generator: Use "Backwards-compatible" comment to omit deprecated aliases

vk.xml now contains the comment text "Backwards-compatible alias
containing a typo" which we can use to detect intentional renames,
without needing to specify explicit overrides/exceptions in the
generator anymore.

These deprecated constants exist for the sole reason of backwards
compatibility which Vulkan cannot permit itself to remove in the C
headers, but are unreasonable for crate authors to use anyway due to
their `#[deprecated]` annotation whose cargo-check warnings are easy to
fix by just using the non-deprecated variant instead.  Furthermore, Ash
is still allowing itself to perform breaking changes in its releases
making this the perfect time to get rid of all these useless variants
and the generator support code that comes with it.  No need to come up
with a "more proper" variant name if we don't generate those that
"intentionally" fail to adhere to the "enum variant name" specification
in the first place.

ash/src/vk/bitflags.rs

@@ -498,8 +498,6 @@ impl StencilFaceFlags {
     pub const BACK: Self = Self(0b10);
     #[doc = "Front and back faces"]
     pub const FRONT_AND_BACK: Self = Self(0x0000_0003);
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const STENCIL_FRONT_AND_BACK: Self = Self::FRONT_AND_BACK;
 }
 #[repr(transparent)]
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]

ash/src/vk/enums.rs

@@ -1090,8 +1090,6 @@ impl ColorSpaceKHR {
 }
 impl ColorSpaceKHR {
     pub const SRGB_NONLINEAR: Self = Self(0);
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const COLORSPACE_SRGB_NONLINEAR: Self = Self::SRGB_NONLINEAR;
 }
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 #[repr(transparent)]
@@ -1153,13 +1151,9 @@ impl DebugReportObjectTypeEXT {
     pub const SURFACE_KHR: Self = Self(26);
     pub const SWAPCHAIN_KHR: Self = Self(27);
     pub const DEBUG_REPORT_CALLBACK_EXT: Self = Self(28);
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const DEBUG_REPORT: Self = Self::DEBUG_REPORT_CALLBACK_EXT;
     pub const DISPLAY_KHR: Self = Self(29);
     pub const DISPLAY_MODE_KHR: Self = Self(30);
     pub const VALIDATION_CACHE_EXT: Self = Self(33);
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const VALIDATION_CACHE: Self = Self::VALIDATION_CACHE_EXT;
 }
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 #[repr(transparent)]
@@ -1957,12 +1951,6 @@ impl PerformanceCounterScopeKHR {
     pub const COMMAND_BUFFER: Self = Self(0);
     pub const RENDER_PASS: Self = Self(1);
     pub const COMMAND: Self = Self(2);
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const QUERY_SCOPE_COMMAND_BUFFER: Self = Self::COMMAND_BUFFER;
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const QUERY_SCOPE_RENDER_PASS: Self = Self::RENDER_PASS;
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const QUERY_SCOPE_COMMAND: Self = Self::COMMAND;
 }
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
 #[repr(transparent)]

ash/src/vk/extensions.rs

@@ -1972,11 +1972,6 @@ impl StructureType {
     pub const DEBUG_REPORT_CALLBACK_CREATE_INFO_EXT: Self = Self(1_000_011_000);
 }
 #[doc = "Generated from 'VK_EXT_debug_report'"]
-impl StructureType {
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const DEBUG_REPORT_CREATE_INFO_EXT: Self = Self::DEBUG_REPORT_CALLBACK_CREATE_INFO_EXT;
-}
-#[doc = "Generated from 'VK_EXT_debug_report'"]
 impl Result {
     pub const ERROR_VALIDATION_FAILED_EXT: Self = Self(-1_000_011_001);
 }
@@ -4479,12 +4474,6 @@ impl PipelineCreateFlags {
         Self(0b10_0000_0000_0000_0000_0000);
 }
 #[doc = "Generated from 'VK_KHR_dynamic_rendering'"]
-impl PipelineCreateFlags {
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const RASTERIZATION_STATE_FRAGMENT_SHADING_RATE_ATTACHMENT_KHR: Self =
-        Self::RENDERING_FRAGMENT_SHADING_RATE_ATTACHMENT_KHR;
-}
-#[doc = "Generated from 'VK_KHR_dynamic_rendering'"]
 impl StructureType {
     pub const RENDERING_FRAGMENT_SHADING_RATE_ATTACHMENT_INFO_KHR: Self = Self(1_000_044_006);
 }
@@ -4494,12 +4483,6 @@ impl PipelineCreateFlags {
         Self(0b100_0000_0000_0000_0000_0000);
 }
 #[doc = "Generated from 'VK_KHR_dynamic_rendering'"]
-impl PipelineCreateFlags {
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const RASTERIZATION_STATE_FRAGMENT_DENSITY_MAP_ATTACHMENT_EXT: Self =
-        Self::RENDERING_FRAGMENT_DENSITY_MAP_ATTACHMENT_EXT;
-}
-#[doc = "Generated from 'VK_KHR_dynamic_rendering'"]
 impl StructureType {
     pub const RENDERING_FRAGMENT_DENSITY_MAP_ATTACHMENT_INFO_EXT: Self = Self(1_000_044_007);
 }
@@ -7691,11 +7674,6 @@ impl ExtDisplaySurfaceCounterFn {
 impl StructureType {
     pub const SURFACE_CAPABILITIES_2_EXT: Self = Self(1_000_090_000);
 }
-#[doc = "Generated from 'VK_EXT_display_surface_counter'"]
-impl StructureType {
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const SURFACE_CAPABILITIES2_EXT: Self = Self::SURFACE_CAPABILITIES_2_EXT;
-}
 impl ExtDisplayControlFn {
     pub fn name() -> &'static ::std::ffi::CStr {
         ::std::ffi::CStr::from_bytes_with_nul(b"VK_EXT_display_control\0")
@@ -8359,11 +8337,6 @@ impl ColorSpaceKHR {
 impl ColorSpaceKHR {
     pub const EXTENDED_SRGB_NONLINEAR_EXT: Self = Self(1_000_104_014);
 }
-#[doc = "Generated from 'VK_EXT_swapchain_colorspace'"]
-impl ColorSpaceKHR {
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const DCI_P3_LINEAR_EXT: Self = Self::DISPLAY_P3_LINEAR_EXT;
-}
 impl ExtHdrMetadataFn {
     pub fn name() -> &'static ::std::ffi::CStr {
         ::std::ffi::CStr::from_bytes_with_nul(b"VK_EXT_hdr_metadata\0")
@@ -16898,12 +16871,6 @@ impl StructureType {
     pub const QUERY_POOL_PERFORMANCE_QUERY_CREATE_INFO_INTEL: Self = Self(1_000_210_000);
 }
 #[doc = "Generated from 'VK_INTEL_performance_query'"]
-impl StructureType {
-    #[deprecated = "Backwards-compatible alias containing a typo"]
-    pub const QUERY_POOL_CREATE_INFO_INTEL: Self =
-        Self::QUERY_POOL_PERFORMANCE_QUERY_CREATE_INFO_INTEL;
-}
-#[doc = "Generated from 'VK_INTEL_performance_query'"]
 impl StructureType {
     pub const INITIALIZE_PERFORMANCE_API_INFO_INTEL: Self = Self(1_000_210_001);
 }

generator/src/lib.rs

@@ -18,6 +18,8 @@ use std::hash::BuildHasher;
 use std::path::Path;
 use syn::Ident;
 
+const BACKWARDS_COMPATIBLE_ALIAS_COMMENT: &str = "Backwards-compatible alias containing a typo";
+
 pub trait ExtensionExt {}
 #[derive(Copy, Clone, Debug)]
 pub enum CType {
@@ -360,8 +362,13 @@ pub trait ConstantExt {
         false
     }
     fn doc_attribute(&self) -> TokenStream {
+        assert_ne!(
+            self.notation(),
+            Some(BACKWARDS_COMPATIBLE_ALIAS_COMMENT),
+            "Backwards-compatible constants should not be emitted"
+        );
         match self.notation() {
-            Some(n) if n.starts_with("Backwards") || n.starts_with("Alias") => {
+            Some(n) if n.starts_with("Alias") => {
                 quote!(#[deprecated = #n])
             }
             Some(n) => quote!(#[doc = #n]),
@@ -384,7 +391,7 @@ impl ConstantExt for vkxml::ExtensionEnum {
 
 impl ConstantExt for vk_parse::Enum {
     fn constant(&self, enum_name: &str) -> Constant {
-        Constant::from_vk_parse_enum_spec(&self.spec, Some(enum_name), None)
+        Constant::from_vk_parse_enum(self, Some(enum_name), None)
             .unwrap()
             .0
     }
@@ -517,14 +524,14 @@ impl Constant {
     }
 
     /// Returns (Constant, optional base type, is_alias)
-    pub fn from_vk_parse_enum_spec(
-        spec: &vk_parse::EnumSpec,
+    pub fn from_vk_parse_enum(
+        enum_: &vk_parse::Enum,
         enum_name: Option<&str>,
         extension_number: Option<i64>,
     ) -> Option<(Self, Option<String>, bool)> {
         use vk_parse::EnumSpec;
 
-        match spec {
+        match &enum_.spec {
             EnumSpec::Bitpos { bitpos, extends } => {
                 Some((Self::BitPos(*bitpos as u32), extends.clone(), false))
             }
@@ -1107,8 +1114,12 @@ pub fn generate_extension_constants<'a>(
                 return None;
             }
 
+            if enum_.comment.as_deref() == Some(BACKWARDS_COMPATIBLE_ALIAS_COMMENT) {
+                return None;
+            }
+
             let (constant, extends, is_alias) =
-                Constant::from_vk_parse_enum_spec(&enum_.spec, None, Some(extension_number))?;
+                Constant::from_vk_parse_enum(enum_, None, Some(extension_number))?;
             let extends = extends?;
             let ext_constant = ExtensionConstant {
                 name: &enum_.name,
@@ -1353,19 +1364,6 @@ pub enum EnumType {
     Enum(TokenStream),
 }
 
-fn is_enum_variant_with_typo(variant_name: &str) -> bool {
-    // All these names are aliases and make little sense in our
-    // enum structure, they are better omitted entirely.
-    matches!(
-        variant_name,
-        "VK_STENCIL_FRONT_AND_BACK"
-            | "VK_COLORSPACE_SRGB_NONLINEAR"
-            | "VK_QUERY_SCOPE_COMMAND_BUFFER"
-            | "VK_QUERY_SCOPE_RENDER_PASS"
-            | "VK_QUERY_SCOPE_COMMAND"
-    )
-}
-
 static TRAILING_NUMBER: Lazy<Regex> = Lazy::new(|| Regex::new("(\\d+)$").unwrap());
 
 pub fn variant_ident(enum_name: &str, variant_name: &str) -> Ident {
@@ -1392,16 +1390,8 @@ pub fn variant_ident(enum_name: &str, variant_name: &str) -> Ident {
     let new_variant_name = variant_name
         .strip_prefix(struct_name.as_ref())
         .unwrap_or_else(|| {
-            if enum_name == "VkResult" || is_enum_variant_with_typo(variant_name) {
+            if enum_name == "VkResult" {
                 variant_name.strip_prefix("VK").unwrap()
-            } else if variant_name
-                == "VK_PIPELINE_RASTERIZATION_STATE_CREATE_FRAGMENT_SHADING_RATE_ATTACHMENT_BIT_KHR"
-            {
-                "_RASTERIZATION_STATE_FRAGMENT_SHADING_RATE_ATTACHMENT_BIT_KHR"
-            } else if variant_name
-                == "VK_PIPELINE_RASTERIZATION_STATE_CREATE_FRAGMENT_DENSITY_MAP_ATTACHMENT_BIT_EXT"
-            {
-                "_RASTERIZATION_STATE_FRAGMENT_DENSITY_MAP_ATTACHMENT_BIT_EXT"
             } else {
                 panic!(
                     "Failed to strip {} prefix from enum variant {}",
@@ -1434,6 +1424,7 @@ pub fn bitflags_impl_block(
 ) -> TokenStream {
     let variants = constants
         .iter()
+        .filter(|constant| constant.notation() != Some(BACKWARDS_COMPATIBLE_ALIAS_COMMENT))
         .map(|constant| {
             let variant_ident = constant.variant_ident(enum_name);
             let constant = constant.constant(enum_name);
@@ -1482,6 +1473,7 @@ pub fn generate_enum<'a>(
             vk_parse::EnumsChild::Enum(ref constant) => Some(constant),
             _ => None,
         })
+        .filter(|constant| constant.notation() != Some(BACKWARDS_COMPATIBLE_ALIAS_COMMENT))
         .filter(|constant| match &constant.spec {
             vk_parse::EnumSpec::Alias { alias, .. } => {
                 // Remove any alias whose name is identical after name de-mangling. For example