1 files changed, 174 insertions, 0 deletions
diff --git a/compiler/rustc_public/src/crate_def.rs b/compiler/rustc_public/src/crate_def.rs
new file mode 100644
index 00000000000..75228135e4c
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+++ b/compiler/rustc_public/src/crate_def.rs
@@ -0,0 +1,174 @@
+//! Module that define a common trait for things that represent a crate definition,
+//! such as, a function, a trait, an enum, and any other definitions.
+
+use serde::Serialize;
+
+use crate::ty::{GenericArgs, Span, Ty};
+use crate::{AssocItems, Crate, Symbol, with};
+
+/// A unique identification number for each item accessible for the current compilation unit.
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Serialize)]
+pub struct DefId(pub(crate) usize);
+
+impl DefId {
+    /// Return fully qualified name of this definition
+    pub fn name(&self) -> Symbol {
+        with(|cx| cx.def_name(*self, false))
+    }
+
+    /// Return a trimmed name of this definition.
+    ///
+    /// This can be used to print more user friendly diagnostic messages.
+    ///
+    /// If a symbol name can only be imported from one place for a type, and as
+    /// long as it was not glob-imported anywhere in the current crate, we trim its
+    /// path and print only the name.
+    ///
+    /// For example, this function may shorten `std::vec::Vec` to just `Vec`,
+    /// as long as there is no other `Vec` importable anywhere.
+    pub fn trimmed_name(&self) -> Symbol {
+        with(|cx| cx.def_name(*self, true))
+    }
+}
+
+/// A trait for retrieving information about a particular definition.
+///
+/// Implementors must provide the implementation of `def_id` which will be used to retrieve
+/// information about a crate's definition.
+pub trait CrateDef {
+    /// Retrieve the unique identifier for the current definition.
+    fn def_id(&self) -> DefId;
+
+    /// Return the fully qualified name of the current definition.
+    ///
+    /// See [`DefId::name`] for more details
+    fn name(&self) -> Symbol {
+        self.def_id().name()
+    }
+
+    /// Return a trimmed name of this definition.
+    ///
+    /// See [`DefId::trimmed_name`] for more details
+    fn trimmed_name(&self) -> Symbol {
+        self.def_id().trimmed_name()
+    }
+
+    /// Return information about the crate where this definition is declared.
+    ///
+    /// This will return the crate number and its name.
+    fn krate(&self) -> Crate {
+        let def_id = self.def_id();
+        with(|cx| cx.krate(def_id))
+    }
+
+    /// Return the span of this definition.
+    fn span(&self) -> Span {
+        let def_id = self.def_id();
+        with(|cx| cx.span_of_an_item(def_id))
+    }
+
+    /// Return registered tool attributes with the given attribute name.
+    ///
+    /// FIXME(jdonszelmann): may panic on non-tool attributes. After more attribute work, non-tool
+    /// attributes will simply return an empty list.
+    ///
+    /// Single segmented name like `#[clippy]` is specified as `&["clippy".to_string()]`.
+    /// Multi-segmented name like `#[rustfmt::skip]` is specified as `&["rustfmt".to_string(), "skip".to_string()]`.
+    fn tool_attrs(&self, attr: &[Symbol]) -> Vec<Attribute> {
+        let def_id = self.def_id();
+        with(|cx| cx.tool_attrs(def_id, attr))
+    }
+
+    /// Return all tool attributes of this definition.
+    fn all_tool_attrs(&self) -> Vec<Attribute> {
+        let def_id = self.def_id();
+        with(|cx| cx.all_tool_attrs(def_id))
+    }
+}
+
+/// A trait that can be used to retrieve a definition's type.
+///
+/// Note that not every CrateDef has a type `Ty`. They should not implement this trait.
+pub trait CrateDefType: CrateDef {
+    /// Returns the type of this crate item.
+    fn ty(&self) -> Ty {
+        with(|cx| cx.def_ty(self.def_id()))
+    }
+
+    /// Retrieve the type of this definition by instantiating and normalizing it with `args`.
+    ///
+    /// This will panic if instantiation fails.
+    fn ty_with_args(&self, args: &GenericArgs) -> Ty {
+        with(|cx| cx.def_ty_with_args(self.def_id(), args))
+    }
+}
+
+/// A trait for retrieving all items from a definition within a crate.
+pub trait CrateDefItems: CrateDef {
+    /// Retrieve all associated items from a definition.
+    fn associated_items(&self) -> AssocItems {
+        with(|cx| cx.associated_items(self.def_id()))
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Attribute {
+    value: String,
+    span: Span,
+}
+
+impl Attribute {
+    pub fn new(value: String, span: Span) -> Attribute {
+        Attribute { value, span }
+    }
+
+    /// Get the span of this attribute.
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    /// Get the string representation of this attribute.
+    pub fn as_str(&self) -> &str {
+        &self.value
+    }
+}
+
+macro_rules! crate_def {
+    ( $(#[$attr:meta])*
+      $vis:vis $name:ident $(;)?
+    ) => {
+        $(#[$attr])*
+        #[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
+        $vis struct $name(pub DefId);
+
+        impl CrateDef for $name {
+            fn def_id(&self) -> DefId {
+                self.0
+            }
+        }
+    };
+}
+
+macro_rules! crate_def_with_ty {
+    ( $(#[$attr:meta])*
+      $vis:vis $name:ident $(;)?
+    ) => {
+        $(#[$attr])*
+        #[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
+        $vis struct $name(pub DefId);
+
+        impl CrateDef for $name {
+            fn def_id(&self) -> DefId {
+                self.0
+            }
+        }
+
+        impl CrateDefType for $name {}
+    };
+}
+
+macro_rules! impl_crate_def_items {
+    ( $name:ident $(;)? ) => {
+        impl CrateDefItems for $name {}
+    };
+}