Rollup merge of #140863 - GuillaumeGomez:cleanup-tyalias-render, r=lolbinarycat

[rustdoc] Unify type aliases rendering with other ADT

Fixes #140739.

Better reviewed one commit at a time.

Just one thing I'm wondering: should we also render non-`repr` attributes? If so, I wonder if we shouldn't simply change `clean::TypeAlias` to contain the other ADT directly (`Struct`, `Enum` and `Union`) and remove the `TypeAlias::generics` field.

Can be done in a follow-up too.

cc ``@camelid``
r? ``@notriddle``

Author: jhpratt

src/librustdoc/clean/types.rs

@@ -610,6 +610,9 @@ impl Item {
             UnionItem(ref union_) => Some(union_.has_stripped_entries()),
             EnumItem(ref enum_) => Some(enum_.has_stripped_entries()),
             VariantItem(ref v) => v.has_stripped_entries(),
+            TypeAliasItem(ref type_alias) => {
+                type_alias.inner_type.as_ref().and_then(|t| t.has_stripped_entries())
+            }
             _ => None,
         }
     }
@@ -761,14 +764,11 @@ impl Item {
         Some(tcx.visibility(def_id))
     }
 
-    pub(crate) fn attributes(&self, tcx: TyCtxt<'_>, cache: &Cache, is_json: bool) -> Vec<String> {
+    pub(crate) fn attributes_without_repr(&self, tcx: TyCtxt<'_>, is_json: bool) -> Vec<String> {
         const ALLOWED_ATTRIBUTES: &[Symbol] =
             &[sym::export_name, sym::link_section, sym::no_mangle, sym::non_exhaustive];
 
-        use rustc_abi::IntegerType;
-
-        let mut attrs: Vec<String> = self
-            .attrs
+        self.attrs
             .other_attrs
             .iter()
             .filter_map(|attr| {
@@ -796,74 +796,28 @@ impl Item {
                     None
                 }
             })
-            .collect();
+            .collect()
+    }
 
-        // Add #[repr(...)]
-        if let Some(def_id) = self.def_id()
-            && let ItemType::Struct | ItemType::Enum | ItemType::Union = self.type_()
-        {
-            let adt = tcx.adt_def(def_id);
-            let repr = adt.repr();
-            let mut out = Vec::new();
-            if repr.c() {
-                out.push("C");
-            }
-            if repr.transparent() {
-                // Render `repr(transparent)` iff the non-1-ZST field is public or at least one
-                // field is public in case all fields are 1-ZST fields.
-                let render_transparent = is_json
-                    || cache.document_private
-                    || adt
-                        .all_fields()
-                        .find(|field| {
-                            let ty =
-                                field.ty(tcx, ty::GenericArgs::identity_for_item(tcx, field.did));
-                            tcx.layout_of(
-                                ty::TypingEnv::post_analysis(tcx, field.did).as_query_input(ty),
-                            )
-                            .is_ok_and(|layout| !layout.is_1zst())
-                        })
-                        .map_or_else(
-                            || adt.all_fields().any(|field| field.vis.is_public()),
-                            |field| field.vis.is_public(),
-                        );
+    pub(crate) fn attributes_and_repr(
+        &self,
+        tcx: TyCtxt<'_>,
+        cache: &Cache,
+        is_json: bool,
+    ) -> Vec<String> {
+        let mut attrs = self.attributes_without_repr(tcx, is_json);
 
-                if render_transparent {
-                    out.push("transparent");
-                }
-            }
-            if repr.simd() {
-                out.push("simd");
-            }
-            let pack_s;
-            if let Some(pack) = repr.pack {
-                pack_s = format!("packed({})", pack.bytes());
-                out.push(&pack_s);
-            }
-            let align_s;
-            if let Some(align) = repr.align {
-                align_s = format!("align({})", align.bytes());
-                out.push(&align_s);
-            }
-            let int_s;
-            if let Some(int) = repr.int {
-                int_s = match int {
-                    IntegerType::Pointer(is_signed) => {
-                        format!("{}size", if is_signed { 'i' } else { 'u' })
-                    }
-                    IntegerType::Fixed(size, is_signed) => {
-                        format!("{}{}", if is_signed { 'i' } else { 'u' }, size.size().bytes() * 8)
-                    }
-                };
-                out.push(&int_s);
-            }
-            if !out.is_empty() {
-                attrs.push(format!("#[repr({})]", out.join(", ")));
-            }
+        if let Some(repr_attr) = self.repr(tcx, cache, is_json) {
+            attrs.push(repr_attr);
         }
         attrs
     }
 
+    /// Returns a stringified `#[repr(...)]` attribute.
+    pub(crate) fn repr(&self, tcx: TyCtxt<'_>, cache: &Cache, is_json: bool) -> Option<String> {
+        repr_attributes(tcx, cache, self.def_id()?, self.type_(), is_json)
+    }
+
     pub fn is_doc_hidden(&self) -> bool {
         self.attrs.is_doc_hidden()
     }
@@ -873,6 +827,73 @@ impl Item {
     }
 }
 
+pub(crate) fn repr_attributes(
+    tcx: TyCtxt<'_>,
+    cache: &Cache,
+    def_id: DefId,
+    item_type: ItemType,
+    is_json: bool,
+) -> Option<String> {
+    use rustc_abi::IntegerType;
+
+    if !matches!(item_type, ItemType::Struct | ItemType::Enum | ItemType::Union) {
+        return None;
+    }
+    let adt = tcx.adt_def(def_id);
+    let repr = adt.repr();
+    let mut out = Vec::new();
+    if repr.c() {
+        out.push("C");
+    }
+    if repr.transparent() {
+        // Render `repr(transparent)` iff the non-1-ZST field is public or at least one
+        // field is public in case all fields are 1-ZST fields.
+        let render_transparent = cache.document_private
+            || is_json
+            || adt
+                .all_fields()
+                .find(|field| {
+                    let ty = field.ty(tcx, ty::GenericArgs::identity_for_item(tcx, field.did));
+                    tcx.layout_of(ty::TypingEnv::post_analysis(tcx, field.did).as_query_input(ty))
+                        .is_ok_and(|layout| !layout.is_1zst())
+                })
+                .map_or_else(
+                    || adt.all_fields().any(|field| field.vis.is_public()),
+                    |field| field.vis.is_public(),
+                );
+
+        if render_transparent {
+            out.push("transparent");
+        }
+    }
+    if repr.simd() {
+        out.push("simd");
+    }
+    let pack_s;
+    if let Some(pack) = repr.pack {
+        pack_s = format!("packed({})", pack.bytes());
+        out.push(&pack_s);
+    }
+    let align_s;
+    if let Some(align) = repr.align {
+        align_s = format!("align({})", align.bytes());
+        out.push(&align_s);
+    }
+    let int_s;
+    if let Some(int) = repr.int {
+        int_s = match int {
+            IntegerType::Pointer(is_signed) => {
+                format!("{}size", if is_signed { 'i' } else { 'u' })
+            }
+            IntegerType::Fixed(size, is_signed) => {
+                format!("{}{}", if is_signed { 'i' } else { 'u' }, size.size().bytes() * 8)
+            }
+        };
+        out.push(&int_s);
+    }
+    if !out.is_empty() { Some(format!("#[repr({})]", out.join(", "))) } else { None }
+}
+
 #[derive(Clone, Debug)]
 pub(crate) enum ItemKind {
     ExternCrateItem {
@@ -2107,7 +2128,7 @@ impl Enum {
         self.variants.iter().any(|f| f.is_stripped())
     }
 
-    pub(crate) fn variants(&self) -> impl Iterator<Item = &Item> {
+    pub(crate) fn non_stripped_variants(&self) -> impl Iterator<Item = &Item> {
         self.variants.iter().filter(|v| !v.is_stripped())
     }
 }
@@ -2345,6 +2366,17 @@ pub(crate) enum TypeAliasInnerType {
     Struct { ctor_kind: Option<CtorKind>, fields: Vec<Item> },
 }
 
+impl TypeAliasInnerType {
+    fn has_stripped_entries(&self) -> Option<bool> {
+        Some(match self {
+            Self::Enum { variants, .. } => variants.iter().any(|v| v.is_stripped()),
+            Self::Union { fields } | Self::Struct { fields, .. } => {
+                fields.iter().any(|f| f.is_stripped())
+            }
+        })
+    }
+}
+
 #[derive(Clone, Debug)]
 pub(crate) struct TypeAlias {
     pub(crate) type_: Type,

src/librustdoc/html/render/mod.rs

@@ -1194,18 +1194,36 @@ fn render_assoc_item(
 // a whitespace prefix and newline.
 fn render_attributes_in_pre(it: &clean::Item, prefix: &str, cx: &Context<'_>) -> impl fmt::Display {
     fmt::from_fn(move |f| {
-        for a in it.attributes(cx.tcx(), cx.cache(), false) {
+        for a in it.attributes_and_repr(cx.tcx(), cx.cache(), false) {
             writeln!(f, "{prefix}{a}")?;
         }
         Ok(())
     })
 }
 
+struct CodeAttribute(String);
+
+fn render_code_attribute(code_attr: CodeAttribute, w: &mut impl fmt::Write) {
+    write!(w, "<div class=\"code-attribute\">{}</div>", code_attr.0).unwrap();
+}
+
 // When an attribute is rendered inside a <code> tag, it is formatted using
 // a div to produce a newline after it.
 fn render_attributes_in_code(w: &mut impl fmt::Write, it: &clean::Item, cx: &Context<'_>) {
-    for attr in it.attributes(cx.tcx(), cx.cache(), false) {
-        write!(w, "<div class=\"code-attribute\">{attr}</div>").unwrap();
+    for attr in it.attributes_and_repr(cx.tcx(), cx.cache(), false) {
+        render_code_attribute(CodeAttribute(attr), w);
+    }
+}
+
+/// used for type aliases to only render their `repr` attribute.
+fn render_repr_attributes_in_code(
+    w: &mut impl fmt::Write,
+    cx: &Context<'_>,
+    def_id: DefId,
+    item_type: ItemType,
+) {
+    if let Some(repr) = clean::repr_attributes(cx.tcx(), cx.cache(), def_id, item_type, false) {
+        render_code_attribute(CodeAttribute(repr), w);
     }
 }