Auto merge of rust-lang#135095 - matthiaskrgr:rollup-tmgxckq, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#133964 (core: implement `bool::select_unpredictable`)
 - rust-lang#135001 (Allow using self-contained LLD in bootstrap)
 - rust-lang#135055 (Report impl method has stricter requirements even when RPITIT inference gets in the way)
 - rust-lang#135064 (const-in-pattern: test that the PartialEq impl does not need to be const)
 - rust-lang#135066 (bootstrap: support `./x check run-make-support`)
 - rust-lang#135069 (remove unused function params)
 - rust-lang#135084 (Update carrying_mul_add test to tolerate `nuw`)

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

Author: bors

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -529,6 +529,26 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
     let infcx = &tcx.infer_ctxt().build(TypingMode::non_body_analysis());
     let ocx = ObligationCtxt::new_with_diagnostics(infcx);
 
+    // Check that the where clauses of the impl are satisfied by the hybrid param env.
+    // You might ask -- what does this have to do with RPITIT inference? Nothing.
+    // We check these because if the where clauses of the signatures do not match
+    // up, then we don't want to give spurious other errors that point at the RPITITs.
+    // They're not necessary to check, though, because we already check them in
+    // `compare_method_predicate_entailment`.
+    let impl_m_own_bounds = tcx.predicates_of(impl_m_def_id).instantiate_own_identity();
+    for (predicate, span) in impl_m_own_bounds {
+        let normalize_cause = traits::ObligationCause::misc(span, impl_m_def_id);
+        let predicate = ocx.normalize(&normalize_cause, param_env, predicate);
+
+        let cause =
+            ObligationCause::new(span, impl_m_def_id, ObligationCauseCode::CompareImplItem {
+                impl_item_def_id: impl_m_def_id,
+                trait_item_def_id: trait_m.def_id,
+                kind: impl_m.kind,
+            });
+        ocx.register_obligation(traits::Obligation::new(tcx, cause, param_env, predicate));
+    }
+
     // Normalize the impl signature with fresh variables for lifetime inference.
     let misc_cause = ObligationCause::misc(return_span, impl_m_def_id);
     let impl_sig = ocx.normalize(

compiler/rustc_middle/src/ty/diagnostics.rs

@@ -69,10 +69,10 @@ impl<'tcx> Ty<'tcx> {
     /// description in error messages. This is used in the primary span label. Beyond what
     /// `is_simple_ty` includes, it also accepts ADTs with no type arguments and references to
     /// ADTs with no type arguments.
-    pub fn is_simple_text(self, tcx: TyCtxt<'tcx>) -> bool {
+    pub fn is_simple_text(self) -> bool {
         match self.kind() {
             Adt(_, args) => args.non_erasable_generics().next().is_none(),
-            Ref(_, ty, _) => ty.is_simple_text(tcx),
+            Ref(_, ty, _) => ty.is_simple_text(),
             _ => self.is_simple_ty(),
         }
     }

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -491,6 +491,10 @@ fn type_has_partial_eq_impl<'tcx>(
     // `PartialEq` for some lifetime but *not* for `'static`? If this ever becomes a problem
     // we'll need to leave some sort of trace of this requirement in the MIR so that borrowck
     // can ensure that the type really implements `PartialEq`.
+    // We also do *not* require `const PartialEq`, not even in `const fn`. This violates the model
+    // that patterns can only do things that the code could also do without patterns, but it is
+    // needed for backwards compatibility. The actual pattern matching compares primitive values,
+    // `PartialEq::eq` never gets invoked, so there's no risk of us running non-const code.
     (
         infcx.predicate_must_hold_modulo_regions(&partial_eq_obligation),
         automatically_derived,

compiler/rustc_mir_transform/src/coroutine.rs

@@ -1822,9 +1822,6 @@ impl<'tcx> Visitor<'tcx> for EnsureCoroutineFieldAssignmentsNeverAlias<'_> {
 fn check_suspend_tys<'tcx>(tcx: TyCtxt<'tcx>, layout: &CoroutineLayout<'tcx>, body: &Body<'tcx>) {
     let mut linted_tys = FxHashSet::default();
 
-    // We want a user-facing param-env.
-    let param_env = tcx.param_env(body.source.def_id());
-
     for (variant, yield_source_info) in
         layout.variant_fields.iter().zip(&layout.variant_source_info)
     {
@@ -1838,7 +1835,7 @@ fn check_suspend_tys<'tcx>(tcx: TyCtxt<'tcx>, layout: &CoroutineLayout<'tcx>, bo
                     continue;
                 };
 
-                check_must_not_suspend_ty(tcx, decl.ty, hir_id, param_env, SuspendCheckData {
+                check_must_not_suspend_ty(tcx, decl.ty, hir_id, SuspendCheckData {
                     source_span: decl.source_info.span,
                     yield_span: yield_source_info.span,
                     plural_len: 1,
@@ -1868,7 +1865,6 @@ fn check_must_not_suspend_ty<'tcx>(
     tcx: TyCtxt<'tcx>,
     ty: Ty<'tcx>,
     hir_id: hir::HirId,
-    param_env: ty::ParamEnv<'tcx>,
     data: SuspendCheckData<'_>,
 ) -> bool {
     if ty.is_unit() {
@@ -1883,16 +1879,13 @@ fn check_must_not_suspend_ty<'tcx>(
         ty::Adt(_, args) if ty.is_box() => {
             let boxed_ty = args.type_at(0);
             let allocator_ty = args.type_at(1);
-            check_must_not_suspend_ty(tcx, boxed_ty, hir_id, param_env, SuspendCheckData {
+            check_must_not_suspend_ty(tcx, boxed_ty, hir_id, SuspendCheckData {
                 descr_pre: &format!("{}boxed ", data.descr_pre),
                 ..data
-            }) || check_must_not_suspend_ty(
-                tcx,
-                allocator_ty,
-                hir_id,
-                param_env,
-                SuspendCheckData { descr_pre: &format!("{}allocator ", data.descr_pre), ..data },
-            )
+            }) || check_must_not_suspend_ty(tcx, allocator_ty, hir_id, SuspendCheckData {
+                descr_pre: &format!("{}allocator ", data.descr_pre),
+                ..data
+            })
         }
         ty::Adt(def, _) => check_must_not_suspend_def(tcx, def.did(), hir_id, data),
         // FIXME: support adding the attribute to TAITs
@@ -1937,7 +1930,7 @@ fn check_must_not_suspend_ty<'tcx>(
             let mut has_emitted = false;
             for (i, ty) in fields.iter().enumerate() {
                 let descr_post = &format!(" in tuple element {i}");
-                if check_must_not_suspend_ty(tcx, ty, hir_id, param_env, SuspendCheckData {
+                if check_must_not_suspend_ty(tcx, ty, hir_id, SuspendCheckData {
                     descr_post,
                     ..data
                 }) {
@@ -1948,7 +1941,7 @@ fn check_must_not_suspend_ty<'tcx>(
         }
         ty::Array(ty, len) => {
             let descr_pre = &format!("{}array{} of ", data.descr_pre, plural_suffix);
-            check_must_not_suspend_ty(tcx, ty, hir_id, param_env, SuspendCheckData {
+            check_must_not_suspend_ty(tcx, ty, hir_id, SuspendCheckData {
                 descr_pre,
                 // FIXME(must_not_suspend): This is wrong. We should handle printing unevaluated consts.
                 plural_len: len.try_to_target_usize(tcx).unwrap_or(0) as usize + 1,
@@ -1959,10 +1952,7 @@ fn check_must_not_suspend_ty<'tcx>(
         // may not be considered live across the await point.
         ty::Ref(_region, ty, _mutability) => {
             let descr_pre = &format!("{}reference{} to ", data.descr_pre, plural_suffix);
-            check_must_not_suspend_ty(tcx, ty, hir_id, param_env, SuspendCheckData {
-                descr_pre,
-                ..data
-            })
+            check_must_not_suspend_ty(tcx, ty, hir_id, SuspendCheckData { descr_pre, ..data })
         }
         _ => false,
     }

compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs

@@ -1496,8 +1496,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     ValuePairs::Terms(ExpectedFound { expected, found }) => {
                         match (expected.unpack(), found.unpack()) {
                             (ty::TermKind::Ty(expected), ty::TermKind::Ty(found)) => {
-                                let is_simple_err = expected.is_simple_text(self.tcx)
-                                    && found.is_simple_text(self.tcx);
+                                let is_simple_err =
+                                    expected.is_simple_text() && found.is_simple_text();
                                 OpaqueTypesVisitor::visit_expected_found(
                                     self.tcx, expected, found, span,
                                 )
@@ -1736,8 +1736,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         (true, _) => format!(" ({})", ty.sort_string(self.tcx)),
                         (false, _) => "".to_string(),
                     };
-                    if !(values.expected.is_simple_text(self.tcx)
-                        && values.found.is_simple_text(self.tcx))
+                    if !(values.expected.is_simple_text() && values.found.is_simple_text())
                         || (exp_found.is_some_and(|ef| {
                             // This happens when the type error is a subset of the expectation,
                             // like when you have two references but one is `usize` and the other

library/core/src/bool.rs

@@ -61,4 +61,52 @@ impl bool {
     pub fn then<T, F: FnOnce() -> T>(self, f: F) -> Option<T> {
         if self { Some(f()) } else { None }
     }
+
+    /// Returns either `true_val` or `false_val` depending on the value of
+    /// `self`, with a hint to the compiler that `self` is unlikely
+    /// to be correctly predicted by a CPU’s branch predictor.
+    ///
+    /// This method is functionally equivalent to
+    /// ```ignore (this is just for illustrative purposes)
+    /// fn select_unpredictable<T>(b: bool, true_val: T, false_val: T) -> T {
+    ///     if b { true_val } else { false_val }
+    /// }
+    /// ```
+    /// but might generate different assembly. In particular, on platforms with
+    /// a conditional move or select instruction (like `cmov` on x86 or `csel`
+    /// on ARM) the optimizer might use these instructions to avoid branches,
+    /// which can benefit performance if the branch predictor is struggling
+    /// with predicting `condition`, such as in an implementation of  binary
+    /// search.
+    ///
+    /// Note however that this lowering is not guaranteed (on any platform) and
+    /// should not be relied upon when trying to write constant-time code. Also
+    /// be aware that this lowering might *decrease* performance if `condition`
+    /// is well-predictable. It is advisable to perform benchmarks to tell if
+    /// this function is useful.
+    ///
+    /// # Examples
+    ///
+    /// Distribute values evenly between two buckets:
+    /// ```
+    /// #![feature(select_unpredictable)]
+    ///
+    /// use std::hash::BuildHasher;
+    ///
+    /// fn append<H: BuildHasher>(hasher: &H, v: i32, bucket_one: &mut Vec<i32>, bucket_two: &mut Vec<i32>) {
+    ///     let hash = hasher.hash_one(&v);
+    ///     let bucket = (hash % 2 == 0).select_unpredictable(bucket_one, bucket_two);
+    ///     bucket.push(v);
+    /// }
+    /// # let hasher = std::collections::hash_map::RandomState::new();
+    /// # let mut bucket_one = Vec::new();
+    /// # let mut bucket_two = Vec::new();
+    /// # append(&hasher, 42, &mut bucket_one, &mut bucket_two);
+    /// # assert_eq!(bucket_one.len() + bucket_two.len(), 1);
+    /// ```
+    #[inline(always)]
+    #[unstable(feature = "select_unpredictable", issue = "133962")]
+    pub fn select_unpredictable<T>(self, true_val: T, false_val: T) -> T {
+        crate::intrinsics::select_unpredictable(self, true_val, false_val)
+    }
 }

library/core/src/intrinsics/mod.rs

@@ -1545,7 +1545,7 @@ pub const fn unlikely(b: bool) -> bool {
 /// Therefore, implementations must not require the user to uphold
 /// any safety invariants.
 ///
-/// This intrinsic does not have a stable counterpart.
+/// The public form of this instrinsic is [`bool::select_unpredictable`].
 #[unstable(feature = "core_intrinsics", issue = "none")]
 #[rustc_intrinsic]
 #[rustc_nounwind]

library/core/src/slice/mod.rs

@@ -7,7 +7,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::cmp::Ordering::{self, Equal, Greater, Less};
-use crate::intrinsics::{exact_div, select_unpredictable, unchecked_sub};
+use crate::intrinsics::{exact_div, unchecked_sub};
 use crate::mem::{self, SizedTypeProperties};
 use crate::num::NonZero;
 use crate::ops::{Bound, OneSidedRange, Range, RangeBounds, RangeInclusive};
@@ -2835,7 +2835,7 @@ impl<T> [T] {
             // Binary search interacts poorly with branch prediction, so force
             // the compiler to use conditional moves if supported by the target
             // architecture.
-            base = select_unpredictable(cmp == Greater, base, mid);
+            base = (cmp == Greater).select_unpredictable(base, mid);
 
             // This is imprecise in the case where `size` is odd and the
             // comparison returns Greater: the mid element still gets included

src/bootstrap/src/core/build_steps/check.rs

@@ -491,6 +491,11 @@ tool_check_step!(MiroptTestTools { path: "src/tools/miropt-test-tools" });
 tool_check_step!(TestFloatParse { path: "src/etc/test-float-parse" });
 
 tool_check_step!(Bootstrap { path: "src/bootstrap", default: false });
+
+// `run-make-support` will be built as part of suitable run-make compiletest test steps, but support
+// check to make it easier to work on.
+tool_check_step!(RunMakeSupport { path: "src/tools/run-make-support", default: false });
+
 // Compiletest is implicitly "checked" when it gets built in order to run tests,
 // so this is mainly for people working on compiletest to run locally.
 tool_check_step!(Compiletest { path: "src/tools/compiletest", default: false });

src/bootstrap/src/core/build_steps/test.rs

@@ -1893,7 +1893,6 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
 
         let mut targetflags = flags;
         targetflags.push(format!("-Lnative={}", builder.test_helpers_out(target).display()));
-        targetflags.extend(linker_flags(builder, compiler.host, LldThreads::No));
         for flag in targetflags {
             cmd.arg("--target-rustcflags").arg(flag);
         }