Set visibility of exceptions to default.

Co-authored-by: XZiar <[email protected]>

include/pybind11/detail/common.h

@@ -723,16 +723,23 @@ using expand_side_effects = bool[];
 
 PYBIND11_NAMESPACE_END(detail)
 
+#if defined(_MSC_VER)
+#  pragma warning(push)
+#  pragma warning(disable: 4275) // warning C4275: An exported class was derived from a class that wasn't exported. Can be ignored when derived from a STL class.
+#endif
 /// C++ bindings of builtin Python exceptions
-class builtin_exception : public std::runtime_error {
+class PYBIND11_EXPORT builtin_exception : public std::runtime_error {
 public:
     using std::runtime_error::runtime_error;
     /// Set the error using the Python C API
     virtual void set_error() const = 0;
 };
+#if defined(_MSC_VER)
+#  pragma warning(pop)
+#endif
 
 #define PYBIND11_RUNTIME_EXCEPTION(name, type) \
-    class name : public builtin_exception { public: \
+    class PYBIND11_EXPORT name : public builtin_exception { public: \
         using builtin_exception::builtin_exception; \
         name() : name("") { } \
         void set_error() const override { PyErr_SetString(type, what()); } \

include/pybind11/pytypes.h

@@ -319,11 +319,15 @@ PYBIND11_NAMESPACE_BEGIN(detail)
 inline std::string error_string();
 PYBIND11_NAMESPACE_END(detail)
 
+#if defined(_MSC_VER)
+#  pragma warning(push)
+#  pragma warning(disable: 4275 4251) // warning C4275: An exported class was derived from a class that wasn't exported. Can be ignored when derived from a STL class.
+#endif
 /// Fetch and hold an error which was already set in Python.  An instance of this is typically
 /// thrown to propagate python-side errors back through C++ which can either be caught manually or
 /// else falls back to the function dispatcher (which then raises the captured error back to
 /// python).
-class error_already_set : public std::runtime_error {
+class PYBIND11_EXPORT error_already_set : public std::runtime_error {
 public:
     /// Constructs a new exception from the current Python error indicator, if any.  The current
     /// Python error indicator will be cleared.
@@ -371,6 +375,9 @@ class error_already_set : public std::runtime_error {
 private:
     object m_type, m_value, m_trace;
 };
+#if defined(_MSC_VER)
+#  pragma warning(pop)
+#endif
 
 /** \defgroup python_builtins _
     Unless stated otherwise, the following C++ functions behave the same