[EXPAND] Do not expand tilde in parameter expansion within quotes

Previously code was added so that tilde expansion was carried out
parameter expansions within double quotes.  This change was made
with reference the behaviour of bash at the time.  Bash has since
be fixed so that this behaviour no longer occurs which is in line
with most other POSIX shells.

So this patch removes that behaviour in dash as well.

Test case:

	unset a
	echo "${a:-~root}"

Old result:

	/root

New result:

	~root

2 files changed, 4 insertions, 8 deletions

diff --git a/src/expand.c b/src/expand.c
index 1443c14..c9f09ff 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -278,7 +278,7 @@ argstr(char *p, int flag)
 	const char *reject = spclchars;
 	int c;
 	int quotes = flag & QUOTES_ESC;
-	int breakall = flag & EXP_WORD;
+	int breakall = (flag & (EXP_WORD | EXP_QUOTED)) == EXP_WORD;
 	int inquotes;
 	size_t length;
 	int startloc;
@@ -296,8 +296,6 @@ argstr(char *p, int flag)
 		flag &= ~EXP_TILDE;
 tilde:
 		q = p;
-		if (*q == (char)CTLESC && (flag & EXP_QWORD))
-			q++;
 		if (*q == '~')
 			p = exptilde(p, q, flag);
 	}
@@ -780,10 +778,8 @@ again:
 	if (subtype == VSMINUS) {
 vsplus:
 		if (varlen < 0) {
-			argstr(
-				p, flag | EXP_TILDE |
-					(quoted ?  EXP_QWORD : EXP_WORD)
-			);
+			argstr(p, flag | EXP_TILDE | EXP_WORD |
+				  (quoted ? EXP_QUOTED : 0));
 			goto end;
 		}
 		if (easy)
diff --git a/src/expand.h b/src/expand.h
index 6b7d607..be7ec6f 100644
--- a/src/expand.h
+++ b/src/expand.h
@@ -56,7 +56,7 @@ struct arglist {
 #define EXP_RECORD	0x20	/* need to record arguments for ifs breakup */
 #define EXP_VARTILDE2	0x40	/* expand tildes after colons only */
 #define EXP_WORD	0x80	/* expand word in parameter expansion */
-#define EXP_QWORD	0x100	/* expand word in quoted parameter expansion */
+#define EXP_QUOTED	0x100	/* expand word in double quotes */
 
 
 union node;