Rollup of 11 pull requests

compiler/rustc/Cargo.toml

@@ -27,6 +27,7 @@ features = ['unprefixed_malloc_on_supported_platforms']
 
 [features]
 # tidy-alphabetical-start
+check_only = ['rustc_driver_impl/check_only']
 jemalloc = ['dep:tikv-jemalloc-sys']
 llvm = ['rustc_driver_impl/llvm']
 max_level_info = ['rustc_driver_impl/max_level_info']

compiler/rustc_codegen_llvm/Cargo.toml

@@ -43,3 +43,6 @@ serde_json = "1"
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
 tracing = "0.1"
 # tidy-alphabetical-end
+
+[features]
+check_only = ["rustc_llvm/check_only"]

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -1498,7 +1498,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             dest_alloc
                 .write_uninit(&tcx, dest_range)
                 .map_err(|e| e.to_interp_error(dest_alloc_id))?;
-            // We can forget about the provenance, this is all not initialized anyway.
+            // `write_uninit` also resets the provenance, so we are done.
             return interp_ok(());
         }
 

compiler/rustc_driver_impl/Cargo.toml

@@ -72,6 +72,7 @@ ctrlc = "3.4.4"
 
 [features]
 # tidy-alphabetical-start
+check_only = ['rustc_interface/check_only']
 llvm = ['rustc_interface/llvm']
 max_level_info = ['rustc_log/max_level_info']
 rustc_randomized_layouts = [

compiler/rustc_interface/Cargo.toml

@@ -56,5 +56,6 @@ rustc_abi = { path = "../rustc_abi" }
 
 [features]
 # tidy-alphabetical-start
+check_only = ['rustc_codegen_llvm?/check_only']
 llvm = ['dep:rustc_codegen_llvm']
 # tidy-alphabetical-end

compiler/rustc_llvm/Cargo.toml

@@ -14,3 +14,7 @@ libc = "0.2.73"
 # pinned `cc` in `rustc_codegen_ssa` if you update `cc` here.
 cc = "=1.2.16"
 # tidy-alphabetical-end
+
+[features]
+# Used by ./x.py check --compile-time-deps to skip building C++ code
+check_only = []

compiler/rustc_llvm/build.rs

@@ -106,6 +106,10 @@ fn output(cmd: &mut Command) -> String {
 }
 
 fn main() {
+    if cfg!(feature = "check_only") {
+        return;
+    }
+
     for component in REQUIRED_COMPONENTS.iter().chain(OPTIONAL_COMPONENTS.iter()) {
         println!("cargo:rustc-check-cfg=cfg(llvm_component,values(\"{component}\"))");
     }

compiler/rustc_middle/src/mir/interpret/allocation.rs

@@ -101,6 +101,8 @@ pub struct Allocation<Prov: Provenance = CtfeProvenance, Extra = (), Bytes = Box
     /// at the given offset.
     provenance: ProvenanceMap<Prov>,
     /// Denotes which part of this allocation is initialized.
+    ///
+    /// Invariant: the uninitialized parts have no provenance.
     init_mask: InitMask,
     /// The alignment of the allocation to detect unaligned reads.
     /// (`Align` guarantees that this is a power of two.)
@@ -796,24 +798,19 @@ impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes>
         Ok(())
     }
 
-    /// Initialize all previously uninitialized bytes in the entire allocation, and set
-    /// provenance of everything to `Wildcard`. Before calling this, make sure all
-    /// provenance in this allocation is exposed!
-    pub fn prepare_for_native_access(&mut self) {
-        let full_range = AllocRange { start: Size::ZERO, size: Size::from_bytes(self.len()) };
-        // Overwrite uninitialized bytes with 0, to ensure we don't leak whatever their value happens to be.
-        for chunk in self.init_mask.range_as_init_chunks(full_range) {
-            if !chunk.is_init() {
-                let uninit_bytes = &mut self.bytes
-                    [chunk.range().start.bytes_usize()..chunk.range().end.bytes_usize()];
-                uninit_bytes.fill(0);
-            }
-        }
-        // Mark everything as initialized now.
-        self.mark_init(full_range, true);
-
-        // Set provenance of all bytes to wildcard.
-        self.provenance.write_wildcards(self.len());
+    /// Mark all bytes in the given range as initialised and reset the provenance
+    /// to wildcards. This entirely breaks the normal mechanisms for tracking
+    /// initialisation and is only provided for Miri operating in native-lib
+    /// mode. UB will be missed if the underlying bytes were not actually written to.
+    ///
+    /// If `range` is `None`, defaults to performing this on the whole allocation.
+    pub fn process_native_write(&mut self, cx: &impl HasDataLayout, range: Option<AllocRange>) {
+        let range = range.unwrap_or_else(|| AllocRange {
+            start: Size::ZERO,
+            size: Size::from_bytes(self.len()),
+        });
+        self.mark_init(range, true);
+        self.provenance.write_wildcards(cx, range);
     }
 
     /// Remove all provenance in the given memory range.

compiler/rustc_middle/src/mir/interpret/allocation/provenance_map.rs

@@ -212,21 +212,37 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
         Ok(())
     }
 
-    /// Overwrites all provenance in the allocation with wildcard provenance.
+    /// Overwrites all provenance in the given range with wildcard provenance.
+    /// Pointers partially overwritten will have their provenances preserved
+    /// bytewise on their remaining bytes.
     ///
     /// Provided for usage in Miri and panics otherwise.
-    pub fn write_wildcards(&mut self, alloc_size: usize) {
+    pub fn write_wildcards(&mut self, cx: &impl HasDataLayout, range: AllocRange) {
         assert!(
             Prov::OFFSET_IS_ADDR,
             "writing wildcard provenance is not supported when `OFFSET_IS_ADDR` is false"
         );
         let wildcard = Prov::WILDCARD.unwrap();
 
-        // Remove all pointer provenances, then write wildcards into the whole byte range.
-        self.ptrs.clear();
-        let last = Size::from_bytes(alloc_size);
         let bytes = self.bytes.get_or_insert_with(Box::default);
-        for offset in Size::ZERO..last {
+
+        // Remove pointer provenances that overlap with the range, then readd the edge ones bytewise.
+        let ptr_range = Self::adjusted_range_ptrs(range, cx);
+        let ptrs = self.ptrs.range(ptr_range.clone());
+        if let Some((offset, prov)) = ptrs.first() {
+            for byte_ofs in *offset..range.start {
+                bytes.insert(byte_ofs, *prov);
+            }
+        }
+        if let Some((offset, prov)) = ptrs.last() {
+            for byte_ofs in range.end()..*offset + cx.data_layout().pointer_size() {
+                bytes.insert(byte_ofs, *prov);
+            }
+        }
+        self.ptrs.remove_range(ptr_range);
+
+        // Overwrite bytewise provenance.
+        for offset in range.start..range.end() {
             bytes.insert(offset, wildcard);
         }
     }

compiler/rustc_passes/src/dead.rs

@@ -18,7 +18,7 @@ use rustc_hir::{self as hir, ImplItem, ImplItemKind, Node, PatKind, QPath, TyKin
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::middle::privacy::Level;
 use rustc_middle::query::Providers;
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::{self, AssocTag, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_session::lint::builtin::DEAD_CODE;
 use rustc_session::lint::{self, LintExpectationId};
@@ -115,7 +115,10 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
 
     fn handle_res(&mut self, res: Res) {
         match res {
-            Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::TyAlias, def_id) => {
+            Res::Def(
+                DefKind::Const | DefKind::AssocConst | DefKind::AssocTy | DefKind::TyAlias,
+                def_id,
+            ) => {
                 self.check_def_id(def_id);
             }
             _ if self.in_pat => {}
@@ -482,7 +485,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
     ) -> bool {
         let trait_def_id = match self.tcx.def_kind(local_def_id) {
             // assoc impl items of traits are live if the corresponding trait items are live
-            DefKind::AssocFn => self
+            DefKind::AssocConst | DefKind::AssocTy | DefKind::AssocFn => self
                 .tcx
                 .associated_item(local_def_id)
                 .trait_item_def_id
@@ -647,6 +650,31 @@ impl<'tcx> Visitor<'tcx> for MarkSymbolVisitor<'tcx> {
 
         self.in_pat = in_pat;
     }
+
+    fn visit_trait_ref(&mut self, t: &'tcx hir::TraitRef<'tcx>) {
+        if let Some(trait_def_id) = t.path.res.opt_def_id()
+            && let Some(segment) = t.path.segments.last()
+            && let Some(args) = segment.args
+        {
+            for constraint in args.constraints {
+                if let Some(local_def_id) = self
+                    .tcx
+                    .associated_items(trait_def_id)
+                    .find_by_ident_and_kind(
+                        self.tcx,
+                        constraint.ident,
+                        AssocTag::Const,
+                        trait_def_id,
+                    )
+                    .and_then(|item| item.def_id.as_local())
+                {
+                    self.worklist.push((local_def_id, ComesFromAllowExpect::No));
+                }
+            }
+        }
+
+        intravisit::walk_trait_ref(self, t);
+    }
 }
 
 fn has_allow_dead_code_or_lang_attr(
@@ -744,18 +772,12 @@ fn check_item<'tcx>(
                 {
                     worklist.push((local_def_id, comes_from_allow));
                 } else if of_trait {
-                    // FIXME: This condition can be removed
-                    // if we support dead check for assoc consts and tys.
-                    if !matches!(tcx.def_kind(local_def_id), DefKind::AssocFn) {
-                        worklist.push((local_def_id, ComesFromAllowExpect::No));
-                    } else {
-                        // We only care about associated items of traits,
-                        // because they cannot be visited directly,
-                        // so we later mark them as live if their corresponding traits
-                        // or trait items and self types are both live,
-                        // but inherent associated items can be visited and marked directly.
-                        unsolved_items.push((id, local_def_id));
-                    }
+                    // We only care about associated items of traits,
+                    // because they cannot be visited directly,
+                    // so we later mark them as live if their corresponding traits
+                    // or trait items and self types are both live,
+                    // but inherent associated items can be visited and marked directly.
+                    unsolved_items.push((id, local_def_id));
                 }
             }
         }
@@ -791,15 +813,14 @@ fn check_trait_item(
     worklist: &mut Vec<(LocalDefId, ComesFromAllowExpect)>,
     id: hir::TraitItemId,
 ) {
-    use hir::TraitItemKind::{Const, Fn};
-    if matches!(tcx.def_kind(id.owner_id), DefKind::AssocConst | DefKind::AssocFn) {
-        let trait_item = tcx.hir_trait_item(id);
-        if matches!(trait_item.kind, Const(_, Some(_)) | Fn(..))
-            && let Some(comes_from_allow) =
-                has_allow_dead_code_or_lang_attr(tcx, trait_item.owner_id.def_id)
-        {
-            worklist.push((trait_item.owner_id.def_id, comes_from_allow));
-        }
+    use hir::TraitItemKind::{Const, Fn, Type};
+
+    let trait_item = tcx.hir_trait_item(id);
+    if matches!(trait_item.kind, Const(_, Some(_)) | Type(_, Some(_)) | Fn(..))
+        && let Some(comes_from_allow) =
+            has_allow_dead_code_or_lang_attr(tcx, trait_item.owner_id.def_id)
+    {
+        worklist.push((trait_item.owner_id.def_id, comes_from_allow));
     }
 }
 
@@ -1163,6 +1184,7 @@ impl<'tcx> DeadVisitor<'tcx> {
         }
         match self.tcx.def_kind(def_id) {
             DefKind::AssocConst
+            | DefKind::AssocTy
             | DefKind::AssocFn
             | DefKind::Fn
             | DefKind::Static { .. }

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -32,10 +32,9 @@ use crate::def_collector::collect_definitions;
 use crate::imports::{ImportData, ImportKind};
 use crate::macros::{MacroRulesBinding, MacroRulesScope, MacroRulesScopeRef};
 use crate::{
-    BindingKey, Determinacy, ExternPreludeEntry, Finalize, MacroData, Module, ModuleKind,
-    ModuleOrUniformRoot, NameBinding, NameBindingData, NameBindingKind, ParentScope, PathResult,
-    ResolutionError, Resolver, ResolverArenas, Segment, ToNameBinding, Used, VisResolutionError,
-    errors,
+    BindingKey, ExternPreludeEntry, Finalize, MacroData, Module, ModuleKind, ModuleOrUniformRoot,
+    NameBinding, NameBindingData, NameBindingKind, ParentScope, PathResult, ResolutionError,
+    Resolver, ResolverArenas, Segment, ToNameBinding, Used, VisResolutionError, errors,
 };
 
 type Res = def::Res<NodeId>;
@@ -620,16 +619,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                 let kind = ImportKind::Single {
                     source: source.ident,
                     target: ident,
-                    source_bindings: PerNS {
-                        type_ns: Cell::new(Err(Determinacy::Undetermined)),
-                        value_ns: Cell::new(Err(Determinacy::Undetermined)),
-                        macro_ns: Cell::new(Err(Determinacy::Undetermined)),
-                    },
-                    target_bindings: PerNS {
-                        type_ns: Cell::new(None),
-                        value_ns: Cell::new(None),
-                        macro_ns: Cell::new(None),
-                    },
+                    bindings: Default::default(),
                     type_ns_only,
                     nested,
                     id,

compiler/rustc_resolve/src/check_unused.rs

@@ -511,7 +511,7 @@ impl Resolver<'_, '_> {
             for (_key, resolution) in self.resolutions(*module).borrow().iter() {
                 let resolution = resolution.borrow();
 
-                if let Some(binding) = resolution.binding
+                if let Some(binding) = resolution.best_binding()
                     && let NameBindingKind::Import { import, .. } = binding.kind
                     && let ImportKind::Single { id, .. } = import.kind
                 {

compiler/rustc_resolve/src/diagnostics.rs

@@ -1440,7 +1440,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         |(key, name_resolution)| {
                             if key.ns == TypeNS
                                 && key.ident == ident
-                                && let Some(binding) = name_resolution.borrow().binding
+                                && let Some(binding) = name_resolution.borrow().best_binding()
                             {
                                 match binding.res() {
                                     // No disambiguation needed if the identically named item we
@@ -1494,7 +1494,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     return None;
                 };
                 for (_, resolution) in this.resolutions(m).borrow().iter() {
-                    let Some(binding) = resolution.borrow().binding else {
+                    let Some(binding) = resolution.borrow().best_binding() else {
                         continue;
                     };
                     let Res::Def(DefKind::Macro(MacroKind::Derive | MacroKind::Attr), def_id) =

compiler/rustc_resolve/src/ident.rs

@@ -875,15 +875,15 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // binding if it exists. What we really want here is having two separate scopes in
         // a module - one for non-globs and one for globs, but until that's done use this
         // hack to avoid inconsistent resolution ICEs during import validation.
-        let binding = [resolution.binding, resolution.shadowed_glob]
+        let binding = [resolution.non_glob_binding, resolution.glob_binding]
             .into_iter()
             .find_map(|binding| if binding == ignore_binding { None } else { binding });
 
         if let Some(finalize) = finalize {
             return self.finalize_module_binding(
                 ident,
                 binding,
-                resolution.shadowed_glob,
+                if resolution.non_glob_binding.is_some() { resolution.glob_binding } else { None },
                 parent_scope,
                 finalize,
                 shadowing,
@@ -1090,14 +1090,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             let Some(module) = single_import.imported_module.get() else {
                 return true;
             };
-            let ImportKind::Single { source, target, target_bindings, .. } = &single_import.kind
-            else {
+            let ImportKind::Single { source, target, bindings, .. } = &single_import.kind else {
                 unreachable!();
             };
             if source != target {
-                if target_bindings.iter().all(|binding| binding.get().is_none()) {
+                if bindings.iter().all(|binding| binding.get().binding().is_none()) {
                     return true;
-                } else if target_bindings[ns].get().is_none() && binding.is_some() {
+                } else if bindings[ns].get().binding().is_none() && binding.is_some() {
                     return true;
                 }
             }