Environment variables disappear when the program forks when debugging a C++ program

Environment

• OS and version: Ubuntu 20.04.5 LTS (x64 5.15.0-56-generic)
• VS Code: 1.95.3 (Commit: https://github.com/microsoft/vscode/commit/f1a4fb101478ce6ec82fe9627c43efbf9e98c813)
• C/C++ extension: v1.22.11
• OS and version of remote machine (if applicable): N/A
• GDB / LLDB version: GNU gdb (Ubuntu 9.2-0ubuntu1~20.04.1) 9.2

Bug Summary and Steps to Reproduce

Bug Summary: Environment variables disappear when the program forks when debugging a C++ program

VScode gets rid of environment variables when I debug a C++ programs which forks.

Here is an example with a 2 files project :

hello1.cpp

#include <boost/process.hpp>


namespace ps = boost::process;

int main() {
  std::string command = "/home/user/MyProject/hello2";
  ps::child c(command);

  c.wait();

  return 0;
}

hello2.cpp

#include <iostream>


int main() {
  std::cout << "Hello world" << std::endl;

  const char* myVarEnv = std::getenv("FOO");
  std::cout << "myVarEnv = " << myVarEnv << std::endl;

  return 0;
}

to build hello1.cpp and hello2.cpp :

g++ -g hello1.cpp -o hello1 -lpthread
g++ -g hello2.cpp -o hello2

What is astonishing is when I debug hello1 I can see my FOO environment variable is correctly defined :

-exec show environment FOO
FOO = foo

Then I switch the follow-fork-mode to child :

-exec set follow-fork-mode child

But when I fork in hello2, gdb can't find the FOO environment variable anymore :

-exec show environment FOO
Environment variable "FOO" not defined.

but oddly enough, the program hello2 manages to print the environment variable correctly :

myVarEnv = foo

Moreover, if I debug this program with gdb, gdb can find the FOO environment variable perfectly in both hello1 and hello2 :

(gdb) show environment FOO     
FOO = foo

Since, VScode just uses gdb, that means VScode should be able to find the FOO environment normally, right ?

Debugger Configurations

{
  // Use IntelliSense to learn about possible attributes.
  // Hover to view descriptions of existing attributes.
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "name": "(gdb) Launch",
      "type": "cppdbg",
      "request": "launch",
      "program": "/home/user/MyProject/hello1",
      "args": [],
      "stopAtEntry": false,
      "cwd": "${fileDirname}",
      "environment": [
        {"name": "FOO", "value": "foo"}
      ],
      "externalConsole": false,
      "MIMode": "gdb",
      "setupCommands": [
          {
              "description": "Enable pretty-printing for gdb",
              "text": "-enable-pretty-printing",
              "ignoreFailures": true
          },
          {
              "description": "Set Disassembly Flavor to Intel",
              "text": "-gdb-set disassembly-flavor intel",
              "ignoreFailures": true
          }
      ]
    }
  ]
}

Debugger Logs

Hello world
myVarEnv = foo
[1] + Done

Other Extensions

No response

Additional Information

No response

Start by reproducing the issue with hello1.cpp and hello2.cpp, the launch configuration, and GDB's follow-fork-mode set to child. Compare show environment FOO before and after the fork while confirming the child still prints FOO; done means the debugger reports the variable in both processes as standalone GDB does.