LPython parses but CPython does not

[certik]

These are curious cases that LPython parses but CPython does not. These are artificial cases, but if we want to be 100% strict with regards to #1139, we should not allow it either, so that if things compile with LPython, they also work with CPython.

def f():
    i: i32
    a: i32 = 5; for i in range(10): print(i)

f()

Which gives:

$ lpython --show-ast a.py         
(Module [(FunctionDef f ([] [] [] [] [] [] []) [(AnnAssign (Name i Store) (Name i32 Load) () 1) (AnnAssign (Name a Store) (Name i32 Load) (ConstantInt 5 ()) 1) (For (Name i Store) (Call (Name range Load) [(ConstantInt 10 ())] []) [(Expr (Call (Name print Load) [(Name i Load)] []))] [] ())] [] () ()) (Expr (Call (Name f Load) [] []))] [])
$ python  a.py            
  File "/Users/ondrej/repos/lpython/a.py", line 3
    a: i32 = 5; for i in range(10): print(i)
                ^^^
SyntaxError: invalid syntax

[Thirumalai-Shaktivel]

The problem is: we should not allow single-line multi-statements to follow the single-line statements.