add PhantomData as a hdl bundle

crates/fayalite-proc-macros-impl/src/hdl_type_common.rs

@@ -1273,6 +1273,130 @@ make_parsed_type_or_const! {
     }
 }
 
+#[derive(Debug, Clone)]
+pub(crate) struct ParsedTypePhantomData {
+    pub(crate) phantom_data: known_items::PhantomData,
+    pub(crate) lt_token: Token![<],
+    pub(crate) ty: Box<ParsedType>,
+    pub(crate) gt_token: Token![>],
+}
+
+impl_fold! {
+    struct ParsedTypePhantomData<> {
+        phantom_data: known_items::PhantomData,
+        lt_token: Token![<],
+        ty: Box<ParsedType>,
+        gt_token: Token![>],
+    }
+}
+
+impl ParsedTypePhantomData {
+    pub(crate) fn try_from_named(
+        named: ParsedTypeNamed,
+        parser: &mut TypesParser<'_>,
+    ) -> Result<Result<Self, ParsedTypeNamed>, ParseFailed> {
+        let ParsedTypeNamed { path, args } = named;
+        let parsed_path = known_items::PhantomData::parse_path(path);
+        let phantom_data = match parsed_path {
+            Ok(phantom_data) => phantom_data,
+            Err(path) => return Ok(Err(ParsedTypeNamed { path, args })),
+        };
+        let Some(ParsedGenericArguments {
+            colon2_token: _,
+            lt_token,
+            args,
+            gt_token,
+        }) = args
+        else {
+            parser
+                .errors()
+                .error(phantom_data, "PhantomData requires generic arguments");
+            return Err(ParseFailed);
+        };
+        let args_len = args.len();
+        if args_len != 1 {
+            parser.errors().error(
+                phantom_data,
+                format_args!(
+                    "wrong number of generic arguments supplied: got {args_len}, expected 1"
+                ),
+            );
+            return Err(ParseFailed);
+        }
+        let ty = args.into_iter().next().unwrap();
+        let ParsedGenericArgument::Type(ty) = ty else {
+            parser.errors().error(ty, "expected a type");
+            return Err(ParseFailed);
+        };
+        Ok(Ok(Self {
+            phantom_data,
+            lt_token,
+            ty: Box::new(ty),
+            gt_token,
+        }))
+    }
+}
+
+impl From<ParsedTypePhantomData> for Type {
+    fn from(value: ParsedTypePhantomData) -> Type {
+        let ParsedTypePhantomData {
+            phantom_data,
+            lt_token,
+            ty,
+            gt_token,
+        } = value;
+        let path = phantom_data.path;
+        let mut args = Punctuated::new();
+        args.push(GenericArgument::Type(ty.into()));
+        let args = AngleBracketedGenericArguments {
+            colon2_token: Some(Token![::](lt_token.span)),
+            lt_token,
+            args,
+            gt_token,
+        };
+        let mut segments = path.segments;
+        segments.last_mut().unwrap().arguments = PathArguments::AngleBracketed(args);
+        Type::Path(TypePath {
+            qself: None,
+            path: Path {
+                leading_colon: path.leading_colon,
+                segments,
+            },
+        })
+    }
+}
+
+impl MakeHdlTypeExpr for ParsedTypePhantomData {
+    fn make_hdl_type_expr(&self, _context: &MakeHdlTypeExprContext) -> Expr {
+        let ParsedTypePhantomData {
+            phantom_data,
+            lt_token: _,
+            ty: _,
+            gt_token: _,
+        } = self;
+        Expr::Path(ExprPath {
+            attrs: vec![],
+            qself: None,
+            path: phantom_data.path.clone(),
+        })
+    }
+}
+
+impl ToTokens for ParsedTypePhantomData {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Self {
+            phantom_data,
+            lt_token,
+            ty,
+            gt_token,
+        } = self;
+        phantom_data.to_tokens(tokens);
+        lt_token.to_tokens(tokens);
+        ty.to_tokens(tokens);
+        gt_token.to_tokens(tokens);
+    }
+}
+
 #[derive(Debug, Clone)]
 pub(crate) enum ParsedType {
     Delimited(ParsedTypeDelimited),
@@ -1280,6 +1404,7 @@ pub(crate) enum ParsedType {
     NamedParam(ParsedTypeNamedParam),
     Tuple(ParsedTypeTuple),
     ConstUsize(ParsedTypeConstUsize),
+    PhantomData(ParsedTypePhantomData),
     Array(ParsedTypeArray),
     UInt(ParsedTypeUInt),
     SInt(ParsedTypeSInt),
@@ -1294,6 +1419,7 @@ impl_fold! {
         NamedParam(ParsedTypeNamedParam),
         Tuple(ParsedTypeTuple),
         ConstUsize(ParsedTypeConstUsize),
+        PhantomData(ParsedTypePhantomData),
         Array(ParsedTypeArray),
         UInt(ParsedTypeUInt),
         SInt(ParsedTypeSInt),
@@ -1310,6 +1436,7 @@ impl From<ParsedType> for Type {
             ParsedType::NamedParam(v) => v.into(),
             ParsedType::Tuple(v) => v.into(),
             ParsedType::ConstUsize(v) => v.into(),
+            ParsedType::PhantomData(v) => v.into(),
             ParsedType::Array(v) => v.into(),
             ParsedType::UInt(v) => v.into(),
             ParsedType::SInt(v) => v.into(),
@@ -1360,6 +1487,7 @@ impl ToTokens for ParsedType {
             ParsedType::Named(ty) => ty.to_tokens(tokens),
             ParsedType::Tuple(ty) => ty.to_tokens(tokens),
             ParsedType::ConstUsize(ty) => ty.to_tokens(tokens),
+            ParsedType::PhantomData(ty) => ty.to_tokens(tokens),
             ParsedType::Array(ty) => ty.to_tokens(tokens),
             ParsedType::UInt(ty) => ty.to_tokens(tokens),
             ParsedType::SInt(ty) => ty.to_tokens(tokens),
@@ -1467,6 +1595,10 @@ impl ParseTypes<Path> for ParsedType {
             Ok(v) => return Ok(Self::ConstUsize(v)),
             Err(named) => named,
         };
+        let named = match ParsedTypePhantomData::try_from_named(named, parser)? {
+            Ok(v) => return Ok(Self::PhantomData(v)),
+            Err(named) => named,
+        };
         let named = match ParsedTypeUInt::try_from_named(named, parser)? {
             Ok(v) => return Ok(Self::UInt(v)),
             Err(named) => named,
@@ -1784,7 +1916,7 @@ pub(crate) mod known_items {
 
             #[allow(non_snake_case, dead_code)]
             pub(crate) fn $known_item(span: Span) -> $known_item {
-                let segments = $known_item::PATH_SEGMENTS.iter()
+                let segments = $known_item::PATH_SEGMENTS[0].iter()
                     .copied()
                     .map(|seg| PathSegment::from(Ident::new(seg, span)))
                     .collect();
@@ -1810,21 +1942,22 @@ pub(crate) mod known_items {
                             return Ok(Self { span: ident.span(), path });
                         }
                     }
-                    if path.segments.len() == Self::PATH_SEGMENTS.len()
+                    for &path_segments in Self::PATH_SEGMENTS.iter() {
+                        if path.segments.len() == path_segments.len()
                             && path
                                 .segments
                                 .iter()
-                            .zip(Self::PATH_SEGMENTS)
+                                .zip(path_segments)
                                 .all(|(seg, expected)| {
                                     matches!(seg.arguments, PathArguments::None)
                                     && seg.ident == *expected
                                 })
                         {
-                        Ok(Self { span: path.segments.last().unwrap().ident.span(), path })
-                    } else {
-                        Err(path)
+                            return Ok(Self { span: path.segments.last().unwrap().ident.span(), path });
                         }
                     }
+                    Err(path)
+                }
                 #[allow(dead_code)]
                 pub(crate) fn parse_path_with_arguments(mut path: Path) -> Result<(Self, PathArguments), Path> {
                     let Some(last_segment) = path.segments.last_mut() else {
@@ -1878,19 +2011,24 @@ pub(crate) mod known_items {
     }
 
     macro_rules! impl_known_item {
-        ($([$(::$head:ident)*])? ::$next:ident $(::$tail:ident)+) => {
-            impl_known_item!([$($(::$head)*)? ::$next] $(::$tail)+);
-        };
-        ([$(::$seg:ident)+] ::$known_item:ident) => {
+        ($(#[alias = $(::$alias:ident)+])* [$(::$seg:ident)+] ::$known_item:ident) => {
             impl_known_item_body!($known_item);
 
             impl $known_item {
-                pub(crate) const PATH_SEGMENTS: &'static [&'static str] = &[
+                pub(crate) const PATH_SEGMENTS: &'static [&'static [&'static str]] = &[
+                    &[
                         $(stringify!($seg),)+
                         stringify!($known_item),
+                    ],
+                    $(&[
+                        $(stringify!($alias),)+
+                    ],)*
                 ];
             }
         };
+        ($(#[alias = $(::$alias:ident)+])* $([$(::$head:ident)*])? ::$next:ident $(::$tail:ident)+) => {
+            impl_known_item!($(#[alias = $(::$alias)+])* [$($(::$head)*)? ::$next] $(::$tail)+);
+        };
     }
 
     impl_known_item!(::fayalite::array::Array);
@@ -1911,7 +2049,16 @@ pub(crate) mod known_items {
     impl_known_item!(::fayalite::ty::Type);
     impl_known_item!(::fayalite::ty::Type::MaskType);
     impl_known_item!(::fayalite::util::ConstUsize);
-    impl_known_item!(::fayalite::__std::primitive::usize);
+    impl_known_item!(
+        #[alias = ::std::primitive::usize]
+        #[alias = ::core::primitive::usize]
+        ::fayalite::__std::primitive::usize
+    );
+    impl_known_item!(
+        #[alias = ::std::marker::PhantomData]
+        #[alias = ::core::marker::PhantomData]
+        ::fayalite::__std::marker::PhantomData
+    );
 }
 
 macro_rules! impl_bounds {
@@ -3969,6 +4116,7 @@ impl MakeHdlTypeExpr for ParsedType {
             Self::NamedParam(v) => v.make_hdl_type_expr(context),
             Self::Tuple(v) => v.make_hdl_type_expr(context),
             Self::ConstUsize(v) => v.make_hdl_type_expr(context),
+            Self::PhantomData(v) => v.make_hdl_type_expr(context),
             Self::Array(v) => v.make_hdl_type_expr(context),
             Self::UInt(v) => v.make_hdl_type_expr(context),
             Self::SInt(v) => v.make_hdl_type_expr(context),

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)]