gdb (MinGW) doesn't break on failed asserts (VSCode config) - c++

Question

I'm trying to debug a program, in VSCode, which violates an assert, but doesn't break and doesn't allow me to inspect the callstack or anything. Instead the program just exits with exitcode 3 and prints out the following text:
Assertion failed!
Program: C:\Users\Sewbacca\Projects\Practice\CppTest\build\Test.exe
File: C:\Users\Sewbacca\Projects\Practice\CppTest\src\main.cpp, Line 6
Expression: false
I tried to add the following commands to "setupCommands" in .vscode/launch.json with no success:
{
"text": "break _assert (const char *_Message, const char *_File, unsigned _Line)"
},
{
"text": "break abort"
},
{
"text": "break exit"
},
Sidenote: I'm not experienced with gdb and I don't know exactly what setupCommands does change. I would have expected that vscode send these to gdb directly.
My only workarround is to set a breakpoint before main() and type -exec break abort into the debug console. Then it will break on any failed asserts.
Edit:
Adding the following config to "setupCommands":
{
"text": "-exec break abort"
},
Resulted in following error message:
[Window Title]
Visual Studio Code
[Content]
Unable to start debugging. Unexpected GDB output from command "-exec break abort". Undefined MI command: exec
[Open 'launch.json'] [Cancel]
End of Edit
Is there a way to automate this or is there a proper way to tell gdb (especially in VSCode) to break on failed asserts, rather than just exit the program?
Edit:
There was nothing wrong with my configuration. It seems like my gdb version was buggy. Sometimes it exited randomly when I told gdb to break before entering main, which led me to this issue. As stated there, gdb 8.1 for x86_64-w64-mingw32 has this bug. Since there is no newer version available in the installer, I downgraded to 7.2 which solved this issue for me. However, after using winlibs version 11.1.0, the issue still persists.
End of edit
Thanks in advance!
Setup:
src/main.cpp
#include <cassert>
int main()
{
assert(false);
}
CMakeLists.txt
project(Test)
add_executable(${PROJECT_NAME} src/main.cpp)
.vscode/launch.json
{
"version": "0.2.0",
"configurations": [
{
"name": "(gdb) Launch",
"type": "cppdbg",
"request": "launch",
// Resolved by CMake Tools:
"program": "${command:cmake.launchTargetPath}",
"args": [],
"stopAtEntry": false,
"cwd": "${workspaceFolder}",
"environment": [
{
// add the directory where our target was built to the PATHs
// it gets resolved by CMake Tools:
"name": "PATH",
"value": "${env:PATH}:${command:cmake.getLaunchTargetDirectory}"
}
],
"MIMode": "gdb",
"setupCommands": [
{
"description": "Enable pretty-printing for gdb",
"text": "-enable-pretty-printing",
"ignoreFailures": true
},
{
"text": "break _assert (const char *_Message, const char *_File, unsigned _Line)"
},
{
"text": "break abort"
},
{
"text": "break exit"
},
]
}
],
"compounds": []
}
My Environment:
Platform: Windows 10
Toolchain: mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0
Build system: CMake
IDE: VSCode with extension CMake Tools

Answer 1

I found a solution:
gdb breaks on failed asserts, when adding the following code to setupCommands in launch.json:
"setupCommands": {
...
{
"text": "set breakpoint pending on",
"description": "Ensures that a breakpoint for abort will be set!",
"ignoreFailures": true
},
{
"text": "break abort",
"description": "Breaks on failed asserts",
"ignoreFailures": true
},
{
"text": "set breakpoint pending auto",
"description": "Setting back to default behaviour",
"ignoreFailures": true
}
...
}
Explaination:
To break on assert failures, I found this Stack Overflow Post, which worked, when I tested it manually, but not when I used it in launch.json.
I don't understand why it doesn't break on its own, but I do understand why break abort didn't worked, at least I have a guess: The symbols haven't been loaded yet and break abort asks you in gdb, if a pending breakpoint should be created, which defaults to no. So setting pending breakpoints to on, solved this issue for me and now I can finally debug my program.