Make Debug impls optional

When disabled, this buys us a 12% reduction in buildtime.

Changelog.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Device extension `khr::PipelineExecutableProperties` and `khr::TimelineSemaphore` now expose `fn device()` instead of `fn instance()` (#499)
 - Changed `khr::PipelineExecutableProperties::new()` and `khr::TimelineSemaphore::new()` to take `instance` and `device` as arguments (#499)
+- Vulkan structures only implement `Debug` if the `debug` feature is enabled (#482)
 
 ### Removed
 

ash/Cargo.toml

@@ -19,6 +19,8 @@ default = ["linked"]
 linked = []
 # Support searching for the Vulkan loader manually at runtime.
 loaded = ["libloading"]
+# Whether Vulkan structs should implement Debug
+debug = []
 
 [package.metadata.release]
 no-dev-version = true

generator/src/lib.rs

@@ -1711,6 +1711,7 @@ pub fn derive_debug(_struct: &vkxml::Struct, union_types: &HashSet<&str>) -> Opt
     });
     let name_str = name.to_string();
     let q = quote! {
+        #[cfg(feature = "debug")]
         impl fmt::Debug for #name {
             fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
                 fmt.debug_struct(#name_str)
@@ -2134,7 +2135,7 @@ pub fn generate_struct(
     let setter_tokens = derive_setters(_struct, root_structs);
     let manual_derive_tokens = manual_derives(_struct);
     let dbg_str = if debug_tokens.is_none() {
-        quote!(Debug,)
+        quote!(#[cfg_attr(feature = "debug", derive(Debug))])
     } else {
         quote!()
     };
@@ -2146,7 +2147,8 @@ pub fn generate_struct(
     let khronos_link = khronos_link(&_struct.name);
     quote! {
         #[repr(C)]
-        #[derive(Copy, Clone, #default_str #dbg_str #manual_derive_tokens)]
+        #dbg_str
+        #[derive(Copy, Clone, #default_str #manual_derive_tokens)]
         #[doc = #khronos_link]
         pub struct #name {
             #(#params,)*