compiler: properly inline methods, use receiver

Notice that this doesn't differentiate between (*T) and (T) receivers always
treating them as is. But we have the same problem with arguments now and the
number of inlined calls is limited, usually we want this behavior.

pkg/compiler/inline.go

@@ -55,6 +55,15 @@ func (c *codegen) inlineCall(f *funcScope, n *ast.CallExpr) {
 	copy(newScope, c.scope.vars.locals)
 	defer c.scope.vars.dropScope()
 
+	if f.decl.Recv != nil {
+		c.scope.vars.locals = newScope
+		name := f.decl.Recv.List[0].Names[0].Name
+		c.scope.vars.addAlias(name, -1, unspecifiedVarIndex, &varContext{
+			importMap: c.importMap,
+			expr:      f.selector,
+			scope:     oldScope,
+		})
+	}
 	hasVarArgs := !n.Ellipsis.IsValid()
 	needPack := sig.Variadic() && hasVarArgs
 	for i := range n.Args {

pkg/compiler/inline_test.go

@@ -336,3 +336,22 @@ func TestPackageVarsInInlinedCalls(t *testing.T) {
 		}`
 	eval(t, src, big.NewInt(13))
 }
+
+func TestInlinedMethod(t *testing.T) {
+	src := `package foo
+	import "github.com/nspcc-dev/neo-go/pkg/compiler/testdata/inline"
+	func Main() int {
+		// It's important for this variable to not be named 't'.
+		var z inline.T
+		i := z.Inc(42)
+		if i != 0 || z.N != 42 {
+			return 0
+		}
+		i = z.Inc(100500)
+		if i != 42 {
+			return 0
+		}
+		return z.N
+	}`
+	eval(t, src, big.NewInt(100542))
+}

pkg/compiler/testdata/inline/inline.go

@@ -46,3 +46,13 @@ func SumVar(a, b int) int {
 func Concat(n int) int {
 	return n*100 + b.A*10 + A
 }
+
+type T struct {
+	N int
+}
+
+func (t *T) Inc(i int) int {
+	n := t.N
+	t.N += i
+	return n
+}