Expanded RegEx Support?

@pvdrz
Following on the heels of #2328 ... I've changed to start using the new option and it's working great but I ran into a snag...

Some of the older c libs that I'm using have structs that don't always follow proper naming patterns.
Rather than having to exclude them from the bindgen, I'd like to just filter them from having a derive applied to them.

Here's a sample of the RegEx I was trying to use:
https://regex101.com/r/pjeUkB/1

Basically, If the struct starts with "My" and doesn't contain Foo in it, then apply the derive.
This doesn't seem to work, and seems to silently ignore the regex. Am I doing this wrong?

--with-derive-custom-struct '^My((?!Foo).)+$'=MyStructTrait

This doesn't seem to match anything. I have verified that this does though:

--with-derive-custom-struct '^My.+$'=MyStructTrait

But it matches the ones I don't want as well.
Does the regex impl in use not support lookahead or negative lookahead?

I would have expected the regex compile to fail or something.

Bindgen Invocation

--with-derive-custom-struct '^My((?!Foo).)+$'=MyStructTrait

Actual Results

No structs are labeled with a MyStructTrait derive.

Expected Results

I expect to see:

#[derive(MyStructTrait)]
struct MyStruct {}

struct MyFoo {}

Reproduce the bindgen invocation from the issue with the two shown regular expressions and compare the generated derives against the expected MyStruct and MyFoo results. Investigate the regular-expression handling used by the --with-derive-custom-struct option, then add coverage for the reported lookahead behavior and confirm the intended result.