Reapply "Revert a011d42"

This reverts commit fe615c4.

Author: krlmlr

inst/include/cpp11/declarations.hpp

@@ -46,7 +46,7 @@ T& unmove(T&& t) {
   SEXP err = R_NilValue;              \
   char buf[CPP11_ERROR_BUFSIZE] = ""; \
   try {
-#define END_CPP11_EX(RET)                                       \
+#define END_CPP11                                               \
   }                                                             \
   catch (cpp11::unwind_exception & e) {                         \
     err = e.token;                                              \
@@ -62,5 +62,4 @@ T& unmove(T&& t) {
   } else if (err != R_NilValue) {                               \
     CPP11_UNWIND                                                \
   }                                                             \
-  return RET;
-#define END_CPP11 END_CPP11_EX(R_NilValue)
+  return R_NilValue;

inst/include/cpp11/protect.hpp

@@ -214,10 +214,14 @@ void stop [[noreturn]] (const std::string& fmt_arg, Args&&... args) {
   safe.noreturn(Rf_errorcall)(R_NilValue, "%s", msg.c_str());
 }
 
-// Always making copy of string to avoid weird unwind behavior.
+template <typename... Args>
+void warning(const char* fmt_arg, Args&&... args) {
+  std::string msg = fmt::format(fmt_arg, std::forward<Args>(args)...);
+  safe[Rf_warningcall](R_NilValue, "%s", msg.c_str());
+}
 
 template <typename... Args>
-void warning(const std::string fmt_arg, Args&&... args) {
+void warning(const std::string& fmt_arg, Args&&... args) {
   std::string msg = fmt::format(fmt_arg, std::forward<Args>(args)...);
   safe[Rf_warningcall](R_NilValue, "%s", msg.c_str());
 }
@@ -232,10 +236,13 @@ void stop [[noreturn]] (const std::string& fmt, Args... args) {
   safe.noreturn(Rf_errorcall)(R_NilValue, fmt.c_str(), args...);
 }
 
-// Always making copy of string to avoid weird unwind behavior.
+template <typename... Args>
+void warning(const char* fmt, Args... args) {
+  safe[Rf_warningcall](R_NilValue, fmt, args...);
+}
 
 template <typename... Args>
-void warning(const std::string fmt, Args... args) {
+void warning(const std::string& fmt, Args... args) {
   safe[Rf_warningcall](R_NilValue, fmt.c_str(), args...);
 }
 #endif