microsoft / microsoft/vscode-cpptools
debugging inside a lambda that captures this shows the 'lambda' this instead of the 'this' 'this'
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Description
Type: Bug
I admit that the context for the debugger is kind of ambiguous. Lambdas are generated as anonymous structs and the lambda itself is a method on this anonymous struct. However
struct Foo {
void do(){
auto l = [this]{
foo = 10; // <- stop debugger here
};
l();
}
int foo 0;
}
when you look at the debugger a this in the locals shown but it's actually the lambda rather than the Foo class. Also it is not possible to inspect member foo from the point where the debugger is stopped
Extension version: 1.20.1
VS Code version: Code 1.88.1 (e170252f762678dec6ca2cc69aba1570769a5d39, 2024-04-10T17:41:02.734Z)
OS version: Windows_NT x64 10.0.22631
Modes:
System Info
| Item | Value |
|---|---|
| CPUs | AMD Ryzen 9 5900X 12-Core Processor (24 x 3700) |
| GPU Status | 2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled |
| Load (avg) | undefined |
| Memory (System) | 63.93GB (35.99GB free) |
| Process Argv | --crash-reporter-id 8e0f3da2-bd7f-4547-b593-29b86ad0a63e |
| Screen Reader | no |
| VM | 0% |
A/B Experiments
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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
Reproduce the issue with the provided C++ lambda example in VS Code using the C/C++ extension, stopping at the marked assignment. Start by tracing how the debugger presents locals and captured this values; done means the stopped frame exposes the Foo instance and permits inspection of foo rather than showing only the lambda object.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp, vscode
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100