How to ignore within class function

[pbrisbin]

We have a few IsString instances that use some safe conversion function and error on invalid input:

module Example.Whatever where

instance IsString Whatever where
  fromString = either error id . whateverFromString

whateverFromString :: String -> Either String Whatever
whateverFromString = undefined

But we also have a rule to avoid error generally, which this trips over:

- warn:
    name: "Avoid error"
    lhs: "error"
    rhs: "error"
    note: ...

We consider using error in fromString acceptable because there is no other way to signal failure and it's (as long as we're disciplined) used only on literals we control. So I would like to tell HLint to ignore the error lint specifically in any function named fromString. Seems easy, but I can't make it work.

# I confirmed this works, just to make sure my config is being respected
- ignore: {name: "Avoid error"}

# This also works, but is too broad
- ignore: {name: "Avoid error", within: "Example.Whatever"}

# This does not work
- ignore: {name: "Avoid error", within: "fromString"}

# This does not work either
- ignore: {name: "Avoid error", within: "**.*.fromString"}

# Nor this
- ignore: {name: "Avoid error", within: "Example.Whatever.fromString"}

# Or this
- ignore: {name: "Avoid error", within: "Example.Whatever.IsString.fromString"}

# Or this
- ignore: {name: "Avoid error", within: "Example.Whatever.IsString"}

I'm assuming it's the fact that it's a class function and not a normal top-level. Is that it? Is there any way to do what I'm after here?