Added support for Out[S]

[anutosh491]

Thanks to the well framed subroutine_from_function pass. Now we can return symbolic objects through a cummulative result of the subroutine_from_function and symbolic pass.

[anutosh491]

I think the subroutine_from_function pass is aligned before the symbolic pass so we don't need to alter that!

[anutosh491]

So currently we can do something like

(lf) anutosh491@spbhat68:~/lpython/lpython$ cat examples/expr2.py 
from lpython import S
from sympy import pi, Symbol

def func() -> S:
    print(Symbol("x"))
    return pi

def test_func():
    z: S = func()
    print(z)

test_func()

(lf) anutosh491@spbhat68:~/lpython/lpython$ lpython --enable-symengine --backend=c examples/expr2.py 
x
pi

But through the llvm backend we would still be stuck as we had discussed previously (#2411 (comment))

code generation error: asr_to_llvm: module failed verification. Error:
Call parameter type does not match function signature!
void** %_lpython_return_variable
 void*  call void @basic_const_pi(void** %_lpython_return_variable)
Call parameter type does not match function signature!
  %4 = load void*, void** %__libasr__created__var__0__func_call_res, align 8
 void**  call void @__module___main___func(void* %4)

[certik]

I think this is good. Can you please add a test?

Also, can you submit just the libasr change to lfortran, to ensure everything works there?

[anutosh491]

I think this is good. Can you please add a test?
Also, can you submit just the libasr change to lfortran, to ensure everything works there?

Done.

[anutosh491]

We should also discuss as to how we would address comment (#2411 (comment)) because if you think about it, the function definition for mrv would look like the following

def mrv(e: S, x: S) -> tuple[dict[S, S], S]:

Trying to replicate something like the following

>>> from sympy.series.gruntz import mrv
>>> mrv(exp(x), x)
({exp(x): _Dummy_40}, {}, _Dummy_40)

Which means we need to return a tuple with a dict inside it and dictionaries aren't currently supported through the C backend, so untill we get the llvm backend working, we might be blocked.

[certik]

I think that's fine. Can you also add a test for Out[S] explicitly? Right now it is only tested implicitly via the subroutine_from_function.

[anutosh491]

Can you also add a test for Out[S] explicitly?

Sure.