interp: force root scope for binPkgT selector

interp/type.go

@@ -513,9 +513,31 @@ func nodeType(interp *Interpreter, sc *scope, n *node) (*itype, error) {
 	case selectorExpr:
 		// Resolve the left part of selector, then lookup the right part on it
 		var lt *itype
-		if lt, err = nodeType(interp, sc, n.child[0]); err != nil {
+
+		// If we are in a list of func parameters, and we are a selector on a binPkgT, but
+		// one of the other parameters has the same name as the pkg name, in the list of
+		// symbols we would find the other parameter instead of the pkg because it comes
+		// first when looking up in the stack of scopes. So in that case we force the
+		// lookup directly in the root scope to shortcircuit that issue.
+		var localScope *scope
+		localScope = sc
+		if n.anc != nil && len(n.anc.child) > 1 && n.anc.child[1] == n &&
+			// This check is weaker than what we actually want to know, i.e. whether
+			// n.anc.child[0] is a variable, but it seems at this point in the run we have no
+			// way of knowing that yet (typ is nil, so there's no typ.cat yet).
+			n.anc.child[0].kind == identExpr {
+			for {
+				if localScope.level == 0 {
+					break
+				}
+				localScope = localScope.anc
+			}
+		}
+
+		if lt, err = nodeType(interp, localScope, n.child[0]); err != nil {
 			return nil, err
 		}
+
 		if lt.incomplete {
 			t.incomplete = true
 			break