Internal Compiler Error: Unhandled exception

[davidbrochart]

It seems asyncio is not supported yet? I get the following error while importing it:

semantic error: Could not find the module 'asyncio'. If an import path is available, please use the `-I` option to specify it

As a workaround, I wanted to try this simple coroutine runner:

async def main():
    print("done")

def run_async_fn(async_fn, *args, **kwargs):
    coro = async_fn(*args, **kwargs)
    try:
        coro.send(None)
    except StopIteration as exc:
        return exc.value
    else:
        raise RuntimeError("Cannot run async function")

run_async_fn(main)

But I get:

Internal Compiler Error: Unhandled exception

[certik]

Yes, we don't support asyncio natively yet. The second example should give a nice error, so that's a bug. Thanks for reporting it!

[davidbrochart]

Actually I get a better error message with lpython from conda-forge (the above was with lpython compiled locally):

Internal Compiler Error: Unhandled exception
Traceback (most recent call last):
LCompilersException: visit_AsyncFunctionDef() not implemented

So I guess this issue should be closed?

[certik]

Leave it open. This error message is a general developer error message that we have not implemented visit_AsyncFunctionDef in the AST->ASR visitor.

However the error message should actually be the user error message where we underline the code that is not supported and explain why, possibly linking to a github issue.

[ujjwaltwitx]

Hello everyone, I want to work on this issue but I have no idea on how to approach this. Can someone just guide me a bit in the right direction.

[certik]

@ujjwaltwitx you have to override the function visit_AsyncFunctionDef in AST to ASR, and raise a nice error message to the user. You can watch https://www.youtube.com/watch?v=yuYsyM08bss to get an idea how the internals work.

[ujjwaltwitx]

Sorry for replying this late. I was busy doing some other work. I will watch the video and if I face any difficulties, I will definitely get back to the community for help.

[ujjwaltwitx]

I have implemented visit_AsyncFunctionDef in SymbolTableVisitor class. Here's the definition of the function

void visit_AsyncFunctionDef(const AST::AsyncFunctionDef_t &x){
        try
        {
            // to be implemented
        }
        catch(const std::exception& e)
        {
            std::cerr << e.what() << '\n';
        }        
    }

Am I required to add something more to this function. I have also add the visit_AsyncFunctionDef in BodyVisitor class. Here's the definition of the same

void visit_AsyncFunctionDef(const AST::AsyncFunctionDef_t &x) {
        try
        {
            // BodyVisitor for visit_AsyncFunctionDef to be implemented
        }
        catch(const std::exception& e)
        {
            std::cerr << e.what() << '\n';
        }
    }

Any feedback will be much appreciated.

[syheliel]

This problem has been fixed in #2442 . should we close this issue?

[certik]

Here is what I get on the above code now:

$ lpython a.py 
semantic error: The `async` keyword is currently not supported
 --> a.py:1:1 - 2:17
  |
1 |    async def main():
  |    ^^^^^^^^^^^^^^^^^...
...
  |
2 |        print("done")
  | ...^^^^^^^^^^^^^^^^^ 


Note: Please report unclear or confusing messages as bugs at
https://github.com/lcompilers/lpython/issues.

So I think this issue is now fixed.