Improve ineffassign static code analyzer

[farazdagi]

🚀 Feature Request

Description

@nisdas has found an interesting use case where our ineffassign analyzer can be improved, this issue is to track the possible resolution for such a case.

Describe the solution you'd like

Consider the following snippet:

unusedSlice := make([][]byte,100) 

for i,_ := range unusedSlice {
  unusedSlice[i] = []byte{'j','u','n','k'}
} 

and then unusedSlice is never used.

Our ineffassign should be able to catch cases like this.

[eshaan7]

Hi. This is my first interaction on this repository.

From what I can gather, this improvement needs to be made in the ineffassign repository, right ?

[prestonvanloon]

@eshaan7 This refers to our static analysis tooling https://github.com/prysmaticlabs/prysm/tree/develop/tools/analyzers/ineffassign