throw doesn't work as expected with xeus-cpp

[anutosh491]

I am guessing something changed in clang/clang-repl/llvm after version 17

We could achieve this I think using CppInterOp 1.3.0 (part of our example notebook)

I know throw basically should end "erroring" out ..... but we would prefer something like the above where we error out through the console and not our kernel crashing and restarting

[anutosh491]

I'm sorry, this still works

One might ask why do I see the kernel restarting above ?
Ans: Because I am on Apple Mac M2 and there is something not correct about how exception handling works with any Mac ARM device (llvm/llvm-project#92121)

[anutosh491]

That being said there is still an error here !

I shall be changing the issue title to make a note of it.

This was discovered while playing around with throw. Let's say we miss out of the placeholder from the above catch block (basically any sort of wrong syntax)... this would end up seeing this

clang-repl> #include <stdio.h>            
clang-repl> try { throw 1; } catch { printf("Caught exception\n"); }
In file included from <<< inputs >>>:1:
input_line_2:1:23: error: expected '('
    1 | try { throw 1; } catch { printf("Caught exception\n"); }
      |                       ^
      |                       (
clang-repl: /home/abhinav/Desktop/Coding/CERN_HSF_Compiler_Research/llvm-project/clang/lib/AST/DeclBase.cpp:1737: void clang::DeclContext::addHiddenDecl(clang::Decl*): Assertion `D->getLexicalDeclContext() == this && "Decl inserted into wrong lexical context"' failed.
Aborted (core dumped)

So this segfaults and crashes the clang-repl instance. Whereas I would expected it to gracefully fail giving back a parsing error. Just like what I see below

clang-repl> #include <iostream>
clang-repl> std::cut << "hello";
In file included from <<< inputs >>>:1:
input_line_2:1:6: error: no member named 'cut' in namespace 'std'; did you mean 'cout'?
    1 | std::cut << "hello";
      | ~~~~~^~~
      |      cout
/Users/anutosh491/micromamba/envs/clang-repl-env/bin/../include/c++/v1/iostream:54:42: note: 'cout' declared here
   54 | extern _LIBCPP_EXPORTED_FROM_ABI ostream cout;
      |                                          ^
error: Parsing failed.

[kr-2003]

@anutosh491

Some Observations

Problems using try-catch block in xeus-cpp-lite(wasm)

1. Using normal try-catch block throws Failed to execute via ::process:Failed to load incremental module.

2. Using malformed try-catch block throws Aborted(visible in console)

Expected results

This should be the expected output. xeus-cpp gives proper results.

[kr-2003]

After every aborted code, I have to restart the kernel in xeus-cpp-lite manually. If any code is aborted, then the notebook should popup a dialog box for restarting kernel.

[anutosh491]

I think you didn't notice this #222

Have been working on this already. I think I might be close too ;)

[kr-2003]

I think you didn't notice this #222

Have been working on this already. I think I might be close too ;)

Aah sorry. Should have seen it.

[anutosh491]

@kr-2003 what's the status of this ? Did we address this issue to the fullest ?

[kr-2003]

@kr-2003 what's the status of this ? Did we address this issue to the fullest ?

Yes, since it works on

1. xeus-cpp-lite(Here is the PR that fixes this issue).
2. xeus-cpp(native)
   • Working on macos
   • Working on ubuntu

We can close this issue.

Works on ubuntu

[anutosh491]

Thank you. I confirmed it on macos too !