26055: ensure process substitution is handled before parameter and command

ChangeLog

@@ -1,5 +1,9 @@
 2008-11-17  Peter Stephenson  <pws@csr.com>
 
+	* 26055: README, Doc/Zsh/expn.yo, Src/subst.c: ensure process
+	substitution is handled completely before parameter and
+	command substitution.
+
 	* 26053: Completion/Base/Utility/_arguments: handle
 	"<cmd> --help" output that includes optional parts of options
 	in square brackets.

Doc/Zsh/expn.yo

@@ -360,9 +360,8 @@ Each part of a command argument that takes the form
 is subject to process substitution.  The expression may be preceeded
 or followed by other strings except that, to prevent clashes with
 commonly occurring strings and patterns, the last
-form must occur at the start of a command argument, and none of
-the forms may occur inside parentheses used for grouping of patterns or
-inside parameter substitutions.
+form must occur at the start of a command argument, and the forms
+are only expanded when first parsing command or assignment arguments.
 
 In the case of the tt(<) or tt(>) forms, the shell runs the commands in
 var(list) asynchronously.  If the system supports the tt(/dev/fd)

README

@@ -74,11 +74,9 @@ were only handled if they appeared as separate command arguments.
 (However, the latter two forms caused the current argument to be
 terminated and a new one started even if they occurred in the middle of
 a string.)  Now all three may be followed by other strings, and the
-latter two may also be preceeded by other strings.  None may occur inside
-parameter substitutions, or inside parentheses used for grouping of
-patterns, in order to avoid clashes with cases where
-tt(<) or tt(>) were not treated specially in previous versions of the
-shell.
+latter two may also be preceeded by other strings.  Remaining
+limitations on their use (to reduce incompatibilities to a minimum)
+are documented in the zshexpn.1 manual.
 
 In previous versions of the shell it was possible to use index 0 in an
 array or string subscript to refer to the same element as index 1 if the

Src/subst.c

@@ -152,8 +152,8 @@ stringsubst(LinkList list, LinkNode node, int ssub, int asssub)
     char *str  = str3, c;
 
     while (!errflag && (c = *str)) {
-	if ((c == Inang || c == Outang || (str == str3 && c == Equals)) &&
-	    str[1] == Inpar) {
+	if (((c = *str) == Inang || c == Outang || (str == str3 && c == Equals))
+	    && str[1] == Inpar) {
 	    char *subst, *rest, *snew, *sptr;
 	    int str3len = str - str3, sublen, restlen;
 
@@ -181,8 +181,13 @@ stringsubst(LinkList list, LinkNode node, int ssub, int asssub)
 	    str3 = snew;
 	    str = snew + str3len + sublen;
 	    setdata(node, str3);
-	    continue;
-	} else if ((qt = c == Qstring) || c == String) {
+	} else
+	    str++;
+    }
+    str = str3;
+
+    while (!errflag && (c = *str)) {
+	if ((qt = c == Qstring) || c == String) {
 	    if ((c = str[1]) == Inpar) {
 		if (!qt)
 		    list->list.flags |= LF_ARRAY;