microsoft / microsoft/vscode-cpptools
C++ Debug breakpoint doesn't work with linked libraries built with the application in VSCode when using `-Og` compilation flag/option.
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Description
Environment
- OS and version: Ubuntu 25.10
- VS Code: 1.114.0
- C/C++ extension: 1.5.1
- OS and version of remote machine (if applicable):
- GDB / LLDB version: 16.3
Bug Summary and Steps to Reproduce
Bug Summary:
Breakpoints set inside a statically linked library built with the same C++ application in the same source tree are greyed out and not hit.
Steps to reproduce:
Console.cpp CMakeLists.txt:
target_link_libraries(${PROJECT_NAME} PRIVATE
MyLibrary.Core
)
top-level CMakeLists.txt:
set(CMAKE_CXX_STANDARD 26)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_BUILD_TYPE "Debug")
# ###############################################################################
# Global compiler options
# https://stackoverflow.com/questions/79444534/vscode-cmake-configure-does-not-generate-cmakecache-txt-from-cmakelists-txt
# CMAKE_CXX_COMPILER_ID is set only at the project() call, when CMake actually detect compilers.
# ###############################################################################
if(MSVC)
# remove default flags provided with CMake for MSVC
set(CMAKE_CXX_FLAGS "")
set(CMAKE_CXX_FLAGS_DEBUG "")
set(CMAKE_CXX_FLAGS_RELEASE "")
elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
message("-- Setting GNU options from CMakeLists.txt")
set(CMAKE_CXX_FLAGS "-std=gnu++26 -fdiagnostics-color=always" CACHE STRING "CXX build flags" FORCE)
set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS} -ggdb3 -Og -g3" CACHE STRING "Debug build flags" FORCE)
set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS} -O3 -DNDEBUG" CACHE STRING "Release build flags" FORCE)
endif()
Debugger Configurations
launch.json:
{
"name": "C++ Launch (Console)",
"type": "cppdbg",
"request": "launch",
"preLaunchTask": "CMake: build all",
"postDebugTask": "",
"program": "${workspaceFolder}/Debug/Console",
"cwd": "${workspaceFolder}/build",
"stopAtEntry": false,
"externalConsole": false,
"launchCompleteCommand": "exec-run",
"linux": {
"MIMode": "gdb",
"miDebuggerPath": "/usr/bin/gdb"
},
"osx": {
"MIMode": "lldb"
},
"windows": {
"MIMode": "gdb",
"miDebuggerPath": "C:\\MinGw\\bin\\gdb.exe"
},
"args": [],
"setupCommands": [
{
"description": "Disable MI-async",
"text": "set mi-async off",
"ignoreFailures": true
},
{
"description": "Enable auto-load for all paths. Considered a security risk. See link for details: https://sourceware.org/gdb/current/onlinedocs/gdb.html/Auto_002dloading-safe-path.html",
"text": "set auto-load safe-path /",
"ignoreFailures": true
},
{
"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
},
{
"description": "Do not display function arguments when printing a stack frame",
"text": "set print frame-arguments none",
"ignoreFailures": true
}
]
},
tasks.json:
{
"version": "2.0.0",
"tasks": [
{
"type": "cmake",
"label": "CMake: build all",
"command": "build",
"targets": [
"all"
],
"group": {
"kind": "build",
"isDefault": true
},
"problemMatcher": ["$gcc"],
"detail": "CMake build all"
},
{
"type": "cmake",
"label": "CMake: build Console",
"command": "build",
"targets": [
"Console"
],
"group": {
"kind": "build",
"isDefault": false
},
"problemMatcher": ["$gcc"],
"detail": "CMake build Console"
},
{
"type": "cmake",
"label": "CMake: build Core",
"command": "build",
"targets": [
"DataStructuresAlgorithms.Core"
],
"group": {
"kind": "build",
"isDefault": false
},
"problemMatcher": ["$gcc"],
"detail": "CMake build Core"
},
{
"type": "cmake",
"label": "CMake: build Tests",
"command": "build",
"targets": [
"DataStructuresAlgorithms.Tests"
],
"group": {
"kind": "build",
"isDefault": false
},
"problemMatcher": ["$gcc"],
"detail": "CMake build Tests"
},
]
}
Debugger Logs
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (590) DebuggerPid=583206\n"},"seq":185}
1: (590) DebuggerPid=583206
<-- C (setBreakpoints-4): {"command":"setBreakpoints","arguments":{"source":{"name":"Arithmetic.cpp","path":"/usr/src/DataStructuresAlgorithms/src/Arithmetic.cpp"},"lines":[299,323],"breakpoints":[{"line":299},{"line":323}],"sourceModified":false},"type":"request","seq":4}
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (604) <-1016-break-insert -f Arithmetic.cpp:299\n"},"seq":188}
1: (604) <-1016-break-insert -f Arithmetic.cpp:299
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (701) ->&\"No compiled code for line 299 in file \\\"Arithmetic.cpp\\\".\\n\"\n"},"seq":190}
1: (701) ->&"No compiled code for line 299 in file \"Arithmetic.cpp\".\n"
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (702) ->1016^done,bkpt={number=\"2\",type=\"breakpoint\",disp=\"keep\",enabled=\"y\",addr=\"<PENDING>\",pending=\"Arithmetic.cpp:299\",times=\"0\",original-location=\"Arithmetic.cpp:299\"}\n"},"seq":192}
1: (702) ->1016^done,bkpt={number="2",type="breakpoint",disp="keep",enabled="y",addr="<PENDING>",pending="Arithmetic.cpp:299",times="0",original-location="Arithmetic.cpp:299"}
--> E (output): {"type":"event","event":"output","body":{"category":"console","output":"1: (702) ->(gdb)\n"},"seq":194}
Other Extensions
No response
Additional Information
No response
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the supplied launch.json, tasks.json, and top-level CMakeLists.txt, then reproduce the pending breakpoint for Arithmetic.cpp:299 using GDB and the -Og flags. Compare the debugger logs while building the Console and DataStructuresAlgorithms.Core targets; done means the breakpoint resolves to compiled code and is hit inside the statically linked library.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cmake, cpp, vscode
- Domain
- build-system, developer-experience, devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100