fix: unify LogMessage and LogMessageInfo (#1057)

Deprecate the custom prefix callback accepting LogMessageInfo in favor
of existing LogMessage data structure extended with necessary data
fields to avoid redundancies.

.bazelci/presubmit.yml

@@ -1,8 +1,8 @@
 ---
 tasks:
   ubuntu1804:
-    name: "Ubuntu 18.04"
-    platform: ubuntu1804
+    name: "Ubuntu 22.04"
+    platform: ubuntu2204
     build_flags:
     - "--features=layering_check"
     - "--copt=-Werror"

README.rst

@@ -320,6 +320,54 @@ Example:
    caution when comparing the low bits of timestamps from different machines.
 
 
+Customizing the Log Line Prefix
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The predefined log line prefix can be replaced using a user-provided callback
+that formats the corresponding output.
+
+For each log entry, the callback will be invoked with a reference to a
+``google::LogMessage`` instance containing the severity, filename, line number,
+thread ID, and time of the event. It will also be given a reference to the
+output stream, whose contents will be prepended to the actual message in the
+final log line.
+
+For example, the following function outputs a prefix that matches glog's default
+format. The third parameter ``data`` can be used to access user-supplied data
+which unless specified defaults to :cpp:`nullptr`.
+
+.. code:: cpp
+
+    void MyPrefixFormatter(std::ostream& s, const google::LogMessage& m, void* /*data*/) {
+       s << google::GetLogSeverityName(m.severity())[0]
+       << setw(4) << 1900 + m.time().year()
+       << setw(2) << 1 + m.time().month()
+       << setw(2) << m.time().day()
+       << ' '
+       << setw(2) << m.time().hour() << ':'
+       << setw(2) << m.time().min()  << ':'
+       << setw(2) << m.time().sec() << "."
+       << setw(6) << m.time().usec()
+       << ' '
+       << setfill(' ') << setw(5)
+       << m.thread_id() << setfill('0')
+       << ' '
+       << m.basename() << ':' << m.line() << "]";
+    }
+
+
+To enable the use of a prefix formatter, use the
+
+.. code:: cpp
+
+    google::InstallPrefixFormatter(&MyPrefixFormatter);
+
+function to pass a pointer to the corresponding :cpp:`MyPrefixFormatter`
+callback during initialization. :cpp:`InstallPrefixFormatter` takes a second
+optional argument of type  :cpp:`void*` that allows supplying user data to the
+callback.
+
+
 Setting Flags
 ~~~~~~~~~~~~~
 
@@ -650,50 +698,6 @@ severity level.
          "Present occurrence is " << google::COUNTER;
 
 
-Custom Log Prefix Format
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-glog supports changing the format of the prefix attached to log messages by
-receiving a user-provided callback that generates such strings.
-
-For each log entry, the callback will be invoked with a ``LogMessageInfo``
-struct containing the severity, filename, line number, thread ID, and time of
-the event. It will also be given a reference to the output stream, whose
-contents will be prepended to the actual message in the final log line.
-
-For example, the following function outputs a prefix that matches glog's default
-format. The third parameter ``data`` can be used to access user-supplied data
-which unless specified defaults to :cpp:`nullptr`.
-
-.. code:: cpp
-
-    void CustomPrefix(std::ostream& s, const LogMessageInfo& l, void* /*data*/) {
-       s << l.severity[0]
-       << setw(4) << 1900 + l.time.year()
-       << setw(2) << 1 + l.time.month()
-       << setw(2) << l.time.day()
-       << ' '
-       << setw(2) << l.time.hour() << ':'
-       << setw(2) << l.time.min()  << ':'
-       << setw(2) << l.time.sec() << "."
-       << setw(6) << l.time.usec()
-       << ' '
-       << setfill(' ') << setw(5)
-       << l.thread_id << setfill('0')
-       << ' '
-       << l.filename << ':' << l.line_number << "]";
-    }
-
-
-To enable the use of a custom prefix, use the
-
-.. code:: cpp
-
-    InitGoogleLogging(argv[0], &CustomPrefix);
-
-overload to pass a pointer to the corresponding :cpp:`CustomPrefix` function during
-initialization. :cpp:`InitGoogleLogging()` takes a third optional argument of
-type  :cpp:`void*` that allows supplying user data to the callback.
 
 Failure Signal Handler
 ~~~~~~~~~~~~~~~~~~~~~~

src/glog/logging.h

@@ -115,7 +115,7 @@ struct GLOG_EXPORT LogMessageTime {
   std::chrono::seconds gmtoffset_;
 };
 
-struct LogMessageInfo {
+struct [[deprecated("Use LogMessage instead.")]] LogMessageInfo {
   explicit LogMessageInfo(const char* const severity_,
                           const char* const filename_, const int& line_number_,
                           std::thread::id thread_id_,
@@ -133,9 +133,6 @@ struct LogMessageInfo {
   const LogMessageTime& time;
 };
 
-typedef void (*CustomPrefixCallback)(std::ostream& s, const LogMessageInfo& l,
-                                     void* data);
-
 }  // namespace google
 
 // The global value of GOOGLE_STRIP_LOG. All the messages logged to
@@ -485,9 +482,26 @@ namespace google {
 // specified by argv0 in log outputs.
 GLOG_EXPORT void InitGoogleLogging(const char* argv0);
 
-GLOG_EXPORT void InitGoogleLogging(const char* argv0,
-                                   CustomPrefixCallback prefix_callback,
-                                   void* prefix_callback_data = nullptr);
+class LogMessage;
+
+#if defined(__GNUG__)
+#  pragma GCC diagnostic push
+#  pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#elif defined(_MSC_VER)
+#  pragma warning(push)
+#  pragma warning(disable : 4996)
+#endif  // __GNUG__
+using CustomPrefixCallback
+    [[deprecated("Use PrefixFormatterCallback instead.")]] =
+        void (*)(std::ostream&, const LogMessageInfo&, void*);
+#if defined(__GNUG__)
+#  pragma GCC diagnostic pop
+#elif defined(_MSC_VER)
+#  pragma warning(pop)
+#endif  // __GNUG__
+[[deprecated("Use InstallPrefixFormatter instead.")]] GLOG_EXPORT void
+InitGoogleLogging(const char* argv0, CustomPrefixCallback prefix_callback,
+                  void* prefix_callback_data = nullptr);
 
 // Check if google's logging library has been initialized.
 GLOG_EXPORT bool IsGoogleLoggingInitialized();
@@ -501,6 +515,12 @@ typedef void (*logging_fail_func_t)() __attribute__((noreturn));
 typedef void (*logging_fail_func_t)();
 #endif
 
+using PrefixFormatterCallback = void (*)(std::ostream&, const LogMessage&,
+                                         void*);
+
+GLOG_EXPORT void InstallPrefixFormatter(PrefixFormatterCallback callback,
+                                        void* data = nullptr);
+
 // Install a function which will be called after LOG(FATAL).
 GLOG_EXPORT void InstallFailureFunction(logging_fail_func_t fail_func);
 
@@ -1343,9 +1363,15 @@ class GLOG_EXPORT LogMessage {
     return time();
   }
 
-  const LogMessageTime& time() const;
+  LogSeverity severity() const noexcept;
+  int line() const noexcept;
+  const std::thread::id& thread_id() const noexcept;
+  const char* fullname() const noexcept;
+  const char* basename() const noexcept;
+  const LogMessageTime& time() const noexcept;
 
-  struct LogMessageData;
+  LogMessage(const LogMessage&) = delete;
+  LogMessage& operator=(const LogMessage&) = delete;
 
  private:
   // Fully internal SendMethod cases:
@@ -1373,9 +1399,6 @@ class GLOG_EXPORT LogMessage {
   LogMessageTime time_;
 
   friend class LogDestination;
-
-  LogMessage(const LogMessage&);
-  void operator=(const LogMessage&);
 };
 
 // This class happens to be thread-hostile because all instances share
@@ -1493,7 +1516,7 @@ class GLOG_EXPORT LogSink {
   // during this call.
   virtual void send(LogSeverity severity, const char* full_filename,
                     const char* base_filename, int line,
-                    const LogMessageTime& logmsgtime, const char* message,
+                    const LogMessageTime& time, const char* message,
                     size_t message_len);
   // Provide an overload for compatibility purposes
   GLOG_DEPRECATED
@@ -1519,8 +1542,8 @@ class GLOG_EXPORT LogSink {
   // Returns the normal text output of the log message.
   // Can be useful to implement send().
   static std::string ToString(LogSeverity severity, const char* file, int line,
-                              const LogMessageTime& logmsgtime,
-                              const char* message, size_t message_len);
+                              const LogMessageTime& time, const char* message,
+                              size_t message_len);
 };
 
 // Add or remove a LogSink as a consumer of logging data.  Thread-safe.