feat: put feature under a feature flag

Author: ascandone

internal/interpreter/evaluate_expr.go

@@ -19,6 +19,11 @@ func (st *programState) evaluateExpr(expr parser.ValueExpr) (Value, InterpreterE
 			case parser.AccountTextPart:
 				parts = append(parts, part.Name)
 			case *parser.Variable:
+				err := st.checkFeatureFlag(ExperimentalAccountInterpolationFlag)
+				if err != nil {
+					return nil, err
+				}
+
 				value, err := st.evaluateExpr(part)
 				if err != nil {
 					return nil, err

internal/interpreter/interpreter.go

@@ -182,6 +182,7 @@ type FeatureFlag = string
 const (
 	ExperimentalOverdraftFunctionFeatureFlag FeatureFlag = "experimental-overdraft-function"
 	ExperimentalOneofFeatureFlag             FeatureFlag = "experimental-oneof"
+	ExperimentalAccountInterpolationFlag     FeatureFlag = "experimental-account-interpolation"
 )
 
 func RunProgram(

internal/interpreter/interpreter_test.go

@@ -3863,7 +3863,7 @@ func TestAccountInterp(t *testing.T) {
 			"k": machine.AccountAddress("acc:42:pending:user:001"),
 		},
 	}
-	test(t, tc)
+	testWithFeatureFlag(t, tc, machine.ExperimentalAccountInterpolationFlag)
 }
 
 func TestAccountInvalidString(t *testing.T) {
@@ -3893,5 +3893,5 @@ func TestAccountInvalidString(t *testing.T) {
 			},
 		},
 	}
-	test(t, tc)
+	testWithFeatureFlag(t, tc, machine.ExperimentalAccountInterpolationFlag)
 }