1 files changed, 137 insertions, 0 deletions
diff --git a/tests/ui-fulldeps/rustc_public/check_instance.rs b/tests/ui-fulldeps/rustc_public/check_instance.rs
new file mode 100644
index 00000000000..fd7523963fa
--- /dev/null
+++ b/tests/ui-fulldeps/rustc_public/check_instance.rs
@@ -0,0 +1,137 @@
+//@ run-pass
+//! Test that users are able to use stable mir APIs to retrieve monomorphized instances
+
+//@ ignore-stage1
+//@ ignore-cross-compile
+//@ ignore-remote
+//@ edition: 2021
+
+#![feature(rustc_private)]
+#![feature(assert_matches)]
+
+extern crate rustc_middle;
+
+extern crate rustc_driver;
+extern crate rustc_interface;
+extern crate rustc_public;
+
+use std::io::Write;
+use std::ops::ControlFlow;
+
+use mir::mono::Instance;
+use mir::TerminatorKind::*;
+use rustc_public::ty::{RigidTy, TyKind};
+use rustc_public::*;
+
+const CRATE_NAME: &str = "input";
+
+/// This function uses the Stable MIR APIs to get information about the test crate.
+fn test_stable_mir() -> ControlFlow<()> {
+    let items = rustc_public::all_local_items();
+
+    // Get all items and split generic vs monomorphic items.
+    let (generic, mono): (Vec<_>, Vec<_>) =
+        items.into_iter().partition(|item| item.requires_monomorphization());
+    assert_eq!(mono.len(), 3, "Expected 3 mono functions");
+    assert_eq!(generic.len(), 2, "Expected 2 generic functions");
+
+    // For all monomorphic items, get the correspondent instances.
+    let instances = mono
+        .iter()
+        .filter_map(|item| mir::mono::Instance::try_from(*item).ok())
+        .collect::<Vec<mir::mono::Instance>>();
+    assert_eq!(instances.len(), mono.len());
+
+    // For all generic items, try_from should fail.
+    assert!(generic.iter().all(|item| mir::mono::Instance::try_from(*item).is_err()));
+
+    for instance in instances {
+        test_body(instance.body().unwrap())
+    }
+    ControlFlow::Continue(())
+}
+
+/// Inspect the instance body
+fn test_body(body: mir::Body) {
+    for term in body.blocks.iter().map(|bb| &bb.terminator) {
+        match &term.kind {
+            Call { func, .. } => {
+                let TyKind::RigidTy(ty) = func.ty(body.locals()).unwrap().kind() else {
+                    unreachable!()
+                };
+                let RigidTy::FnDef(def, args) = ty else { unreachable!() };
+                let instance = Instance::resolve(def, &args).unwrap();
+                let mangled_name = instance.mangled_name();
+                assert!(instance.has_body() || (mangled_name == "setpwent"), "Failed: {func:?}");
+                assert!(instance.has_body() ^ instance.is_foreign_item());
+                if instance.has_body() {
+                    let body = instance.body().unwrap();
+                    assert!(!body.locals().is_empty(), "Body must at least have a return local");
+                }
+            }
+            Goto { .. } | Assert { .. } | SwitchInt { .. } | Return | Drop { .. } => {
+                /* Do nothing */
+            }
+            _ => {
+                unreachable!("Unexpected terminator {term:?}")
+            }
+        }
+    }
+}
+
+/// This test will generate and analyze a dummy crate using the stable mir.
+/// For that, it will first write the dummy crate into a file.
+/// Then it will create a `RustcPublic` using custom arguments and then
+/// it will run the compiler.
+fn main() {
+    let path = "instance_input.rs";
+    generate_input(&path).unwrap();
+    let args = &[
+        "rustc".to_string(),
+        "-Cpanic=abort".to_string(),
+        "--crate-type=lib".to_string(),
+        "--crate-name".to_string(),
+        CRATE_NAME.to_string(),
+        path.to_string(),
+    ];
+    run!(args, test_stable_mir).unwrap();
+}
+
+fn generate_input(path: &str) -> std::io::Result<()> {
+    let mut file = std::fs::File::create(path)?;
+    write!(
+        file,
+        r#"
+
+    struct Foo(());
+
+    pub fn ty_param<T>(t: &T) -> T where T: Clone {{
+        t.clone()
+    }}
+
+    pub fn const_param<const LEN: usize>(a: [bool; LEN]) -> bool {{
+        LEN > 0 && a[0]
+    }}
+
+    extern "C" {{
+        // Body should not be available.
+        fn setpwent();
+    }}
+
+    pub fn monomorphic() {{
+        Foo(());
+        let v = vec![10];
+        let dup = ty_param(&v);
+        assert_eq!(v, dup);
+        unsafe {{ setpwent() }};
+    }}
+
+    pub mod foo {{
+        pub fn bar_mono(i: i32) -> i64 {{
+            i as i64
+        }}
+    }}
+    "#
+    )?;
+    Ok(())
+}