From 396d769e6e1dd95c2ba5c21283a5bc311425afdd Mon Sep 17 00:00:00 2001
From: Mingun <Alexander_Sergey@mail.ru>
Date: Sun, 14 Apr 2024 00:47:37 +0500
Subject: [PATCH 1/2] Go: add a couple of words to document some variables and
 overridable methods

---
 .../scala/io/kaitai/struct/translators/GoTranslator.scala | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/shared/src/main/scala/io/kaitai/struct/translators/GoTranslator.scala b/shared/src/main/scala/io/kaitai/struct/translators/GoTranslator.scala
index 28647aec8..c3b2dbb50 100644
--- a/shared/src/main/scala/io/kaitai/struct/translators/GoTranslator.scala
+++ b/shared/src/main/scala/io/kaitai/struct/translators/GoTranslator.scala
@@ -26,6 +26,10 @@ class GoTranslator(out: StringLanguageOutputWriter, provider: TypeProvider, impo
 
   import io.kaitai.struct.languages.GoCompiler._
 
+  /**
+    * Dummy return value that should be returned in case of error just because
+    * we cannot return nothing.
+    */
   var returnRes: Option[String] = None
 
   override def translate(v: Ast.expr, extPrec: Int): String = resToStr(translateExpr(v, extPrec))
@@ -542,6 +546,10 @@ class GoTranslator(out: StringLanguageOutputWriter, provider: TypeProvider, impo
 
   def localVarName(n: Int) = s"tmp$n"
 
+  /**
+    * Puts to the output code to check variable `err` for error value and emit
+    * a premature return with value of error.
+    */
   def outAddErrCheck(): Unit = {
     out.puts("if err != nil {")
     out.inc

From 032007ae8fa5872a20e13d17437c492913f0a822 Mon Sep 17 00:00:00 2001
From: Mingun <Alexander_Sergey@mail.ru>
Date: Sun, 14 Apr 2024 01:50:41 +0500
Subject: [PATCH 2/2] Go: introduce `defaultTypeValue` to translate type to the
 default value of type

It will be used in KST to check that we return default values when error is expected
---
 .../io/kaitai/struct/languages/GoCompiler.scala    | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/shared/src/main/scala/io/kaitai/struct/languages/GoCompiler.scala b/shared/src/main/scala/io/kaitai/struct/languages/GoCompiler.scala
index 49e4343e1..b7d8d6255 100644
--- a/shared/src/main/scala/io/kaitai/struct/languages/GoCompiler.scala
+++ b/shared/src/main/scala/io/kaitai/struct/languages/GoCompiler.scala
@@ -485,12 +485,7 @@ class GoCompiler(typeProvider: ClassTypeProvider, config: RuntimeConfig)
   override def instanceHeader(className: List[String], instName: InstanceIdentifier, dataType: DataType, isNullable: Boolean): Unit = {
     out.puts(s"func (this *${types2class(className)}) ${publicMemberName(instName)}() (v ${kaitaiType2NativeType(dataType)}, err error) {")
     out.inc
-    translator.returnRes = Some(dataType match {
-      case _: NumericType => "0"
-      case _: BooleanType => "false"
-      case _: StrType => "\"\""
-      case _ => "nil"
-    })
+    translator.returnRes = Some(defaultTypeValue(dataType))
   }
 
   override def instanceCalculate(instName: Identifier, dataType: DataType, value: Ast.expr): Unit = {
@@ -692,6 +687,13 @@ object GoCompiler extends LanguageCompilerStatic
   def enumToStr(typeName: List[String], enumName: String): String =
     types2class(typeName) + "__" + type2class(enumName)
 
+  def defaultTypeValue(dataType: DataType): String = dataType match {
+    case _: NumericType => "0"
+    case _: BooleanType => "false"
+    case _: StrType => "\"\""
+    case _ => "nil"
+  }
+
   override def kstreamName: String = "kaitai.Stream"
   override def kstructName: String = "kaitai.Struct"
   override def ksErrorName(err: KSError): String = err match {