Allow specifying certain types we shouldn't derive/impl Default for

[fitzgen]

Add --no-default <regex> and Builder::no_default(String) to supply regexes for matching against types that we should not derive or implement Default for.

Adding this feature involves:

• Adding a new RegexSet member to bindgen::Builder (similar to the whitelisted_types set).

• A Builder method to add strings to that RegexSet.

• Plumbing in src/options.rs to convert --no-default <regex> CLI flags into invocations of the builder method.

• Making the MonotoneFramework::constrain function in src/ir/analysis/derive_default.rs check if the given item is explicitly marked not to be Default, and if so, inserting it into the self.cannot_derive_default set via return self.insert(id).

• Tests!

  • When the no-default type is transitively referenced by a whitelisted item

  • When the no-default type is explicitly whitelisted

  • When the no-default type is marked opaque

[GyrosOfWar]

Hi! I'd like to do this.

@highfive: assign me

[highfive]

Hey @GyrosOfWar! Thanks for your interest in working on this issue. It's now assigned to you!

[fitzgen]

@GyrosOfWar let me know if you have any questions :)

This should be pretty similar to the --no-partialeq PR that just landed, so you can take a look at that for guidance: #996

[GyrosOfWar]

Yeah, I've found that one already. Should be pretty straightforward. I've joined the Gitter room, so I'll ask there if I need anything.

[pvdrz]

Already implemented