Add cpptrace::system_error

README.md

@@ -348,6 +348,8 @@ Cpptrace provides an interface for a traced exceptions, `cpptrace::exception`, a
 that that generate stack traces when thrown. These exceptions generate relatively lightweight raw traces and resolve
 symbols and line numbers lazily if and when requested.
 
+These are provided both as a useful utility and as a reference implementation for traced exceptions.
+
 The basic interface is:
 ```cpp
 namespace cpptrace {
@@ -398,7 +400,7 @@ namespace cpptrace {
         const char* message() const noexcept override;
     };
 
-    // All stdexcept errors have analogs here. All have the constructor:
+    // All stdexcept errors have analogs here. All but system_error have the constructor:
     // explicit the_error(
     //     std::string&& message_arg,
     //     raw_trace&& trace = detail::get_raw_trace_and_absorb()
@@ -413,6 +415,15 @@ namespace cpptrace {
     class range_error      : public exception_with_message { ... };
     class overflow_error   : public exception_with_message { ... };
     class underflow_error  : public exception_with_message { ... };
+    class system_error : public runtime_error {
+    public:
+        explicit system_error(
+            int error_code,
+            std::string&& message_arg,
+            raw_trace&& trace = detail::get_raw_trace_and_absorb()
+        ) noexcept;
+        const std::error_code& code() const noexcept;
+    };
 }
 ```
 

include/cpptrace/cpptrace.hpp

@@ -6,6 +6,7 @@
 #include <limits>
 #include <ostream>
 #include <string>
+#include <system_error>
 #include <type_traits>
 #include <utility>
 #include <vector>
@@ -437,6 +438,17 @@ namespace cpptrace {
         std::exception_ptr nested_ptr() const noexcept;
     };
 
+    class CPPTRACE_EXPORT system_error : public runtime_error {
+        std::error_code ec;
+    public:
+        explicit system_error(
+            int error_code,
+            std::string&& message_arg,
+            raw_trace&& trace = detail::get_raw_trace_and_absorb()
+        ) noexcept;
+        const std::error_code& code() const noexcept;
+    };
+
     // [[noreturn]] must come first due to old clang
     [[noreturn]] CPPTRACE_EXPORT void rethrow_and_wrap_if_needed(std::size_t skip = 0);
 }

src/cpptrace.cpp

@@ -577,6 +577,17 @@ namespace cpptrace {
         return user_message.c_str();
     }
 
+    system_error::system_error(int error_code, std::string&& message_arg, raw_trace&& trace) noexcept
+        : runtime_error(
+            message_arg + ": " + std::error_code(error_code, std::generic_category()).message(),
+            std::move(trace)
+          ),
+          ec(std::error_code(error_code, std::generic_category())) {}
+
+    const std::error_code& system_error::code() const noexcept {
+        return ec;
+    }
+
     const char* nested_exception::message() const noexcept {
         if(message_value.empty()) {
             try {