Cannot yield a value in the body of a try block with a catch clause

[alrz]

Consider:

async IAsyncEnumerable<T> M_1<T>(IAsyncEnumerable<T> a) {
    try {
        await foreach (var item in a) {
            yield return Compute(item); // error
        }   
    } catch {
        throw;
    }
}

I worked around this issue by manually iterating over the stream.

async IAsyncEnumerable<T> M_2<T>(IAsyncEnumerable<T> a) {
    await using var e = a.GetAsyncEnumerator(); // notice this is not inside the try-catch block
    while (true) {
        T result;
        try {
            if (!await e.MoveNextAsync())
                break;
            result = Compute(e.Current);
        } catch {
            throw;
        }
        yield return result;
    }
}

This is possible as long as there's nothing else inside the try block other than a foreach, I think.

Is it worth it to have a special syntax for this?

async IAsyncEnumerable<T> M_1<T>(IAsyncEnumerable<T> a) {
    await foreach (var item in a) {
        yield return Compute(item);
    } catch {
        throw;
    }
}

If done using the same transformation, continue and break should be valid inside the catch block.

[svick]

Except for the suggestion for new syntax, this looks like a duplicate of #765, only that now it also applies to async iterator methods.