22760: fix partial string length reports with NO_MULTIBYTE

ChangeLog

@@ -1,3 +1,8 @@
+2017-07-02  Peter Stephenson  <p.w.stephenson@ntlworld.com>
+
+	* 22760: Src/utils.c, Test/D04parameter.ztst: NO_MULTIBYTE
+	partial string lengths were reported as full string lengths.
+
 2017-06-27  Peter Stephenson  <p.stephenson@samsung.com>
 
 	* 41368: Src/Zle/compctl.c: missing unqueue_signals().

Src/utils.c

@@ -5417,7 +5417,7 @@ mb_metastrlenend(char *ptr, int width, char *eptr)
     int num, num_in_char, complete;
 
     if (!isset(MULTIBYTE))
-	return ztrlen(ptr);
+	return eptr ? (int)(eptr - ptr) : ztrlen(ptr);
 
     laststart = ptr;
     ret = MB_INVALID;

Test/D04parameter.ztst

@@ -783,16 +783,36 @@
 0:${(R)...}
 >is the , 
 
+  # Although there's no reliance on multibyte here, the
+  # code exercised is different, so test both paths in the following group.
+  # If the shell isn't multibyte capable the tests are the same;
+  # that's not a problem.
   # This (1) doesn't work with // or /
   #      (2) perhaps ought to be 18, to be consistent with normal zsh
   #          substring indexing and with backreferences.
   print ${(BES)string##white}
+  (unsetopt multibyte; print ${(BES)string##white})
 0:${(BE...)...}
+>14 19
 >14 19
 
   print ${(NS)string##white}
+  (unsetopt multibyte; print ${(NS)string##white})
 0:${(N)...}
 >5
+>5
+
+  fn() {
+    emulate -L zsh
+    local a=abcdef
+    print ${(SNBE)a#abcd}
+    unsetopt multibyte
+    print ${(SNBE)a#abcd}
+  }
+  fn
+0:${(BEN)...} again, with match
+>1 5 4
+>1 5 4
 
   string='abcdefghijklmnopqrstuvwxyz'
   print ${${string%[aeiou]*}/(#m)?(#e)/${(U)MATCH}}