Store IStream instance owning ptrs in reporter instances

This ended up being a surprisingly large refactoring, motivated
by removing a `const_cast` from `Config`'s handling of reporter
streams, forced by previous commit.

src/catch2/interfaces/catch_interfaces_reporter.cpp

@@ -17,21 +17,25 @@
 #include <catch2/internal/catch_move_and_forward.hpp>
 
 #include <algorithm>
+#include <cassert>
 #include <iomanip>
 
 namespace Catch {
 
     ReporterConfig::ReporterConfig(
         IConfig const* _fullConfig,
-        IStream* _stream,
+        Detail::unique_ptr<IStream> _stream,
         ColourMode colourMode,
         std::map<std::string, std::string> customOptions ):
-        m_stream( _stream ),
+        m_stream( CATCH_MOVE(_stream) ),
         m_fullConfig( _fullConfig ),
         m_colourMode( colourMode ),
         m_customOptions( CATCH_MOVE( customOptions ) ) {}
 
-    IStream* ReporterConfig::stream() const { return m_stream; }
+    Detail::unique_ptr<IStream> ReporterConfig::takeStream() && {
+        assert( m_stream );
+        return CATCH_MOVE( m_stream );
+    }
     IConfig const * ReporterConfig::fullConfig() const { return m_fullConfig; }
     ColourMode ReporterConfig::colourMode() const { return m_colourMode; }
 

src/catch2/interfaces/catch_interfaces_reporter.hpp

@@ -36,17 +36,17 @@ namespace Catch {
 
     struct ReporterConfig {
         ReporterConfig( IConfig const* _fullConfig,
-                        IStream* _stream,
+                        Detail::unique_ptr<IStream> _stream,
                         ColourMode colourMode,
                         std::map<std::string, std::string> customOptions );
 
-        IStream* stream() const;
+        Detail::unique_ptr<IStream> takeStream() &&;
         IConfig const* fullConfig() const;
         ColourMode colourMode() const;
         std::map<std::string, std::string> const& customOptions() const;
 
     private:
-        IStream* m_stream;
+        Detail::unique_ptr<IStream> m_stream;
         IConfig const* m_fullConfig;
         ColourMode m_colourMode;
         std::map<std::string, std::string> m_customOptions;

src/catch2/interfaces/catch_interfaces_reporter_factory.hpp

@@ -25,7 +25,7 @@ namespace Catch {
         virtual ~IReporterFactory(); // = default
 
         virtual IEventListenerPtr
-        create( ReporterConfig const& config ) const = 0;
+        create( ReporterConfig&& config ) const = 0;
         virtual std::string getDescription() const = 0;
     };
     using IReporterFactoryPtr = Detail::unique_ptr<IReporterFactory>;

src/catch2/interfaces/catch_interfaces_reporter_registry.hpp

@@ -32,7 +32,7 @@ namespace Catch {
         using Listeners = std::vector<Detail::unique_ptr<EventListenerFactory>>;
 
         virtual ~IReporterRegistry(); // = default
-        virtual IEventListenerPtr create( std::string const& name, ReporterConfig const& config ) const = 0;
+        virtual IEventListenerPtr create( std::string const& name, ReporterConfig&& config ) const = 0;
         virtual FactoryMap const& getFactories() const = 0;
         virtual Listeners const& getListeners() const = 0;
     };