Auto merge of rust-lang#117513 - matthiaskrgr:rollup-jvl6y84, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - rust-lang#117394 (use global cache when computing proof trees)
 - rust-lang#117495 (Clarify `Unsize` documentation)
 - rust-lang#117509 (Remove support for alias `-Z symbol-mangling-version`)
 - rust-lang#117512 (Expand mem::offset_of! docs)

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

Author: bors

compiler/rustc_interface/src/tests.rs

@@ -817,7 +817,6 @@ fn test_unstable_options_tracking_hash() {
     tracked!(split_lto_unit, Some(true));
     tracked!(src_hash_algorithm, Some(SourceFileHashAlgorithm::Sha1));
     tracked!(stack_protector, StackProtector::All);
-    tracked!(symbol_mangling_version, Some(SymbolManglingVersion::V0));
     tracked!(teach, true);
     tracked!(thinlto, Some(true));
     tracked!(thir_unsafeck, true);

compiler/rustc_middle/src/arena.rs

@@ -69,6 +69,7 @@ macro_rules! arena_types {
             [] dtorck_constraint: rustc_middle::traits::query::DropckConstraint<'tcx>,
             [] candidate_step: rustc_middle::traits::query::CandidateStep<'tcx>,
             [] autoderef_bad_ty: rustc_middle::traits::query::MethodAutoderefBadTy<'tcx>,
+            [] canonical_goal_evaluation: rustc_middle::traits::solve::inspect::GoalEvaluationStep<'tcx>,
             [] query_region_constraints: rustc_middle::infer::canonical::QueryRegionConstraints<'tcx>,
             [] type_op_subtype:
                 rustc_middle::infer::canonical::Canonical<'tcx,

compiler/rustc_middle/src/traits/solve/cache.rs

@@ -1,4 +1,4 @@
-use super::{CanonicalInput, QueryResult};
+use super::{inspect, CanonicalInput, QueryResult};
 use crate::ty::TyCtxt;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::Lock;
@@ -14,8 +14,10 @@ pub struct EvaluationCache<'tcx> {
     map: Lock<FxHashMap<CanonicalInput<'tcx>, CacheEntry<'tcx>>>,
 }
 
+#[derive(PartialEq, Eq)]
 pub struct CacheData<'tcx> {
     pub result: QueryResult<'tcx>,
+    pub proof_tree: Option<&'tcx [inspect::GoalEvaluationStep<'tcx>]>,
     pub reached_depth: usize,
     pub encountered_overflow: bool,
 }
@@ -24,22 +26,33 @@ impl<'tcx> EvaluationCache<'tcx> {
     /// Insert a final result into the global cache.
     pub fn insert(
         &self,
+        tcx: TyCtxt<'tcx>,
         key: CanonicalInput<'tcx>,
+        proof_tree: Option<&'tcx [inspect::GoalEvaluationStep<'tcx>]>,
         reached_depth: usize,
-        did_overflow: bool,
+        encountered_overflow: bool,
         cycle_participants: FxHashSet<CanonicalInput<'tcx>>,
         dep_node: DepNodeIndex,
         result: QueryResult<'tcx>,
     ) {
         let mut map = self.map.borrow_mut();
         let entry = map.entry(key).or_default();
-        let data = WithDepNode::new(dep_node, result);
+        let data = WithDepNode::new(dep_node, QueryData { result, proof_tree });
         entry.cycle_participants.extend(cycle_participants);
-        if did_overflow {
+        if encountered_overflow {
             entry.with_overflow.insert(reached_depth, data);
         } else {
             entry.success = Some(Success { data, reached_depth });
         }
+
+        if cfg!(debug_assertions) {
+            drop(map);
+            if Some(CacheData { result, proof_tree, reached_depth, encountered_overflow })
+                != self.get(tcx, key, |_| false, Limit(reached_depth))
+            {
+                bug!("unable to retrieve inserted element from cache: {key:?}");
+            }
+        }
     }
 
     /// Try to fetch a cached result, checking the recursion limit
@@ -62,27 +75,39 @@ impl<'tcx> EvaluationCache<'tcx> {
 
         if let Some(ref success) = entry.success {
             if available_depth.value_within_limit(success.reached_depth) {
+                let QueryData { result, proof_tree } = success.data.get(tcx);
                 return Some(CacheData {
-                    result: success.data.get(tcx),
+                    result,
+                    proof_tree,
                     reached_depth: success.reached_depth,
                     encountered_overflow: false,
                 });
             }
         }
 
-        entry.with_overflow.get(&available_depth.0).map(|e| CacheData {
-            result: e.get(tcx),
-            reached_depth: available_depth.0,
-            encountered_overflow: true,
+        entry.with_overflow.get(&available_depth.0).map(|e| {
+            let QueryData { result, proof_tree } = e.get(tcx);
+            CacheData {
+                result,
+                proof_tree,
+                reached_depth: available_depth.0,
+                encountered_overflow: true,
+            }
         })
     }
 }
 
 struct Success<'tcx> {
-    data: WithDepNode<QueryResult<'tcx>>,
+    data: WithDepNode<QueryData<'tcx>>,
     reached_depth: usize,
 }
 
+#[derive(Clone, Copy)]
+pub struct QueryData<'tcx> {
+    pub result: QueryResult<'tcx>,
+    pub proof_tree: Option<&'tcx [inspect::GoalEvaluationStep<'tcx>]>,
+}
+
 /// The cache entry for a goal `CanonicalInput`.
 ///
 /// This contains results whose computation never hit the
@@ -96,5 +121,5 @@ struct CacheEntry<'tcx> {
     /// See the doc comment of `StackEntry::cycle_participants` for more
     /// details.
     cycle_participants: FxHashSet<CanonicalInput<'tcx>>,
-    with_overflow: FxHashMap<usize, WithDepNode<QueryResult<'tcx>>>,
+    with_overflow: FxHashMap<usize, WithDepNode<QueryData<'tcx>>>,
 }

compiler/rustc_middle/src/traits/solve/inspect.rs

@@ -42,12 +42,6 @@ pub struct State<'tcx, T> {
 
 pub type CanonicalState<'tcx, T> = Canonical<'tcx, State<'tcx, T>>;
 
-#[derive(Debug, Eq, PartialEq)]
-pub enum CacheHit {
-    Provisional,
-    Global,
-}
-
 /// When evaluating the root goals we also store the
 /// original values for the `CanonicalVarValues` of the
 /// canonicalized goal. We use this to map any [CanonicalState]
@@ -78,8 +72,8 @@ pub struct CanonicalGoalEvaluation<'tcx> {
 #[derive(Eq, PartialEq)]
 pub enum CanonicalGoalEvaluationKind<'tcx> {
     Overflow,
-    CacheHit(CacheHit),
-    Uncached { revisions: Vec<GoalEvaluationStep<'tcx>> },
+    CycleInStack,
+    Evaluation { revisions: &'tcx [GoalEvaluationStep<'tcx>] },
 }
 impl Debug for GoalEvaluation<'_> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {

compiler/rustc_middle/src/traits/solve/inspect/format.rs

@@ -74,13 +74,10 @@ impl<'a, 'b> ProofTreeFormatter<'a, 'b> {
             CanonicalGoalEvaluationKind::Overflow => {
                 writeln!(self.f, "OVERFLOW: {:?}", eval.result)
             }
-            CanonicalGoalEvaluationKind::CacheHit(CacheHit::Global) => {
-                writeln!(self.f, "GLOBAL CACHE HIT: {:?}", eval.result)
+            CanonicalGoalEvaluationKind::CycleInStack => {
+                writeln!(self.f, "CYCLE IN STACK: {:?}", eval.result)
             }
-            CanonicalGoalEvaluationKind::CacheHit(CacheHit::Provisional) => {
-                writeln!(self.f, "PROVISIONAL CACHE HIT: {:?}", eval.result)
-            }
-            CanonicalGoalEvaluationKind::Uncached { revisions } => {
+            CanonicalGoalEvaluationKind::Evaluation { revisions } => {
                 for (n, step) in revisions.iter().enumerate() {
                     writeln!(self.f, "REVISION {n}")?;
                     self.nested(|this| this.format_evaluation_step(step))?;

compiler/rustc_session/src/config.rs

@@ -2674,28 +2674,19 @@ pub fn build_session_options(
         );
     }
 
-    // Handle both `-Z symbol-mangling-version` and `-C symbol-mangling-version`; the latter takes
-    // precedence.
-    match (cg.symbol_mangling_version, unstable_opts.symbol_mangling_version) {
-        (Some(smv_c), Some(smv_z)) if smv_c != smv_z => {
-            handler.early_error(
-                "incompatible values passed for `-C symbol-mangling-version` \
-                and `-Z symbol-mangling-version`",
-            );
-        }
-        (Some(SymbolManglingVersion::V0), _) => {}
-        (Some(_), _) if !unstable_opts.unstable_options => {
-            handler
-                .early_error("`-C symbol-mangling-version=legacy` requires `-Z unstable-options`");
-        }
-        (None, None) => {}
-        (None, smv) => {
-            handler.early_warn(
-                "`-Z symbol-mangling-version` is deprecated; use `-C symbol-mangling-version`",
-            );
-            cg.symbol_mangling_version = smv;
+    // Check for unstable values of `-C symbol-mangling-version`.
+    // This is what prevents them from being used on stable compilers.
+    match cg.symbol_mangling_version {
+        // Stable values:
+        None | Some(SymbolManglingVersion::V0) => {}
+        // Unstable values:
+        Some(SymbolManglingVersion::Legacy) => {
+            if !unstable_opts.unstable_options {
+                handler.early_error(
+                    "`-C symbol-mangling-version=legacy` requires `-Z unstable-options`",
+                );
+            }
         }
-        _ => {}
     }
 
     // Check for unstable values of `-C instrument-coverage`.

compiler/rustc_session/src/options.rs

@@ -1529,8 +1529,6 @@ options! {
     dump_solver_proof_tree: DumpSolverProofTree = (DumpSolverProofTree::Never, parse_dump_solver_proof_tree, [UNTRACKED],
         "dump a proof tree for every goal evaluated by the new trait solver. If the flag is specified without any options after it
         then it defaults to `always`. If the flag is not specified at all it defaults to `on-request`."),
-    dump_solver_proof_tree_use_cache: Option<bool> = (None, parse_opt_bool, [UNTRACKED],
-        "determines whether dumped proof trees use the global cache"),
     dwarf_version: Option<u32> = (None, parse_opt_number, [TRACKED],
         "version of DWARF debug information to emit (default: 2 or 4, depending on platform)"),
     dylib_lto: bool = (false, parse_bool, [UNTRACKED],
@@ -1823,9 +1821,6 @@ written to standard error output)"),
         "control if mem::uninitialized and mem::zeroed panic on more UB"),
     strip: Strip = (Strip::None, parse_strip, [UNTRACKED],
         "tell the linker which information to strip (`none` (default), `debuginfo` or `symbols`)"),
-    symbol_mangling_version: Option<SymbolManglingVersion> = (None,
-        parse_symbol_mangling_version, [TRACKED],
-        "which mangling version to use for symbol names ('legacy' (default) or 'v0')"),
     #[rustc_lint_opt_deny_field_access("use `Session::teach` instead of this field")]
     teach: bool = (false, parse_bool, [TRACKED],
         "show extended diagnostic help (default: no)"),

compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs

@@ -119,25 +119,11 @@ impl NestedGoals<'_> {
 
 #[derive(PartialEq, Eq, Debug, Hash, HashStable, Clone, Copy)]
 pub enum GenerateProofTree {
-    Yes(UseGlobalCache),
+    Yes,
     IfEnabled,
     Never,
 }
 
-#[derive(PartialEq, Eq, Debug, Hash, HashStable, Clone, Copy)]
-pub enum UseGlobalCache {
-    Yes,
-    No,
-}
-impl UseGlobalCache {
-    pub fn from_bool(use_cache: bool) -> Self {
-        match use_cache {
-            true => UseGlobalCache::Yes,
-            false => UseGlobalCache::No,
-        }
-    }
-}
-
 pub trait InferCtxtEvalExt<'tcx> {
     /// Evaluates a goal from **outside** of the trait solver.
     ///

compiler/rustc_trait_selection/src/solve/inspect/analyse.rs

@@ -17,7 +17,7 @@ use rustc_middle::traits::solve::{Certainty, Goal};
 use rustc_middle::ty;
 
 use crate::solve::inspect::ProofTreeBuilder;
-use crate::solve::{GenerateProofTree, InferCtxtEvalExt, UseGlobalCache};
+use crate::solve::{GenerateProofTree, InferCtxtEvalExt};
 
 pub struct InspectGoal<'a, 'tcx> {
     infcx: &'a InferCtxt<'tcx>,
@@ -82,8 +82,7 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
                 }
 
                 for &goal in &instantiated_goals {
-                    let (_, proof_tree) =
-                        infcx.evaluate_root_goal(goal, GenerateProofTree::Yes(UseGlobalCache::No));
+                    let (_, proof_tree) = infcx.evaluate_root_goal(goal, GenerateProofTree::Yes);
                     let proof_tree = proof_tree.unwrap();
                     visitor.visit_goal(&InspectGoal::new(
                         infcx,
@@ -169,11 +168,11 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
         let mut candidates = vec![];
         let last_eval_step = match self.evaluation.evaluation.kind {
             inspect::CanonicalGoalEvaluationKind::Overflow
-            | inspect::CanonicalGoalEvaluationKind::CacheHit(_) => {
+            | inspect::CanonicalGoalEvaluationKind::CycleInStack => {
                 warn!("unexpected root evaluation: {:?}", self.evaluation);
                 return vec![];
             }
-            inspect::CanonicalGoalEvaluationKind::Uncached { ref revisions } => {
+            inspect::CanonicalGoalEvaluationKind::Evaluation { ref revisions } => {
                 if let Some(last) = revisions.last() {
                     last
                 } else {
@@ -227,8 +226,7 @@ impl<'tcx> ProofTreeInferCtxtExt<'tcx> for InferCtxt<'tcx> {
         goal: Goal<'tcx, ty::Predicate<'tcx>>,
         visitor: &mut V,
     ) -> ControlFlow<V::BreakTy> {
-        let (_, proof_tree) =
-            self.evaluate_root_goal(goal, GenerateProofTree::Yes(UseGlobalCache::No));
+        let (_, proof_tree) = self.evaluate_root_goal(goal, GenerateProofTree::Yes);
         let proof_tree = proof_tree.unwrap();
         visitor.visit_goal(&InspectGoal::new(self, 0, &proof_tree))
     }