Merge #17218: Replace the LogPrint function with a macro

8734c856f8 Replace the LogPrint function with a macro (Jeffrey Czyz)

Pull request description:

  Calling `LogPrint` with a category that is not enabled results in
  evaluating the remaining function arguments, which may be arbitrarily
  complex (and possibly expensive) expressions. Defining `LogPrint` as a
  macro prevents this unnecessary expression evaluation.

  This is a partial revert of #14209. The decision to revert is discussed
  in #16688, which adds verbose logging for validation event notification.

ACKs for top commit:
  jnewbery:
    ACK 8734c856f8

Tree-SHA512: 19e995eaef0ff008a9f8c1fd6f3882f1fbf6794dd7e2dcf5c68056be787eee198d2956037d4ffba2b01e7658b47eba276cd7132feede78832373b3304203961e

src/logging.h

@@ -155,12 +155,13 @@ static inline void LogPrintf(const char* fmt, const Args&... args)
     }
 }
 
-template <typename... Args>
+// Use a macro instead of a function for conditional logging to prevent
-static inline void LogPrint(const BCLog::LogFlags& category, const Args&... args)
+// evaluating arguments when logging for the category is not enabled.
-{
+#define LogPrint(category, ...)              \
-    if (LogAcceptCategory((category))) {
+    do {                                     \
-        LogPrintf(args...);
+        if (LogAcceptCategory((category))) { \
-    }
+            LogPrintf(__VA_ARGS__);          \
-}
+        }                                    \
+    } while (0)
 
 #endif // BITCOIN_LOGGING_H