Abseil LOG output printed twice in Qt Creator

Question

I have created a simple project which uses Abseil and is built and run inside of Qt Creator.

When I use any abseil logging, I see the output twice in the Qt Creator "Application Output" pane. Once in red and once again in white (I'm using dark theme). Using std::cout, I see the output once as white, as expected. Using std::cerr, I see the output once as red, as expected. I cannot figure out how to stop Abseil logging from printing twice. If I run the same process from the command line, the Abseil logs are only printed to stderr, as expected.

• OS: Windows 10
• Qt Creator versions tested: 11 & 12
• Qt version: 6.2.4 MSVC2019 64bit

Abseil is recently cloned locally as a subdirectory. The commit is 2a636651729cec997a433ce8e363c6344130944e, though it happens with older versions too.

Here is the directory structure:

.
|-- CMakeLists.txt
|-- CMakeLists.txt.user
|-- abseil-cpp
`-- main.cpp

Here is my main:

#include <absl/log/globals.h>
#include <absl/log/initialize.h>
#include <absl/log/log.h>

#include <iostream>

int main() {
  absl::InitializeLog();
  absl::SetStderrThreshold(absl::LogSeverityAtLeast::kInfo);
  std::cout << "Cout test" << std::endl;
  std::cerr << "Cerr test" << std::endl;
  LOG(INFO) << "test";
  return 0;
}

This program will print something like:

Cout test
Cerr test
I0104 17:58:48.312991   20796 main.cpp:12] test
I0104 17:58:48.312991   20796 main.cpp:12] test

("Cerr test" and one of the "main.cpp:12] test" lines are red)

Here is my CMakeLists.txt:

cmake_minimum_required(VERSION 3.26.4)

project(main LANGUAGES CXX)

add_executable(${PROJECT_NAME}
  main.cpp
)

set(ABSL_PROPAGATE_CXX_STD ON)
add_subdirectory(abseil-cpp)

target_link_libraries(${PROJECT_NAME}
PUBLIC
  absl::log
  absl::log_initialize
)

Answer 1

This has been determined to be a bug in Qt Creator. I have come up with a workaround. I've created my own "Log Sink" and registered it with abseil.

class MyLogSink : public absl::LogSink {
public:
  void Send(const absl::LogEntry& entry) override {
    std::cerr << entry.text_message_with_prefix_and_newline();
  }
};
absl::LogSink *mySink = new MyLogSink;
absl::AddLogSink(mySink);

Additionally, the LogSeverity level ought to be set to a maximum to disable the usual absl logging.

absl::SetStderrThreshold(absl::LogSeverityAtLeast::kInfinity);