(non_ascii_char_to_string): Handle modifier bits as

the same as Lisp reader.

1 files changed, 37 insertions, 6 deletions

diff --git a/src/charset.c b/src/charset.c
index b286c655792..9c6da218436 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -142,15 +142,46 @@ non_ascii_char_to_string (c, workbuf, str)
 {
   int charset, c1, c2;
 
-  if (c & ~GLYPH_MASK_CHAR)     /* This includes the case C is negative.  */
+  if (c & CHAR_MODIFIER_MASK)   /* This includes the case C is negative.  */
     {
+      /* Multibyte character can't have a modifier bit.  */
+      if (! SINGLE_BYTE_CHAR_P ((c & ~CHAR_MODIFIER_MASK)))
+        invalid_character (c);
+
+      /* For Meta, Shift, and Control modifiers, we need special care.  */
       if (c & CHAR_META)
-        /* Move the meta bit to the right place for a string.  */
-        c |= 0x80;
+        {
+          /* Move the meta bit to the right place for a string.  */
+          c = (c & ~CHAR_META) | 0x80;
+        }
+      if (c & CHAR_SHIFT)
+        {
+          /* Shift modifier is valid only with [A-Za-z].  */
+          if ((c & 0377) >= 'A' && (c & 0377) <= 'Z')
+            c &= ~CHAR_SHIFT;
+          else if ((c & 0377) >= 'a' && (c & 0377) <= 'z')
+            c = (c & ~CHAR_SHIFT) - ('a' - 'A');
+        }
       if (c & CHAR_CTL)
-        c &= 0x9F;
-      else if (c & CHAR_SHIFT && (c & 0x7F) >= 'a' && (c & 0x7F) <= 'z')
-        c -= 'a' - 'A';
+        {
+          /* Simulate the code in lread.c.  */
+          /* Allow `\C- ' and `\C-?'.  */
+          if (c == (CHAR_CTL | ' '))
+            c = 0;
+          else if (c == (CHAR_CTL | '?'))
+            c = 127;
+          /* ASCII control chars are made from letters (both cases),
+             as well as the non-letters within 0100...0137.  */
+          else if ((c & 0137) >= 0101 && (c & 0137) <= 0132)
+            c &= (037 | (~0177 & ~CHAR_CTL));
+          else if ((c & 0177) >= 0100 && (c & 0177) <= 0137)
+            c &= (037 | (~0177 & ~CHAR_CTL));
+        }
+
+      /* If C still has any modifier bits, it is an invalid character.  */
+      if (c & CHAR_MODIFIER_MASK)
+        invalid_character (c);
+
       *str = workbuf;
       *workbuf = c;
       return 1;