New function ‘char-from-name’

This also fixes the mishandling of "\N{CJK COMPATIBILITY
IDEOGRAPH-F900}", "\N{VARIATION SELECTOR-1}", etc.
Problem reported by Eli Zaretskii in:
http://lists.gnu.org/archive/html/emacs-devel/2016-04/msg00614.html
* doc/lispref/nonascii.texi (Character Codes), etc/NEWS: Document this.
* lisp/international/mule-cmds.el (char-from-name): New function.
(read-char-by-name): Use it.  Document that "BED" is treated as
a name, not as a hexadecimal number.  Reject out-of-range integers,
floating-point numbers, and strings with trailing junk.
* src/lread.c (character_name_to_code): Call char-from-name
instead of inspecting ucs-names directly, so that we handle
computed names like "VARIATION SELECTOR-1".  Do not use an auto
string, since char-from-name might GC.
* test/src/lread-tests.el: Add tests for new behavior, and
fix some old tests that were wrong.

1 files changed, 10 insertions, 21 deletions

diff --git a/src/lread.c b/src/lread.c
index a42c1f60c95..6e97e079650 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -2155,26 +2155,15 @@ grow_read_buffer (void)
 static int
 character_name_to_code (char const *name, ptrdiff_t name_len)
 {
-  Lisp_Object code;
-
-  /* Code point as U+XXXX....  */
-  if (name[0] == 'U' && name[1] == '+')
-    {
-      /* Pass the leading '+' to string_to_number, so that it
-         rejects monstrosities such as negative values.  */
-      code = string_to_number (name + 1, 16, false);
-    }
-  else
-    {
-      /* Look up the name in the table returned by 'ucs-names'.  */
-      AUTO_STRING_WITH_LEN (namestr, name, name_len);
-      Lisp_Object names = call0 (Qucs_names);
-      code = CDR (Fassoc (namestr, names));
-    }
-
-  if (! (INTEGERP (code)
-         && 0 <= XINT (code) && XINT (code) <= MAX_UNICODE_CHAR
-         && ! char_surrogate_p (XINT (code))))
+  /* For "U+XXXX", pass the leading '+' to string_to_number to reject
+     monstrosities like "U+-0000".  */
+  Lisp_Object code
+    = (name[0] == 'U' && name[1] == '+'
+       ? string_to_number (name + 1, 16, false)
+       : call2 (Qchar_from_name, make_unibyte_string (name, name_len), Qt));
+
+  if (! RANGED_INTEGERP (0, code, MAX_UNICODE_CHAR)
+      || char_surrogate_p (XINT (code)))
     {
       AUTO_STRING (format, "\\N{%s}");
       AUTO_STRING_WITH_LEN (namestr, name, name_len);
@@ -4829,5 +4818,5 @@ that are loaded before your customizations are read!  */);
   DEFSYM (Qrehash_size, "rehash-size");
   DEFSYM (Qrehash_threshold, "rehash-threshold");
 
-  DEFSYM (Qucs_names, "ucs-names");
+  DEFSYM (Qchar_from_name, "char-from-name");
 }