compiler: support delete() builtin

pkg/compiler/analysis.go

@@ -14,7 +14,7 @@ import (
 
 var (
 	// Go language builtin functions.
-	goBuiltins = []string{"len", "append", "panic", "make", "copy", "recover"}
+	goBuiltins = []string{"len", "append", "panic", "make", "copy", "recover", "delete"}
 	// Custom builtin utility functions.
 	customBuiltins = []string{
 		"FromAddress", "Equals",

pkg/compiler/codegen.go

@@ -1527,6 +1527,8 @@ func (c *codegen) convertBuiltin(expr *ast.CallExpr) {
 		}
 		emit.Opcode(c.prog.BinWriter, opcode.PUSHNULL)
 		c.emitStoreByIndex(varGlobal, c.exceptionIndex)
+	case "delete":
+		emit.Opcode(c.prog.BinWriter, opcode.REMOVE)
 	case "ToInteger", "ToByteArray", "ToBool":
 		typ := stackitem.IntegerT
 		switch name {

pkg/compiler/map_test.go

@@ -55,6 +55,26 @@ var mapTestCases = []testCase{
 		`,
 		[]byte("Valera"),
 	},
+	{
+		"delete key",
+		`package foo
+		func Main() int {
+			m := map[int]int{1: 2, 3: 4}
+			delete(m, 1)
+			return len(m)
+		}`,
+		big.NewInt(1),
+	},
+	{
+		"delete missing key",
+		`package foo
+		func Main() int {
+			m := map[int]int{3: 4}
+			delete(m, 1)
+			return len(m)
+		}`,
+		big.NewInt(1),
+	},
 }
 
 func TestMaps(t *testing.T) {