fix: correct scoping of method declaration (#175)

_test/method10.go

@@ -1,13 +1,17 @@
 package main
 
-type T int
+const BlockSize = 8
 
-func (t T) foo() { println("foo", t) }
+type Cipher struct{}
+
+func (c *Cipher) BlockSize() int { return BlockSize }
 
 func main() {
-	var t T = 2
-	t.foo()
+	println(BlockSize)
+	s := Cipher{}
+	println(s.BlockSize())
 }
 
 // Output:
-// foo 2
+// 8
+// 8

_test/method11.go

@@ -1,15 +1,17 @@
 package main
 
+func BlockSize() string { return "func" }
+
+type Cipher struct{}
+
+func (c *Cipher) BlockSize() string { return "method" }
+
 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
+	println(BlockSize())
+	s := Cipher{}
+	println(s.BlockSize())
 }
 
 // Output:
-// 25
+// func
+// method

interp/cfg.go

@@ -776,14 +776,16 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 			scope = scope.pop()
 
 		case FuncDecl:
+			n.start = n.child[3].start
 			n.types = scope.types
 			scope = scope.pop()
-			funcName := n.child[1].ident
-			n.start = n.child[3].start
-			interp.scope[pkgName].sym[funcName].index = -1 // to force value to n.val
-			interp.scope[pkgName].sym[funcName].typ = n.typ
-			interp.scope[pkgName].sym[funcName].kind = Func
-			interp.scope[pkgName].sym[funcName].node = n
+			if !isMethod(n) {
+				funcName := n.child[1].ident
+				interp.scope[pkgName].sym[funcName].index = -1 // to force value to n.val
+				interp.scope[pkgName].sym[funcName].typ = n.typ
+				interp.scope[pkgName].sym[funcName].kind = Func
+				interp.scope[pkgName].sym[funcName].node = n
+			}
 
 		case FuncLit:
 			n.types = scope.types
@@ -1348,6 +1350,7 @@ func (n *Node) lastChild() *Node { return n.child[len(n.child)-1] }
 func isKey(n *Node) bool {
 	return n.anc.kind == File ||
 		(n.anc.kind == SelectorExpr && n.anc.child[0] != n) ||
+		(n.anc.kind == FuncDecl && isMethod(n.anc)) ||
 		(n.anc.kind == KeyValueExpr && n.anc.child[0] == n)
 }
 
@@ -1371,6 +1374,10 @@ func isNewDefine(n *Node, scope *Scope) bool {
 	return false
 }
 
+func isMethod(n *Node) bool {
+	return len(n.child[0].child) > 0 // receiver defined
+}
+
 func isMapEntry(n *Node) bool {
 	return n.action == GetIndex && n.child[0].typ.cat == MapT
 }

interp/gta.go

@@ -68,7 +68,9 @@ func (interp *Interpreter) Gta(root *Node, rpath string) error {
 			if n.typ, err = nodeType(interp, scope, n.child[2]); err != nil {
 				return false
 			}
-			scope.sym[n.child[1].ident] = &Symbol{kind: Func, typ: n.typ, node: n, index: -1}
+			if !isMethod(n) {
+				scope.sym[n.child[1].ident] = &Symbol{kind: Func, typ: n.typ, node: n, index: -1}
+			}
 			if len(n.child[0].child) > 0 {
 				// function is a method, add it to the related type
 				var receiverType *Type