Draft: [RUST] Generate human-readable representation of decoders fields

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

@@ -69,6 +69,7 @@ void generate(final Ir ir) throws IOException
             indent(libRs, 0, "#![allow(clippy::all)]\n");
             indent(libRs, 0, "#![allow(non_camel_case_types)]\n\n");
             indent(libRs, 0, "#![allow(ambiguous_glob_reexports)]\n\n");
+            indent(libRs, 0, "#![allow(unused_mut)]\n\n");
             indent(libRs, 0, "use ::core::{convert::TryInto};\n\n");
 
             final ArrayList<String> modules = new ArrayList<>();
@@ -98,7 +99,7 @@ void generate(final Ir ir) throws IOException
 
             generateEncoderTraits(libRs);
             generateDecoderTraits(schemaVersionType, libRs);
-
+            generateSbeToString(libRs);
             generateReadBuf(libRs, byteOrder);
             generateWriteBuf(libRs, byteOrder);
         }
@@ -132,6 +133,18 @@ static void generateDecoderTraits(final String schemaVersionType, final Writer w
         indent(writer, 0, "}\n\n");
     }
 
+    static void generateSbeToString(final Writer writer) throws IOException
+    {
+        indent(writer, 0, "/// Returns a human-readable string representation of the SBE message.\n");
+        indent(writer, 0, "///\n");
+        indent(writer, 0, "/// This trait works like `ToString`, but it takes `self` as value\n");
+        indent(writer, 0, "/// to be compatible with the generated decoders.\n");
+        indent(writer, 0, "pub trait SbeToString: Sized {\n");
+        indent(writer, 1, "/// Returns a human-readable string along with the consumed `self`.\n");
+        indent(writer, 1, "fn sbe_to_string(self) -> SbeResult<(Self, String)>;\n");
+        indent(writer, 0, "}\n\n");
+    }
+
     static void generateSbeSchemaConsts(final Writer writer, final Ir ir) throws IOException
     {
         final String schemaIdType = rustTypeName(ir.headerStructure().schemaIdType());

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

@@ -106,6 +106,12 @@ void generate(
 
         indent(sb, 1, "}\n\n"); // impl end
 
+        if (codecType == Decoder)
+        {
+            RustGenerator.appendImplSbeToStringForDecoder(sb, msgTypeName, msgToken.name(), fields, groups, varData,
+                1);
+        }
+
         // append all subGroup generated code
         for (final SubGroup subGroup : subGroups)
         {