compiler: support non-struct methods

There is no need to restrict ourselves just to structs.

pkg/compiler/codegen.go

@@ -304,15 +304,8 @@ func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl) {
 	// to support other types.
 	if decl.Recv != nil {
 		for _, arg := range decl.Recv.List {
-			ident := arg.Names[0]
-			// Currently only method receives for struct types is supported.
-			_, ok := c.typeInfo.Defs[ident].Type().Underlying().(*types.Struct)
-			if !ok {
-				c.prog.Err = fmt.Errorf("method receives for non-struct types is not yet supported")
-				return
-			}
 			// only create an argument here, it will be stored via INITSLOT
-			c.scope.newVariable(varArgument, ident.Name)
+			c.scope.newVariable(varArgument, arg.Names[0].Name)
 		}
 	}
 

pkg/compiler/type_test.go

@@ -1,6 +1,9 @@
 package compiler_test
 
-import "testing"
+import (
+	"math/big"
+	"testing"
+)
 
 func TestCustomType(t *testing.T) {
 	src := `
@@ -22,3 +25,15 @@ func TestCustomType(t *testing.T) {
 	`
 	eval(t, src, []byte("some short string"))
 }
+
+func TestCustomTypeMethods(t *testing.T) {
+	src := `package foo
+	type bar int
+	func (b bar) add(a bar) bar { return a + b }
+	func Main() bar {
+		var b bar
+		b = 10
+		return b.add(32)
+	}`
+	eval(t, src, big.NewInt(42))
+}