bug: multiple evaluations of DST lead to non-unique symbol error when copying byte arrays or dynamic arrays

[tserg]

Version Information

• vyper Version (output of vyper --version): https://github.com/vyperlang/vyper/commit/9e3b9a2b8ae55aa83b5450080f750be15f819de7
• OS: linux
• Python Version (output of python --version): 3.10.4

What's your issue about?

The destination of byte arrays and dynamic arrays copying is evaluated multiple times as cache_when_complex is not used. This includes make_byte_array_copier and _dynarray_make_setter (both cases: src.value == "multi" and src.value != "multi").

This contract fails to compile with the following error: AssertionError: non-unique symbols {'self.bar()2'}.

a: DynArray[DynArray[uint256, 2],2]

@external
def foo():
    self.a[self.bar()] = [1, 2]

@internal
def bar() -> uint256:
    return 0

reported by @trocher

How can it be fixed?

Fill this in if you know how to fix it.

[trocher]

Another example to add to tests when the issue will be patched:

d:String[4]

@internal
def bar()->uint256:
    return 0
@external
def bar():
    f:DynArray[String[5], 1] = ["aaaaa"]
    f[self.bar()] = self.d