             return SCM_MAKE_CHAR (c);
           else
-            scm_i_input_error (FUNC_NAME, port, 
+            scm_i_input_error (FUNC_NAME, port,
                                "out-of-range octal character escape: ~a",
                                scm_list_1 (charname));
         }
     }
 
-  if (cp == 'x' && (charname_len > 1) && SCM_R6RS_ESCAPES_P)
+  if (cp == 'x' && (charname_len > 1))
     {
       SCM p;
-      
+
       /* Convert from hex, skipping the initial 'x' character in CHARNAME */
       p = scm_string_to_number (scm_c_substring (charname, 1, charname_len),
                                 scm_from_uint (16));

test-suite/tests/reader.test

@@ -332,28 +332,21 @@
        "\\xff;\\x100;\\xfff;\\x1000;\\xffff;\\x10000;"))
 
     (pass-if "one-digit hex escape"
-      (eqv? (with-read-options '(r6rs-hex-escapes)
-              (lambda ()
-                (with-input-from-string "#\\xA" read)))
+      (eqv? (with-input-from-string "#\\xA" read)
             (integer->char #x0A)))
 
     (pass-if "two-digit hex escape"
-      (eqv? (with-read-options '(r6rs-hex-escapes)
-              (lambda ()
-                (with-input-from-string "#\\xFF" read)))
+      (eqv? (with-input-from-string "#\\xFF" read)
             (integer->char #xFF)))
 
     (pass-if "four-digit hex escape"
-      (eqv? (with-read-options '(r6rs-hex-escapes)
-              (lambda ()
-                (with-input-from-string "#\\x00FF" read)))
+      (eqv? (with-input-from-string "#\\x00FF" read)
             (integer->char #xFF)))
 
     (pass-if "eight-digit hex escape"
-      (eqv? (with-read-options '(r6rs-hex-escapes)
-              (lambda ()
-                (with-input-from-string "#\\x00006587" read)))
+      (eqv? (with-input-from-string "#\\x00006587" read)
             (integer->char #x6587)))
+
     (pass-if "write R6RS escapes"
       (string=?
        (with-read-options '(r6rs-hex-escapes)