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Only walk pointer patterns that walk pointers.

--- a/mi/match.c

+++ b/mi/match.c

@@ -21,8 +21,9 @@

 	Node *lbl;

 	Node *load;

 	size_t nconstructors;

-	int accept;

-	int emitted;

+	char accept;

+	char emitted;

+	char ptrwalk;

 	/* the decision tree step */

 	Node **pat;

@@ -244,6 +245,13 @@

 	return ret;

 }

+static int isbasictype(Dtree *dt, Type *ty)

+{

+	if (ty->type == Typtr)

+		return !dt->ptrwalk;

+	return istyprimitive(ty) || ty->type == Tyvoid;

+}

+

 static int addwildrec(Srcloc loc, Type *ty, Dtree *start, Dtree *accept, Dtree ***end, size_t *nend)

 {

 	Dtree *next, **last, **tail;

@@ -255,7 +263,7 @@

 	tail = NULL;

 	ntail = 0;

 	ty = tybase(ty);

-	if (istyprimitive(ty) || ty->type == Tyvoid) {

+	if (isbasictype(start, ty)) {

 		if (start->accept || start == accept)

 			return 0;

 		for (i = 0; i < start->nnext; i++)

@@ -340,15 +348,7 @@

 		lappend(&last, &nlast, accept);

 		break;

 	case Typtr:

-		/* we only want to descend if there's something to match here. */

-		if (start->any || start->nnext > 0) {

-			ret = addwildrec(loc, ty->sub[0], start, accept, &last, &nlast);

-		} else if (!start->any) {

-			start->any = accept;

-			lappend(end, nend, accept);

-			return 1;

-		}

-		break;

+		ret = addwildrec(loc, ty->sub[0], start, accept, &last, &nlast);

 	default:

 		ret = 1;

 		lappend(&last, &nlast, accept);

@@ -601,6 +601,7 @@

 	deref = mkexpr(val->loc, Oderef, val, NULL);

 	deref->expr.type = exprtype(pat->expr.args[0]);

 	start->nconstructors = nconstructors(exprtype(deref));

+	start->ptrwalk = 1;

 	return addpat(pat->expr.args[0], deref, start, accept, cap, ncap, end, nend);

 }