dictionary literals are not decompiled correctly

[mristin]

Hi,
I encountered that dictionary literals can not be decompiled and result in an exception:

>>> import meta.decompiler
>>> f = lambda: {"x": 4}
>>> meta.decompiler.decompile_func(f)

results in a traceback:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/marko/workspace/pqryopen/icontract/venv3/lib/python3.5/site-packages/meta/decompiler/__init__.py", line 37, in decompile_func
    ast_node = make_function(code, defaults=[], lineno=code.co_firstlineno)
  File "/home/marko/workspace/pqryopen/icontract/venv3/lib/python3.5/site-packages/meta/decompiler/instructions.py", line 137, in make_function
    stmnts = instructions.stmnt()
  File "/home/marko/workspace/pqryopen/icontract/venv3/lib/python3.5/site-packages/meta/decompiler/instructions.py", line 310, in stmnt
    self.visit(instr)
  File "/home/marko/workspace/pqryopen/icontract/venv3/lib/python3.5/site-packages/meta/decompiler/instructions.py", line 324, in visit
    method(instr)
  File "/home/marko/workspace/pqryopen/icontract/venv3/lib/python3.5/site-packages/meta/decompiler/simple_instructions.py", line 495, in BUILD_MAP
    new_instr = self.ilst.pop(0)
IndexError: pop from empty list

When I look at meta/decompiler/simple_instructions.py, it seems to me that you expect intructions:

    def BUILD_MAP(self, instr):

        nitems = instr.oparg
        keys = []
        values = []
        for i in range(nitems):
            map_instrs = []
            while 1:
                new_instr = self.ilst.pop(0)

                if new_instr.opname == 'STORE_MAP':
                    break

                map_instrs.append(new_instr)

            items = self.decompile_block(map_instrs).stmnt()
            assert len(items) == 2

            values.append(items[0])
            keys.append(items[1])


        list_ = _ast.Dict(keys=keys, values=values, lineno=instr.lineno, col_offset=0)
        self.push_ast_item(list_)

However, the python 3 byte code looks like:

>>> import dis
>>> f = lambda: {"x": 4}
>>> dis.dis(f)
  1           0 LOAD_CONST               1 ('x')
              3 LOAD_CONST               2 (4)
              6 BUILD_MAP                1
              9 RETURN_VALUE

I tried to read the code, but I was a bit confused where you set self.ilst and what it represents? There seems to be no constructor for the class SimpleInstructions, right?

I would be very grateful if you could guide me a bit how to fix this problem!