[Rust] generate message schema level info in lib.rs (#1019)

* [Rust] generate message schema level info in lib.rs

1. add `SBE_SCHEMA_ID`
2. add `SBE_SCHEMA_VERSION`
3. add `SBE_SEMANTIC_VERSION`

* [Rust] use pub use instead of duplicated defines for message schema items in message codec

* [Rust] add tests for issue #1018

Author: wbprime

rust/tests/baseline_test.rs

@@ -266,3 +266,10 @@ fn encode_car_from_scratch() -> SbeResult<(usize, Vec<u8>)> {
     let limit = car.get_limit();
     Ok((limit, buffer))
 }
+
+#[test]
+fn test_issue_1018() {
+    assert_eq!(1, examples_baseline::SBE_SCHEMA_ID);
+    assert_eq!(0, examples_baseline::SBE_SCHEMA_VERSION);
+    assert_eq!("5.2", examples_baseline::SBE_SEMANTIC_VERSION);
+}

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

@@ -23,6 +23,7 @@
 import java.util.ArrayList;
 import java.util.LinkedHashSet;
 import java.util.stream.Stream;
+import uk.co.real_logic.sbe.ir.Ir;
 
 import static java.nio.ByteOrder.LITTLE_ENDIAN;
 import static uk.co.real_logic.sbe.generation.rust.RustGenerator.*;
@@ -54,7 +55,7 @@ class LibRsDef
         this.schemaVersionType = schemaVersionType;
     }
 
-    void generate() throws IOException
+    void generate(final Ir ir) throws IOException
     {
         try (Writer libRs = outputManager.createOutput("lib"))
         {
@@ -84,6 +85,8 @@ void generate() throws IOException
             }
             indent(libRs, 0, "\n");
 
+            generateSbeSchemaConsts(libRs, ir);
+
             generateSbeErrorEnum(libRs);
             generateEitherEnum(libRs);
 
@@ -123,6 +126,17 @@ static void generateDecoderTraits(final String schemaVersionType, final Writer w
         indent(writer, 0, "}\n\n");
     }
 
+    static void generateSbeSchemaConsts(final Writer writer, final Ir ir) throws IOException
+    {
+        final String schemaIdType = rustTypeName(ir.headerStructure().schemaIdType());
+        final String schemaVersionType = rustTypeName(ir.headerStructure().schemaVersionType());
+        final String semanticVersion = ir.semanticVersion() == null ? "" : ir.semanticVersion();
+
+        indent(writer, 0, "pub const SBE_SCHEMA_ID: %s = %d;\n", schemaIdType, ir.id());
+        indent(writer, 0, "pub const SBE_SCHEMA_VERSION: %s = %d;\n", schemaVersionType, ir.version());
+        indent(writer, 0, "pub const SBE_SEMANTIC_VERSION: &str = \"%s\";\n\n", semanticVersion);
+    }
+
     static void generateSbeErrorEnum(final Writer writer) throws IOException
     {
         indent(writer, 0, "pub type SbeResult<T> = core::result::Result<T, SbeErr>;\n\n");

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

@@ -159,23 +159,22 @@ public void generate() throws IOException
                 indent(out, 0, "use crate::*;\n\n");
                 indent(out, 0, "pub use decoder::%sDecoder;\n", formatStructName(msgToken.name()));
                 indent(out, 0, "pub use encoder::%sEncoder;\n\n", formatStructName(msgToken.name()));
+
+                indent(out, 0, "pub use crate::SBE_SCHEMA_ID;\n");
+                indent(out, 0, "pub use crate::SBE_SCHEMA_VERSION;\n");
+                indent(out, 0, "pub use crate::SBE_SEMANTIC_VERSION;\n\n");
+
                 final String blockLengthType = blockLengthType();
                 final String templateIdType = rustTypeName(ir.headerStructure().templateIdType());
-                final String schemaIdType = rustTypeName(ir.headerStructure().schemaIdType());
-                final String schemaVersionType = schemaVersionType();
-                final String semanticVersion = ir.semanticVersion() == null ? "" : ir.semanticVersion();
                 indent(out, 0, "pub const SBE_BLOCK_LENGTH: %s = %d;\n", blockLengthType, msgToken.encodedLength());
-                indent(out, 0, "pub const SBE_TEMPLATE_ID: %s = %d;\n", templateIdType, msgToken.id());
-                indent(out, 0, "pub const SBE_SCHEMA_ID: %s = %d;\n", schemaIdType, ir.id());
-                indent(out, 0, "pub const SBE_SCHEMA_VERSION: %s = %d;\n", schemaVersionType, ir.version());
-                indent(out, 0, "pub const SBE_SEMANTIC_VERSION: &str = \"%s\";\n\n", semanticVersion);
+                indent(out, 0, "pub const SBE_TEMPLATE_ID: %s = %d;\n\n", templateIdType, msgToken.id());
 
                 MessageCoderDef.generateEncoder(ir, out, msgToken, fields, groups, varData);
                 MessageCoderDef.generateDecoder(ir, out, msgToken, fields, groups, varData);
             }
         }
 
-        libRsDef.generate();
+        libRsDef.generate(ir);
     }
 
     String blockLengthType()