GoTranslator: fix problem with % in the raw string segment in f-str…

…ings; modified common test to accommodate this pattern

jvm/src/test/scala/io/kaitai/struct/translators/TranslatorSpec.scala

@@ -682,17 +682,17 @@ class TranslatorSpec extends AnyFunSuite {
     PythonCompiler -> "u\"abc\""
   ), CalcStrType)
 
-  full("f\"abc{1}def\"", CalcIntType, CalcStrType, Map[LanguageCompilerStatic, String](
-    CppCompiler -> "std::string(\"abc\") + kaitai::kstream::to_string(1) + std::string(\"def\")",
-    CSharpCompiler -> "\"abc\" + Convert.ToString((long) (1), 10) + \"def\"",
-    GoCompiler -> "fmt.Sprintf(\"abc%vdef\", 1)",
-    JavaCompiler -> "\"abc\" + Long.toString(1, 10) + \"def\"",
-    JavaScriptCompiler -> "\"abc\" + (1).toString(10) + \"def\"",
-    LuaCompiler -> "\"abc\" + tostring(1) + \"def\"",
-    PerlCompiler -> "\"abc\" . sprintf('%d', 1) . \"def\"",
-    PHPCompiler -> "\"abc\" . strval(1) . \"def\"",
-    PythonCompiler -> "u\"abc\" + str(1) + u\"def\"",
-    RubyCompiler -> "\"abc\" + 1.to_s(10) + \"def\"",
+  full("f\"abc{1}%def\"", CalcIntType, CalcStrType, Map[LanguageCompilerStatic, String](
+    CppCompiler -> "std::string(\"abc\") + kaitai::kstream::to_string(1) + std::string(\"%def\")",
+    CSharpCompiler -> "\"abc\" + Convert.ToString((long) (1), 10) + \"%def\"",
+    GoCompiler -> "fmt.Sprintf(\"abc%v%%def\", 1)",
+    JavaCompiler -> "\"abc\" + Long.toString(1, 10) + \"%def\"",
+    JavaScriptCompiler -> "\"abc\" + (1).toString(10) + \"%def\"",
+    LuaCompiler -> "\"abc\" + tostring(1) + \"%def\"",
+    PerlCompiler -> "\"abc\" . sprintf('%d', 1) . \"\\%def\"",
+    PHPCompiler -> "\"abc\" . strval(1) . \"%def\"",
+    PythonCompiler -> "u\"abc\" + str(1) + u\"%def\"",
+    RubyCompiler -> "\"abc\" + 1.to_s(10) + \"%def\"",
   ))
 
   /**

shared/src/main/scala/io/kaitai/struct/translators/GoTranslator.scala

@@ -481,8 +481,12 @@ class GoTranslator(out: StringLanguageOutputWriter, provider: TypeProvider, impo
         importList.add("fmt")
 
         val piecesAndArgs: Seq[(String, Option[String])] = exprs.map {
-          case Ast.expr.Str(s) => (doStringLiteralBody(s), None)
-          case e => ("%v", Some(translate(e)))
+          case Ast.expr.Str(s) =>
+            // This string will be used as format string, so we need to escape all `%` as `%%`
+            val escapedFmtStr = s.replace("%", "%%")
+            (doStringLiteralBody(escapedFmtStr), None)
+          case e =>
+            ("%v", Some(translate(e)))
         }
 
         val fmtString = piecesAndArgs.map(x => x._1).mkString