Auto merge of #116728 - matthiaskrgr:rollup-4xzcsnv, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #115653 (Guarantee that Layout::align returns a non-zero power of two)
 - #116577 (add `SAFETY` block on the usage of unsafe `getuid`)
 - #116618 (Add the V (vector) extension to the riscv64-linux-android target spec)
 - #116679 (Remove some unnecessary `unwrap`s)
 - #116689 (explicitly handle auto trait leakage in coherence)

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

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -604,8 +604,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return false;
         }
         let box_found = Ty::new_box(self.tcx, found);
-        let pin_box_found = Ty::new_lang_item(self.tcx, box_found, LangItem::Pin).unwrap();
+        let Some(pin_box_found) = Ty::new_lang_item(self.tcx, box_found, LangItem::Pin) else {
-        let pin_found = Ty::new_lang_item(self.tcx, found, LangItem::Pin).unwrap();
+            return false;
+        };
+        let Some(pin_found) = Ty::new_lang_item(self.tcx, found, LangItem::Pin) else {
+            return false;
+        };
         match expected.kind() {
             ty::Adt(def, _) if Some(def.did()) == pin_did => {
                 if self.can_coerce(pin_box_found, expected) {

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -1616,7 +1616,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         continue;
                     }
 
-                    let range_def_id = self.tcx.require_lang_item(lang_item.unwrap(), None);
+                    let Some(range_def_id) =
+                        lang_item.and_then(|lang_item| self.tcx.lang_items().get(lang_item))
+                    else {
+                        continue;
+                    };
                     let range_ty =
                         self.tcx.type_of(range_def_id).instantiate(self.tcx, &[actual.into()]);
 
@@ -2539,11 +2543,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     Err(_) => (),
                 }
 
-                let pred = ty::TraitRef::new(
+                let Some(unpin_trait) = self.tcx.lang_items().unpin_trait() else {
-                    self.tcx,
+                    return;
-                    self.tcx.lang_items().unpin_trait().unwrap(),
+                };
-                    [*rcvr_ty],
+                let pred = ty::TraitRef::new(self.tcx, unpin_trait, [*rcvr_ty]);
-                );
                 let unpin = self.predicate_must_hold_considering_regions(&Obligation::new(
                     self.tcx,
                     ObligationCause::misc(rcvr.span, self.body_id),

compiler/rustc_lint/src/unused.rs

@@ -353,7 +353,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                 ty::Generator(def_id, ..) => {
                     // async fn should be treated as "implementor of `Future`"
                     let must_use = if cx.tcx.generator_is_async(def_id) {
-                        let def_id = cx.tcx.lang_items().future_trait().unwrap();
+                        let def_id = cx.tcx.lang_items().future_trait()?;
                         is_def_must_use(cx, def_id, span)
                             .map(|inner| MustUsePath::Opaque(Box::new(inner)))
                     } else {

compiler/rustc_target/src/spec/riscv64_linux_android.rs

@@ -9,7 +9,7 @@ pub fn target() -> Target {
         options: TargetOptions {
             code_model: Some(CodeModel::Medium),
             cpu: "generic-rv64".into(),
-            features: "+m,+a,+f,+d,+c,+Zba,+Zbb,+Zbs".into(),
+            features: "+m,+a,+f,+d,+c,+zba,+zbb,+zbs,+v".into(),
             llvm_abiname: "lp64d".into(),
             supported_sanitizers: SanitizerSet::ADDRESS,
             max_atomic_width: Some(64),

compiler/rustc_trait_selection/src/solve/trait_goals.rs

@@ -136,12 +136,13 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
         // `assemble_candidates_after_normalizing_self_ty`, and we'd
         // just be registering an identical candidate here.
         //
-        // Returning `Err(NoSolution)` here is ok in `SolverMode::Coherence`
+        // We always return `Err(NoSolution)` here in `SolverMode::Coherence`
-        // since we'll always be registering an ambiguous candidate in
+        // since we'll always register an ambiguous candidate in
         // `assemble_candidates_after_normalizing_self_ty` due to normalizing
         // the TAIT.
         if let ty::Alias(ty::Opaque, opaque_ty) = goal.predicate.self_ty().kind() {
             if matches!(goal.param_env.reveal(), Reveal::All)
+                || matches!(ecx.solver_mode(), SolverMode::Coherence)
                 || opaque_ty
                     .def_id
                     .as_local()

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -492,7 +492,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     // this trait and type.
                 }
                 ty::Param(..)
-                | ty::Alias(ty::Projection | ty::Inherent, ..)
+                | ty::Alias(ty::Projection | ty::Inherent | ty::Weak, ..)
                 | ty::Placeholder(..)
                 | ty::Bound(..) => {
                     // In these cases, we don't know what the actual
@@ -536,20 +536,25 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     );
                 }
 
-                ty::Alias(_, _)
+                ty::Alias(ty::Opaque, _) => {
-                    if candidates.vec.iter().any(|c| matches!(c, ProjectionCandidate(..))) =>
+                    if candidates.vec.iter().any(|c| matches!(c, ProjectionCandidate(..))) {
-                {
+                        // We do not generate an auto impl candidate for `impl Trait`s which already
-                    // We do not generate an auto impl candidate for `impl Trait`s which already
+                        // reference our auto trait.
-                    // reference our auto trait.
+                        //
-                    //
+                        // For example during candidate assembly for `impl Send: Send`, we don't have
-                    // For example during candidate assembly for `impl Send: Send`, we don't have
+                        // to look at the constituent types for this opaque types to figure out that this
-                    // to look at the constituent types for this opaque types to figure out that this
+                        // trivially holds.
-                    // trivially holds.
+                        //
-                    //
+                        // Note that this is only sound as projection candidates of opaque types
-                    // Note that this is only sound as projection candidates of opaque types
+                        // are always applicable for auto traits.
-                    // are always applicable for auto traits.
+                    } else if self.infcx.intercrate {
+                        // We do not emit auto trait candidates for opaque types in coherence.
+                        // Doing so can result in weird dependency cycles.
+                        candidates.ambiguous = true;
+                    } else {
+                        candidates.vec.push(AutoImplCandidate)
+                    }
                 }
-                ty::Alias(_, _) => candidates.vec.push(AutoImplCandidate),
 
                 ty::Bool
                 | ty::Char

library/core/src/alloc/layout.rs

@@ -130,6 +130,8 @@ impl Layout {
     }
 
     /// The minimum byte alignment for a memory block of this layout.
+    ///
+    /// The returned alignment is guaranteed to be a power of two.
     #[stable(feature = "alloc_layout", since = "1.28.0")]
     #[rustc_const_stable(feature = "const_alloc_layout_size_align", since = "1.50.0")]
     #[must_use = "this returns the minimum alignment, \

src/bootstrap/lib.rs

@@ -359,6 +359,10 @@ impl Build {
         // https://github.com/rust-lang/rust/blob/a8a33cf27166d3eabaffc58ed3799e054af3b0c6/src/bootstrap/bootstrap.py#L796-L797
         let is_sudo = match env::var_os("SUDO_USER") {
             Some(_sudo_user) => {
+                // SAFETY: getuid() system call is always successful and no return value is reserved
+                // to indicate an error.
+                //
+                // For more context, see https://man7.org/linux/man-pages/man2/geteuid.2.html
                 let uid = unsafe { libc::getuid() };
                 uid == 0
             }

src/doc/rustc/src/platform-support/android.md

@@ -45,3 +45,19 @@ The riscv64-linux-android target is supported as a Tier 3 target.
 
 A list of all supported targets can be found
 [here](../platform-support.html)
+
+## Architecture Notes
+
+### riscv64-linux-android
+
+Currently the `riscv64-linux-android` target requires the following architecture features/extensions:
+
+* `a` (atomics)
+* `d` (double-precision floating-point)
+* `c` (compressed instruction set)
+* `f` (single-precision floating-point)
+* `m` (multiplication and division)
+* `v` (vector)
+* `Zba` (address calculation instructions)
+* `Zbb` (base instructions)
+* `Zbs` (single-bit instructions)

tests/ui/impl-trait/auto-trait-coherence.next.stderr

@@ -1,5 +1,5 @@
 error[E0119]: conflicting implementations of trait `AnotherTrait` for type `D<OpaqueType>`
-  --> $DIR/auto-trait.rs:21:1
+  --> $DIR/auto-trait-coherence.rs:24:1
    |
 LL | impl<T: Send> AnotherTrait for T {}
    | -------------------------------- first implementation here

tests/ui/impl-trait/auto-trait-coherence.old.stderr

@@ -0,0 +1,12 @@
+error[E0119]: conflicting implementations of trait `AnotherTrait` for type `D<OpaqueType>`
+  --> $DIR/auto-trait-coherence.rs:24:1
+   |
+LL | impl<T: Send> AnotherTrait for T {}
+   | -------------------------------- first implementation here
+...
+LL | impl AnotherTrait for D<OpaqueType> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `D<OpaqueType>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0119`.

tests/ui/impl-trait/auto-trait-coherence.rs

@@ -1,3 +1,6 @@
+// revisions: old next
+//[next] compile-flags: -Ztrait-solver=next
+
 // Tests that type alias impls traits do not leak auto-traits for
 // the purposes of coherence checking
 #![feature(type_alias_impl_trait)]