fix: set type correctly for variable declaration with assignment (#59)

Do not ignore type node when used in a variable declaration with assign.
The source node in a assign node can be the 2nd or the 3rd (the 2nd being the type).

_test/method10.go

@@ -1,15 +1,13 @@
 package main
 
+type T int
+
+func (t T) foo() { println("foo", t) }
+
 func main() {
-	o := Coord{3, 4}
-	println(o.dist())
-}
-
-func (c Coord) dist() int { return c.x*c.x + c.y*c.y }
-
-type Coord struct {
-	x, y int
+	var t T = 2
+	t.foo()
 }
 
 // Output:
-// 25
+// foo 2

_test/var5.go

@@ -0,0 +1,12 @@
+package main
+
+import "fmt"
+
+func main() {
+	var a int64 = 64
+	fmt.Printf("a: %v %T", a, a)
+	fmt.Println()
+}
+
+// Output:
+// a: 64 int64

interp/cfg.go

@@ -148,10 +148,6 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 			if l := len(n.child); n.anc.kind == ConstDecl && l == 1 {
 				// Implicit iota assignment. TODO: replicate previous explicit assignment
 				n.child = append(n.child, &Node{anc: n, interp: interp, kind: Ident, ident: "iota"})
-			} else if l%2 == 1 {
-				// Odd number of children: remove the type node, useless for assign
-				i := l / 2
-				n.child = append(n.child[:i], n.child[i+1:]...)
 			}
 
 		case BlockStmt:
@@ -221,9 +217,6 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 		case If0, If1, If2, If3:
 			scope = scope.push(0)
 
-		//case SelectStmt:
-		//	err = CfgError(fmt.Errorf("cfg: SelectStmt not implemented; %s", n.fset.Position(n.pos)))
-
 		case Switch0:
 			// Make sure default clause is in last position
 			c := n.child[1].child
@@ -253,12 +246,16 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 			n.findex = scope.inc(interp)
 
 		case Define, AssignStmt:
-			wireChild(n)
-			dest, src := n.child[0], n.child[1]
+			dest, src := n.child[0], n.child[len(n.child)-1]
 			sym, level, _ := scope.lookup(dest.ident)
 			if n.kind == Define {
+				if len(n.child) == 3 {
+					// Type is provided in var declaration
+					dest.typ, err = nodeType(interp, scope, n.child[1])
+				} else {
+					dest.typ = src.typ
+				}
 				dest.val = src.val
-				dest.typ = src.typ
 				dest.recv = src.recv
 				dest.findex = sym.index
 				if src.action == GetFunc {
@@ -273,6 +270,7 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 					sym.typ = dest.typ
 				}
 			}
+			wireChild(n)
 			// Detect invalid float truncate
 			if isInt(dest.typ) && isFloat(src.typ) {
 				err = src.cfgError("invalid float truncate")
@@ -293,9 +291,13 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 				src.level = level
 			case src.kind == BasicLit:
 				// TODO: perform constant folding and propagation here
-				// Convert literal value to destination type
-				src.val = reflect.ValueOf(src.val).Convert(dest.typ.TypeOf())
-				src.typ = dest.typ
+				if dest.typ.cat == InterfaceT {
+					src.val = reflect.ValueOf(src.val)
+				} else {
+					// Convert literal value to destination type
+					src.val = reflect.ValueOf(src.val).Convert(dest.typ.TypeOf())
+					src.typ = dest.typ
+				}
 			}
 			n.typ = dest.typ
 			if sym != nil {
@@ -895,9 +897,15 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 			}
 
 		case StarExpr:
-			wireChild(n)
-			n.typ = n.child[0].typ.val
-			n.findex = scope.inc(interp)
+			if n.anc.kind == Define && len(n.anc.child) == 3 && n.anc.child[1] == n {
+				// pointer type expression in a var definition
+				n.gen = nop
+			} else {
+				// dereference expression
+				wireChild(n)
+				n.typ = n.child[0].typ.val
+				n.findex = scope.inc(interp)
+			}
 
 		case Switch0:
 			n.start = n.child[1].start

interp/interp_test.go

@@ -2926,15 +2926,13 @@ func Example_method10() {
 	src := `
 package main
 
+type T int
+
+func (t T) foo() { println("foo", t) }
+
 func main() {
-	o := Coord{3, 4}
-	println(o.dist())
-}
-
-func (c Coord) dist() int { return c.x*c.x + c.y*c.y }
-
-type Coord struct {
-	x, y int
+	var t T = 2
+	t.foo()
 }
 `
 	i := interp.New(interp.Opt{Entry: "main"})
@@ -2945,7 +2943,7 @@ type Coord struct {
 	}
 
 	// Output:
-	// 25
+	// foo 2
 }
 
 func Example_method11() {
@@ -5709,6 +5707,29 @@ func main() {
 	// 2 3
 }
 
+func Example_var5() {
+	src := `
+package main
+
+import "fmt"
+
+func main() {
+	var a int64 = 64
+	fmt.Printf("a: %v %T", a, a)
+	fmt.Println()
+}
+`
+	i := interp.New(interp.Opt{Entry: "main"})
+	i.Use(stdlib.Value, stdlib.Type)
+	_, err := i.Eval(src)
+	if err != nil {
+		panic(err)
+	}
+
+	// Output:
+	// a: 64 int64
+}
+
 func Example_variadic() {
 	src := `
 package main

interp/run.go

@@ -185,7 +185,7 @@ func assignX(n *Node) {
 // assign implements single value assignment
 func assign(n *Node) {
 	value := genValue(n)
-	value1 := genValue(n.child[1])
+	value1 := genValue(n.child[len(n.child)-1])
 	next := getExec(n.tnext)
 
 	if n.child[0].typ.cat == InterfaceT {