${(q)...} for newline

[Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx>]

Param-style simple (i.e. backslash) quoting of a newline appends a real
newline in double quotes.  It seems to me it would occasion far fewer
surprises if this never output a literal newline, so this uses $'\n'.  We
already bargain for up to 7 output characters per input character.  The
first two hunks are just a tidy up (written before I realised I didn't
need to do any more counting).

Index: Src/utils.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/utils.c,v
retrieving revision 1.242
diff -p -u -r1.242 utils.c
--- Src/utils.c	27 Mar 2010 19:04:36 -0000	1.242
+++ Src/utils.c	23 May 2010 19:54:21 -0000
@@ -4585,11 +4585,12 @@ quotestring(const char *s, char **e, int
      * quotesub = 2:  mechanism active, added opening "'"; need
      *                closing "'".
      */
-    int quotesub = 0;
+    int quotesub = 0, slen;
     char *quotestart;
     convchar_t cc;
     const char *uend;
 
+    slen = strlen(s);
     switch (instring)
     {
     case QT_BACKSLASH:
@@ -4598,21 +4599,22 @@ quotestring(const char *s, char **e, int
 	 * Keep memory usage within limits by allocating temporary
 	 * storage and using heap for correct size at end.
 	 */
-	alloclen = strlen(s) * 7 + 1;
+	alloclen = slen * 7 + 1;
 	break;
 
     case QT_SINGLE_OPTIONAL:
 	/*
 	 * Here, we may need to add single quotes.
 	 */
-	alloclen = strlen(s) * 4 + 3;
+	alloclen = slen * 4 + 3;
 	quotesub = 1;
 	break;
 
     default:
-	alloclen = strlen(s) * 4 + 1;
+	alloclen = slen * 4 + 1;
 	break;
     }
+
     tt = quotestart = v = buf = zshcalloc(alloclen);
 
     DPUTS(instring < QT_BACKSLASH || instring == QT_BACKTICK ||
@@ -4771,15 +4773,19 @@ quotestring(const char *s, char **e, int
 		    continue;
 		} else if (*u == '\n' ||
 			   (instring == QT_SINGLE && *u == '\'')) {
-		    if (unset(RCQUOTES)) {
+		    if (*u == '\n') {
+			*v++ = '$';
+			*v++ = '\'';
+			*v++ = '\\';
+			*v++ = 'n';
+			*v++ = '\'';
+		    } else if (unset(RCQUOTES)) {
 			*v++ = '\'';
 			if (*u == '\'')
 			    *v++ = '\\';
 			*v++ = *u;
 			*v++ = '\'';
-		    } else if (*u == '\n')
-			*v++ = '"', *v++ = '\n', *v++ = '"';
-		    else
+		    } else
 			*v++ = '\'', *v++ = '\'';
 		    u++;
 		    continue;

-- 
Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/