[Rust] Updated RustGenerator.generatePrimitiveOptionalDecoder() to resolve Issue #972 (#981)

Co-authored-by: Michael Ward <mward@drw.com>

Author: mward

build.gradle

@@ -587,6 +587,7 @@ tasks.register('generateRustTestCodecs', JavaExec) {
             'sbe.validation.xsd': validationXsdPath)
     args = ['sbe-tool/src/test/resources/issue435.xml',
             'sbe-tool/src/test/resources/issue895.xml',
+            'sbe-tool/src/test/resources/issue972.xml',
             'sbe-tool/src/test/resources/example-bigendian-test-schema.xml',
             'sbe-tool/src/test/resources/nested-composite-name.xml',
     ]

rust/Cargo.toml

@@ -13,6 +13,7 @@ examples_uk_co_real_logic_sbe_benchmarks_fix = { path = "../generated/rust/uk_co
 
 issue_435 = { path = "../generated/rust/issue435" }
 issue_895 = { path = "../generated/rust/issue895" }
+issue_972 = { path = "../generated/rust/issue972" }
 baseline_bigendian = { path = "../generated/rust/baseline-bigendian" }
 nested_composite_name = { path = "../generated/rust/nested-composite-name" }
 

rust/tests/issue_972_test.rs

@@ -0,0 +1,37 @@
+use issue_972::*;
+
+fn create_encoder(buffer: &mut Vec<u8>) -> Issue972Encoder {
+    let issue_972 = Issue972Encoder::default().wrap(
+        WriteBuf::new(buffer.as_mut_slice()),
+        message_header_codec::ENCODED_LENGTH,
+    );
+    let mut header = issue_972.header(0);
+    header.parent().unwrap()
+}
+
+#[test]
+fn round_trip() -> SbeResult<()> {
+    // encode...
+    let mut buffer = vec![0u8; 256];
+    let encoder = create_encoder(&mut buffer);
+    let mut new_composite_encoder = encoder.new_field_encoder();
+    new_composite_encoder.f1(2007);
+    new_composite_encoder.f2(2012);
+
+    // decode...
+    let buf = ReadBuf::new(buffer.as_slice());
+    let header = MessageHeaderDecoder::default().wrap(buf, 0);
+    assert_eq!(SBE_BLOCK_LENGTH, header.block_length());
+    assert_eq!(SBE_SCHEMA_VERSION, header.version());
+    assert_eq!(SBE_TEMPLATE_ID, header.template_id());
+    assert_eq!(SBE_SCHEMA_ID, header.schema_id());
+
+    let decoder = Issue972Decoder::default().header(header);
+    if let Either::Right(composite) = decoder.new_field_decoder() {
+        assert_eq!(2007, composite.f1().unwrap());
+        assert_eq!(2012, composite.f2().unwrap());
+    } else {
+        panic!()
+    }
+    Ok(())
+}

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/rust/RustGenerator.java

@@ -766,18 +766,10 @@ private static void generatePrimitiveOptionalDecoder(
             formatFunctionName(name),
             rustPrimitiveType);
 
-        if (fieldToken.version() > 0)
-        {
-            indent(sb, level + 1, "if self.acting_version > 0 && self.acting_version < %d {\n", fieldToken.version());
-            indent(sb, level + 2, "return None;\n");
-            indent(sb, level + 1, "}\n\n");
-        }
-
         indent(sb, level + 1, "let value = self.get_buf().get_%s_at(self.%s);\n",
             rustPrimitiveType,
             getBufOffset(fieldToken));
 
-
         final String literal = generateRustLiteral(primitiveType, encoding.applicableNullValue().toString());
         if (literal.endsWith("::NAN"))
         {

sbe-tool/src/test/resources/issue972.xml

@@ -0,0 +1,25 @@
+<sbe:messageSchema
+    xmlns:sbe="http://fixprotocol.io/2016/sbe"
+    package="issue972"
+    id="972"
+    version="2"
+    semanticVersion="5.0.0"
+    byteOrder="littleEndian">
+  <types>
+    <composite name="messageHeader">
+      <type name="blockLength" primitiveType="uint16" description="Length of the root of the FIX message contained before repeating groups or variable/conditions fields."/>
+      <type name="templateId" primitiveType="uint16" description="Template ID used to encode the message."/>
+      <type name="schemaId" primitiveType="uint16" description="ID of the system publishing the message."/>
+      <type name="version" primitiveType="uint16" description="Schema version."/>
+    </composite>
+
+    <composite name="NewComposite" sinceVersion="1">
+      <type name="f1" primitiveType="uint16" presence="optional" nullValue="0" semanticType="Int"/>
+      <type name="f2" primitiveType="uint32" presence="optional" nullValue="0" semanticType="Int" offset="4"/>
+    </composite>
+  </types>
+  <sbe:message name="issue972" id="1">
+    <field name="oldField" id="1" type="uint16" semanticType="Int"/>
+    <field name="newField" id="2" type="NewComposite" presence="optional" sinceVersion="1" />
+  </sbe:message>
+</sbe:messageSchema>