Rollup merge of #144000 - jacob-greenfield:stable-defid-parent, r=celinval

Add `DefId::parent()` accessor for `rustc_public`

Adds a `parent()` method to `DefId` (the `rustc_pub` version) which exposes the parent path, ie. `foo::bar::baz` -> `foo::bar`.

This is useful for organizing/grouping definitions into a tree, and is probably simpler and less brittle than attempting to parse the fully-qualified name into path components (e.g. especially when handling path components with qualified generic parameters).

compiler/rustc_public/src/compiler_interface.rs

@@ -249,6 +249,14 @@ impl<'tcx> CompilerInterface<'tcx> {
         cx.def_name(did, trimmed)
     }
 
+    /// Returns the parent of the given `DefId`.
+    pub(crate) fn def_parent(&self, def_id: DefId) -> Option<DefId> {
+        let mut tables = self.tables.borrow_mut();
+        let cx = &*self.cx.borrow();
+        let did = tables[def_id];
+        cx.def_parent(did).map(|did| tables.create_def_id(did))
+    }
+
     /// Return registered tool attributes with the given attribute name.
     ///
     /// FIXME(jdonszelmann): may panic on non-tool attributes. After more attribute work, non-tool

compiler/rustc_public/src/crate_def.rs

@@ -28,6 +28,12 @@ impl DefId {
     pub fn trimmed_name(&self) -> Symbol {
         with(|cx| cx.def_name(*self, true))
     }
+
+    /// Return the parent of this definition, or `None` if this is the root of a
+    /// crate.
+    pub fn parent(&self) -> Option<DefId> {
+        with(|cx| cx.def_parent(*self))
+    }
 }
 
 /// A trait for retrieving information about a particular definition.

compiler/rustc_public_bridge/src/context/impls.rs

@@ -268,6 +268,11 @@ impl<'tcx, B: Bridge> CompilerCtxt<'tcx, B> {
         }
     }
 
+    /// Returns the parent of the given `DefId`.
+    pub fn def_parent(&self, def_id: DefId) -> Option<DefId> {
+        self.tcx.opt_parent(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

tests/ui-fulldeps/rustc_public/check_def_parent.rs

@@ -0,0 +1,190 @@
+//@ run-pass
+//! Test that users are able to use public MIR APIs to retrieve information about parent
+//! definitions.
+
+//@ ignore-stage1
+//@ ignore-cross-compile
+//@ ignore-remote
+//@ edition: 2024
+// ignore-tidy-linelength
+
+#![feature(rustc_private)]
+
+extern crate rustc_middle;
+
+extern crate rustc_driver;
+extern crate rustc_interface;
+extern crate rustc_public;
+
+use rustc_public::ty::{RigidTy, TyKind};
+use rustc_public::*;
+use std::fmt::Debug;
+use std::io::Write;
+use std::ops::ControlFlow;
+
+const CRATE_NAME: &str = "input";
+
+/// Verify that each def has the correct parent
+fn test_stable_mir() -> ControlFlow<()> {
+    fn set_once<T: Debug + PartialEq>(slot: &mut Option<T>, val: T) {
+        assert_eq!(slot.replace(val), None);
+    }
+
+    let mut const_item = None;
+    let mut static_item = None;
+    let mut trait_method = None;
+    let mut trait_method_helper = None;
+    let mut inherent_method = None;
+    let mut inherent_method_helper = None;
+    let mut main = None;
+    let mut mystruct_ctor = None;
+    let mut trait_decl = None;
+    let mut trait_impl = None;
+
+    let mut mystruct_ctor_ty = None;
+
+    // Extract def-ids of various items
+    let krate = rustc_public::local_crate();
+    for it in rustc_public::all_local_items() {
+        match &*it.0.name() {
+            "wrapper_mod::CONST_ITEM" => {
+                set_once(&mut const_item, it.0);
+            }
+            "wrapper_mod::STATIC_ITEM" => {
+                set_once(&mut static_item, it.0);
+            }
+            "<wrapper_mod::MyStruct as wrapper_mod::MyTrait>::trait_method" => {
+                set_once(&mut trait_method, it.0);
+            }
+            "<wrapper_mod::MyStruct as wrapper_mod::MyTrait>::trait_method::trait_method_helper" => {
+                set_once(&mut trait_method_helper, it.0);
+            }
+            "wrapper_mod::MyStruct::inherent_method" => {
+                set_once(&mut inherent_method, it.0);
+            }
+            "wrapper_mod::MyStruct::inherent_method::inherent_method_helper" => {
+                set_once(&mut inherent_method_helper, it.0);
+            }
+            "main" => {
+                set_once(&mut main, it.0);
+            }
+            "wrapper_mod::MyStruct" => {
+                set_once(&mut mystruct_ctor, it.0);
+                mystruct_ctor_ty = Some(it.ty());
+            }
+            _ => (),
+        }
+    }
+    for it in krate.trait_decls() {
+        match &*it.0.name() {
+            "wrapper_mod::MyTrait" => set_once(&mut trait_decl, it.0),
+            _ => (),
+        }
+    }
+    for it in krate.trait_impls() {
+        match &*it.0.name() {
+            "<wrapper_mod::MyStruct as wrapper_mod::MyTrait>" => set_once(&mut trait_impl, it.0),
+            _ => (),
+        }
+    }
+
+    let const_item = const_item.unwrap();
+    let static_item = static_item.unwrap();
+    let trait_method = trait_method.unwrap();
+    let trait_method_helper = trait_method_helper.unwrap();
+    let inherent_method = inherent_method.unwrap();
+    let inherent_method_helper = inherent_method_helper.unwrap();
+    let main = main.unwrap();
+    let mystruct_ctor = mystruct_ctor.unwrap();
+    let trait_decl = trait_decl.unwrap();
+    let trait_impl = trait_impl.unwrap();
+
+    let mystruct_ctor_ty = mystruct_ctor_ty.unwrap();
+    let mystruct_ty = mystruct_ctor_ty.kind().fn_def().unwrap().0.fn_sig().skip_binder().output();
+    let TyKind::RigidTy(RigidTy::Adt(mystruct_adt_def, _)) = mystruct_ty.kind() else { panic!() };
+
+    let inherent_impl = inherent_method.parent().unwrap();
+    let wrapper_mod = const_item.parent().unwrap();
+    let crate_root = wrapper_mod.parent().unwrap();
+    assert_eq!(&*wrapper_mod.name(), "wrapper_mod");
+
+    // Check that each def-id has the correct parent
+    assert_eq!(crate_root.parent(), None);
+    assert_eq!(inherent_impl.parent(), Some(wrapper_mod));
+    assert_eq!(const_item.parent(), Some(wrapper_mod));
+    assert_eq!(static_item.parent(), Some(wrapper_mod));
+    assert_eq!(trait_method.parent(), Some(trait_impl));
+    assert_eq!(trait_method_helper.parent(), Some(trait_method));
+    assert_eq!(inherent_method_helper.parent(), Some(inherent_method));
+    assert_eq!(main.parent(), Some(crate_root));
+    assert_eq!(trait_decl.parent(), Some(wrapper_mod));
+    assert_eq!(trait_impl.parent(), Some(wrapper_mod));
+    assert_eq!(mystruct_ctor.parent(), Some(mystruct_adt_def.0));
+    assert_eq!(mystruct_adt_def.0.parent(), Some(wrapper_mod));
+
+    ControlFlow::Continue(())
+}
+
+/// 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 = "def_parent_input.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_stable_mir).unwrap();
+}
+
+fn generate_input(path: &str) -> std::io::Result<()> {
+    let mut file = std::fs::File::create(path)?;
+    write!(
+        file,
+        r#"
+        mod wrapper_mod {{
+            pub const CONST_ITEM: u32 = 100;
+            pub static STATIC_ITEM: u32 = 150;
+
+            pub struct MyStruct(pub u32);
+
+            pub trait MyTrait {{
+                fn trait_method(&self);
+            }}
+
+            impl MyTrait for MyStruct {{
+                fn trait_method(&self) {{
+                    fn trait_method_helper() {{}}
+
+                    trait_method_helper()
+                }}
+            }}
+
+            impl MyStruct {{
+                pub fn inherent_method(&self) {{
+                    println!("{{}}", self.0);
+
+                    fn inherent_method_helper() {{}}
+
+                    inherent_method_helper()
+                }}
+            }}
+        }}
+        use wrapper_mod::{{MyStruct, MyTrait, CONST_ITEM, STATIC_ITEM}};
+
+        fn main() {{
+            let mystruct = MyStruct(200);
+            mystruct.trait_method();
+            mystruct.inherent_method();
+            let _const = CONST_ITEM;
+            let _static = STATIC_ITEM;
+        }}
+    "#
+    )?;
+    Ok(())
+}