声明在llvmlite中返回void的函数时出现AssertionError

Question

I am trying to create a function which returns void in llvm-ir but a creation of such function gives AssertionError

import llvmlite.ir as ir

int32 = ir.IntType(32)
m = ir.Module('demo')

main_ty = ir.FunctionType(int32, [])
main_fn = ir.Function(m, main_ty, "main")

print(str(m))

The above code works fine as the return type is int32 , and gives the following output, which is as expected.

; ModuleID = "demo"
target triple = "unknown-unknown-unknown"
target datalayout = ""

declare i32 @"main"() 

but when I change the return type from int32 to VoidType it raises the AssertionError.

m = ir.Module('demo')
main_ty = ir.FunctionType(ir.VoidType, [])
main_fn = ir.Function(m, main_ty, "main")
print(str(m))

---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)
<ipython-input-2-298d109233fd> in <module>
      1 m = ir.Module('demo')
      2 main_ty = ir.FunctionType(ir.VoidType, [])
----> 3 main_fn = ir.Function(m, main_ty, "main")
      4 print(str(m))

~/.local/lib/python3.6/site-packages/llvmlite/ir/values.py in __init__(self, module, ftype, name)
    593         self.args = tuple([Argument(self, t)
    594                            for t in ftype.args])
--> 595         self.return_value = ReturnValue(self, ftype.return_type)
    596         self.parent.add_global(self)
    597         self.calling_convention = ''

~/.local/lib/python3.6/site-packages/llvmlite/ir/values.py in __init__(self, parent, typ, name)
    718 class _BaseArgument(NamedValue):
    719     def __init__(self, parent, typ, name=''):
--> 720         assert isinstance(typ, types.Type)
    721         super(_BaseArgument, self).__init__(parent, typ, name=name)
    722         self.parent = parent

AssertionError: 

Can anyone help me what I am missing here?

Answer 1

VoidType is a class just like IntType is. You still need to apply it (with zero arguments), to create an instance:

main_ty = ir.FunctionType(ir.VoidType(), [])
//                                   ^^