Drop the custom external json logger

Use the internal one instead. This has the drawback that the internal
logger is not as user-friendly as the old one (because of its use of
magic numbers), but that makes maintenance much simpler.

src/libmain/loggers.cc

@@ -31,77 +31,12 @@ LogFormat parseLogFormat(const string &logFormatStr) {
                 logFormatStr);
 }
 
-/**
- * A json logger intended for external consumption
- * (contrary to 'JSONLogger' which is an internal thing
- */
-struct ExternalJSONLogger : JSONLogger {
-    ExternalJSONLogger(Logger &prevLogger) : JSONLogger(prevLogger) {}
-
-    nlohmann::json jsonActivityType(ActivityType type) override {
-        switch (type) {
-        case actUnknown:
-            return "actUnknown";
-        case actCopyPath:
-            return "actCopyPath";
-        case actDownload:
-            return "actDownload";
-        case actRealise:
-            return "actRealise";
-        case actCopyPaths:
-            return "actCopyPaths";
-        case actBuilds:
-            return "actBuilds";
-        case actBuild:
-            return "actBuild";
-        case actOptimiseStore:
-            return "actOptimiseStore";
-        case actVerifyPaths:
-            return "actVerifyPaths";
-        case actSubstitute:
-            return "actSubstitute";
-        case actQueryPathInfo:
-            return "actQueryPathInfo";
-        case actPostBuildHook:
-            return "actPostBuildHook";
-        default:
-            return "UnknownActivity";
-        }
-    }
-
-    nlohmann::json jsonResultType(ResultType type) override {
-        switch (type) {
-        case resFileLinked:
-            return "resFileLinked";
-        case resBuildLogLine:
-            return "resBuildLogLine";
-        case resUntrustedPath:
-            return "resUntrustedPath";
-        case resCorruptedPath:
-            return "resCorruptedPath";
-        case resSetPhase:
-            return "resSetPhase";
-        case resProgress:
-            return "resProgress";
-        case resSetExpected:
-            return "resSetExpected";
-        case resPostBuildLogLine:
-            return "resPostBuildLogLine";
-        default:
-            return "UnknownResultType";
-        }
-    }
-
-    void result(ActivityId act, ResultType type,
-                const Fields &fields) override{};
-};
-
 Logger *makeDefaultLogger() {
     switch (logFormat) {
     case logFormatRaw:
         return makeSimpleLogger();
     case logFormatJSON:
-        return new ExternalJSONLogger(*makeSimpleLogger());
+        return new JSONLogger();
     case logFormatBar:
         return createProgressBar();
     case logFormatBarWithLogs:

src/libutil/json-logger.cc

@@ -10,10 +10,6 @@ JSONLogger::JSONLogger(Logger &prevLogger) : prevLogger(prevLogger) {}
 
 JSONLogger::JSONLogger() : JSONLogger(*makeSimpleLogger()) {}
 
-nlohmann::json JSONLogger::jsonActivityType(ActivityType type) { return type; }
-
-nlohmann::json JSONLogger::jsonResultType(ResultType type) { return type; }
-
 void JSONLogger::addFields(nlohmann::json &json, const Fields &fields) {
     if (fields.empty())
         return;
@@ -46,7 +42,7 @@ void JSONLogger::startActivity(ActivityId act, Verbosity lvl, ActivityType type,
     json["action"] = "start";
     json["id"] = act;
     json["level"] = lvl;
-    json["type"] = jsonActivityType(type);
+    json["type"] = type;
     json["text"] = s;
     addFields(json, fields);
     // FIXME: handle parent
@@ -64,7 +60,7 @@ void JSONLogger::result(ActivityId act, ResultType type, const Fields &fields) {
     nlohmann::json json;
     json["action"] = "result";
     json["id"] = act;
-    json["type"] = jsonResultType(type);
+    json["type"] = type;
     addFields(json, fields);
     write(json);
 }

src/libutil/json-logger.hh

@@ -32,11 +32,6 @@ class JSONLogger : public Logger {
     virtual void stopActivity(ActivityId act);
 
     virtual void result(ActivityId act, ResultType type, const Fields &fields);
-
-  protected:
-    virtual nlohmann::json jsonActivityType(ActivityType type);
-
-    virtual nlohmann::json jsonResultType(ResultType type);
 };
 
 /**