fix: correct branch action in parenthesis expression

_test/if7.go

@@ -0,0 +1,15 @@
+package main
+
+func main() {
+	a := 0
+	b := false
+	if (b) {
+		a = 1
+	} else {
+		a = -1
+	}
+	println(a)
+}
+
+// Output:
+// -1

interp/cfg.go

@@ -1004,10 +1004,7 @@ func (interp *Interpreter) cfg(root *node, pkgID string) ([]*node, error) {
 						}
 					}
 					if sym.kind == varSym && sym.typ != nil && sym.typ.TypeOf().Kind() == reflect.Bool {
-						switch n.anc.kind {
-						case ifStmt0, ifStmt1, ifStmt2, ifStmt3, forStmt1, forStmt2, forStmt3, forStmt4:
-							n.gen = branch
-						}
+						fixBranch(n)
 					}
 				}
 				if n.sym != nil {
@@ -1668,6 +1665,17 @@ func genRun(nod *node) error {
 	return err
 }
 
+// FixBranch sets the branch action to the identExpr node if it is a bool
+// used in a conditional expression.
+func fixBranch(n *node) {
+	switch n.anc.kind {
+	case ifStmt0, ifStmt1, ifStmt2, ifStmt3, forStmt1, forStmt2, forStmt3, forStmt4:
+		n.gen = branch
+	case parenExpr:
+		fixBranch(n.anc)
+	}
+}
+
 // GetDefault return the index of default case clause in a switch statement, or -1.
 func getDefault(n *node) int {
 	for i, c := range n.lastChild().child {