From a99fb98f84d2106f497a2593cc753589174c86a7 Mon Sep 17 00:00:00 2001
From: Marc Vertes <mvertes@free.fr>
Date: Wed, 6 Feb 2019 14:50:37 +0100
Subject: [PATCH] fix: append() was not returning a type (#84)

append() now returns the underlying array type.
Method lookup was skipped for selector expression on arrays.
Pointer expression was incorrectly parsed as a dereference instead of
type expression.
---
 _test/a20.go          | 19 +++++++++++++++++++
 interp/cfg.go         | 17 +++++++++++------
 interp/interp_test.go | 30 ++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 6 deletions(-)
 create mode 100644 _test/a20.go

diff --git a/_test/a20.go b/_test/a20.go
new file mode 100644
index 00000000..02f951ef
--- /dev/null
+++ b/_test/a20.go
@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+type IntArray []int
+
+func (h *IntArray) Add(x int) {
+	*h = append(*h, x)
+}
+
+func main() {
+	a := IntArray{}
+	a.Add(4)
+
+	fmt.Println(a)
+}
+
+// Output:
+// [4]
diff --git a/interp/cfg.go b/interp/cfg.go
index 34833314..8b559e3f 100644
--- a/interp/cfg.go
+++ b/interp/cfg.go
@@ -450,6 +450,10 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 				n.gen = n.child[0].sym.builtin
 				n.child[0].typ = &Type{cat: BuiltinT}
 				switch n.child[0].ident {
+				case "append":
+					if n.typ = scope.getType(n.child[1].ident); n.typ == nil {
+						n.typ, err = nodeType(interp, scope, n.child[1])
+					}
 				case "cap", "len":
 					n.typ = scope.getType("int")
 				case "make":
@@ -472,7 +476,7 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 					n.typ = &Type{cat: ValueT, rtype: typ.Out(0)}
 				}
 			} else if typ := n.child[0].typ; len(typ.ret) > 0 {
-				n.typ = n.child[0].typ.ret[0]
+				n.typ = typ.ret[0]
 				n.fsize = len(typ.ret)
 			}
 
@@ -877,9 +881,6 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 						n.fsize = s.NumOut()
 					}
 				}
-			} else if n.typ.cat == ArrayT {
-				n.typ = n.typ.val
-				n.gen = nop
 			} else if n.typ.cat == SrcPkgT {
 				// Resolve source package symbol
 				if sym, ok := interp.scope[n.child[0].ident].sym[n.child[1].ident]; ok {
@@ -914,10 +915,14 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 			}
 
 		case StarExpr:
-			if n.anc.kind == Define && len(n.anc.child) == 3 && n.anc.child[1] == n {
+			switch {
+			case 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 {
+			case n.anc.kind == Field:
+				// pointer type expression in a field expression (arg or struct field)
+				n.gen = nop
+			default:
 				// dereference expression
 				wireChild(n)
 				n.typ = n.child[0].typ.val
diff --git a/interp/interp_test.go b/interp/interp_test.go
index 581c5ff4..2f044b47 100644
--- a/interp/interp_test.go
+++ b/interp/interp_test.go
@@ -326,6 +326,36 @@ func main() {
 	// 4
 }
 
+func Example_a20() {
+	src := `
+package main
+
+import "fmt"
+
+type IntArray []int
+
+func (h *IntArray) Add(x int) {
+	*h = append(*h, x)
+}
+
+func main() {
+	a := IntArray{}
+	a.Add(4)
+
+	fmt.Println(a)
+}
+`
+	i := interp.New(interp.Opt{Entry: "main"})
+	i.Use(stdlib.Value, stdlib.Type)
+	_, err := i.Eval(src)
+	if err != nil {
+		panic(err)
+	}
+
+	// Output:
+	// [4]
+}
+
 func Example_a3() {
 	src := `
 package main