Auto merge of rust-lang#14905 - Veykril:hover-hex, r=Veykril

feat: Render niches on hover

Author: bors

crates/hir/src/lib.rs

@@ -62,7 +62,7 @@ use hir_ty::{
     consteval::{try_const_usize, unknown_const_as_generic, ConstEvalError, ConstExt},
     diagnostics::BodyValidationDiagnostic,
     display::HexifiedConst,
-    layout::{Layout, LayoutError, RustcEnumVariantIdx, TagEncoding},
+    layout::{Layout as TyLayout, LayoutError, RustcEnumVariantIdx, TagEncoding},
     method_resolution::{self, TyFingerprint},
     mir::{self, interpret_mir},
     primitive::UintTy,
@@ -961,8 +961,8 @@ impl Field {
         Type::new(db, var_id, ty)
     }
 
-    pub fn layout(&self, db: &dyn HirDatabase) -> Result<Arc<Layout>, LayoutError> {
-        db.layout_of_ty(self.ty(db).ty.clone(), self.parent.module(db).krate().into())
+    pub fn layout(&self, db: &dyn HirDatabase) -> Result<Layout, LayoutError> {
+        db.layout_of_ty(self.ty(db).ty.clone(), self.parent.module(db).krate().into()).map(Layout)
     }
 
     pub fn parent_def(&self, _db: &dyn HirDatabase) -> VariantDef {
@@ -1135,10 +1135,10 @@ impl Enum {
         self.variants(db).iter().any(|v| !matches!(v.kind(db), StructKind::Unit))
     }
 
-    pub fn layout(self, db: &dyn HirDatabase) -> Result<(Arc<Layout>, usize), LayoutError> {
+    pub fn layout(self, db: &dyn HirDatabase) -> Result<(Layout, usize), LayoutError> {
         let layout = Adt::from(self).layout(db)?;
         let tag_size =
-            if let layout::Variants::Multiple { tag, tag_encoding, .. } = &layout.variants {
+            if let layout::Variants::Multiple { tag, tag_encoding, .. } = &layout.0.variants {
                 match tag_encoding {
                     TagEncoding::Direct => {
                         let target_data_layout = db
@@ -1219,11 +1219,11 @@ impl Variant {
         let parent_enum = self.parent_enum(db);
         let (parent_layout, tag_size) = parent_enum.layout(db)?;
         Ok((
-            match &parent_layout.variants {
+            match &parent_layout.0.variants {
                 layout::Variants::Multiple { variants, .. } => {
-                    variants[RustcEnumVariantIdx(self.id)].clone()
+                    Layout(Arc::new(variants[RustcEnumVariantIdx(self.id)].clone()))
                 }
-                _ => (*parent_layout).clone(),
+                _ => parent_layout,
             },
             tag_size,
         ))
@@ -1255,11 +1255,11 @@ impl Adt {
         })
     }
 
-    pub fn layout(self, db: &dyn HirDatabase) -> Result<Arc<Layout>, LayoutError> {
+    pub fn layout(self, db: &dyn HirDatabase) -> Result<Layout, LayoutError> {
         if db.generic_params(self.into()).iter().count() != 0 {
             return Err(LayoutError::HasPlaceholder);
         }
-        db.layout_of_adt(self.into(), Substitution::empty(Interner), self.krate(db).id)
+        db.layout_of_adt(self.into(), Substitution::empty(Interner), self.krate(db).id).map(Layout)
     }
 
     /// Turns this ADT into a type. Any type parameters of the ADT will be
@@ -4243,8 +4243,8 @@ impl Type {
             .collect()
     }
 
-    pub fn layout(&self, db: &dyn HirDatabase) -> Result<Arc<Layout>, LayoutError> {
-        db.layout_of_ty(self.ty.clone(), self.env.krate)
+    pub fn layout(&self, db: &dyn HirDatabase) -> Result<Layout, LayoutError> {
+        db.layout_of_ty(self.ty.clone(), self.env.krate).map(Layout)
     }
 }
 
@@ -4355,6 +4355,35 @@ fn closure_source(db: &dyn HirDatabase, closure: ClosureId) -> Option<ast::Closu
     }
 }
 
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Layout(Arc<TyLayout>);
+
+impl Layout {
+    pub fn size(&self) -> u64 {
+        self.0.size.bytes()
+    }
+
+    pub fn align(&self) -> u64 {
+        self.0.align.abi.bytes()
+    }
+
+    pub fn niches(&self, db: &dyn HirDatabase, krate: Crate) -> Option<u128> {
+        Some(self.0.largest_niche?.available(&*db.target_data_layout(krate.id)?))
+    }
+
+    pub fn field_offset(&self, idx: usize) -> Option<u64> {
+        match self.0.fields {
+            layout::FieldsShape::Primitive => None,
+            layout::FieldsShape::Union(_) => Some(0),
+            layout::FieldsShape::Array { stride, count } => {
+                let i = u64::try_from(idx).ok()?;
+                (i < count).then_some((stride * i).bytes())
+            }
+            layout::FieldsShape::Arbitrary { ref offsets, .. } => Some(offsets.get(idx)?.bytes()),
+        }
+    }
+}
+
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum BindingMode {
     Move,
@@ -4506,6 +4535,12 @@ impl HasCrate for Union {
     }
 }
 
+impl HasCrate for Enum {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
 impl HasCrate for Field {
     fn krate(&self, db: &dyn HirDatabase) -> Crate {
         self.parent_def(db).module(db).krate()

crates/ide/src/hover/render.rs

@@ -3,8 +3,8 @@ use std::fmt::Display;
 
 use either::Either;
 use hir::{
-    Adt, AsAssocItem, AttributeTemplate, CaptureKind, HasAttrs, HasSource, HirDisplay, Semantics,
-    TypeInfo,
+    Adt, AsAssocItem, AttributeTemplate, CaptureKind, HasAttrs, HasCrate, HasSource, HirDisplay,
+    Layout, Semantics, TypeInfo,
 };
 use ide_db::{
     base_db::SourceDatabase,
@@ -401,25 +401,23 @@ pub(super) fn definition(
                 hir::VariantDef::Struct(s) => Adt::from(s)
                     .layout(db)
                     .ok()
-                    .map(|layout| format!(", offset = {:#X}", layout.fields.offset(id).bytes())),
+                    .and_then(|layout| Some(format!(", offset = {:#X}", layout.field_offset(id)?))),
                 _ => None,
             };
+            let niches = niches(db, it, &layout).unwrap_or_default();
             Some(format!(
-                "size = {:#X}, align = {:#X}{}",
-                layout.size.bytes(),
-                layout.align.abi.bytes(),
+                "size = {:#X}, align = {:#X}{}{niches}",
+                layout.size(),
+                layout.align(),
                 offset.as_deref().unwrap_or_default()
             ))
         }),
         Definition::Module(it) => label_and_docs(db, it),
         Definition::Function(it) => label_and_docs(db, it),
         Definition::Adt(it) => label_and_layout_info_and_docs(db, it, config, |&it| {
             let layout = it.layout(db).ok()?;
-            Some(format!(
-                "size = {:#X}, align = {:#X}",
-                layout.size.bytes(),
-                layout.align.abi.bytes()
-            ))
+            let niches = niches(db, it, &layout).unwrap_or_default();
+            Some(format!("size = {:#X}, align = {:#X}{niches}", layout.size(), layout.align()))
         }),
         Definition::Variant(it) => label_value_and_layout_info_and_docs(
             db,
@@ -437,14 +435,15 @@ pub(super) fn definition(
                     None
                 }
             },
-            |it| {
+            |&it| {
                 let (layout, tag_size) = it.layout(db).ok()?;
-                let size = layout.size.bytes_usize() - tag_size;
+                let size = layout.size() as usize - tag_size;
                 if size == 0 {
                     // There is no value in showing layout info for fieldless variants
                     return None;
                 }
-                Some(format!("size = {:#X}", layout.size.bytes()))
+                let niches = niches(db, it, &layout).unwrap_or_default();
+                Some(format!("size = {:#X}{niches}", layout.size()))
             },
         ),
         Definition::Const(it) => label_value_and_docs(db, it, |it| {
@@ -473,11 +472,8 @@ pub(super) fn definition(
         Definition::TraitAlias(it) => label_and_docs(db, it),
         Definition::TypeAlias(it) => label_and_layout_info_and_docs(db, it, config, |&it| {
             let layout = it.ty(db).layout(db).ok()?;
-            Some(format!(
-                "size = {:#X}, align = {:#X}",
-                layout.size.bytes(),
-                layout.align.abi.bytes()
-            ))
+            let niches = niches(db, it, &layout).unwrap_or_default();
+            Some(format!("size = {:#X}, align = {:#X}{niches}", layout.size(), layout.align(),))
         }),
         Definition::BuiltinType(it) => {
             return famous_defs
@@ -513,6 +509,10 @@ pub(super) fn definition(
     markup(docs, label, mod_path)
 }
 
+fn niches(db: &RootDatabase, it: impl HasCrate, layout: &Layout) -> Option<String> {
+    Some(format!(", niches = {}", layout.niches(db, it.krate(db).into())?))
+}
+
 fn type_info(
     sema: &Semantics<'_, RootDatabase>,
     config: &HoverConfig,
@@ -560,7 +560,7 @@ fn closure_ty(
     let layout = if config.memory_layout {
         original
             .layout(sema.db)
-            .map(|x| format!(" // size = {}, align = {}", x.size.bytes(), x.align.abi.bytes()))
+            .map(|x| format!(" // size = {}, align = {}", x.size(), x.align()))
             .unwrap_or_default()
     } else {
         String::default()
@@ -771,12 +771,7 @@ fn local(db: &RootDatabase, it: hir::Local, config: &HoverConfig) -> Option<Mark
     };
     if config.memory_layout {
         if let Ok(layout) = it.ty(db).layout(db) {
-            format_to!(
-                desc,
-                " // size = {}, align = {}",
-                layout.size.bytes(),
-                layout.align.abi.bytes()
-            );
+            format_to!(desc, " // size = {}, align = {}", layout.size(), layout.align());
         }
     }
     markup(None, desc, None)

crates/ide/src/hover/tests.rs

@@ -1528,7 +1528,7 @@ fn test_hover_function_pointer_show_identifiers() {
             ```
 
             ```rust
-            type foo = fn(a: i32, b: i32) -> i32 // size = 0x8, align = 0x8
+            type foo = fn(a: i32, b: i32) -> i32 // size = 0x8, align = 0x8, niches = 1
             ```
         "#]],
     );
@@ -1546,7 +1546,7 @@ fn test_hover_function_pointer_no_identifier() {
             ```
 
             ```rust
-            type foo = fn(i32, i32) -> i32 // size = 0x8, align = 0x8
+            type foo = fn(i32, i32) -> i32 // size = 0x8, align = 0x8, niches = 1
             ```
         "#]],
     );
@@ -1904,7 +1904,7 @@ fn test_hover_layout_of_enum() {
             ```
 
             ```rust
-            enum Foo // size = 0x10, align = 0x8
+            enum Foo // size = 0x10, align = 0x8, niches = 254
             ```
         "#]],
     );