compiler: support make()

docs/compiler.md

@@ -7,8 +7,8 @@ The neo-go compiler compiles Go programs to bytecode that the NEO virtual machin
 The compiler is mostly compatible with regular Go language specification, but
 there are some important deviations that you need to be aware of that make it
 a dialect of Go rather than a complete port of the language:
- * `make()` ane `new()` are not supported, most of the time you can substitute
+ * `new()` is not supported, most of the time you can substitute structs with composite literals
-   them with composite literals
+ * `make()` is supported for maps and slices with elements of basic types
  * pointers are supported only for struct literals, one can't take an address
    of an arbitrary variable
  * there is no real distinction between different integer types, all of them

pkg/compiler/analysis.go

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

pkg/compiler/codegen.go

@@ -1305,6 +1305,24 @@ func (c *codegen) convertBuiltin(expr *ast.CallExpr) {
 	}
 
 	switch name {
+	case "make":
+		typ := c.typeOf(expr.Args[0])
+		switch {
+		case isMap(typ):
+			emit.Opcode(c.prog.BinWriter, opcode.NEWMAP)
+		default:
+			if len(expr.Args) == 3 {
+				c.prog.Err = fmt.Errorf("`make()` with a capacity argument is not supported")
+				return
+			}
+			ast.Walk(c, expr.Args[1])
+			if isByteSlice(typ) {
+				emit.Opcode(c.prog.BinWriter, opcode.NEWBUFFER)
+			} else {
+				neoT := toNeoType(typ.(*types.Slice).Elem())
+				emit.Instruction(c.prog.BinWriter, opcode.NEWARRAYT, []byte{byte(neoT)})
+			}
+		}
 	case "len":
 		emit.Opcode(c.prog.BinWriter, opcode.DUP)
 		emit.Opcode(c.prog.BinWriter, opcode.ISNULL)
@@ -1397,6 +1415,9 @@ func transformArgs(fun ast.Expr, args []ast.Expr) []ast.Expr {
 		if f.Name == "panic" {
 			return args[1:]
 		}
+		if f.Name == "make" {
+			return nil
+		}
 	}
 
 	return args

pkg/compiler/slice_test.go

@@ -2,9 +2,12 @@ package compiler_test
 
 import (
 	"math/big"
+	"strings"
 	"testing"
 
+	"github.com/nspcc-dev/neo-go/pkg/compiler"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+	"github.com/stretchr/testify/require"
 )
 
 var sliceTestCases = []testCase{
@@ -323,3 +326,41 @@ func TestJumps(t *testing.T) {
 	`
 	eval(t, src, []byte{0x62, 0x01, 0x00})
 }
+
+func TestMake(t *testing.T) {
+	t.Run("Map", func(t *testing.T) {
+		src := `package foo
+		func Main() int {
+			a := make(map[int]int)
+			a[1] = 10
+			a[2] = 20
+			return a[1]
+		}`
+		eval(t, src, big.NewInt(10))
+	})
+	t.Run("IntSlice", func(t *testing.T) {
+		src := `package foo
+		func Main() int {
+			a := make([]int, 10)
+			return len(a) + a[0]
+		}`
+		eval(t, src, big.NewInt(10))
+	})
+	t.Run("ByteSlice", func(t *testing.T) {
+		src := `package foo
+		func Main() int {
+			a := make([]byte, 10)
+			return len(a) + int(a[0])
+		}`
+		eval(t, src, big.NewInt(10))
+	})
+	t.Run("CapacityError", func(t *testing.T) {
+		src := `package foo
+		func Main() int {
+			a := make([]int, 1, 2)
+			return a[0]
+		}`
+		_, err := compiler.Compile("foo.go", strings.NewReader(src))
+		require.Error(t, err)
+	})
+}

pkg/compiler/types.go

@@ -27,6 +27,11 @@ func isBasicTypeOfKind(typ types.Type, ks ...types.BasicKind) bool {
 	return false
 }
 
+func isMap(typ types.Type) bool {
+	_, ok := typ.Underlying().(*types.Map)
+	return ok
+}
+
 func isByte(typ types.Type) bool {
 	return isBasicTypeOfKind(typ, types.Uint8, types.Int8)
 }