Merge ref '401ae5542752' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: 401ae55
Filtered ref: 1bd47ec470de5c7eab11a24bfee0e7f663cd56a2
Upstream diff: 5f9dd05...401ae55

This merge was created using https://github.com/rust-lang/josh-sync.

Author: The Miri Cronjob Bot

compiler/rustc_abi/src/canon_abi.rs

@@ -51,6 +51,20 @@ pub enum CanonAbi {
     X86(X86Call),
 }
 
+impl CanonAbi {
+    pub fn is_rustic_abi(self) -> bool {
+        match self {
+            CanonAbi::Rust | CanonAbi::RustCold => true,
+            CanonAbi::C
+            | CanonAbi::Custom
+            | CanonAbi::Arm(_)
+            | CanonAbi::GpuKernel
+            | CanonAbi::Interrupt(_)
+            | CanonAbi::X86(_) => false,
+        }
+    }
+}
+
 impl fmt::Display for CanonAbi {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // convert to the ExternAbi that *shares a string* with this CanonAbi.

compiler/rustc_abi/src/layout.rs

@@ -812,7 +812,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         let (max, min) = largest_niche
             // We might have no inhabited variants, so pretend there's at least one.
             .unwrap_or((0, 0));
-        let (min_ity, signed) = discr_range_of_repr(min, max); //Integer::repr_discr(tcx, ty, &repr, min, max);
+        let (min_ity, signed) = discr_range_of_repr(min, max); //Integer::discr_range_of_repr(tcx, ty, &repr, min, max);
 
         let mut align = dl.aggregate_align;
         let mut max_repr_align = repr.align;

compiler/rustc_abi/src/layout/ty.rs

@@ -172,6 +172,8 @@ pub trait TyAbiInterface<'a, C>: Sized + std::fmt::Debug {
     fn is_tuple(this: TyAndLayout<'a, Self>) -> bool;
     fn is_unit(this: TyAndLayout<'a, Self>) -> bool;
     fn is_transparent(this: TyAndLayout<'a, Self>) -> bool;
+    /// See [`TyAndLayout::pass_indirectly_in_non_rustic_abis`] for details.
+    fn is_pass_indirectly_in_non_rustic_abis_flag_set(this: TyAndLayout<'a, Self>) -> bool;
 }
 
 impl<'a, Ty> TyAndLayout<'a, Ty> {
@@ -269,6 +271,30 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
         Ty::is_transparent(self)
     }
 
+    /// If this method returns `true`, then this type should always have a `PassMode` of
+    /// `Indirect { on_stack: false, .. }` when being used as the argument type of a function with a
+    /// non-Rustic ABI (this is true for structs annotated with the
+    /// `#[rustc_pass_indirectly_in_non_rustic_abis]` attribute).
+    ///
+    /// This is used to replicate some of the behaviour of C array-to-pointer decay; however unlike
+    /// C any changes the caller makes to the passed value will not be reflected in the callee, so
+    /// the attribute is only useful for types where observing the value in the caller after the
+    /// function call isn't allowed (a.k.a. `va_list`).
+    ///
+    /// This function handles transparent types automatically.
+    pub fn pass_indirectly_in_non_rustic_abis<C>(mut self, cx: &C) -> bool
+    where
+        Ty: TyAbiInterface<'a, C> + Copy,
+    {
+        while self.is_transparent()
+            && let Some((_, field)) = self.non_1zst_field(cx)
+        {
+            self = field;
+        }
+
+        Ty::is_pass_indirectly_in_non_rustic_abis_flag_set(self)
+    }
+
     /// Finds the one field that is not a 1-ZST.
     /// Returns `None` if there are multiple non-1-ZST fields or only 1-ZST-fields.
     pub fn non_1zst_field<C>(&self, cx: &C) -> Option<(FieldIdx, Self)>

compiler/rustc_abi/src/lib.rs

@@ -1,9 +1,7 @@
 // tidy-alphabetical-start
 #![cfg_attr(feature = "nightly", allow(internal_features))]
-#![cfg_attr(feature = "nightly", doc(rust_logo))]
 #![cfg_attr(feature = "nightly", feature(assert_matches))]
 #![cfg_attr(feature = "nightly", feature(rustc_attrs))]
-#![cfg_attr(feature = "nightly", feature(rustdoc_internals))]
 #![cfg_attr(feature = "nightly", feature(step_trait))]
 // tidy-alphabetical-end
 
@@ -88,14 +86,17 @@ bitflags! {
         const IS_C               = 1 << 0;
         const IS_SIMD            = 1 << 1;
         const IS_TRANSPARENT     = 1 << 2;
-        // Internal only for now. If true, don't reorder fields.
-        // On its own it does not prevent ABI optimizations.
+        /// Internal only for now. If true, don't reorder fields.
+        /// On its own it does not prevent ABI optimizations.
         const IS_LINEAR          = 1 << 3;
-        // If true, the type's crate has opted into layout randomization.
-        // Other flags can still inhibit reordering and thus randomization.
-        // The seed stored in `ReprOptions.field_shuffle_seed`.
+        /// If true, the type's crate has opted into layout randomization.
+        /// Other flags can still inhibit reordering and thus randomization.
+        /// The seed stored in `ReprOptions.field_shuffle_seed`.
         const RANDOMIZE_LAYOUT   = 1 << 4;
-        // Any of these flags being set prevent field reordering optimisation.
+        /// If true, the type is always passed indirectly by non-Rustic ABIs.
+        /// See [`TyAndLayout::pass_indirectly_in_non_rustic_abis`] for details.
+        const PASS_INDIRECTLY_IN_NON_RUSTIC_ABIS = 1 << 5;
+        /// Any of these flags being set prevent field reordering optimisation.
         const FIELD_ORDER_UNOPTIMIZABLE   = ReprFlags::IS_C.bits()
                                  | ReprFlags::IS_SIMD.bits()
                                  | ReprFlags::IS_LINEAR.bits();
@@ -183,6 +184,11 @@ impl ReprOptions {
 
     /// Returns the discriminant type, given these `repr` options.
     /// This must only be called on enums!
+    ///
+    /// This is the "typeck type" of the discriminant, which is effectively the maximum size:
+    /// discriminant values will be wrapped to fit (with a lint). Layout can later decide to use a
+    /// smaller type for the tag that stores the discriminant at runtime and that will work just
+    /// fine, it just induces casts when getting/setting the discriminant.
     pub fn discr_type(&self) -> IntegerType {
         self.int.unwrap_or(IntegerType::Pointer(true))
     }

compiler/rustc_arena/src/lib.rs

@@ -12,18 +12,13 @@
 #![allow(internal_features)]
 #![cfg_attr(test, feature(test))]
 #![deny(unsafe_op_in_unsafe_fn)]
-#![doc(
-    html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
-    test(no_crate_inject, attr(deny(warnings)))
-)]
-#![doc(rust_logo)]
+#![doc(test(no_crate_inject, attr(deny(warnings), allow(internal_features))))]
 #![feature(core_intrinsics)]
 #![feature(decl_macro)]
 #![feature(dropck_eyepatch)]
 #![feature(maybe_uninit_slice)]
 #![feature(never_type)]
 #![feature(rustc_attrs)]
-#![feature(rustdoc_internals)]
 #![feature(unwrap_infallible)]
 // tidy-alphabetical-end
 

compiler/rustc_ast/src/lib.rs

@@ -5,19 +5,13 @@
 //! This API is completely unstable and subject to change.
 
 // tidy-alphabetical-start
-#![allow(internal_features)]
-#![doc(
-    html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
-    test(attr(deny(warnings)))
-)]
-#![doc(rust_logo)]
+#![doc(test(attr(deny(warnings), allow(internal_features))))]
 #![feature(array_windows)]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(iter_order_by)]
 #![feature(macro_metavar_expr)]
-#![feature(rustdoc_internals)]
 #![recursion_limit = "256"]
 // tidy-alphabetical-end
 

compiler/rustc_ast_lowering/src/lib.rs

@@ -31,11 +31,8 @@
 //! in the HIR, especially for multiple identifiers.
 
 // tidy-alphabetical-start
-#![allow(internal_features)]
-#![doc(rust_logo)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
-#![feature(rustdoc_internals)]
 // tidy-alphabetical-end
 
 use std::sync::Arc;

compiler/rustc_ast_passes/src/lib.rs

@@ -3,12 +3,9 @@
 //! by `rustc_ast_lowering`.
 
 // tidy-alphabetical-start
-#![allow(internal_features)]
-#![doc(rust_logo)]
 #![feature(box_patterns)]
 #![feature(if_let_guard)]
 #![feature(iter_is_partitioned)]
-#![feature(rustdoc_internals)]
 // tidy-alphabetical-end
 
 pub mod ast_validation;

compiler/rustc_ast_pretty/src/lib.rs

@@ -1,9 +1,6 @@
 // tidy-alphabetical-start
-#![allow(internal_features)]
-#![doc(rust_logo)]
 #![feature(box_patterns)]
 #![feature(negative_impls)]
-#![feature(rustdoc_internals)]
 // tidy-alphabetical-end
 
 mod helpers;

compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs

@@ -676,3 +676,12 @@ impl<S: Stage> SingleAttributeParser<S> for SanitizeParser {
         Some(AttributeKind::Sanitize { on_set, off_set, span: cx.attr_span })
     }
 }
+
+pub(crate) struct RustcPassIndirectlyInNonRusticAbisParser;
+
+impl<S: Stage> NoArgsAttributeParser<S> for RustcPassIndirectlyInNonRusticAbisParser {
+    const PATH: &[Symbol] = &[sym::rustc_pass_indirectly_in_non_rustic_abis];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Struct)]);
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::RustcPassIndirectlyInNonRusticAbis;
+}