aeron-io · vyazelenko · Jan 8, 2025 · Jan 8, 2025
diff --git a/sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/CppGenerator.java b/sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/CppGenerator.java
@@ -3027,7 +3027,7 @@ private CharSequence generateMessageFlyweightCode(
 
             "    SBE_NODISCARD std::uint64_t decodeLength() const\n" +
             "    {\n" +
-            "        %10$s skipper(m_buffer, m_offset, m_bufferLength, sbeBlockLength(), m_actingVersion);\n" +
+            "        %10$s skipper(m_buffer, m_offset, m_bufferLength, m_actingBlockLength, m_actingVersion);\n" +
             "        skipper.skip();\n" +
             "        return skipper.encodedLength();\n" +
             "    }\n\n" +

diff --git a/sbe-tool/src/test/cpp/CMakeLists.txt b/sbe-tool/src/test/cpp/CMakeLists.txt
@@ -43,6 +43,8 @@ set(DTO_SCHEMA ${CODEC_SCHEMA_DIR}/dto-test-schema.xml)
 set(ISSUE835_SCHEMA ${CODEC_SCHEMA_DIR}/issue835.xml)
 set(ISSUE889_SCHEMA ${CODEC_SCHEMA_DIR}/issue889.xml)
 set(ACCESS_ORDER_SCHEMA ${CODEC_SCHEMA_DIR}/field-order-check-schema.xml)
+set(VERSIONED_MESSAGE_V1_SCHEMA ${CODEC_SCHEMA_DIR}/versioned-message-v1.xml)
+set(VERSIONED_MESSAGE_V2_SCHEMA ${CODEC_SCHEMA_DIR}/versioned-message-v2.xml)
 
 set(GENERATED_CODECS
     ${CXX_CODEC_TARGET_DIR}
@@ -59,6 +61,8 @@ add_custom_command(
         ${ISSUE835_SCHEMA}
         ${ISSUE889_SCHEMA}
         ${ACCESS_ORDER_SCHEMA}
+        ${VERSIONED_MESSAGE_V1_SCHEMA}
+        ${VERSIONED_MESSAGE_V2_SCHEMA}
     sbe-jar ${SBE_JAR}
     COMMAND
         ${Java_JAVA_EXECUTABLE} --add-opens java.base/jdk.internal.misc=ALL-UNNAMED
@@ -79,6 +83,8 @@ add_custom_command(
             ${ISSUE835_SCHEMA}
             ${ISSUE889_SCHEMA}
             ${ACCESS_ORDER_SCHEMA}
+            ${VERSIONED_MESSAGE_V1_SCHEMA}
+            ${VERSIONED_MESSAGE_V2_SCHEMA}
 )
 
 add_custom_target(codecs DEPENDS ${GENERATED_CODECS})
@@ -96,6 +102,7 @@ sbe_test(Issue835Test codecs)
 sbe_test(Issue889Test codecs)
 sbe_test(FieldAccessOrderCheckTest codecs)
 target_compile_definitions(FieldAccessOrderCheckTest PRIVATE SBE_ENABLE_PRECEDENCE_CHECKS_IN_TESTS)
+sbe_test(VersionedMessageTest codecs)
 
 if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     # Check if the GCC version supports C++17

diff --git a/sbe-tool/src/test/cpp/VersionedMessageTest.cpp b/sbe-tool/src/test/cpp/VersionedMessageTest.cpp
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2013-2025 Real Logic Limited.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include "versmsg/VersionedMessageV1.h"
+#include "versmsg/VersionedMessageV2.h"
+
+using namespace versmsg;
+
+static const std::size_t BUFFER_LEN = 2048;
+
+class VersionedMessageTest : public testing::Test
+{
+public:
+    VersionedMessageV2 m_versionedMessageV2 = {};
+    VersionedMessageV1 m_versionedMessageV1Decoder = {};
+};
+
+TEST_F(VersionedMessageTest, shouldV1DecodeV2Message)
+{
+    char buffer[BUFFER_LEN] = {};
+
+    m_versionedMessageV2.wrapForEncode(buffer, 0, sizeof(buffer));
+    m_versionedMessageV2.fieldA1(1);
+    m_versionedMessageV2.fieldB1(2);
+    m_versionedMessageV2.fieldC2(3);
+    m_versionedMessageV2.fieldD2(4);
+    m_versionedMessageV2.fieldE2(5);
+    m_versionedMessageV2.putString1("asdf", 4);
+
+    m_versionedMessageV1Decoder.wrapForDecode(
+        buffer,
+        0,
+        VersionedMessageV2::sbeBlockLength(),
+        VersionedMessageV2::sbeSchemaVersion(),
+        m_versionedMessageV2.encodedLength());
+
+    EXPECT_EQ(m_versionedMessageV1Decoder.fieldA1(), (uint32_t)1);
+    EXPECT_EQ(m_versionedMessageV1Decoder.fieldB1(), (uint32_t)2);
+    EXPECT_STREQ(m_versionedMessageV1Decoder.string1(), "asdf");
+
+    EXPECT_EQ(m_versionedMessageV1Decoder.decodeLength(), (uint64_t)26);
+}
diff --git a/sbe-tool/src/test/resources/versioned-message-v1.xml b/sbe-tool/src/test/resources/versioned-message-v1.xml
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<messageSchema package="versmsg"
+               id="1"
+               version="1"
+               semanticVersion="1"
+               description="Unit Test"
+               byteOrder="littleEndian">
+    <types>
+        <composite name="messageHeader" description="Message identifiers and length of message root">
+            <type name="blockLength" primitiveType="uint16"/>
+            <type name="templateId" primitiveType="uint16"/>
+            <type name="schemaId" primitiveType="uint16"/>
+            <type name="version" primitiveType="uint16"/>
+        </composite>
+        <composite name="varStringEncoding">
+            <type name="length" primitiveType="uint16"/>
+            <type name="varData" primitiveType="uint8" length="0" characterEncoding="UTF-8"/>
+        </composite>
+    </types>
+    <message name="VersionedMessageV1" id="50001" description="A versioned message" blockLength="8">
+        <field name="FieldA1" id="1" type="uint32" semanticType="int"/>
+        <field name="FieldB1" id="2" type="uint32" semanticType="int"/>
+        <data name="String1" id="10" type="varStringEncoding"/>
+    </message>
+</messageSchema>
diff --git a/sbe-tool/src/test/resources/versioned-message-v2.xml b/sbe-tool/src/test/resources/versioned-message-v2.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<messageSchema package="versmsg"
+               id="1"
+               version="2"
+               semanticVersion="2"
+               description="Unit Test"
+               byteOrder="littleEndian">
+    <types>
+        <composite name="messageHeader" description="Message identifiers and length of message root">
+            <type name="blockLength" primitiveType="uint16"/>
+            <type name="templateId" primitiveType="uint16"/>
+            <type name="schemaId" primitiveType="uint16"/>
+            <type name="version" primitiveType="uint16"/>
+        </composite>
+        <composite name="varStringEncoding">
+            <type name="length" primitiveType="uint16"/>
+            <type name="varData" primitiveType="uint8" length="0" characterEncoding="UTF-8"/>
+        </composite>
+    </types>
+    <message name="VersionedMessageV2" id="50001" description="A versioned message" blockLength="20">
+        <field name="FieldA1" id="1" type="uint32" semanticType="int"/>
+        <field name="FieldB1" id="2" type="uint32" semanticType="int"/>
+        <field name="FieldC2" id="3" type="uint32" semanticType="int"/>
+        <field name="FieldD2" id="4" type="uint32" semanticType="int"/>
+        <field name="FieldE2" id="5" type="uint32" semanticType="int"/>
+        <data name="String1" id="10" type="varStringEncoding"/>
+    </message>
+</messageSchema>