Make message macros (FAIL, WARN, INFO, etc) thread safe

This builds on the existing work to make assertion thread safe,
by adding an extra synchronization point in the holder of
`ReusableStringStream`'s stream instances, as those are used to
build the messages, and finishing the move of message scope holders
to be thread-local.

1 files changed, 11 insertions, 4 deletions

diff --git a/src/catch2/internal/catch_reusable_string_stream.cpp b/src/catch2/internal/catch_reusable_string_stream.cpp
index 33eafde4..a2dd5a63 100644
--- a/src/catch2/internal/catch_reusable_string_stream.cpp
+++ b/src/catch2/internal/catch_reusable_string_stream.cpp
@@ -7,6 +7,7 @@
 // SPDX-License-Identifier: BSL-1.0
 #include <catch2/internal/catch_reusable_string_stream.hpp>
 #include <catch2/internal/catch_singletons.hpp>
+#include <catch2/internal/catch_thread_support.hpp>
 #include <catch2/internal/catch_unique_ptr.hpp>
 
 #include <cstdio>
@@ -20,8 +21,10 @@ namespace Catch {
         std::vector<Detail::unique_ptr<std::ostringstream>> m_streams;
         std::vector<std::size_t> m_unused;
         std::ostringstream m_referenceStream; // Used for copy state/ flags from
+        Detail::Mutex m_mutex;
 
         auto add() -> std::size_t {
+            Detail::LockGuard _( m_mutex );
             if( m_unused.empty() ) {
                 m_streams.push_back( Detail::make_unique<std::ostringstream>() );
                 return m_streams.size()-1;
@@ -33,9 +36,13 @@ namespace Catch {
             }
         }
 
-        void release( std::size_t index ) {
-            m_streams[index]->copyfmt( m_referenceStream ); // Restore initial flags and other state
-            m_unused.push_back(index);
+        void release( std::size_t index, std::ostream* originalPtr ) {
+            assert( originalPtr );
+            originalPtr->copyfmt( m_referenceStream );  // Restore initial flags and other state
+
+            Detail::LockGuard _( m_mutex );
+            assert( originalPtr == m_streams[index].get() && "Mismatch between release index and stream ptr" );
+            m_unused.push_back( index );
         }
     };
 
@@ -47,7 +54,7 @@ namespace Catch {
     ReusableStringStream::~ReusableStringStream() {
         static_cast<std::ostringstream*>( m_oss )->str("");
         m_oss->clear();
-        Singleton<StringStreams>::getMutable().release( m_index );
+        Singleton<StringStreams>::getMutable().release( m_index, m_oss );
     }
 
     std::string ReusableStringStream::str() const {