(read1): Redesign strategy for force_multibyte and

force_singlebyte.  Now is_multibyte records whether read_buffer
is multibyte.  Encountering any multibyte character makes it so.

diff --git a/src/lread.c b/src/lread.c
index ae8339ac3d00fc5ceffcb65b030ceb9b70ec5436..10baf509918ab628568ea6701225c5d9d421930c 100644 (file)
--- a/src/lread.c
+++ b/src/lread.c
@@ -2145,14 +2145,16 @@ read1 (readcharfun, pch, first_in_list)
        char *p = read_buffer;
        char *end = read_buffer + read_buffer_size;
        register int c;
-       /* Nonzero if we saw an escape sequence specifying
-          a multibyte character.  */
+       /* 1 if we saw an escape sequence specifying
+          a multibyte character, or a multibyte character.  */
        int force_multibyte = 0;
-       /* Nonzero if we saw an escape sequence specifying
+       /* 1 if we saw an escape sequence specifying
           a single-byte character.  */
        int force_singlebyte = 0;
+       /* 1 if read_buffer contains multibyte text now.  */
+       int is_multibyte = 0;
        int cancel = 0;
-       int nchars;
+       int nchars = 0;
 
        while ((c = READCHAR) >= 0
               && c != '\"')
@@ -2186,39 +2188,47 @@ read1 (readcharfun, pch, first_in_list)
                  force_multibyte = 1;
              }
 
-           if (! SINGLE_BYTE_CHAR_P ((c & ~CHAR_MODIFIER_MASK)))
+           /* A character that must be multibyte forces multibyte.  */
+           if (! SINGLE_BYTE_CHAR_P (c & ~CHAR_MODIFIER_MASK))
+             force_multibyte = 1;
+
+           /* If we just discovered the need to be multibyte,
+              convert the text accumulated thus far.  */
+           if (force_multibyte && ! is_multibyte)
              {
-               /* Any modifiers for a multibyte character are invalid.  */
-               if (c & CHAR_MODIFIER_MASK)
-                 error ("Invalid modifier in string");
-               p += CHAR_STRING (c, p);
-               force_multibyte = 1;
+               is_multibyte = 1;
+               to_multibyte (&p, &end, &nchars);
              }
-           else
-             {
-               /* Allow `\C- ' and `\C-?'.  */
-               if (c == (CHAR_CTL | ' '))
-                 c = 0;
-               else if (c == (CHAR_CTL | '?'))
-                 c = 127;
 
-               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');
-                 }
+           /* Allow `\C- ' and `\C-?'.  */
+           if (c == (CHAR_CTL | ' '))
+             c = 0;
+           else if (c == (CHAR_CTL | '?'))
+             c = 127;
 
-               if (c & CHAR_META)
-                 /* Move the meta bit to the right place for a string.  */
-                 c = (c & ~CHAR_META) | 0x80;
-               if (c & ~0xff)
-                 error ("Invalid modifier in string");
-               *p++ = c;
+           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_META)
+             /* Move the meta bit to the right place for a string.  */
+             c = (c & ~CHAR_META) | 0x80;
+           if (c & CHAR_MODIFIER_MASK)
+             error ("Invalid modifier in string");
+
+           if (is_multibyte)
+             p += CHAR_STRING (c, p);
+           else
+             *p++ = c;
+
+           nchars++;
          }
+
        if (c < 0)
          end_of_file_error ();
 
@@ -2228,10 +2238,8 @@ read1 (readcharfun, pch, first_in_list)
        if (!NILP (Vpurify_flag) && NILP (Vdoc_file_name) && cancel)
          return make_number (0);
 
-       if (force_multibyte)
-         to_multibyte (&p, &end, &nchars);
-       else if (force_singlebyte)
-         nchars = p - read_buffer;
+       if (is_multibyte || force_singlebyte)
+         ;
        else if (load_convert_to_unibyte)
          {
            Lisp_Object string;
@@ -2242,6 +2250,8 @@ read1 (readcharfun, pch, first_in_list)
                                                p - read_buffer);
                return Fstring_make_unibyte (string);
              }
+           /* We can make a unibyte string directly.  */
+           is_multibyte = 0;
          }
        else if (EQ (readcharfun, Qget_file_char)
                 || EQ (readcharfun, Qlambda))
@@ -2252,19 +2262,18 @@ read1 (readcharfun, pch, first_in_list)
               for reading dynamic byte code (compiled with
               byte-compile-dynamic = t).  */
            to_multibyte (&p, &end, &nchars);
+           is_multibyte = 1;
          }
        else
          /* In all other cases, if we read these bytes as
             separate characters, treat them as separate characters now.  */
-         nchars = p - read_buffer;
+         ;
 
        if (read_pure)
          return make_pure_string (read_buffer, nchars, p - read_buffer,
-                                  (force_multibyte
-                                   || (p - read_buffer != nchars)));
+                                  is_multibyte);
        return make_specified_string (read_buffer, nchars, p - read_buffer,
-                                     (force_multibyte
-                                      || (p - read_buffer != nchars)));
+                                     is_multibyte);
       }
 
     case '.':