Auto merge of rust-lang#118003 - matthiaskrgr:rollup-80t3uky, r=matth…

…iaskrgr

Rollup of 3 pull requests

Successful merges:

 - rust-lang#115476 (document ABI compatibility)
 - rust-lang#117688 (Misc changes to StableMIR required to Kani use case.)
 - rust-lang#117998 (On resolve error of `[rest..]`, suggest `[rest @ ..]`)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_resolve/src/late.rs

@@ -603,6 +603,8 @@ struct DiagnosticMetadata<'ast> {
     /// Only used for better errors on `let <pat>: <expr, not type>;`.
     current_let_binding: Option<(Span, Option<Span>, Option<Span>)>,
 
+    current_pat: Option<&'ast Pat>,
+
     /// Used to detect possible `if let` written without `let` and to provide structured suggestion.
     in_if_condition: Option<&'ast Expr>,
 
@@ -703,6 +705,12 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
     fn visit_expr(&mut self, expr: &'ast Expr) {
         self.resolve_expr(expr, None);
     }
+    fn visit_pat(&mut self, p: &'ast Pat) {
+        let prev = self.diagnostic_metadata.current_pat;
+        self.diagnostic_metadata.current_pat = Some(p);
+        visit::walk_pat(self, p);
+        self.diagnostic_metadata.current_pat = prev;
+    }
     fn visit_local(&mut self, local: &'ast Local) {
         let local_spans = match local.pat.kind {
             // We check for this to avoid tuple struct fields.

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -431,6 +431,7 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
             code,
         );
 
+        self.suggest_at_operator_in_slice_pat_with_range(&mut err, path);
         self.suggest_swapping_misplaced_self_ty_and_trait(&mut err, source, res, base_error.span);
 
         if let Some((span, label)) = base_error.span_label {
@@ -1063,6 +1064,32 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
         true
     }
 
+    fn suggest_at_operator_in_slice_pat_with_range(
+        &mut self,
+        err: &mut Diagnostic,
+        path: &[Segment],
+    ) {
+        if let Some(pat) = self.diagnostic_metadata.current_pat
+            && let ast::PatKind::Range(Some(start), None, range) = &pat.kind
+            && let ExprKind::Path(None, range_path) = &start.kind
+            && let [segment] = &range_path.segments[..]
+            && let [s] = path
+            && segment.ident == s.ident
+        {
+            // We've encountered `[first, rest..]` where the user might have meant
+            // `[first, rest @ ..]` (#88404).
+            err.span_suggestion_verbose(
+                segment.ident.span.between(range.span),
+                format!(
+                    "if you meant to collect the rest of the slice in `{}`, use the at operator",
+                    segment.ident,
+                ),
+                " @ ",
+                Applicability::MaybeIncorrect,
+            );
+        }
+    }
+
     fn suggest_swapping_misplaced_self_ty_and_trait(
         &mut self,
         err: &mut Diagnostic,

compiler/rustc_smir/src/rustc_internal/internal.rs

@@ -6,11 +6,23 @@
 // Prefer importing stable_mir over internal rustc constructs to make this file more readable.
 use crate::rustc_smir::Tables;
 use rustc_middle::ty::{self as rustc_ty, Ty as InternalTy};
-use stable_mir::ty::{Const, GenericArgKind, GenericArgs, Region, Ty};
-use stable_mir::DefId;
+use rustc_span::Symbol;
+use stable_mir::mir::mono::{Instance, MonoItem, StaticDef};
+use stable_mir::ty::{
+    Binder, BoundRegionKind, BoundTyKind, BoundVariableKind, ClosureKind, Const, GenericArgKind,
+    GenericArgs, Region, TraitRef, Ty,
+};
+use stable_mir::{AllocId, CrateItem, DefId};
 
 use super::RustcInternal;
 
+impl<'tcx> RustcInternal<'tcx> for CrateItem {
+    type T = rustc_span::def_id::DefId;
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        self.0.internal(tables)
+    }
+}
+
 impl<'tcx> RustcInternal<'tcx> for DefId {
     type T = rustc_span::def_id::DefId;
     fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
@@ -38,8 +50,9 @@ impl<'tcx> RustcInternal<'tcx> for GenericArgKind {
 
 impl<'tcx> RustcInternal<'tcx> for Region {
     type T = rustc_ty::Region<'tcx>;
-    fn internal(&self, _tables: &mut Tables<'tcx>) -> Self::T {
-        todo!()
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        // Cannot recover region. Use erased instead.
+        tables.tcx.lifetimes.re_erased
     }
 }
 
@@ -65,3 +78,118 @@ impl<'tcx> RustcInternal<'tcx> for Const {
         tables.constants[self.id]
     }
 }
+
+impl<'tcx> RustcInternal<'tcx> for MonoItem {
+    type T = rustc_middle::mir::mono::MonoItem<'tcx>;
+
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        use rustc_middle::mir::mono as rustc_mono;
+        match self {
+            MonoItem::Fn(instance) => rustc_mono::MonoItem::Fn(instance.internal(tables)),
+            MonoItem::Static(def) => rustc_mono::MonoItem::Static(def.internal(tables)),
+            MonoItem::GlobalAsm(_) => {
+                unimplemented!()
+            }
+        }
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for Instance {
+    type T = rustc_ty::Instance<'tcx>;
+
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        tables.instances[self.def]
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for StaticDef {
+    type T = rustc_span::def_id::DefId;
+
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        self.0.internal(tables)
+    }
+}
+
+#[allow(rustc::usage_of_qualified_ty)]
+impl<'tcx, T> RustcInternal<'tcx> for Binder<T>
+where
+    T: RustcInternal<'tcx>,
+    T::T: rustc_ty::TypeVisitable<rustc_ty::TyCtxt<'tcx>>,
+{
+    type T = rustc_ty::Binder<'tcx, T::T>;
+
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        rustc_ty::Binder::bind_with_vars(
+            self.value.internal(tables),
+            tables.tcx.mk_bound_variable_kinds_from_iter(
+                self.bound_vars.iter().map(|bound| bound.internal(tables)),
+            ),
+        )
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for BoundVariableKind {
+    type T = rustc_ty::BoundVariableKind;
+
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        match self {
+            BoundVariableKind::Ty(kind) => rustc_ty::BoundVariableKind::Ty(match kind {
+                BoundTyKind::Anon => rustc_ty::BoundTyKind::Anon,
+                BoundTyKind::Param(def, symbol) => {
+                    rustc_ty::BoundTyKind::Param(def.0.internal(tables), Symbol::intern(&symbol))
+                }
+            }),
+            BoundVariableKind::Region(kind) => rustc_ty::BoundVariableKind::Region(match kind {
+                BoundRegionKind::BrAnon => rustc_ty::BoundRegionKind::BrAnon,
+                BoundRegionKind::BrNamed(def, symbol) => rustc_ty::BoundRegionKind::BrNamed(
+                    def.0.internal(tables),
+                    Symbol::intern(&symbol),
+                ),
+                BoundRegionKind::BrEnv => rustc_ty::BoundRegionKind::BrEnv,
+            }),
+            BoundVariableKind::Const => rustc_ty::BoundVariableKind::Const,
+        }
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for TraitRef {
+    type T = rustc_ty::TraitRef<'tcx>;
+
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        rustc_ty::TraitRef::new(
+            tables.tcx,
+            self.def_id.0.internal(tables),
+            self.args().internal(tables),
+        )
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for AllocId {
+    type T = rustc_middle::mir::interpret::AllocId;
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        tables.alloc_ids[*self]
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for ClosureKind {
+    type T = rustc_ty::ClosureKind;
+
+    fn internal(&self, _tables: &mut Tables<'tcx>) -> Self::T {
+        match self {
+            ClosureKind::Fn => rustc_ty::ClosureKind::Fn,
+            ClosureKind::FnMut => rustc_ty::ClosureKind::FnMut,
+            ClosureKind::FnOnce => rustc_ty::ClosureKind::FnOnce,
+        }
+    }
+}
+
+impl<'tcx, T> RustcInternal<'tcx> for &T
+where
+    T: RustcInternal<'tcx>,
+{
+    type T = T::T;
+
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        (*self).internal(tables)
+    }
+}

compiler/rustc_smir/src/rustc_internal/mod.rs

@@ -13,6 +13,7 @@ use rustc_span::def_id::{CrateNum, DefId};
 use rustc_span::Span;
 use scoped_tls::scoped_thread_local;
 use stable_mir::ty::IndexedVal;
+use stable_mir::Error;
 use std::cell::Cell;
 use std::cell::RefCell;
 use std::fmt::Debug;
@@ -21,11 +22,11 @@ use std::ops::Index;
 
 mod internal;
 
-pub fn stable<'tcx, S: Stable<'tcx>>(item: &S) -> S::T {
+pub fn stable<'tcx, S: Stable<'tcx>>(item: S) -> S::T {
     with_tables(|tables| item.stable(tables))
 }
 
-pub fn internal<'tcx, S: RustcInternal<'tcx>>(item: &S) -> S::T {
+pub fn internal<'tcx, S: RustcInternal<'tcx>>(item: S) -> S::T {
     with_tables(|tables| item.internal(tables))
 }
 
@@ -144,12 +145,13 @@ pub fn crate_num(item: &stable_mir::Crate) -> CrateNum {
 // datastructures and stable MIR datastructures
 scoped_thread_local! (static TLV: Cell<*const ()>);
 
-pub(crate) fn init<'tcx>(tables: &TablesWrapper<'tcx>, f: impl FnOnce()) {
+pub(crate) fn init<'tcx, F, T>(tables: &TablesWrapper<'tcx>, f: F) -> T
+where
+    F: FnOnce() -> T,
+{
     assert!(!TLV.is_set());
     let ptr = tables as *const _ as *const ();
-    TLV.set(&Cell::new(ptr), || {
-        f();
-    });
+    TLV.set(&Cell::new(ptr), || f())
 }
 
 /// Loads the current context and calls a function with it.
@@ -165,7 +167,10 @@ pub(crate) fn with_tables<'tcx, R>(f: impl FnOnce(&mut Tables<'tcx>) -> R) -> R
     })
 }
 
-pub fn run(tcx: TyCtxt<'_>, f: impl FnOnce()) {
+pub fn run<F, T>(tcx: TyCtxt<'_>, f: F) -> Result<T, Error>
+where
+    F: FnOnce() -> T,
+{
     let tables = TablesWrapper(RefCell::new(Tables {
         tcx,
         def_ids: IndexMap::default(),
@@ -175,7 +180,7 @@ pub fn run(tcx: TyCtxt<'_>, f: impl FnOnce()) {
         instances: IndexMap::default(),
         constants: IndexMap::default(),
     }));
-    stable_mir::run(&tables, || init(&tables, f));
+    stable_mir::run(&tables, || init(&tables, f))
 }
 
 #[macro_export]
@@ -241,7 +246,8 @@ macro_rules! run {
                 queries.global_ctxt().unwrap().enter(|tcx| {
                     rustc_internal::run(tcx, || {
                         self.result = Some((self.callback)(tcx));
-                    });
+                    })
+                    .unwrap();
                     if self.result.as_ref().is_some_and(|val| val.is_continue()) {
                         Compilation::Continue
                     } else {

compiler/rustc_smir/src/rustc_smir/builder.rs

@@ -19,10 +19,15 @@ impl<'tcx> BodyBuilder<'tcx> {
         BodyBuilder { tcx, instance }
     }
 
+    /// Build a stable monomorphic body for a given instance based on the MIR body.
+    ///
+    /// Note that we skip instantiation for static and constants. Trying to do so can cause ICE.
+    ///
+    /// We do monomorphize non-generic functions to eval unevaluated constants.
     pub fn build(mut self, tables: &mut Tables<'tcx>) -> stable_mir::mir::Body {
         let mut body = self.tcx.instance_mir(self.instance.def).clone();
-        let generics = self.tcx.generics_of(self.instance.def_id());
-        if generics.requires_monomorphization(self.tcx) {
+        if self.tcx.def_kind(self.instance.def_id()).is_fn_like() || !self.instance.args.is_empty()
+        {
             self.visit_body(&mut body);
         }
         body.stable(tables)
@@ -49,6 +54,20 @@ impl<'tcx> MutVisitor<'tcx> for BodyBuilder<'tcx> {
         *ty = self.monomorphize(*ty);
     }
 
+    fn visit_constant(&mut self, constant: &mut mir::ConstOperand<'tcx>, location: mir::Location) {
+        let const_ = self.monomorphize(constant.const_);
+        let val = match const_.eval(self.tcx, ty::ParamEnv::reveal_all(), None) {
+            Ok(v) => v,
+            Err(mir::interpret::ErrorHandled::Reported(..)) => return,
+            Err(mir::interpret::ErrorHandled::TooGeneric(..)) => {
+                unreachable!("Failed to evaluate instance constant: {:?}", const_)
+            }
+        };
+        let ty = constant.ty();
+        constant.const_ = mir::Const::Val(val, ty);
+        self.super_constant(constant, location);
+    }
+
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }