Merge ref '51ff895062ba' from rust-lang/rust

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

Upstream ref: 51ff895
Filtered ref: 5057370cda58bcaad24ea094ec11c8c01b24c2bc

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

Author: The Miri Cronjob Bot

Cargo.lock

@@ -158,11 +158,11 @@ checksum = "b0674a1ddeecb70197781e945de4b3b8ffb61fa939a5597bcf48503737663100"
 
 [[package]]
 name = "ar_archive_writer"
-version = "0.4.2"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "01667f6f40216b9a0b2945e05fed5f1ad0ab6470e69cb9378001e37b1c0668e4"
+checksum = "7eb93bbb63b9c227414f6eb3a0adfddca591a8ce1e9b60661bb08969b87e340b"
 dependencies = [
- "object 0.36.7",
+ "object 0.37.3",
 ]
 
 [[package]]

Cargo.toml

@@ -59,33 +59,6 @@ exclude = [
   "obj",
 ]
 
-[workspace.dependencies]
-# tidy-alphabetical-start
-bitflags = "2.9.3"
-derive-where = "1.6.0"
-either = "1.15.0"
-indexmap = "2.10.0"
-itertools = "0.12.1"
-# FIXME: Remove this pin once this rustix issue is resolved
-# https://github.com/bytecodealliance/rustix/issues/1496
-libc = "=0.2.174"
-measureme = "12.0.3"
-memchr = "2.7.5"
-odht = { version = "0.3.1", features = ["nightly"] }
-polonius-engine = "0.13.0"
-proc-macro2 = "1.0.101"
-quote = "1.0.40"
-rustc-demangle = "0.1.26"
-rustc-hash = "2.1.1"
-rustc-literal-escaper = "0.0.5"
-rustc_apfloat = "0.2.3"
-scoped-tls = "1.0.1"
-serde_json = "1.0.142"
-tempfile = "3.20.0"
-thin-vec = "0.2.14"
-tracing = "0.1.37"
-# tidy-alphabetical-end
-
 [profile.release.package.rustc_thread_pool]
 # The rustc fork of Rayon has deadlock detection code which intermittently
 # causes overflows in the CI (see https://github.com/rust-lang/rust/issues/90227)

compiler/rustc_abi/Cargo.toml

@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags.workspace = true
+bitflags = "2.4.1"
 rand = { version = "0.9.0", default-features = false, optional = true }
 rand_xoshiro = { version = "0.7.0", optional = true }
 rustc_data_structures = { path = "../rustc_data_structures", optional = true }
@@ -15,7 +15,7 @@ rustc_index = { path = "../rustc_index", default-features = false }
 rustc_macros = { path = "../rustc_macros", optional = true }
 rustc_serialize = { path = "../rustc_serialize", optional = true }
 rustc_span = { path = "../rustc_span", optional = true }
-tracing.workspace = true
+tracing = "0.1"
 # tidy-alphabetical-end
 
 [features]

compiler/rustc_abi/src/extern_abi.rs

@@ -6,6 +6,8 @@ use std::hash::{Hash, Hasher};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableOrd};
 #[cfg(feature = "nightly")]
 use rustc_macros::{Decodable, Encodable};
+#[cfg(feature = "nightly")]
+use rustc_span::Symbol;
 
 use crate::AbiFromStrErr;
 
@@ -226,6 +228,13 @@ impl StableOrd for ExternAbi {
 #[cfg(feature = "nightly")]
 rustc_error_messages::into_diag_arg_using_display!(ExternAbi);
 
+#[cfg(feature = "nightly")]
+pub enum CVariadicStatus {
+    NotSupported,
+    Stable,
+    Unstable { feature: Symbol },
+}
+
 impl ExternAbi {
     /// An ABI "like Rust"
     ///
@@ -238,23 +247,33 @@ impl ExternAbi {
         matches!(self, Rust | RustCall | RustCold)
     }
 
-    pub fn supports_varargs(self) -> bool {
+    /// Returns whether the ABI supports C variadics. This only controls whether we allow *imports*
+    /// of such functions via `extern` blocks; there's a separate check during AST construction
+    /// guarding *definitions* of variadic functions.
+    #[cfg(feature = "nightly")]
+    pub fn supports_c_variadic(self) -> CVariadicStatus {
         // * C and Cdecl obviously support varargs.
         // * C can be based on Aapcs, SysV64 or Win64, so they must support varargs.
         // * EfiApi is based on Win64 or C, so it also supports it.
+        // * System automatically falls back to C when used with variadics, therefore supports it.
         //
         // * Stdcall does not, because it would be impossible for the callee to clean
         //   up the arguments. (callee doesn't know how many arguments are there)
         // * Same for Fastcall, Vectorcall and Thiscall.
         // * Other calling conventions are related to hardware or the compiler itself.
+        //
+        // All of the supported ones must have a test in `tests/codegen/cffi/c-variadic-ffi.rs`.
         match self {
             Self::C { .. }
             | Self::Cdecl { .. }
             | Self::Aapcs { .. }
             | Self::Win64 { .. }
             | Self::SysV64 { .. }
-            | Self::EfiApi => true,
-            _ => false,
+            | Self::EfiApi => CVariadicStatus::Stable,
+            Self::System { .. } => {
+                CVariadicStatus::Unstable { feature: rustc_span::sym::extern_system_varargs }
+            }
+            _ => CVariadicStatus::NotSupported,
         }
     }
 }

compiler/rustc_abi/src/lib.rs

@@ -63,6 +63,8 @@ mod tests;
 
 pub use callconv::{Heterogeneous, HomogeneousAggregate, Reg, RegKind};
 pub use canon_abi::{ArmCall, CanonAbi, InterruptKind, X86Call};
+#[cfg(feature = "nightly")]
+pub use extern_abi::CVariadicStatus;
 pub use extern_abi::{ExternAbi, all_names};
 #[cfg(feature = "nightly")]
 pub use layout::{FIRST_VARIANT, FieldIdx, Layout, TyAbiInterface, TyAndLayout, VariantIdx};

compiler/rustc_ast/Cargo.toml

@@ -5,16 +5,16 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags.workspace = true
-memchr.workspace = true
-rustc-literal-escaper.workspace = true
+bitflags = "2.4.1"
+memchr = "2.7.4"
+rustc-literal-escaper = "0.0.5"
 rustc_ast_ir = { path = "../rustc_ast_ir" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec.workspace = true
-tracing.workspace = true
+thin-vec = "0.2.12"
+tracing = "0.1"
 # tidy-alphabetical-end

compiler/rustc_ast/src/ast.rs

@@ -937,7 +937,7 @@ pub enum PatKind {
 #[derive(Clone, Copy, Encodable, Decodable, Debug, PartialEq, Walkable)]
 pub enum PatFieldsRest {
     /// `module::StructName { field, ..}`
-    Rest,
+    Rest(Span),
     /// `module::StructName { field, syntax error }`
     Recovered(ErrorGuaranteed),
     /// `module::StructName { field }`
@@ -4051,8 +4051,8 @@ mod size_asserts {
     static_assert_size!(Local, 96);
     static_assert_size!(MetaItemLit, 40);
     static_assert_size!(Param, 40);
-    static_assert_size!(Pat, 72);
-    static_assert_size!(PatKind, 48);
+    static_assert_size!(Pat, 80);
+    static_assert_size!(PatKind, 56);
     static_assert_size!(Path, 24);
     static_assert_size!(PathSegment, 24);
     static_assert_size!(Stmt, 32);

compiler/rustc_ast_lowering/Cargo.toml

@@ -24,6 +24,6 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec.workspace = true
-tracing.workspace = true
+thin-vec = "0.2.12"
+tracing = "0.1"
 # tidy-alphabetical-end

compiler/rustc_ast_lowering/src/expr.rs

@@ -1434,10 +1434,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         self.dcx().emit_err(FunctionalRecordUpdateDestructuringAssignment {
                             span: e.span,
                         });
-                        true
+                        Some(self.lower_span(e.span))
                     }
-                    StructRest::Rest(_) => true,
-                    StructRest::None => false,
+                    StructRest::Rest(span) => Some(self.lower_span(*span)),
+                    StructRest::None => None,
                 };
                 let struct_pat = hir::PatKind::Struct(qpath, field_pats, fields_omitted);
                 return self.pat_without_dbm(lhs.span, struct_pat);

compiler/rustc_ast_lowering/src/lib.rs

@@ -2028,7 +2028,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
                 (
                     hir::ParamName::Plain(self.lower_ident(param.ident)),
-                    hir::GenericParamKind::Const { ty, default, synthetic: false },
+                    hir::GenericParamKind::Const { ty, default },
                 )
             }
         }
@@ -2508,7 +2508,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         fields: &'hir [hir::PatField<'hir>],
     ) -> &'hir hir::Pat<'hir> {
         let qpath = hir::QPath::LangItem(lang_item, self.lower_span(span));
-        self.pat(span, hir::PatKind::Struct(qpath, fields, false))
+        self.pat(span, hir::PatKind::Struct(qpath, fields, None))
     }
 
     fn pat_ident(&mut self, span: Span, ident: Ident) -> (&'hir hir::Pat<'hir>, HirId) {