Let validation check for more unsupported builtins.

Add `valid::Capabilities` flags for the `ClipDistance` and
`CullDistance` builtins, which are not supported by all back ends.

Have the CLI perform valation with only those capabilities that the
requested back ends support.

Fixes #1961.

cli/src/main.rs

@@ -317,12 +317,23 @@ fn run() -> Result<(), Box<dyn std::error::Error>> {
  _ => return Err(CliError("Unknown input file extension").into()),
  };
 
+ // Decide which capabilities our output formats can support.
+ let validation_caps =
+ output_paths
+ .iter()
+ .fold(naga::valid::Capabilities::all(), |caps, path| {
+ use naga::valid::Capabilities as C;
+ let missing = match Path::new(path).extension().and_then(|ex| ex.to_str()) {
+ Some("wgsl") => C::CLIP_DISTANCE | C::CULL_DISTANCE,
+ Some("metal") => C::CULL_DISTANCE,
+ _ => C::empty(),
+ };
+ caps & !missing
+ });
+
  // validate the IR
- let info = match naga::valid::Validator::new(
- params.validation_flags,
- naga::valid::Capabilities::all(),
- )
- .validate(&module)
+ let info = match naga::valid::Validator::new(params.validation_flags, validation_caps)
+ .validate(&module)
  {
  Ok(info) => Some(info),
  Err(error) => {

src/valid/interface.rs

@@ -135,6 +135,16 @@ impl VaryingContext<'_> {
  }
  self.built_ins.insert(canonical);
 
+ let required = match built_in {
+ Bi::ClipDistance => Capabilities::CLIP_DISTANCE,
+ Bi::CullDistance => Capabilities::CULL_DISTANCE,
+ Bi::PrimitiveIndex => Capabilities::PRIMITIVE_INDEX,
+ _ => Capabilities::empty(),
+ };
+ if !self.capabilities.contains(required) {
+ return Err(VaryingError::UnsupportedCapability(required));
+ }
+
  let width = 4;
  let (visible, type_good) = match built_in {
  Bi::BaseInstance | Bi::BaseVertex | Bi::InstanceIndex | Bi::VertexIndex => (
@@ -206,21 +216,14 @@ impl VaryingContext<'_> {
  width: crate::BOOL_WIDTH,
  },
  ),
- Bi::PrimitiveIndex => {
- if !self.capabilities.contains(Capabilities::PRIMITIVE_INDEX) {
- return Err(VaryingError::UnsupportedCapability(
- Capabilities::PRIMITIVE_INDEX,
- ));
- }
- (
- self.stage == St::Fragment && !self.output,
- *ty_inner
- == Ti::Scalar {
- kind: Sk::Uint,
- width,
- },
- )
- }
+ Bi::PrimitiveIndex => (
+ self.stage == St::Fragment && !self.output,
+ *ty_inner
+ == Ti::Scalar {
+ kind: Sk::Uint,
+ width,
+ },
+ ),
  Bi::SampleIndex => (
  self.stage == St::Fragment && !self.output,
  *ty_inner

src/valid/mod.rs

@@ -82,18 +82,22 @@ bitflags::bitflags! {
  #[cfg_attr(feature = "serialize", derive(serde::Serialize))]
  #[cfg_attr(feature = "deserialize", derive(serde::Deserialize))]
  pub struct Capabilities: u8 {
- /// Support for `AddressSpace:PushConstant`.
+ /// Support for [`AddressSpace:PushConstant`].
  const PUSH_CONSTANT = 0x1;
  /// Float values with width = 8.
  const FLOAT64 = 0x2;
- /// Support for `Builtin:PrimitiveIndex`.
+ /// Support for [`Builtin:PrimitiveIndex`].
  const PRIMITIVE_INDEX = 0x4;
  /// Support for non-uniform indexing of sampled textures and storage buffer arrays.
  const SAMPLED_TEXTURE_AND_STORAGE_BUFFER_ARRAY_NON_UNIFORM_INDEXING = 0x8;
  /// Support for non-uniform indexing of uniform buffers and storage texture arrays.
  const UNIFORM_BUFFER_AND_STORAGE_TEXTURE_ARRAY_NON_UNIFORM_INDEXING = 0x10;
  /// Support for non-uniform indexing of samplers.
  const SAMPLER_NON_UNIFORM_INDEXING = 0x20;
+ /// Support for [`Builtin::ClipDistance`].
+ const CLIP_DISTANCE = 0x40;
+ /// Support for [`Builtin::CullDistance`].
+ const CULL_DISTANCE = 0x80;
  }
 }