Fix wrong noexcept, improve testing.

Author: bluescarni

include/tanuki/tanuki.hpp

@@ -1527,7 +1527,7 @@ class TANUKI_VISIBLE wrap : private detail::wrap_storage<IFace, Cfg.static_size,
     }
 
 private:
-    void copy_init_from(const wrap &other) noexcept
+    void copy_init_from(const wrap &other)
     {
         static_assert(Cfg.semantics == wrap_semantics::value);
 
@@ -1860,8 +1860,7 @@ class TANUKI_VISIBLE wrap : private detail::wrap_storage<IFace, Cfg.static_size,
             try {
                 w.template ctor_impl<T>(std::forward<Args>(args)...);
             } catch (...) {
-                // NOTE: if ctor_impl fails there's no cleanup required.
-                // Invalidate this before rethrowing.
+                // NOTE: if ctor_impl fails there's no cleanup required, except to invalidate this before rethrowing.
                 w.m_pv_iface = nullptr;
 
                 throw;

test/test_basics.cpp

@@ -372,6 +372,44 @@ TEST_CASE("assignment")
     }
 }
 
+// NOTE: a small test to check the cleanup logic in the copy assignment operator of wrap when the assignment is
+// implemented via destroy + copy init and copy init throws.
+TEST_CASE("throwing copy assignment")
+{
+    using tanuki::wrap;
+    using wrap_t = wrap<any_iface>;
+
+    // NOLINTNEXTLINE
+    struct throw_copy {
+        throw_copy() = default;
+        throw_copy(const throw_copy &)
+        {
+            throw std::invalid_argument("");
+        }
+        throw_copy(throw_copy &&) = default;
+        throw_copy &operator=(const throw_copy &) = default;
+        throw_copy &operator=(throw_copy &&) = default;
+    };
+
+    {
+        wrap_t w1(
+            large{.str = "bsadsadasdsadsadsadsadsadsadsadasdkjsadkldjlsakdsjaljdklajdlksajdlkajdkljsakldjakllif"}),
+            w2(throw_copy{});
+
+        REQUIRE_THROWS_AS((w1 = w2), std::invalid_argument);
+
+        REQUIRE(!is_valid(w1));
+    }
+
+    {
+        wrap_t w1(small{}), w2(throw_copy{});
+
+        REQUIRE_THROWS_AS((w1 = w2), std::invalid_argument);
+
+        REQUIRE(!is_valid(w1));
+    }
+}
+
 #if defined(TANUKI_WITH_BOOST_S11N)
 
 TEST_CASE("s11n nostatic")