compiler: allow to omit types for nested slices

pkg/compiler/codegen.go

@@ -594,15 +594,11 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		return nil
 
 	case *ast.CompositeLit:
-		typ := c.typeOf(n.Type).Underlying()
+		switch typ := c.typeOf(n).Underlying().(type) {
-		switch n.Type.(type) {
-		case *ast.Ident, *ast.SelectorExpr, *ast.MapType:
-			switch typ.(type) {
 		case *types.Struct:
 			c.convertStruct(n)
 		case *types.Map:
 			c.convertMap(n)
-			}
 		default:
 			ln := len(n.Elts)
 			// ByteArrays needs a different approach than normal arrays.

pkg/compiler/slice_test.go

@@ -222,6 +222,27 @@ var sliceTestCases = []testCase{
 		}`,
 		big.NewInt(42),
 	},
+	{
+		"nested slice omitted type (slice)",
+		`package foo
+		func Main() int {
+			a := [][]int{{1, 2}, {3, 4}}
+			a[1][0] = 42
+			return a[1][0]
+		}`,
+		big.NewInt(42),
+	},
+	{
+		"nested slice omitted type (struct)",
+		`package foo
+		type pair struct { a, b int }
+		func Main() int {
+			a := []pair{{a: 1, b: 2}, {a: 3, b: 4}}
+			a[1].a = 42
+			return a[1].a
+		}`,
+		big.NewInt(42),
+	},
 }
 
 func TestSliceOperations(t *testing.T) {