Add non-allocating overload for error category message function

Fixes #2646

include/boost/beast/_experimental/test/impl/error.ipp

@@ -29,8 +29,8 @@ public:
     }
 
     BOOST_BEAST_DECL
-    std::string
+    char const*
-    message(int ev) const override
+    message(int ev, char*, std::size_t) const noexcept override
     {
         switch(static_cast<error>(ev))
         {
@@ -40,6 +40,13 @@ public:
         }
     }
 
+    BOOST_BEAST_DECL
+    std::string
+    message(int ev) const override
+    {
+        return message(ev, nullptr, 0);
+    }
+
     BOOST_BEAST_DECL
     error_condition
     default_error_condition(int ev) const noexcept override

include/boost/beast/core/impl/error.ipp

@@ -28,10 +28,9 @@ public:
 
     error_codes() : error_category(0x002f6e94401c6e8bu)  {}
 
-
     BOOST_BEAST_DECL
-    std::string
+    char const*
-    message(int ev) const override
+    message(int ev, char*, std::size_t) const noexcept override
     {
         switch(static_cast<error>(ev))
         {
@@ -41,6 +40,13 @@ public:
         }
     }
 
+    BOOST_BEAST_DECL
+    std::string
+    message(int ev) const override
+    {
+        return message(ev, nullptr, 0);
+    }
+
     BOOST_BEAST_DECL
     error_condition
     default_error_condition(int ev) const noexcept override
@@ -67,10 +73,9 @@ public:
 
     error_conditions() : error_category(0x3dd0b0ce843c5b10u)  {}
 
-
     BOOST_BEAST_DECL
-    std::string
+    char const*
-    message(int cv) const override
+    message(int cv, char*, std::size_t) const noexcept override
     {
         switch(static_cast<condition>(cv))
         {
@@ -79,6 +84,13 @@ public:
             return "The operation timed out";
         }
     }
+
+    BOOST_BEAST_DECL
+    std::string
+    message(int cv) const override
+    {
+        return message(cv, nullptr, 0);
+    }
 };
 
 } // detail

include/boost/beast/http/impl/error.ipp

@@ -29,8 +29,9 @@ public:
 
     http_error_category() : error_category(0x964627da815bf210u)  {}
 
-    std::string
+    BOOST_BEAST_DECL
-    message(int ev) const override
+    char const*
+    message(int ev, char*, std::size_t) const noexcept override
     {
         switch(static_cast<error>(ev))
         {
@@ -66,6 +67,12 @@ public:
         }
     }
 
+    std::string
+    message(int ev) const override
+    {
+        return message(ev, nullptr, 0);
+    }
+
     error_condition
     default_error_condition(
         int ev) const noexcept override

include/boost/beast/websocket/impl/error.ipp

@@ -29,8 +29,9 @@ public:
         return "boost.beast.websocket";
     }
 
-    std::string
+    BOOST_BEAST_DECL
-    message(int ev) const override
+    char const*
+    message(int ev, char*, std::size_t) const noexcept override
     {
         switch(static_cast<error>(ev))
         {
@@ -71,6 +72,12 @@ public:
         }
     }
 
+    std::string
+    message(int ev) const override
+    {
+        return message(ev, nullptr, 0);
+    }
+
     error_condition
     default_error_condition(int ev) const noexcept override
     {
@@ -128,9 +135,9 @@ public:
 
     error_conditions() : error_category(0x7a8de5d61799ce9eu)  {}
 
-
+    BOOST_BEAST_DECL
-    std::string
+    char const*
-    message(int cv) const override
+    message(int cv, char*, std::size_t) const noexcept override
     {
         switch(static_cast<condition>(cv))
         {
@@ -139,6 +146,12 @@ public:
         case condition::protocol_violation: return "A WebSocket protocol violation occurred";
         }
     }
+
+    std::string
+    message(int cv) const override
+    {
+        return message(cv, nullptr, 0);
+    }
 };
 
 } // detail

include/boost/beast/zlib/impl/error.ipp

@@ -55,8 +55,9 @@ public:
         return "boost.beast.zlib";
     }
 
-    std::string
+    BOOST_BEAST_DECL
-    message(int ev) const override
+    char const*
+    message(int ev, char*, std::size_t) const noexcept override
     {
         switch(static_cast<error>(ev))
         {
@@ -84,6 +85,12 @@ public:
         }
     }
 
+    std::string
+    message(int ev) const override
+    {
+        return message(ev, nullptr, 0);
+    }
+
     error_condition
     default_error_condition(int ev) const noexcept override
     {

test/beast/core/error.cpp

@@ -34,12 +34,14 @@ public:
             BEAST_EXPECT(ec.category().name() != nullptr);
             BEAST_EXPECT(! ec.message().empty());
             BEAST_EXPECT(ec == c);
+            BEAST_EXPECT(ec.message(nullptr, 0) != nullptr);
         }
         {
             auto ec = make_error_condition(c);
             BEAST_EXPECT(ec.category().name() != nullptr);
             BEAST_EXPECT(! ec.message().empty());
             BEAST_EXPECT(ec == c);
+            BEAST_EXPECT(ec.message(nullptr, 0) != nullptr);
         }
     }
 

test/beast/http/error.cpp

@@ -36,6 +36,8 @@ public:
                     static_cast<std::underlying_type<error>::type>(ev))));
         BEAST_EXPECT(cat.equivalent(ec,
             static_cast<std::underlying_type<error>::type>(ev)));
+
+        BEAST_EXPECT(ec.message(nullptr, 0) != nullptr);
     }
 
     void

test/beast/websocket/error.cpp

@@ -35,6 +35,9 @@ public:
         BEAST_EXPECT(ec.category().name() != nullptr);
         BEAST_EXPECT(! ec.message().empty());
         BEAST_EXPECT(ec == c);
+
+        BEAST_EXPECT(ec.message(nullptr, 0) != nullptr);
+        BEAST_EXPECT(make_error_condition(c).message(nullptr, 0) != nullptr);
     }
 
     void run() override

test/beast/zlib/error.cpp

@@ -35,6 +35,8 @@ public:
                     static_cast<std::underlying_type<error>::type>(ev))));
         BEAST_EXPECT(cat.equivalent(ec,
             static_cast<std::underlying_type<error>::type>(ev)));
+
+        BEAST_EXPECT(ec.message(nullptr, 0) != nullptr);
     }
 
     void run() override