rust-lang · bors · Jun 12, 2025 · May 20, 2025 · Jun 2, 2025
diff --git a/compiler/rustc_smir/src/stable_mir/ty.rs b/compiler/rustc_smir/src/stable_mir/ty.rs
@@ -742,6 +742,14 @@ crate_def! {
     pub ClosureDef;
 }
 
+impl ClosureDef {
+    /// Retrieves the body of the closure definition. Returns None if the body
+    /// isn't available.
+    pub fn body(&self) -> Option<Body> {
+        with(|ctx| ctx.has_body(self.0).then(|| ctx.mir_body(self.0)))
+    }
+}
+
 crate_def! {
     #[derive(Serialize)]
     pub CoroutineDef;

diff --git a/tests/ui-fulldeps/stable-mir/closure-generic-body.rs b/tests/ui-fulldeps/stable-mir/closure-generic-body.rs
@@ -0,0 +1,90 @@
+//@ run-pass
+//! Tests stable mir API for retrieving the body of a closure.
+
+//@ ignore-stage1
+//@ ignore-cross-compile
+//@ ignore-remote
+//@ edition: 2021
+
+#![feature(rustc_private)]
+#![feature(assert_matches)]
+
+extern crate rustc_middle;
+#[macro_use]
+extern crate rustc_smir;
+extern crate rustc_driver;
+extern crate rustc_interface;
+extern crate stable_mir;
+
+use std::io::Write;
+use std::ops::ControlFlow;
+
+use stable_mir::mir::{Body, ConstOperand, Operand, TerminatorKind};
+use stable_mir::ty::{FnDef, RigidTy, TyKind};
+
+const CRATE_NAME: &str = "crate_closure_body";
+
+fn test_closure_body() -> ControlFlow<()> {
+    let crate_items = stable_mir::all_local_items();
+    for item in crate_items {
+        let item_ty = item.ty();
+        match &item_ty.kind() {
+            TyKind::RigidTy(RigidTy::Closure(closure_def, _)) => {
+                let closure_body = closure_def.body().unwrap();
+                check_incr_closure_body(closure_body);
+            }
+            _ => {}
+        }
+    }
+
+    ControlFlow::Continue(())
+}
+
+fn check_incr_closure_body(body: Body) {
+    let first_block = &body.blocks[0];
+    let TerminatorKind::Call { func: Operand::Constant(ConstOperand { const_, .. }), .. } =
+        &first_block.terminator.kind
+    else {
+        panic!("expected Call Terminator, got: ");
+    };
+
+    let TyKind::RigidTy(RigidTy::FnDef(FnDef(def_id), ..), ..) = const_.ty().kind() else {
+        panic!("expected FnDef");
+    };
+
+    assert_eq!(def_id.name(), "id");
+}
+
+fn main() {
+    let path = "closure_body.rs";
+    generate_input(&path).unwrap();
+    let args = &[
+        "rustc".to_string(),
+        "-Cpanic=abort".to_string(),
+        "--crate-name".to_string(),
+        CRATE_NAME.to_string(),
+        path.to_string(),
+    ];
+    run!(args, test_closure_body).unwrap();
+}
+
+fn generate_input(path: &str) -> std::io::Result<()> {
+    let mut file = std::fs::File::create(path)?;
+    write!(
+        file,
+        r#"
+        fn id<T>(y: T) -> T {{
+            y
+        }}
+
+        fn main() {{
+            let cl_id= |x| {{
+                id(x)
+            }};
+
+            let _= cl_id(5);
+        }}
+    "#
+    )?;
+    Ok(())
+}
diff --git a/tests/ui-fulldeps/stable-mir/closure_body.rs b/tests/ui-fulldeps/stable-mir/closure_body.rs
@@ -0,0 +1,90 @@
+//@ run-pass
+//! Tests stable mir API for retrieving the body of a closure.
+
+//@ ignore-stage1
+//@ ignore-cross-compile
+//@ ignore-remote
+//@ edition: 2021
+
+#![feature(rustc_private)]
+#![feature(assert_matches)]
+
+extern crate rustc_middle;
+#[macro_use]
+extern crate rustc_smir;
+extern crate rustc_driver;
+extern crate rustc_interface;
+extern crate stable_mir;
+
+use std::io::Write;
+use std::ops::ControlFlow;
+
+use stable_mir::mir::{Body, ConstOperand, Operand, TerminatorKind};
+use stable_mir::ty::{FnDef, RigidTy, TyKind};
+
+const CRATE_NAME: &str = "crate_closure_body";
+
+fn test_closure_body() -> ControlFlow<()> {
+    let crate_items = stable_mir::all_local_items();
+    for item in crate_items {
+        let item_ty = item.ty();
+        match &item_ty.kind() {
+            TyKind::RigidTy(RigidTy::Closure(closure_def, _)) => {
+                let closure_body = closure_def.body().unwrap();
+                check_incr_closure_body(closure_body);
+            }
+            _ => {}
+        }
+    }
+
+    ControlFlow::Continue(())
+}
+
+fn check_incr_closure_body(body: Body) {
+    let first_block = &body.blocks[0];
+    let TerminatorKind::Call { func: Operand::Constant(ConstOperand { const_, .. }), .. } =
+        &first_block.terminator.kind
+    else {
+        panic!("expected Call Terminator, got: ");
+    };
+
+    let TyKind::RigidTy(RigidTy::FnDef(FnDef(def_id), ..), ..) = const_.ty().kind() else {
+        panic!("expected FnDef");
+    };
+
+    assert_eq!(def_id.name(), "incr");
+}
+
+fn main() {
+    let path = "closure_body.rs";
+    generate_input(&path).unwrap();
+    let args = &[
+        "rustc".to_string(),
+        "-Cpanic=abort".to_string(),
+        "--crate-name".to_string(),
+        CRATE_NAME.to_string(),
+        path.to_string(),
+    ];
+    run!(args, test_closure_body).unwrap();
+}
+
+fn generate_input(path: &str) -> std::io::Result<()> {
+    let mut file = std::fs::File::create(path)?;
+    write!(
+        file,
+        r#"
+        fn incr(y: i32) -> i32 {{
+            y + 1
+        }}
+
+        fn main() {{
+            let cl_incr = |x: i32| {{
+                incr(x)
+            }};
+
+            let _= cl_incr(5);
+        }}
+    "#
+    )?;
+    Ok(())
+}