[Fixbug] Report duplicated param names of relay function when bind params

[yaoyaoding]

Hi community,

This PR fixes a bug in binding params for relay function. When we bind constant params for relay function, we hope to report the duplicated param names that we want to bind, but the current implementation does not. In the demo code:

from tvm import relay

a = relay.var('a', shape=(1,))
aa = relay.var('a', shape=(1,))
s = a + aa
func = relay.Function([a, aa], s)
func = relay.build_module.bind_params_by_name(func, {'a': [1.0]})

there are two variables with duplicated names, but we can bind the value to the first 'a'.

With this PR, we will have the following error message:

Traceback (most recent call last):
  File "demo.py", line 7, in <module>
    func = relay.build_module.bind_params_by_name(func, {'a': [1.0]})
  File "/home/yaoyao/repos/tvm/python/tvm/relay/build_module.py", line 449, in bind_params_by_name
    return _build_module.BindParamsByName(func, inputs)
  File "/home/yaoyao/repos/tvm/python/tvm/_ffi/_ctypes/packed_func.py", line 237, in __call__
    raise get_last_ffi_error()
tvm._ffi.base.TVMError: Traceback (most recent call last):
  2: TVMFuncCall
  1: std::_Function_handler<void (tvm::runtime::TVMArgs, tvm::runtime::TVMRetValue*), tvm::relay::backend::{lambda(tvm::runtime::TVMArgs, tvm::runtime::TVMRetValue*)#2}>::_M_invoke(std::_Any_data const&, tvm::runtime::TVMArgs&&, tvm::runtime::TVMRetValue*&&)
  0: tvm::relay::backend::BindParamsByName(tvm::relay::Function, std::unordered_map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, tvm::runtime::NDArray, std::hash<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::equal_to<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, tvm::runtime::NDArray> > > const&)
  File "/home/yaoyao/repos/tvm/src/relay/backend/utils.h", line 343
TVMError: Multiple args in the function have name a

@icemelon @comaniac @jroesch

[junrushao]

Hey thanks @yaoyaoding! Would you like to add a unittest? You may use pytest.raises to assert the error message

[yaoyaoding]

Sure, do you have any suggestion about where to put the test?

[comaniac]

LGTM. Please fix the CI.