Debug MSVC failure; cat xatomic.h

.github/workflows/ci.yml

@@ -598,6 +598,8 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
 
+    - run: cat "c:\program files (x86)\microsoft visual studio 14.0\vc\include\xatomic.h"
+
     - name: Update CMake
       uses: jwlawson/actions-setup-cmake@v1.4
 

tests/test_iostream.cpp

@@ -31,7 +31,7 @@ void noisy_funct_dual(std::string msg, std::string emsg) {
 // simply repeatedly write to std::cerr until stopped
 // redirect is called at some point to test the safety of scoped_estream_redirect
 struct TestThread {
-    TestThread() : t_{nullptr}, stop_{false} {
+    TestThread() : t_{nullptr}, stop_{0} {
         auto thread_f = [this] {
             while (!stop_) {
                 std::cout << "x" << std::flush;
@@ -57,7 +57,7 @@ struct TestThread {
     }
 
     std::thread * t_;
-    std::atomic<bool> stop_;
+    std::atomic<int> stop_;  // VS 2015's MSVC doesn't like `std::atomic<bool>`: ...\xatomic.h(382): warning C4702: unreachable code
 };