add PhantomData as a hdl bundle

crates/fayalite/src/bundle.rs

@@ -446,3 +446,85 @@ impl_tuples! {
         {#[num = 11, field = field_11] v11: T11}
     ]
 }
+
+impl<T: ?Sized + Send + Sync + 'static> Type for PhantomData<T> {
+    type BaseType = Bundle;
+    type MaskType = ();
+    type MatchVariant = PhantomData<T>;
+    type MatchActiveScope = ();
+    type MatchVariantAndInactiveScope = MatchVariantWithoutScope<Self::MatchVariant>;
+    type MatchVariantsIter = std::iter::Once<Self::MatchVariantAndInactiveScope>;
+    fn match_variants(
+        this: Expr<Self>,
+        source_location: SourceLocation,
+    ) -> Self::MatchVariantsIter {
+        let _ = this;
+        let _ = source_location;
+        std::iter::once(MatchVariantWithoutScope(PhantomData))
+    }
+    fn mask_type(&self) -> Self::MaskType {
+        ()
+    }
+    fn canonical(&self) -> CanonicalType {
+        Bundle::new(self.fields()).canonical()
+    }
+    #[track_caller]
+    fn from_canonical(canonical_type: CanonicalType) -> Self {
+        let CanonicalType::Bundle(bundle) = canonical_type else {
+            panic!("expected bundle");
+        };
+        assert!(
+            bundle.fields().is_empty(),
+            "bundle has wrong number of fields"
+        );
+        PhantomData
+    }
+    fn source_location() -> SourceLocation {
+        SourceLocation::builtin()
+    }
+}
+
+pub struct PhantomDataBuilder<T: ?Sized + Send + Sync + 'static>(PhantomData<T>);
+
+impl<T: ?Sized + Send + Sync + 'static> Default for PhantomDataBuilder<T> {
+    fn default() -> Self {
+        Self(PhantomData)
+    }
+}
+
+impl<T: ?Sized + Send + Sync + 'static> ToExpr for PhantomDataBuilder<T> {
+    type Type = PhantomData<T>;
+
+    fn to_expr(&self) -> Expr<Self::Type> {
+        PhantomData.to_expr()
+    }
+}
+
+impl<T: ?Sized + Send + Sync + 'static> BundleType for PhantomData<T> {
+    type Builder = PhantomDataBuilder<T>;
+    type FilledBuilder = PhantomDataBuilder<T>;
+    fn fields(&self) -> Interned<[BundleField]> {
+        Interned::default()
+    }
+}
+
+impl<T: ?Sized + Send + Sync + 'static> TypeWithDeref for PhantomData<T> {
+    fn expr_deref(_this: &Expr<Self>) -> &Self::MatchVariant {
+        &PhantomData
+    }
+}
+
+impl<T: ?Sized + Send + Sync + 'static> StaticType for PhantomData<T> {
+    const TYPE: Self = PhantomData;
+    const MASK_TYPE: Self::MaskType = ();
+    const TYPE_PROPERTIES: TypeProperties = <()>::TYPE_PROPERTIES;
+    const MASK_TYPE_PROPERTIES: TypeProperties = <()>::TYPE_PROPERTIES;
+}
+
+impl<T: ?Sized + Send + Sync + 'static> ToExpr for PhantomData<T> {
+    type Type = PhantomData<T>;
+
+    fn to_expr(&self) -> Expr<Self::Type> {
+        BundleLiteral::new(PhantomData, Interned::default()).to_expr()
+    }
+}

crates/fayalite/tests/hdl_types.rs

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: LGPL-3.0-or-later
 // See Notices.txt for copyright information
 use fayalite::prelude::*;
+use std::marker::PhantomData;
 
 #[hdl(outline_generated)]
 pub struct S<T, Len: Size, T2> {
@@ -8,6 +9,8 @@ pub struct S<T, Len: Size, T2> {
     b: UInt<3>,
     pub(crate) c: ArrayType<UInt<1>, Len>,
     pub d: T2,
+    pub e: PhantomData<T>,
+    pub f: PhantomData<Len>,
 }
 
 #[hdl(outline_generated)]