Can we use google::NullStream instead of google::LogMessageVoidify in LOG_IF? #1119
Description
#define LOG_IF(severity, condition) \
static_cast<void>(0), \
!(condition) \
? (void)0 \
: google::logging::internal::LogMessageVoidify() & LOG(severity)
This is how LOG_IF is implemented now. After reading the doc https://github.com/asplingzhang/asplingzhang.github.io/blob/main/docs/_posts/webrtc/logging/2022-06-14-why-static_cast-void-and-LogMessageVoidify-needed-in-logging-macros.md,
I understand the reason for using LogMessageVoidify, while it turns the LOG_IF from ostream into void. If someone wants to wrap LOG_IF or VLOG, it causes error:
#define VLOG(verboselevel) LOG_IF(INFO, VLOG_IS_ON(verboselevel))
#define MYLOG \
static_cast<void>(0), \
!(condition) \
? (void)0 \
: google::logging::internal::LogMessageVoidify() & VLOG(1)
The code above causes errors like error: no match for 'operator&' (operand types are 'google::LogMessageVoidify' and 'void')
I can't use VLOG_IF in my wrapper for other reasons.
So I want to know if I can use NullStream instead like:
#define LOG_IF(severity, condition) \
!(condition) \
? google::NullStream().stream() \
: LOG(severity)
Thus LOG_IF is still an ostream and we can wrap it.
What's the difference between using google::NullStream and LogMessageVoidify?