feat(rust): make return type works

Author: phodal

chapi-ast-rust/src/main/kotlin/chapi/ast/rustast/RustAstBaseListener.kt

@@ -333,7 +333,8 @@ open class RustAstBaseListener(private val fileName: String) : RustParserBaseLis
     }
 
     open fun buildReturnType(functionReturnType: RustParser.FunctionReturnTypeContext?): String {
-        return functionReturnType?.type_()?.text ?: ""
+        val typeContext: Type_Context? = functionReturnType?.type_()
+        return lookupType(typeContext)
     }
 
     open fun buildParameters(functionParameters: RustParser.FunctionParametersContext?): List<CodeProperty> {

chapi-ast-rust/src/test/kotlin/chapi/ast/rustast/RustFullIdentListenerTest.kt

@@ -412,7 +412,7 @@ class RustFullIdentListenerTest {
 
         val secondFunction = codeDataStruct.Functions[1]
         assertEquals("main", secondFunction.Name)
-//        assertEquals("std::io::Result", secondFunction.ReturnType)
+        assertEquals("std::io::Result", secondFunction.ReturnType)
         assertEquals(9, secondFunction.FunctionCalls.size)
         secondFunction.FunctionCalls.map {
             println("${it.NodeName} -> ${it.FunctionName} -> ${it.OriginNodeName}")