--no-derive-debug prevents even manual Debug on enumerations

[VeaaC]

Input C/C++ Header

// lots of enums like this
/// <div rustbindgen derive="Clone"></div>
/// <div rustbindgen derive="Debug"></div>
/// <div rustbindgen derive="Copy"></div>
/// <div rustbindgen derive="PartialEq"></div>
/// <div rustbindgen derive="PartialOrd"></div>
enum NeedsDebug { VALUE };

// Lots of structs like this
typedef struct MustNotHaveDebug MustNotHaveDebug;

Bindgen Invocation

bindgen --no-derive-debug --rustified-enum input.h

Actual Results

/* automatically generated by rust-bindgen 0.59.0 */

#[repr(u32)]
#[doc = " <div rustbindgen derive=\"Clone\"></div>"]
#[doc = " <div rustbindgen derive=\"Debug\"></div>"]
#[doc = " <div rustbindgen derive=\"Copy\"></div>"]
#[doc = " <div rustbindgen derive=\"PartialEq\"></div>"]
#[doc = " <div rustbindgen derive=\"PartialOrd\"></div>"]
#[derive(Copy, Clone, Hash, PartialEq, Eq)]
pub enum NeedsDebug {
    VALUE = 0,
}
#[repr(C)]
#[derive(Copy, Clone)]
pub struct MustNotHaveDebug {
    _unused: [u8; 0],
}

Expected Results

I would expect manual overrides to overrule default settings. The main use case here is that I need Debug on all enumerations, a few structs, but not on most other types.

[emilio]

curious, does Default behave like Debug?

[VeaaC]

I realized that enumeration are not adding any derive directives from annotations at all. It is a simple change to support that, e.g.:

@@ -3003,13 +3004,16 @@ impl CodeGenerator for Enum {
                     DerivableTraits::PARTIAL_EQ |
                     DerivableTraits::EQ,
             );
+            let mut derives: Vec<_> = derives.into();
+            derives.extend(
+                item.annotations().derives().iter().map(String::as_str),
+           );
-            let derives: Vec<_> = derives.into();
             attrs.push(attributes::derives(&derives));

However, the code also talks about backwards compatibility:

            // For backwards compat, enums always derive Clone/Eq/PartialEq/Hash, even
            // if we don't generate those by default.

And it seems like Debug should have most likely also been part of the same backwards compatibility.

I could prepare a PR with a fix / implementation based on what kind of change you would prefer (supporting annotations, adding Debug always, or both).

[VeaaC]

I created two possible fixes for this: #2089 is kind of a minimal fix, restoring the previous behaviour. #2090 is a more complete fix, restoring the previous behaviour, but also adding full support for annotations on enumerations (which allows the user to opt out of Debug)