Allow to initialize nested structs using "Transactions(transactions=[], accounts=[])"

[certik]

With the following definitions:

from lpython import dataclass, i64

@dataclass
class TransactionItem:
    account_idx: i64
    commodity: str
    amount: i64

@dataclass
class Transaction:
    date: str
    name: str
    cleared: bool
    comments: str
    items: list[TransactionItem]

@dataclass
class Account:
    name: str

@dataclass
class Transactions:
    transactions: list[Transaction]
    accounts: list[Account]

This does not work:

asr: Transactions = Transactions(transactions=[], accounts=[])

This workaround works:

transactions: list[Transaction] = []
accounts: list[Account] = []
asr: Transactions = Transactions(transactions=transactions, accounts=accounts)

[certik]

The workaround above gives ASR, but fails to compile:

$ lpython -I. process.py
ASR verify pass error: ASR verify: The symbol table was not found in the scope of `symtab`.

ASR verify pass error: ASR verify: Struct::m_derived_type 'Transaction' cannot point outside of its symbol table, owner: model
Internal Compiler Error: Unhandled exception
Traceback (most recent call last):
  File "/Users/ondrej/repos/lpython/src/bin/lpython.cpp", line 1869
    err = compile_python_to_object_file(arg_file, tmp_o, runtime_library_dir,
  File "/Users/ondrej/repos/lpython/src/bin/lpython.cpp", line 828
    res = fe.get_llvm3(*asr, pass_manager, diagnostics, infile);
  File "/Users/ondrej/repos/lpython/src/lpython/python_evaluator.cpp", line 71
    run_fn, infile);
  File "/Users/ondrej/repos/lpython/src/libasr/codegen/asr_to_llvm.cpp", line 8933
    pass_manager.apply_passes(al, &asr, pass_options, diagnostics);
  File "/Users/ondrej/repos/lpython/src/libasr/pass/pass_manager.h", line 305
    apply_passes(al, asr, _passes, pass_options, diagnostics);
  File "/Users/ondrej/repos/lpython/src/libasr/pass/pass_manager.h", line 169
    + passes[i]);
LCompilersException: Verify failed in the pass: class_constructor

[arteevraina]

Hi @certik ,
I tried to reproduce the above issue for the work around code.

from lpython import dataclass, i64

@dataclass
class TransactionItem:
    account_idx: i64
    commodity: str
    amount: i64

@dataclass
class Transaction:
    date: str
    name: str
    cleared: bool
    comments: str
    items: list[TransactionItem]

@dataclass
class Account:
    name: str

@dataclass
class Transactions:
    transactions: list[Transaction]
    accounts: list[Account]

transactions: list[Transaction] = []
accounts: list[Account] = []
asr: Transactions = Transactions(transactions=transactions, accounts=accounts)

I am able to reproduce the issue for the workaround code when I use two different modules/files. One contains the definition of the classes and in the other file i import the classes and use the workaround initialization but when I put definition and initialization in a single file I am not able to reproduce it.

[certik]

Yes, I was using two different files.

[certik]

To fix this, we need to do lfortran/lfortran#2957.