Fix all_trait* methods to return all trait available

Also provide a mechanism to retrieve traits and implementations for a
given crate.

compiler/rustc_smir/src/rustc_internal/internal.rs

@@ -17,7 +17,7 @@ use stable_mir::ty::{
     GenericArgKind, GenericArgs, IndexedVal, IntTy, Movability, Region, RigidTy, Span, TermKind,
     TraitRef, Ty, UintTy, VariantDef, VariantIdx,
 };
-use stable_mir::{CrateItem, DefId};
+use stable_mir::{CrateItem, CrateNum, DefId};
 
 use super::RustcInternal;
 
@@ -28,6 +28,13 @@ impl<'tcx> RustcInternal<'tcx> for CrateItem {
     }
 }
 
+impl<'tcx> RustcInternal<'tcx> for CrateNum {
+    type T = rustc_span::def_id::CrateNum;
+    fn internal(&self, _tables: &mut Tables<'tcx>) -> Self::T {
+        rustc_span::def_id::CrateNum::from_usize(*self)
+    }
+}
+
 impl<'tcx> RustcInternal<'tcx> for DefId {
     type T = rustc_span::def_id::DefId;
     fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {

compiler/rustc_smir/src/rustc_smir/context.rs

@@ -25,8 +25,9 @@ use stable_mir::ty::{
     AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, Const, FieldDef, FnDef, GenericArgs,
     LineInfo, PolyFnSig, RigidTy, Span, Ty, TyKind, VariantDef,
 };
-use stable_mir::{Crate, CrateItem, DefId, Error, Filename, ItemKind, Symbol};
+use stable_mir::{Crate, CrateItem, CrateNum, DefId, Error, Filename, ItemKind, Symbol};
 use std::cell::RefCell;
+use std::iter;
 
 use crate::rustc_internal::{internal, RustcInternal};
 use crate::rustc_smir::builder::BodyBuilder;
@@ -67,10 +68,15 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
     }
 
     fn all_trait_decls(&self) -> stable_mir::TraitDecls {
+        let mut tables = self.0.borrow_mut();
+        tables.tcx.all_traits().map(|trait_def_id| tables.trait_def(trait_def_id)).collect()
+    }
+
+    fn trait_decls(&self, crate_num: CrateNum) -> stable_mir::TraitDecls {
         let mut tables = self.0.borrow_mut();
         tables
             .tcx
-            .traits(LOCAL_CRATE)
+            .traits(crate_num.internal(&mut *tables))
             .iter()
             .map(|trait_def_id| tables.trait_def(*trait_def_id))
             .collect()
@@ -84,10 +90,20 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
     }
 
     fn all_trait_impls(&self) -> stable_mir::ImplTraitDecls {
+        let mut tables = self.0.borrow_mut();
+        let tcx = tables.tcx;
+        iter::once(LOCAL_CRATE)
+            .chain(tables.tcx.crates(()).iter().copied())
+            .flat_map(|cnum| tcx.trait_impls_in_crate(cnum).iter())
+            .map(|impl_def_id| tables.impl_def(*impl_def_id))
+            .collect()
+    }
+
+    fn trait_impls(&self, crate_num: CrateNum) -> stable_mir::ImplTraitDecls {
         let mut tables = self.0.borrow_mut();
         tables
             .tcx
-            .trait_impls_in_crate(LOCAL_CRATE)
+            .trait_impls_in_crate(crate_num.internal(&mut *tables))
             .iter()
             .map(|impl_def_id| tables.impl_def(*impl_def_id))
             .collect()

compiler/stable_mir/src/compiler_interface.rs

@@ -16,8 +16,8 @@ use crate::ty::{
     TraitDef, Ty, TyKind, VariantDef,
 };
 use crate::{
-    mir, Crate, CrateItem, CrateItems, DefId, Error, Filename, ImplTraitDecls, ItemKind, Symbol,
-    TraitDecls,
+    mir, Crate, CrateItem, CrateItems, CrateNum, DefId, Error, Filename, ImplTraitDecls, ItemKind,
+    Symbol, TraitDecls,
 };
 
 /// This trait defines the interface between stable_mir and the Rust compiler.
@@ -32,8 +32,10 @@ pub trait Context {
     /// Check whether the body of a function is available.
     fn has_body(&self, item: DefId) -> bool;
     fn all_trait_decls(&self) -> TraitDecls;
+    fn trait_decls(&self, crate_num: CrateNum) -> TraitDecls;
     fn trait_decl(&self, trait_def: &TraitDef) -> TraitDecl;
     fn all_trait_impls(&self) -> ImplTraitDecls;
+    fn trait_impls(&self, crate_num: CrateNum) -> ImplTraitDecls;
     fn trait_impl(&self, trait_impl: &ImplDef) -> ImplTrait;
     fn generics_of(&self, def_id: DefId) -> Generics;
     fn predicates_of(&self, def_id: DefId) -> GenericPredicates;

compiler/stable_mir/src/lib.rs

@@ -31,7 +31,7 @@ pub use crate::error::*;
 use crate::mir::pretty::function_name;
 use crate::mir::Body;
 use crate::mir::Mutability;
-use crate::ty::{ImplDef, ImplTrait, IndexedVal, Span, TraitDecl, TraitDef, Ty};
+use crate::ty::{ImplDef, IndexedVal, Span, TraitDef, Ty};
 
 pub mod abi;
 #[macro_use]
@@ -86,6 +86,18 @@ pub struct Crate {
     pub is_local: bool,
 }
 
+impl Crate {
+    /// The list of traits declared in this crate.
+    pub fn trait_decls(&self) -> TraitDecls {
+        with(|cx| cx.trait_decls(self.id))
+    }
+
+    /// The list of trait implementations in this crate.
+    pub fn trait_impls(&self) -> ImplTraitDecls {
+        with(|cx| cx.trait_impls(self.id))
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
 pub enum ItemKind {
     Fn,
@@ -169,18 +181,10 @@ pub fn all_trait_decls() -> TraitDecls {
     with(|cx| cx.all_trait_decls())
 }
 
-pub fn trait_decl(trait_def: &TraitDef) -> TraitDecl {
-    with(|cx| cx.trait_decl(trait_def))
-}
-
 pub fn all_trait_impls() -> ImplTraitDecls {
     with(|cx| cx.all_trait_impls())
 }
 
-pub fn trait_impl(trait_impl: &ImplDef) -> ImplTrait {
-    with(|cx| cx.trait_impl(trait_impl))
-}
-
 /// A type that provides internal information but that can still be used for debug purpose.
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct Opaque(String);

compiler/stable_mir/src/ty.rs

@@ -714,9 +714,16 @@ crate_def! {
 }
 
 crate_def! {
+    /// A trait's definition.
     pub TraitDef;
 }
 
+impl TraitDef {
+    pub fn declaration(trait_def: &TraitDef) -> TraitDecl {
+        with(|cx| cx.trait_decl(trait_def))
+    }
+}
+
 crate_def! {
     pub GenericDef;
 }
@@ -726,9 +733,17 @@ crate_def! {
 }
 
 crate_def! {
+    /// A trait impl definition.
     pub ImplDef;
 }
 
+impl ImplDef {
+    /// Retrieve information about this implementation.
+    pub fn trait_impl(&self) -> ImplTrait {
+        with(|cx| cx.trait_impl(self))
+    }
+}
+
 crate_def! {
     pub RegionDef;
 }

tests/ui-fulldeps/stable-mir/check_trait_queries.rs

@@ -0,0 +1,125 @@
+// run-pass
+//! Test that users are able to retrieve information about trait declarations and implementations.
+
+// ignore-stage1
+// ignore-cross-compile
+// ignore-remote
+// ignore-windows-gnu mingw has troubles with linking https://github.com/rust-lang/rust/pull/116837
+// edition: 2021
+
+#![feature(rustc_private)]
+#![feature(assert_matches)]
+#![feature(control_flow_enum)]
+
+extern crate rustc_middle;
+#[macro_use]
+extern crate rustc_smir;
+extern crate rustc_driver;
+extern crate rustc_interface;
+extern crate stable_mir;
+
+use rustc_middle::ty::TyCtxt;
+use rustc_smir::rustc_internal;
+use stable_mir::CrateDef;
+use std::collections::HashSet;
+use std::io::Write;
+use std::ops::ControlFlow;
+
+const CRATE_NAME: &str = "trait_test";
+
+/// This function uses the Stable MIR APIs to get information about the test crate.
+fn test_traits() -> ControlFlow<()> {
+    let local_crate = stable_mir::local_crate();
+    let local_traits = local_crate.trait_decls();
+    assert_eq!(local_traits.len(), 1, "Expected `Max` trait, but found {:?}", local_traits);
+    assert_eq!(&local_traits[0].name(), "Max");
+
+    let local_impls = local_crate.trait_impls();
+    let impl_names = local_impls.iter().map(|trait_impl| trait_impl.name()).collect::<HashSet<_>>();
+    assert_impl(&impl_names, "<Positive as Max>");
+    assert_impl(&impl_names, "<Positive as std::marker::Copy>");
+    assert_impl(&impl_names, "<Positive as std::clone::Clone>");
+    assert_impl(&impl_names, "<Positive as std::fmt::Debug>");
+    assert_impl(&impl_names, "<Positive as std::cmp::PartialEq>");
+    assert_impl(&impl_names, "<Positive as std::cmp::Eq>");
+    assert_impl(&impl_names, "<Positive as std::convert::TryFrom<u64>>");
+    assert_impl(&impl_names, "<u64 as Max>");
+    assert_impl(&impl_names, "<impl std::convert::From<Positive> for u64>");
+
+    let all_traits = stable_mir::all_trait_decls();
+    assert!(all_traits.len() > local_traits.len());
+    assert!(
+        local_traits.iter().all(|t| all_traits.contains(t)),
+        "Local: {local_traits:#?}, All: {all_traits:#?}"
+    );
+
+    let all_impls = stable_mir::all_trait_impls();
+    assert!(all_impls.len() > local_impls.len());
+    assert!(
+        local_impls.iter().all(|t| all_impls.contains(t)),
+        "Local: {local_impls:#?}, All: {all_impls:#?}"
+    );
+    ControlFlow::Continue(())
+}
+
+fn assert_impl(impl_names: &HashSet<String>, target: &str) {
+    assert!(
+        impl_names.contains(target),
+        "Failed to find `{target}`. Implementations available: {impl_names:?}",
+    );
+}
+
+/// 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 `StableMir` using custom arguments and then
+/// it will run the compiler.
+fn main() {
+    let path = "trait_queries.rs";
+    generate_input(&path).unwrap();
+    let args = vec![
+        "rustc".to_string(),
+        "--crate-type=lib".to_string(),
+        "--crate-name".to_string(),
+        CRATE_NAME.to_string(),
+        path.to_string(),
+    ];
+    run!(args, test_traits()).unwrap();
+}
+
+fn generate_input(path: &str) -> std::io::Result<()> {
+    let mut file = std::fs::File::create(path)?;
+    write!(
+        file,
+        r#"
+        use std::convert::TryFrom;
+
+        #[derive(Copy, Clone, Debug, PartialEq, Eq)]
+        pub struct Positive(u64);
+
+        impl TryFrom<u64> for Positive {{
+            type Error = ();
+            fn try_from(val: u64) -> Result<Positive, Self::Error> {{
+                if val > 0 {{ Ok(Positive(val)) }} else {{ Err(()) }}
+            }}
+        }}
+
+        impl From<Positive> for u64 {{
+            fn from(val: Positive) -> u64 {{ val.0 }}
+        }}
+
+        pub trait Max {{
+            fn is_max(&self) -> bool;
+        }}
+
+        impl Max for u64 {{
+            fn is_max(&self) -> bool {{ *self == u64::MAX }}
+        }}
+
+        impl Max for Positive {{
+            fn is_max(&self) -> bool {{ self.0.is_max() }}
+        }}
+
+    "#
+    )?;
+    Ok(())
+}