Various fixes, warnings:

* Fix sig_wait
* Fix websocket strict aliasing warning
* Fix invokable strict aliasing
* Silence fread warning in examples
* Silence integer conversion warnings
* Build parser-bench as test
* Disable unused variable warning for asio:
    Caused by static variables declared in <boost/asio/error.hpp>
    No known workaround.

test/http/basic_parser.cpp

@@ -33,6 +33,80 @@ class basic_parser_test : public beast::detail::unit_test::suite
     std::mt19937 rng_;
 
 public:
+    struct cb_req_checker
+    {
+        bool method = false;
+        bool uri = false;
+        bool request = false;
+    };
+
+    struct cb_res_checker
+    {
+        bool reason = false;
+        bool response = false;
+    };
+
+    template<bool isRequest>
+    struct cb_checker
+        : public basic_parser<isRequest, cb_checker<isRequest>>
+        , std::conditional<isRequest,
+                cb_req_checker, cb_res_checker>::type
+
+    {
+        bool field = false;
+        bool value = false;
+        bool headers = false;
+        bool body = false;
+        bool complete = false;
+
+    private:
+        friend class basic_parser<isRequest, cb_checker<isRequest>>;
+
+        void on_method(boost::string_ref const&, error_code&)
+        {
+            this->method = true;
+        }
+        void on_uri(boost::string_ref const&, error_code&)
+        {
+            this->uri = true;
+        }
+        void on_reason(boost::string_ref const&, error_code&)
+        {
+            this->reason = true;
+        }
+        void on_request(error_code&)
+        {
+            this->request = true;
+        }
+        void on_response(error_code&)
+        {
+            this->response = true;
+        }
+        void on_field(boost::string_ref const&, error_code&)
+        {
+            field = true;
+        }
+        void on_value(boost::string_ref const&, error_code&)
+        {
+            value = true;
+        }
+        int on_headers(error_code&)
+        {
+            headers = true;
+            return 0;
+        }
+        void on_body(boost::string_ref const&, error_code&)
+        {
+            body = true;
+        }
+        void on_complete(error_code&)
+        {
+            complete = true;
+        }
+    };
+
+    //--------------------------------------------------------------------------
+
     static
     std::string
     escaped_string(boost::string_ref const& s)
@@ -106,6 +180,54 @@ public:
         }
     };
 
+    void
+    testCallbacks()
+    {
+        {
+            cb_checker<true> p;
+            error_code ec;
+            std::string const s =
+                "GET / HTTP/1.1\r\n"
+                "User-Agent: test\r\n"
+                "Content-Length: 1\r\n"
+                "\r\n"
+                "*";
+            p.write(s.data(), s.size(), ec);
+            if( expect(! ec))
+            {
+                expect(p.method);
+                expect(p.uri);
+                expect(p.request);
+                expect(p.field);
+                expect(p.value);
+                expect(p.headers);
+                expect(p.body);
+                expect(p.complete);
+            }
+        }
+        {
+            cb_checker<false> p;
+            error_code ec;
+            std::string const s =
+                "HTTP/1.1 200 OK\r\n"
+                "Server: test\r\n"
+                "Content-Length: 1\r\n"
+                "\r\n"
+                "*";
+            p.write(s.data(), s.size(), ec);
+            if( expect(! ec))
+            {
+                expect(p.reason);
+                expect(p.response);
+                expect(p.field);
+                expect(p.value);
+                expect(p.headers);
+                expect(p.body);
+                expect(p.complete);
+            }
+        }
+    }
+
     // Parse the entire input buffer as a valid message,
     // then parse in two pieces of all possible lengths.
     //
@@ -497,6 +619,7 @@ public:
 
     void run() override
     {
+        testCallbacks();
         testVersion();
         testFlags();
         testUpgrade();