1 files changed, 69 insertions, 0 deletions
diff --git a/compiler/stable_mir/src/crate_def.rs b/compiler/stable_mir/src/crate_def.rs
new file mode 100644
index 000000000..70ca9e682
--- /dev/null
+++ b/compiler/stable_mir/src/crate_def.rs
@@ -0,0 +1,69 @@
+//! 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 crate::ty::Span;
+use crate::{with, Crate, Symbol};
+
+/// A unique identification number for each item accessible for the current compilation unit.
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+pub struct DefId(pub(crate) usize);
+
+/// 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.
+    fn name(&self) -> Symbol {
+        let def_id = self.def_id();
+        with(|cx| cx.def_name(def_id, 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.
+    fn trimmed_name(&self) -> Symbol {
+        let def_id = self.def_id();
+        with(|cx| cx.def_name(def_id, true))
+    }
+
+    /// 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))
+    }
+}
+
+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
+            }
+        }
+    };
+}