Auto merge of #154203 - Zalathar:rollup-tqV88T3, r=Zalathar

Rollup of 7 pull requests

Successful merges:

 - #122668 (Add APIs for dealing with titlecase)
 - #153312 (Packages as namespaces part 1)
 - #153534 (Remove a flaky `got_timeout` assert from two channel tests)
 - #154175 (Add new alias for Guillaume Gomez email address)
 - #154182 (diagnostics: avoid ICE for undeclared generic parameter in impl)
 - #154188 (Update the tracking issue for #[diagnostic::on_move])
 - #154201 (Use enums to clarify `DepNodeColorMap` color marking )

Author: bors

.mailmap

@@ -262,6 +262,7 @@ Guillaume Gomez <guillaume1.gomez@gmail.com>
 Guillaume Gomez <guillaume1.gomez@gmail.com> ggomez <ggomez@ggo.ifr.lan>
 Guillaume Gomez <guillaume1.gomez@gmail.com> Guillaume Gomez <ggomez@ggo.ifr.lan>
 Guillaume Gomez <guillaume1.gomez@gmail.com> Guillaume Gomez <guillaume.gomez@huawei.com>
+Guillaume Gomez <guillaume1.gomez@gmail.com> Guillaume Gomez <contact@guillaume-gomez.fr>
 gnzlbg <gonzalobg88@gmail.com> <gnzlbg@users.noreply.github.com>
 hamidreza kalbasi <hamidrezakalbasi@protonmail.com>
 Hanna Kruppe <hanna.kruppe@gmail.com> <robin.kruppe@gmail.com>

compiler/rustc_feature/src/unstable.rs

@@ -473,7 +473,7 @@ declare_features! (
     /// Allows giving non-const impls custom diagnostic messages if attempted to be used as const
     (unstable, diagnostic_on_const, "1.93.0", Some(143874)),
     /// Allows giving on-move borrowck custom diagnostic messages for a type
-    (unstable, diagnostic_on_move, "CURRENT_RUSTC_VERSION", Some(150935)),
+    (unstable, diagnostic_on_move, "CURRENT_RUSTC_VERSION", Some(154181)),
     /// Allows `#[doc(cfg(...))]`.
     (unstable, doc_cfg, "1.21.0", Some(43781)),
     /// Allows `#[doc(masked)]`.

compiler/rustc_hir/src/def.rs

@@ -590,6 +590,13 @@ pub enum Res<Id = hir::HirId> {
     /// **Belongs to the type namespace.**
     ToolMod,
 
+    /// The resolution for an open module in a namespaced crate. E.g. `my_api`
+    /// in the namespaced crate `my_api::utils` when `my_api` isn't part of the
+    /// extern prelude.
+    ///
+    /// **Belongs to the type namespace.**
+    OpenMod(Symbol),
+
     // Macro namespace
     /// An attribute that is *not* implemented via macro.
     /// E.g., `#[inline]` and `#[rustfmt::skip]`, which are essentially directives,
@@ -838,6 +845,7 @@ impl<Id> Res<Id> {
             | Res::SelfTyAlias { .. }
             | Res::SelfCtor(..)
             | Res::ToolMod
+            | Res::OpenMod(..)
             | Res::NonMacroAttr(..)
             | Res::Err => None,
         }
@@ -869,6 +877,7 @@ impl<Id> Res<Id> {
             Res::Local(..) => "local variable",
             Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } => "self type",
             Res::ToolMod => "tool module",
+            Res::OpenMod(..) => "namespaced crate",
             Res::NonMacroAttr(attr_kind) => attr_kind.descr(),
             Res::Err => "unresolved item",
         }
@@ -895,6 +904,7 @@ impl<Id> Res<Id> {
                 Res::SelfTyAlias { alias_to, is_trait_impl }
             }
             Res::ToolMod => Res::ToolMod,
+            Res::OpenMod(sym) => Res::OpenMod(sym),
             Res::NonMacroAttr(attr_kind) => Res::NonMacroAttr(attr_kind),
             Res::Err => Res::Err,
         }
@@ -911,6 +921,7 @@ impl<Id> Res<Id> {
                 Res::SelfTyAlias { alias_to, is_trait_impl }
             }
             Res::ToolMod => Res::ToolMod,
+            Res::OpenMod(sym) => Res::OpenMod(sym),
             Res::NonMacroAttr(attr_kind) => Res::NonMacroAttr(attr_kind),
             Res::Err => Res::Err,
         })
@@ -936,9 +947,11 @@ impl<Id> Res<Id> {
     pub fn ns(&self) -> Option<Namespace> {
         match self {
             Res::Def(kind, ..) => kind.ns(),
-            Res::PrimTy(..) | Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } | Res::ToolMod => {
-                Some(Namespace::TypeNS)
-            }
+            Res::PrimTy(..)
+            | Res::SelfTyParam { .. }
+            | Res::SelfTyAlias { .. }
+            | Res::ToolMod
+            | Res::OpenMod(..) => Some(Namespace::TypeNS),
             Res::SelfCtor(..) | Res::Local(..) => Some(Namespace::ValueNS),
             Res::NonMacroAttr(..) => Some(Namespace::MacroNS),
             Res::Err => None,

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2830,6 +2830,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             | Res::SelfCtor(_)
             | Res::Local(_)
             | Res::ToolMod
+            | Res::OpenMod(..)
             | Res::NonMacroAttr(_)
             | Res::Err) => Const::new_error_with_message(
                 tcx,

compiler/rustc_middle/src/dep_graph/graph.rs

@@ -164,9 +164,10 @@ impl DepGraph {
         );
         assert_eq!(red_node_index, DepNodeIndex::FOREVER_RED_NODE);
         if prev_graph_node_count > 0 {
-            colors.insert_red(SerializedDepNodeIndex::from_u32(
-                DepNodeIndex::FOREVER_RED_NODE.as_u32(),
-            ));
+            let prev_index =
+                const { SerializedDepNodeIndex::from_u32(DepNodeIndex::FOREVER_RED_NODE.as_u32()) };
+            let result = colors.try_set_color(prev_index, DesiredColor::Red);
+            assert_matches!(result, TrySetColorResult::Success);
         }
 
         DepGraph {
@@ -1415,28 +1416,29 @@ impl DepNodeColorMap {
         if value <= DepNodeIndex::MAX_AS_U32 { Some(DepNodeIndex::from_u32(value)) } else { None }
     }
 
-    /// This tries to atomically mark a node green and assign `index` as the new
-    /// index if `green` is true, otherwise it will try to atomicaly mark it red.
+    /// Atomically sets the color of a previous-session dep node to either green
+    /// or red, if it has not already been colored.
     ///
-    /// This returns `Ok` if `index` gets assigned or the node is marked red, otherwise it returns
-    /// the already allocated index in `Err` if it is green already. If it was already
-    /// red, `Err(None)` is returned.
+    /// If the node already has a color, the new color is ignored, and the
+    /// return value indicates the existing color.
     #[inline(always)]
-    pub(super) fn try_mark(
+    pub(super) fn try_set_color(
         &self,
         prev_index: SerializedDepNodeIndex,
-        index: DepNodeIndex,
-        green: bool,
-    ) -> Result<(), Option<DepNodeIndex>> {
-        let value = &self.values[prev_index];
-        match value.compare_exchange(
+        color: DesiredColor,
+    ) -> TrySetColorResult {
+        match self.values[prev_index].compare_exchange(
             COMPRESSED_UNKNOWN,
-            if green { index.as_u32() } else { COMPRESSED_RED },
+            match color {
+                DesiredColor::Red => COMPRESSED_RED,
+                DesiredColor::Green { index } => index.as_u32(),
+            },
             Ordering::Relaxed,
             Ordering::Relaxed,
         ) {
-            Ok(_) => Ok(()),
-            Err(v) => Err(if v == COMPRESSED_RED { None } else { Some(DepNodeIndex::from_u32(v)) }),
+            Ok(_) => TrySetColorResult::Success,
+            Err(COMPRESSED_RED) => TrySetColorResult::AlreadyRed,
+            Err(index) => TrySetColorResult::AlreadyGreen { index: DepNodeIndex::from_u32(index) },
         }
     }
 
@@ -1454,13 +1456,28 @@ impl DepNodeColorMap {
             DepNodeColor::Unknown
         }
     }
+}
 
-    #[inline]
-    pub(super) fn insert_red(&self, index: SerializedDepNodeIndex) {
-        let value = self.values[index].swap(COMPRESSED_RED, Ordering::Release);
-        // Sanity check for duplicate nodes
-        assert_eq!(value, COMPRESSED_UNKNOWN, "tried to color an already colored node as red");
-    }
+/// The color that [`DepNodeColorMap::try_set_color`] should try to apply to a node.
+#[derive(Clone, Copy, Debug)]
+pub(super) enum DesiredColor {
+    /// Try to mark the node red.
+    Red,
+    /// Try to mark the node green, associating it with a current-session node index.
+    Green { index: DepNodeIndex },
+}
+
+/// Return value of [`DepNodeColorMap::try_set_color`], indicating success or failure,
+/// and (on failure) what the existing color is.
+#[derive(Clone, Copy, Debug)]
+pub(super) enum TrySetColorResult {
+    /// The [`DesiredColor`] was freshly applied to the node.
+    Success,
+    /// Coloring failed because the node was already marked red.
+    AlreadyRed,
+    /// Coloring failed because the node was already marked green,
+    /// and corresponds to node `index` in the current-session dep graph.
+    AlreadyGreen { index: DepNodeIndex },
 }
 
 #[inline(never)]

compiler/rustc_middle/src/dep_graph/serialized.rs

@@ -58,7 +58,7 @@ use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use rustc_session::Session;
 use tracing::{debug, instrument};
 
-use super::graph::{CurrentDepGraph, DepNodeColorMap};
+use super::graph::{CurrentDepGraph, DepNodeColorMap, DesiredColor, TrySetColorResult};
 use super::retained::RetainedDepGraph;
 use super::{DepKind, DepNode, DepNodeIndex};
 use crate::dep_graph::edges::EdgesVec;
@@ -905,13 +905,14 @@ impl GraphEncoder {
         let mut local = self.status.local.borrow_mut();
 
         let index = self.status.next_index(&mut *local);
+        let color = if is_green { DesiredColor::Green { index } } else { DesiredColor::Red };
 
-        // Use `try_mark` to avoid racing when `send_promoted` is called concurrently
+        // Use `try_set_color` to avoid racing when `send_promoted` is called concurrently
         // on the same index.
-        match colors.try_mark(prev_index, index, is_green) {
-            Ok(()) => (),
-            Err(None) => panic!("dep node {:?} is unexpectedly red", prev_index),
-            Err(Some(dep_node_index)) => return dep_node_index,
+        match colors.try_set_color(prev_index, color) {
+            TrySetColorResult::Success => {}
+            TrySetColorResult::AlreadyRed => panic!("dep node {prev_index:?} is unexpectedly red"),
+            TrySetColorResult::AlreadyGreen { index } => return index,
         }
 
         self.status.bump_index(&mut *local);
@@ -923,7 +924,8 @@ impl GraphEncoder {
     /// from the previous dep graph and expects all edges to already have a new dep node index
     /// assigned.
     ///
-    /// This will also ensure the dep node is marked green if `Some` is returned.
+    /// Tries to mark the dep node green, and returns Some if it is now green,
+    /// or None if had already been concurrently marked red.
     #[inline]
     pub(crate) fn send_promoted(
         &self,
@@ -935,10 +937,10 @@ impl GraphEncoder {
         let mut local = self.status.local.borrow_mut();
         let index = self.status.next_index(&mut *local);
 
-        // Use `try_mark_green` to avoid racing when `send_promoted` or `send_and_color`
+        // Use `try_set_color` to avoid racing when `send_promoted` or `send_and_color`
         // is called concurrently on the same index.
-        match colors.try_mark(prev_index, index, true) {
-            Ok(()) => {
+        match colors.try_set_color(prev_index, DesiredColor::Green { index }) {
+            TrySetColorResult::Success => {
                 self.status.bump_index(&mut *local);
                 self.status.encode_promoted_node(
                     index,
@@ -949,7 +951,8 @@ impl GraphEncoder {
                 );
                 Some(index)
             }
-            Err(dep_node_index) => dep_node_index,
+            TrySetColorResult::AlreadyRed => None,
+            TrySetColorResult::AlreadyGreen { index } => Some(index),
         }
     }
 

compiler/rustc_passes/src/dead.rs

@@ -157,7 +157,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
             Res::Def(_, def_id) => self.check_def_id(def_id),
             Res::SelfTyParam { trait_: t } => self.check_def_id(t),
             Res::SelfTyAlias { alias_to: i, .. } => self.check_def_id(i),
-            Res::ToolMod | Res::NonMacroAttr(..) | Res::Err => {}
+            Res::ToolMod | Res::NonMacroAttr(..) | Res::OpenMod(..) | Res::Err => {}
         }
     }
 

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -357,6 +357,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             | Res::SelfTyParam { .. }
             | Res::SelfTyAlias { .. }
             | Res::SelfCtor(..)
+            | Res::OpenMod(..)
             | Res::Err => bug!("unexpected resolution: {:?}", res),
         }
     }

compiler/rustc_resolve/src/diagnostics.rs

@@ -1740,8 +1740,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 Res::Def(DefKind::Macro(kinds), _) => {
                     format!("{} {}", kinds.article(), kinds.descr())
                 }
-                Res::ToolMod => {
-                    // Don't confuse the user with tool modules.
+                Res::ToolMod | Res::OpenMod(..) => {
+                    // Don't confuse the user with tool modules or open modules.
                     continue;
                 }
                 Res::Def(DefKind::Trait, _) if macro_kind == MacroKind::Derive => {
@@ -1978,7 +1978,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             let (built_in, from) = match scope {
                 Scope::StdLibPrelude | Scope::MacroUsePrelude => ("", " from prelude"),
                 Scope::ExternPreludeFlags
-                    if self.tcx.sess.opts.externs.get(ident.as_str()).is_some() =>
+                    if self.tcx.sess.opts.externs.get(ident.as_str()).is_some()
+                        || matches!(res, Res::OpenMod(..)) =>
                 {
                     ("", " passed with `--extern`")
                 }

compiler/rustc_resolve/src/ident.rs

@@ -26,7 +26,7 @@ use crate::{
     AmbiguityError, AmbiguityKind, AmbiguityWarning, BindingKey, CmResolver, Decl, DeclKind,
     Determinacy, Finalize, IdentKey, ImportKind, LateDecl, Module, ModuleKind, ModuleOrUniformRoot,
     ParentScope, PathResult, PrivacyError, Res, ResolutionError, Resolver, Scope, ScopeSet,
-    Segment, Stage, Used, errors,
+    Segment, Stage, Symbol, Used, errors,
 };
 
 #[derive(Copy, Clone)]
@@ -386,7 +386,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     }
 
     /// Resolve an identifier in the specified set of scopes.
-    #[instrument(level = "debug", skip(self))]
     pub(crate) fn resolve_ident_in_scope_set<'r>(
         self: CmResolver<'r, 'ra, 'tcx>,
         orig_ident: Ident,
@@ -976,6 +975,14 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     ignore_import,
                 )
             }
+            ModuleOrUniformRoot::OpenModule(sym) => {
+                let open_ns_name = format!("{}::{}", sym.as_str(), ident.name);
+                let ns_ident = IdentKey::with_root_ctxt(Symbol::intern(&open_ns_name));
+                match self.extern_prelude_get_flag(ns_ident, ident.span, finalize.is_some()) {
+                    Some(decl) => Ok(decl),
+                    None => Err(Determinacy::Determined),
+                }
+            }
             ModuleOrUniformRoot::ModuleAndExternPrelude(module) => self.resolve_ident_in_scope_set(
                 ident,
                 ScopeSet::ModuleAndExternPrelude(ns, module),
@@ -1962,7 +1969,10 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     }
 
                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
-                    if let Some(def_id) = binding.res().module_like_def_id() {
+                    if let Res::OpenMod(sym) = binding.res() {
+                        module = Some(ModuleOrUniformRoot::OpenModule(sym));
+                        record_segment_res(self.reborrow(), finalize, res, id);
+                    } else if let Some(def_id) = binding.res().module_like_def_id() {
                         if self.mods_with_parse_errors.contains(&def_id) {
                             module_had_parse_errors = true;
                         }