Clang-repl fails while trying Lambdas with capture

[anutosh491]

Unfortunately I didn't have clang-repl built locally while trying this but I tried in through xeus-cpp (a C++ Jupyter Kernel that is based on clang-repl) and also through xeus-cpp-lite (xeus-cpp + jupyterlite that helps run clang-repl completely in the browser, here's a link to try it out https://compiler-research.github.io/xeus-cpp/lab/index.html

The following fails (or rather leads to a kernel crash in my case)

int x = 42;
auto capture = [&]() { return x * 2; };
std::cout << capture() << "\n"; // Output: 84

The error message is this

Assertion failed: getPtr() && "getFETokenInfo on an empty DeclarationName!", at: /home/runner/work/recipes/recipes/output/bld/rattler-build_llvm_1734801187/work/clang/include/clang/AST/DeclarationName.h,503,getFETokenInfo)

[ferdymercury]

You might try as a workaround with https://github.com/jupyter-xeus/xeus-cling

@vgvassilev might know about the assertion

[anutosh491]

Okay I finally had the time to run this through clang-repl 19.1.7 @ferdymercury

I think the error might be justified too. But why does it crash out here ?

clang-repl> int x = 42;
clang-repl> auto capture = [&]() { return x * 2; };
In file included from <<< inputs >>>:1:
input_line_4:1:17: error: non-local lambda expression cannot have a capture-default
    1 | auto capture = [&]() { return x * 2; };
      |                 ^
zsh: segmentation fault  clang-repl --Xcc="-v"

Shouldn't I simply see

error: Parsing failed.

[ferdymercury]

Did you try also xeus-cling?

Pinging @devajithvs

[anutosh491]

Did you try also xeus-cling?

Pinging @devajithvs

I think I should. Shall get back after my attempt. Though I've always had problems fetching cling (root-project/cling#542)