Auto merge of rust-lang#135101 - workingjubilee:rollup-owp3czl, r=workingjubilee

Rollup of 6 pull requests

Successful merges:

 - rust-lang#135046 (turn rustc_box into an intrinsic)
 - rust-lang#135061 (crashes: add latest batch of tests)
 - rust-lang#135070 (std: sync to dep versions of backtrace)
 - rust-lang#135088 (Force code generation in assembly generation smoke-tests)
 - rust-lang#135091 (Bump backtrace to 0.3.75)
 - rust-lang#135094 (bootstrap: If dir_is_empty fails, show the non-existent directory path)

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

Author: bors

compiler/rustc_feature/src/builtin_attrs.rs

@@ -933,11 +933,6 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         "#[rustc_has_incoherent_inherent_impls] allows the addition of incoherent inherent impls for \
          the given type by annotating all impl items with #[rustc_allow_incoherent_impl]."
     ),
-    rustc_attr!(
-        rustc_box, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
-        "#[rustc_box] allows creating boxes \
-        and it is only intended to be used in `alloc`."
-    ),
 
     BuiltinAttribute {
         name: sym::rustc_diagnostic_item,

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -86,6 +86,7 @@ pub fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -
         | sym::assert_inhabited
         | sym::assert_zero_valid
         | sym::assert_mem_uninitialized_valid
+        | sym::box_new
         | sym::breakpoint
         | sym::size_of
         | sym::min_align_of
@@ -606,6 +607,8 @@ pub fn check_intrinsic_type(
 
             sym::ub_checks => (0, 0, Vec::new(), tcx.types.bool),
 
+            sym::box_new => (1, 0, vec![param(0)], Ty::new_box(tcx, param(0))),
+
             sym::simd_eq
             | sym::simd_ne
             | sym::simd_lt

compiler/rustc_mir_build/messages.ftl

@@ -287,11 +287,6 @@ mir_build_privately_uninhabited = pattern `{$witness_1}` is currently uninhabite
 
 mir_build_rust_2024_incompatible_pat = this pattern relies on behavior which may change in edition 2024
 
-mir_build_rustc_box_attribute_error = `#[rustc_box]` attribute used incorrectly
-    .attributes = no other attributes may be applied
-    .not_box = `#[rustc_box]` may only be applied to a `Box::new()` call
-    .missing_box = `#[rustc_box]` requires the `owned_box` lang item
-
 mir_build_static_in_pattern = statics cannot be referenced in patterns
     .label = can't be used in patterns
 mir_build_static_in_pattern_def = `static` defined here

compiler/rustc_mir_build/src/errors.rs

@@ -1067,25 +1067,6 @@ pub(crate) enum MiscPatternSuggestion {
     },
 }
 
-#[derive(Diagnostic)]
-#[diag(mir_build_rustc_box_attribute_error)]
-pub(crate) struct RustcBoxAttributeError {
-    #[primary_span]
-    pub(crate) span: Span,
-    #[subdiagnostic]
-    pub(crate) reason: RustcBoxAttrReason,
-}
-
-#[derive(Subdiagnostic)]
-pub(crate) enum RustcBoxAttrReason {
-    #[note(mir_build_attributes)]
-    Attributes,
-    #[note(mir_build_not_box)]
-    NotBoxNew,
-    #[note(mir_build_missing_box)]
-    MissingBox,
-}
-
 #[derive(LintDiagnostic)]
 #[diag(mir_build_rust_2024_incompatible_pat)]
 pub(crate) struct Rust2024IncompatiblePat<'a> {

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -20,7 +20,6 @@ use rustc_middle::{bug, span_bug};
 use rustc_span::{Span, sym};
 use tracing::{debug, info, instrument, trace};
 
-use crate::errors;
 use crate::thir::cx::Cx;
 use crate::thir::util::UserAnnotatedTyHelpers;
 
@@ -380,45 +379,25 @@ impl<'tcx> Cx<'tcx> {
                         from_hir_call: true,
                         fn_span: expr.span,
                     }
-                } else {
-                    let attrs = tcx.hir().attrs(expr.hir_id);
-                    if attrs.iter().any(|a| a.name_or_empty() == sym::rustc_box) {
-                        if attrs.len() != 1 {
-                            tcx.dcx().emit_err(errors::RustcBoxAttributeError {
-                                span: attrs[0].span,
-                                reason: errors::RustcBoxAttrReason::Attributes,
-                            });
-                        } else if let Some(box_item) = tcx.lang_items().owned_box() {
-                            if let hir::ExprKind::Path(hir::QPath::TypeRelative(ty, fn_path)) =
-                                fun.kind
-                                && let hir::TyKind::Path(hir::QPath::Resolved(_, path)) = ty.kind
-                                && path.res.opt_def_id().is_some_and(|did| did == box_item)
-                                && fn_path.ident.name == sym::new
-                                && let [value] = args
-                            {
-                                return Expr {
-                                    temp_lifetime: TempLifetime {
-                                        temp_lifetime,
-                                        backwards_incompatible,
-                                    },
-                                    ty: expr_ty,
-                                    span: expr.span,
-                                    kind: ExprKind::Box { value: self.mirror_expr(value) },
-                                };
-                            } else {
-                                tcx.dcx().emit_err(errors::RustcBoxAttributeError {
-                                    span: expr.span,
-                                    reason: errors::RustcBoxAttrReason::NotBoxNew,
-                                });
-                            }
-                        } else {
-                            tcx.dcx().emit_err(errors::RustcBoxAttributeError {
-                                span: attrs[0].span,
-                                reason: errors::RustcBoxAttrReason::MissingBox,
-                            });
-                        }
+                } else if let ty::FnDef(def_id, _) = self.typeck_results().expr_ty(fun).kind()
+                    && let Some(intrinsic) = self.tcx.intrinsic(def_id)
+                    && intrinsic.name == sym::box_new
+                {
+                    // We don't actually evaluate `fun` here, so make sure that doesn't miss any side-effects.
+                    if !matches!(fun.kind, hir::ExprKind::Path(_)) {
+                        span_bug!(
+                            expr.span,
+                            "`box_new` intrinsic can only be called via path expression"
+                        );
                     }
-
+                    let value = &args[0];
+                    return Expr {
+                        temp_lifetime: TempLifetime { temp_lifetime, backwards_incompatible },
+                        ty: expr_ty,
+                        span: expr.span,
+                        kind: ExprKind::Box { value: self.mirror_expr(value) },
+                    };
+                } else {
                     // Tuple-like ADTs are represented as ExprKind::Call. We convert them here.
                     let adt_data = if let hir::ExprKind::Path(ref qpath) = fun.kind
                         && let Some(adt_def) = expr_ty.ty_adt_def()

compiler/rustc_span/src/symbol.rs

@@ -1696,7 +1696,6 @@ symbols! {
         rustc_as_ptr,
         rustc_attrs,
         rustc_autodiff,
-        rustc_box,
         rustc_builtin_macro,
         rustc_capture_analysis,
         rustc_clean,

library/Cargo.lock

@@ -4,21 +4,21 @@ version = 4
 
 [[package]]
 name = "addr2line"
-version = "0.22.0"
+version = "0.24.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6e4503c46a5c0c7844e948c9a4d6acd9f50cccb4de1c48eb9e291ea17470c678"
+checksum = "dfbe277e56a376000877090da837660b4427aad530e3028d44e0bffe4f89a1c1"
 dependencies = [
  "compiler_builtins",
- "gimli 0.29.0",
+ "gimli",
  "rustc-std-workspace-alloc",
  "rustc-std-workspace-core",
 ]
 
 [[package]]
-name = "adler"
-version = "1.0.2"
+name = "adler2"
+version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
+checksum = "512761e0bb2578dd7380c6baaa0f4ce03e84f95e960231d1dec8bf4d7d6e2627"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-core",
@@ -111,17 +111,6 @@ dependencies = [
  "unicode-width",
 ]
 
-[[package]]
-name = "gimli"
-version = "0.29.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "40ecd4077b5ae9fd2e9e169b102c6c330d0605168eb0e8bf79952b256dbefffd"
-dependencies = [
- "compiler_builtins",
- "rustc-std-workspace-alloc",
- "rustc-std-workspace-core",
-]
-
 [[package]]
 name = "gimli"
 version = "0.31.1"
@@ -177,11 +166,11 @@ dependencies = [
 
 [[package]]
 name = "miniz_oxide"
-version = "0.7.4"
+version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b8a240ddb74feaf34a79a7add65a741f3167852fba007066dcac1ca548d89c08"
+checksum = "4ffbe83022cedc1d264172192511ae958937694cd57ce297164951b8b3568394"
 dependencies = [
- "adler",
+ "adler2",
  "compiler_builtins",
  "rustc-std-workspace-alloc",
  "rustc-std-workspace-core",
@@ -408,7 +397,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "51f06a05848f650946acef3bf525fe96612226b61f74ae23ffa4e98bfbb8ab3c"
 dependencies = [
  "compiler_builtins",
- "gimli 0.31.1",
+ "gimli",
  "rustc-std-workspace-core",
 ]
 

library/alloc/src/alloc.rs

@@ -339,7 +339,7 @@ unsafe impl Allocator for Global {
     }
 }
 
-/// The allocator for unique pointers.
+/// The allocator for `Box`.
 #[cfg(all(not(no_global_oom_handling), not(test)))]
 #[lang = "exchange_malloc"]
 #[inline]

library/alloc/src/boxed.rs

@@ -233,6 +233,27 @@ pub struct Box<
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
 >(Unique<T>, A);
 
+/// Constructs a `Box<T>` by calling the `exchange_malloc` lang item and moving the argument into
+/// the newly allocated memory. This is an intrinsic to avoid unnecessary copies.
+///
+/// This is the surface syntax for `box <expr>` expressions.
+#[cfg(not(bootstrap))]
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+#[unstable(feature = "liballoc_internals", issue = "none")]
+pub fn box_new<T>(_x: T) -> Box<T> {
+    unreachable!()
+}
+
+/// Transition function for the next bootstrap bump.
+#[cfg(bootstrap)]
+#[unstable(feature = "liballoc_internals", issue = "none")]
+#[inline(always)]
+pub fn box_new<T>(x: T) -> Box<T> {
+    #[rustc_box]
+    Box::new(x)
+}
+
 impl<T> Box<T> {
     /// Allocates memory on the heap and then places `x` into it.
     ///
@@ -250,8 +271,7 @@ impl<T> Box<T> {
     #[rustc_diagnostic_item = "box_new"]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub fn new(x: T) -> Self {
-        #[rustc_box]
-        Box::new(x)
+        return box_new(x);
     }
 
     /// Constructs a new box with uninitialized contents.

library/alloc/src/lib.rs

@@ -168,6 +168,7 @@
 #![feature(dropck_eyepatch)]
 #![feature(fundamental)]
 #![feature(hashmap_internals)]
+#![feature(intrinsics)]
 #![feature(lang_items)]
 #![feature(min_specialization)]
 #![feature(multiple_supertrait_upcastable)]