[Rust] Do not escape bit set choice names used in accessors

build.gradle

@@ -683,6 +683,7 @@ tasks.register('generateRustTestCodecs', JavaExec) {
             'sbe-tool/src/test/resources/issue1057.xml',
             'sbe-tool/src/test/resources/issue1066.xml',
             'sbe-tool/src/test/resources/issue1116.xml',
+            'sbe-tool/src/test/resources/issue1118.xml',
             'sbe-tool/src/test/resources/optional_enum_nullify.xml',
             'sbe-tool/src/test/resources/basic-variable-length-schema.xml',
             'sbe-tool/src/test/resources/example-bigendian-test-schema.xml',

rust/Cargo.toml

@@ -20,6 +20,7 @@ issue_1028 = { path = "../generated/rust/issue1028" }
 issue_1057 = { path = "../generated/rust/issue1057" }
 issue_1066 = { path = "../generated/rust/issue1066" }
 issue_1116 = { path = "../generated/rust/issue1116" }
+issue_1118 = { path = "../generated/rust/issue1118" }
 baseline_bigendian = { path = "../generated/rust/baseline_bigendian" }
 nested_composite_name = { path = "../generated/rust/nested_composite_name" }
 sbe_tests = { path = "../generated/rust/sbe_tests" }

rust/tests/issue_1118_test.rs

@@ -0,0 +1,64 @@
+use issue_1118::{
+    flags::Flags,
+    issue_1118_codec::{self, Issue1118Decoder, Issue1118Encoder},
+    message_header_codec, ReadBuf, WriteBuf,
+};
+
+/// Choices named after a Rust keyword are reached through `get_` and `set_` prefixed accessors,
+/// so the prefixed name is a plain identifier and the choice name is not escaped. This module
+/// failing to compile is itself the regression this guards, since `get_r#type` does not parse.
+#[test]
+fn keyword_named_choices_have_usable_accessors() {
+    let mut flags = Flags::new(0);
+
+    flags.set_type(true);
+    assert!(flags.get_type());
+    assert!(!flags.get_match());
+    assert!(!flags.get_ordinary());
+
+    flags.set_match(true);
+    flags.set_type(false);
+    assert!(!flags.get_type());
+    assert!(flags.get_match());
+
+    flags.clear();
+    assert_eq!(flags.0, 0);
+}
+
+/// The choice name is written into `Debug` as a label, so it should not carry the raw identifier
+/// escaping either.
+#[test]
+fn debug_uses_the_unescaped_choice_names() {
+    let mut flags = Flags::new(0);
+    flags.set_type(true).set_ordinary(true);
+
+    assert_eq!(
+        format!("{flags:?}"),
+        "Flags[type(0)=true,match(1)=false,ordinary(2)=true]"
+    );
+}
+
+#[test]
+fn round_trips_a_keyword_named_choice() {
+    let mut buffer = vec![0u8; 256];
+
+    {
+        let mut encoder = Issue1118Encoder::default().wrap(
+            WriteBuf::new(&mut buffer),
+            message_header_codec::ENCODED_LENGTH,
+        );
+        let mut flags = Flags::new(0);
+        flags.set_match(true);
+        encoder.flags(flags);
+    }
+
+    let decoder = Issue1118Decoder::default().wrap(
+        ReadBuf::new(&buffer),
+        message_header_codec::ENCODED_LENGTH,
+        issue_1118_codec::SBE_BLOCK_LENGTH,
+        0,
+    );
+    let flags = decoder.flags();
+    assert!(flags.get_match());
+    assert!(!flags.get_type());
+}

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

@@ -1441,7 +1441,7 @@ private static void generateSingleBitSet(
                 continue;
             }
 
-            final String choiceName = formatFunctionName(token.name());
+            final String choiceName = bitSetChoiceName(token);
             final Encoding encoding = token.encoding();
             final String choiceBitIndex = encoding.constValue().toString();
 
@@ -1479,7 +1479,7 @@ private static void generateSingleBitSet(
                 continue;
             }
 
-            final String choiceName = formatFunctionName(token.name());
+            final String choiceName = bitSetChoiceName(token);
             final String choiceBitIndex = token.encoding().constValue().toString();
 
             if (comma)
@@ -1498,6 +1498,14 @@ private static void generateSingleBitSet(
         indent(writer, 0, "}\n");
     }
 
+    // A choice is only ever reached through a get_ or set_ prefixed accessor, so its name cannot
+    // shadow a Rust keyword on its own and must not be escaped as a raw identifier. Escaping it
+    // would place the r# in the middle of the accessor name, where it does not parse.
+    private static String bitSetChoiceName(final Token token)
+    {
+        return toLowerSnakeCase(token.name());
+    }
+
     static void appendImplEncoderTrait(
         final Appendable out,
         final String typeName,

sbe-tool/src/test/resources/issue1118.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<sbe:messageSchema
+    xmlns:sbe="http://fixprotocol.io/2016/sbe"
+    package="issue1118"
+    id="1118"
+    version="0"
+    semanticVersion="1.0.0"
+    byteOrder="littleEndian">
+  <types>
+    <composite name="messageHeader">
+      <type name="blockLength" primitiveType="uint16"/>
+      <type name="templateId" primitiveType="uint16"/>
+      <type name="schemaId" primitiveType="uint16"/>
+      <type name="version" primitiveType="uint16"/>
+    </composite>
+    <set name="Flags" encodingType="uint8">
+      <choice name="Type">0</choice>
+      <choice name="Match">1</choice>
+      <choice name="ordinary">2</choice>
+    </set>
+  </types>
+  <sbe:message name="issue1118" id="1">
+    <field name="flags" id="1" type="Flags"/>
+  </sbe:message>
+</sbe:messageSchema>