Partial implementation of "nameref", sort of.

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

This is incomplete, but presented for consideration of how to proceed
with it.

There are obviously some additional checks that could be made, e.g.,
be sure that a PM_FAKENAMEREF is also a PM_SCALAR and is not a numeric
subtype, etc.

With this patch:

% typeset -n foo=bar
% bar=hello
% echo $foo
hello

However, it doesn't work for ${foo} because the itype_end() test in
paramsubst() doesn't account for the braces.


diff --git a/Src/builtin.c b/Src/builtin.c
index 08be1ac..8d8b125 100644
--- a/Src/builtin.c
+++ b/Src/builtin.c
@@ -120,7 +120,7 @@ static struct builtin builtins[] =
     BUILTIN("trap", BINF_PSPECIAL | BINF_HANDLES_OPTS, bin_trap, 0, -1, 0, NULL, NULL),
     BUILTIN("true", 0, bin_true, 0, -1, 0, NULL, NULL),
     BUILTIN("type", 0, bin_whence, 0, -1, 0, "ampfsSw", "v"),
-    BUILTIN("typeset", BINF_PLUSOPTS | BINF_MAGICEQUALS | BINF_PSPECIAL, bin_typeset, 0, -1, 0, "AE:%F:%HL:%R:%TUZ:%afghi:%klprtuxmz", NULL),
+    BUILTIN("typeset", BINF_PLUSOPTS | BINF_MAGICEQUALS | BINF_PSPECIAL, bin_typeset, 0, -1, 0, "AE:%F:%HL:%R:%TUZ:%afghi:%klprtuxmzn", NULL),
     BUILTIN("umask", 0, bin_umask, 0, 1, 0, "S", NULL),
     BUILTIN("unalias", 0, bin_unhash, 1, -1, 0, "ms", "a"),
     BUILTIN("unfunction", 0, bin_unhash, 1, -1, 0, "m", "f"),
@@ -2369,6 +2369,11 @@ bin_typeset(char *name, char **argv, Options ops, int func)
 	else if (OPT_PLUS(ops,optval))
 	    off |= bit;
     }
+    if (OPT_MINUS(ops,'n')) {
+	on |= PM_FAKENAMEREF;
+    } else if (on || OPT_PLUS(ops,'n')) {
+	off |= PM_FAKENAMEREF;
+    }
     roff = off;
 
     /* Sanity checks on the options.  Remove conflicting options. */
diff --git a/Src/subst.c b/Src/subst.c
index a2bb648..842eb03 100644
--- a/Src/subst.c
+++ b/Src/subst.c
@@ -2237,9 +2237,11 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int pf_flags)
 	while (inull(*s))
 	    s++;
 	v = (Value) NULL;
-    } else if (aspar) {
+    } else if (aspar || ((s = itype_end(s, IIDENT, 0)) && !*s)) {
+	struct value vtmp;
+	char *stmp = s = idbeg;
 	/*
-	 * No subexpression, but in any case the value is going
+	 * No subexpression, but in any case the value may be going
 	 * to give us the name of a parameter on which we do
 	 * our remaining processing.  In other words, this
 	 * makes ${(P)param} work like ${(P)${param}}.  (Probably
@@ -2247,12 +2249,20 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int pf_flags)
 	 * and it's been kludged into the subexp code because no
 	 * opportunity for a kludge has been neglected.)
 	 */
-	if ((v = fetchvalue(&vbuf, &s, 1, (qt ? SCANPM_DQUOTED : 0)))) {
-	    val = idbeg = getstrvalue(v);
-	    subexp = 1;
-	} else
+	if ((v = fetchvalue(&vtmp, &stmp, 1, (qt ? SCANPM_DQUOTED : 0)))) {
+	    if (aspar || (v->pm->node.flags & PM_FAKENAMEREF)) {
+		s = stmp;
+		vbuf = vtmp;
+		val = idbeg = getstrvalue(v);
+		aspar = subexp = 1;
+	    }
+	} else if (aspar)
 	    vunset = 1;
-    }
+	if (!aspar) {
+	    v = (Value) NULL;
+	}
+    } else
+	s = idbeg;
     /*
      * We need to retrieve a value either if we haven't already
      * got it from a subexpression, or if the processing so
diff --git a/Src/zsh.h b/Src/zsh.h
index 94e9ffc..dfd9c53 100644
--- a/Src/zsh.h
+++ b/Src/zsh.h
@@ -1661,6 +1661,7 @@ struct tieddata {
 
 #define PM_KSHSTORED	(1<<17) /* function stored in ksh form              */
 #define PM_ZSHSTORED	(1<<18) /* function stored in zsh form              */
+#define PM_FAKENAMEREF	(1<<19) /* behaves like a ksh nameref, sort of      */
 
 /* Remaining flags do not correspond directly to command line arguments */
 #define PM_LOCAL	(1<<21) /* this parameter will be made local        */