Undo magic-statification of message id counter

The initialization itself is thread unsafe, and as such we cannot
allow it to be delayed until multiple user-spawned threads need it.

.github/workflows/mac-other-builds.yml

@@ -0,0 +1,36 @@
+name: Mac Sanitizer Builds
+
+on: [push, pull_request]
+
+env:
+  CXXFLAGS: -fsanitize=thread,undefined
+
+jobs:
+  build:
+    # From macos-14 forward, the baseline "macos-X" image is Arm based,
+    # and not Intel based.
+    runs-on: ${{matrix.image}}
+    strategy:
+      fail-fast: false
+      matrix:
+        image: [macos-13, macos-14]
+        build_type: [Debug, Release]
+        std: [14, 17]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Configure
+      
+      run: |
+        cmake --preset all-tests -GNinja \
+              -DCMAKE_BUILD_TYPE=${{matrix.build_type}} \
+              -DCMAKE_CXX_STANDARD=${{matrix.std}} \
+              -DCATCH_BUILD_EXTRA_TESTS=ON \
+              -DCATCH_ENABLE_WERROR=OFF
+
+    - name: Build
+      run: cmake --build build
+
+    - name: Test
+      run: ctest --test-dir build -R ThreadSafetyTests --timeout 21600 --verbose

src/catch2/internal/catch_console_colour.cpp

@@ -164,9 +164,7 @@ namespace {
 #if defined( CATCH_PLATFORM_LINUX ) \
  || defined( CATCH_PLATFORM_MAC ) \
  || defined( __GLIBC__ ) \
- || (defined( __FreeBSD__ ) \
-     /* PlayStation platform does not have `isatty()` */ \
-     && !defined(CATCH_PLATFORM_PLAYSTATION)) \
+ || defined( __FreeBSD__ ) \
  || defined( CATCH_PLATFORM_QNX )
 #    define CATCH_INTERNAL_HAS_ISATTY
 #    include <unistd.h>

src/catch2/internal/catch_run_context.cpp

@@ -175,11 +175,11 @@ namespace Catch {
         // below, in the future we will want to allocate piece of memory
         // from heap, to avoid consuming too much thread-local storage.
         //
-        // Note that we also don't want non-trivial the thread-local variables
-        // below be initialized for every thread, only for those that touch
-        // Catch2. To make this work with both GCC/Clang and MSVC, we have to
-        // make them thread-local magic statics. (Class-level statics have the
-        // desired semantics on GCC, but not on MSVC).
+        // Note that we also don't want the thread-local variables below
+        // be initialized for every thread, only for those that touch Catch2.
+        // To make this work with both GCC/Clang and MSVC, we have to make
+        // them thread-local magic statics. (Class-level statics have
+        // the desired semantics on GCC, but not on MSVC).
 
         // This is used for the "if" part of CHECKED_IF/CHECKED_ELSE
         static CATCH_INTERNAL_THREAD_LOCAL bool g_lastAssertionPassed = false;