Make Default trait derive module specific

[johanpel]

Make the use of bindgen's derive_default module-specific. Keep deriving it for anything except the CUPTI module. Fixes: #469

[gemini-code-assist]

Code Review

This pull request correctly makes derive_default a module-specific option, which resolves an issue with the cupti module. This is a good improvement. However, enabling default derivations across the board introduces a soundness issue for the _IO_FILE type, which is pulled in as a dependency for some modules. I've left a critical comment with a suggested fix to prevent bindgen from generating an incorrect Default implementation for this type.

[gemini-code-assist]

While enabling derive_default is a great improvement for ergonomics, it introduces a critical soundness issue. For the cublaslt and cusolver modules, bindgen pulls in the _IO_FILE type (also known as FILE in C) and generates a Default implementation for it.

This generated implementation zero-initializes the struct, which is unsound because a zeroed FILE struct is not guaranteed to be valid. Using a default-initialized _IO_FILE could lead to undefined behavior.

To fix this, you can instruct bindgen to not generate a Default implementation for _IO_FILE using .no_default(). I recommend making this configurable in ModuleConfig by adding a no_default_types field.

You could update ModuleConfig like this:

struct ModuleConfig {
    // ...
    /// Whether to derive Default implementations for types.
    derive_default: bool,
    /// Types to not derive `Default` for.
    no_default_types: Vec<&'static str>,
}

Then, in create_modules(), you can specify no_default_types: vec!["_IO_FILE"] for cublaslt and cusolver, and an empty vec![] for the other modules where derive_default is true.

Finally, apply this configuration in ModuleConfig::builder():

// ... in ModuleConfig::builder()
let mut builder = builder.derive_default(self.derive_default);
for ty in &self.no_default_types {
    builder = builder.no_default(*ty);
}
builder
    .derive_eq(true)
// ...

This will resolve the soundness issue while keeping the benefits of derive_default for the other types.

[chelsea0x3b]

Hi, ty for the fast pr - resolving this with #471 instead