diff --git a/cpp/src/Slice/Parser.cpp b/cpp/src/Slice/Parser.cpp
index 98a1c1165c7..a3ed6471ebb 100644
--- a/cpp/src/Slice/Parser.cpp
+++ b/cpp/src/Slice/Parser.cpp
@@ -96,43 +96,16 @@ namespace Slice
 // ----------------------------------------------------------------------
 Slice::Metadata::Metadata(string rawMetadata, string file, int line) : GrammarBase()
 {
-    std::tie(_directive, _arguments) = parseRawMetadata(std::move(rawMetadata));
     _file = std::move(file);
     _line = line;
-}
-
-string_view
-Slice::Metadata::directive() const
-{
-    return _directive;
-}
-
-string_view
-Slice::Metadata::arguments() const
-{
-    return _arguments;
-}
 
-string
-Slice::Metadata::file() const
-{
-    return _file;
-}
-
-int
-Slice::Metadata::line() const
-{
-    return _line;
-}
-
-pair<string, string>
-Slice::Metadata::parseRawMetadata(string rawMetadata)
-{
     // If the metadata contains no colons, then it must be a directive with no arguments.
     size_t firstColonPos = rawMetadata.find(':');
     if (firstColonPos == string::npos)
     {
-        return {rawMetadata, ""};
+        _directive = rawMetadata;
+        _arguments = "";
+        return;
     }
 
     // Otherwise, we check whether the colon is for a language prefix or for arguments and split the string accordingly.
@@ -148,7 +121,9 @@ Slice::Metadata::parseRawMetadata(string rawMetadata)
         if (isLanguage)
         {
             // If the piece before the colon was a language prefix, don't split up the string.
-            return {rawMetadata, ""};
+            _directive = rawMetadata;
+            _arguments = "";
+            return;
         }
         else
         {
@@ -162,9 +137,32 @@ Slice::Metadata::parseRawMetadata(string rawMetadata)
         splitPos = secondColonPos;
     }
 
-    string directive = rawMetadata.substr(0, splitPos);
-    string arguments = rawMetadata.substr(splitPos + 1);
-    return {directive, arguments};
+    _directive = rawMetadata.substr(0, splitPos);
+    _arguments = rawMetadata.substr(splitPos + 1);
+}
+
+string_view
+Slice::Metadata::directive() const
+{
+    return _directive;
+}
+
+string_view
+Slice::Metadata::arguments() const
+{
+    return _arguments;
+}
+
+string
+Slice::Metadata::file() const
+{
+    return _file;
+}
+
+int
+Slice::Metadata::line() const
+{
+    return _line;
 }
 
 // ----------------------------------------------------------------------
diff --git a/cpp/src/Slice/Parser.h b/cpp/src/Slice/Parser.h
index bdf905879bd..aea82853498 100644
--- a/cpp/src/Slice/Parser.h
+++ b/cpp/src/Slice/Parser.h
@@ -189,9 +189,6 @@ namespace Slice
         friend std::ostream& operator<<(std::ostream& out, const Metadata& metadata);
 
     private:
-        /// Parses a metadata string into a pair of (directive, arguments) strings.
-        static std::pair<std::string, std::string> parseRawMetadata(std::string rawMetadata);
-
         std::string _directive;
         std::string _arguments;
 
diff --git a/cpp/src/slice2cpp/Gen.cpp b/cpp/src/slice2cpp/Gen.cpp
index cb2f9e72397..8c8c789735b 100644
--- a/cpp/src/slice2cpp/Gen.cpp
+++ b/cpp/src/slice2cpp/Gen.cpp
@@ -1097,7 +1097,7 @@ Slice::Gen::MetadataVisitor::visitConst(const ConstPtr& p)
 MetadataList
 Slice::Gen::MetadataVisitor::validate(
     const SyntaxTreeBasePtr& cont,
-    const MetadataList& metadata,
+    MetadataList metadata,
     const string& file,
     bool operation)
 {
@@ -1105,9 +1105,9 @@ Slice::Gen::MetadataVisitor::validate(
     const DefinitionContextPtr dc = ut->findDefinitionContext(file);
     assert(dc);
 
-    MetadataList newMetadata = metadata;
-    for (const auto& meta : metadata)
+    for (MetadataList::const_iterator q = metadata.begin(); q != metadata.end();)
     {
+        MetadataPtr meta = *q++;
         string_view directive = meta->directive();
         string_view arguments = meta->arguments();
 
@@ -1118,7 +1118,7 @@ Slice::Gen::MetadataVisitor::validate(
             ostringstream ostr;
             ostr << "ignoring invalid metadata '" << *meta << "'";
             dc->warning(InvalidMetadata, meta->file(), meta->line(), ostr.str());
-            newMetadata.remove(meta);
+            metadata.remove(meta);
             continue;
         }
 
@@ -1184,9 +1184,9 @@ Slice::Gen::MetadataVisitor::validate(
         ostringstream ostr;
         ostr << "ignoring invalid metadata '" << *meta << "'";
         dc->warning(InvalidMetadata, meta->file(), meta->line(), ostr.str());
-        newMetadata.remove(meta);
+        metadata.remove(meta);
     }
-    return newMetadata;
+    return metadata;
 }
 
 TypeContext
diff --git a/cpp/src/slice2cpp/Gen.h b/cpp/src/slice2cpp/Gen.h
index 16a38821152..5e9b98afb5d 100644
--- a/cpp/src/slice2cpp/Gen.h
+++ b/cpp/src/slice2cpp/Gen.h
@@ -218,7 +218,7 @@ namespace Slice
             void visitConst(const ConstPtr&) final;
 
         private:
-            MetadataList validate(const SyntaxTreeBasePtr&, const MetadataList&, const std::string&, bool = false);
+            MetadataList validate(const SyntaxTreeBasePtr&, MetadataList, const std::string&, bool = false);
         };
 
         static void validateMetadata(const UnitPtr&);