Support fetching `Attribute` of items.

5 files changed, 54 insertions, 2 deletions

diff --git a/compiler/rustc_smir/Cargo.toml b/compiler/rustc_smir/Cargo.toml
index 1e0a60bc371..1230667ee91 100644
--- a/compiler/rustc_smir/Cargo.toml
+++ b/compiler/rustc_smir/Cargo.toml
@@ -6,6 +6,8 @@ edition = "2021"
 [dependencies]
 # tidy-alphabetical-start
 rustc_abi = { path = "../rustc_abi" }
+rustc_ast = { path = "../rustc_ast" }
+rustc_ast_pretty = { path = "../rustc_ast_pretty" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_middle = { path = "../rustc_middle" }
diff --git a/compiler/rustc_smir/src/rustc_smir/context.rs b/compiler/rustc_smir/src/rustc_smir/context.rs
index dde5e30c3d0..0e50241fce7 100644
--- a/compiler/rustc_smir/src/rustc_smir/context.rs
+++ b/compiler/rustc_smir/src/rustc_smir/context.rs
@@ -228,6 +228,25 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
         }
     }
 
+    fn get_attrs_by_path(
+        &self,
+        def_id: stable_mir::DefId,
+        attr: &[stable_mir::Symbol],
+    ) -> Vec<stable_mir::ty::Attribute> {
+        let mut tables = self.0.borrow_mut();
+        let tcx = tables.tcx;
+        let did = tables[def_id];
+        let attr_name: Vec<_> =
+            attr.iter().map(|seg| rustc_span::symbol::Symbol::intern(&seg)).collect();
+        tcx.get_attrs_by_path(did, &attr_name)
+            .map(|attribute| {
+                let attr_str = rustc_ast_pretty::pprust::attribute_to_string(attribute);
+                let span = attribute.span;
+                stable_mir::ty::Attribute::new(attr_str, span.stable(&mut *tables))
+            })
+            .collect()
+    }
+
     fn span_to_string(&self, span: stable_mir::ty::Span) -> String {
         let tables = self.0.borrow();
         tables.tcx.sess.source_map().span_to_diagnostic_string(tables[span])
diff --git a/compiler/stable_mir/src/compiler_interface.rs b/compiler/stable_mir/src/compiler_interface.rs
index 44dbf549c1a..a8f2cd7bcc3 100644
--- a/compiler/stable_mir/src/compiler_interface.rs
+++ b/compiler/stable_mir/src/compiler_interface.rs
@@ -11,7 +11,7 @@ use crate::mir::mono::{Instance, InstanceDef, StaticDef};
 use crate::mir::{BinOp, Body, Place, UnOp};
 use crate::target::MachineInfo;
 use crate::ty::{
-    AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, FieldDef, FnDef, ForeignDef,
+    AdtDef, AdtKind, Allocation, Attribute, ClosureDef, ClosureKind, FieldDef, FnDef, ForeignDef,
     ForeignItemKind, ForeignModule, ForeignModuleDef, GenericArgs, GenericPredicates, Generics,
     ImplDef, ImplTrait, IntrinsicDef, LineInfo, MirConst, PolyFnSig, RigidTy, Span, TraitDecl,
     TraitDef, Ty, TyConst, TyConstId, TyKind, UintTy, VariantDef,
@@ -55,6 +55,9 @@ pub trait Context {
     /// Returns the name of given `DefId`
     fn def_name(&self, def_id: DefId, trimmed: bool) -> Symbol;
 
+    /// Get all attributes with the given attribute name.
+    fn get_attrs_by_path(&self, def_id: DefId, attr: &[Symbol]) -> Vec<Attribute>;
+
     /// Returns printable, human readable form of `Span`
     fn span_to_string(&self, span: Span) -> String;
 
diff --git a/compiler/stable_mir/src/crate_def.rs b/compiler/stable_mir/src/crate_def.rs
index 67752a5e629..ee6214a47cf 100644
--- a/compiler/stable_mir/src/crate_def.rs
+++ b/compiler/stable_mir/src/crate_def.rs
@@ -1,7 +1,7 @@
 //! 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::{GenericArgs, Span, Ty};
+use crate::ty::{Attribute, GenericArgs, Span, Ty};
 use crate::{with, Crate, Symbol};
 
 /// A unique identification number for each item accessible for the current compilation unit.
@@ -50,6 +50,12 @@ pub trait CrateDef {
         let def_id = self.def_id();
         with(|cx| cx.span_of_an_item(def_id))
     }
+
+    /// Return attributes with the given attribute name.
+    fn attrs_by_path(&self, attr: &[Symbol]) -> Vec<Attribute> {
+        let def_id = self.def_id();
+        with(|cx| cx.get_attrs_by_path(def_id, attr))
+    }
 }
 
 /// A trait that can be used to retrieve a definition's type.
diff --git a/compiler/stable_mir/src/ty.rs b/compiler/stable_mir/src/ty.rs
index 01e4f1d1f33..46c163e5bf1 100644
--- a/compiler/stable_mir/src/ty.rs
+++ b/compiler/stable_mir/src/ty.rs
@@ -248,6 +248,28 @@ pub struct Placeholder<T> {
     pub bound: T,
 }
 
+#[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
+    }
+}
+
 #[derive(Clone, Copy, PartialEq, Eq)]
 pub struct Span(usize);