From c620d76ae359d6005b91da7009aa652053ba6b47 Mon Sep 17 00:00:00 2001
From: Folkert de Vries <folkert@folkertdev.nl>
Date: Fri, 28 Feb 2025 19:18:54 +0100
Subject: [PATCH 01/12] move naked function assembly tests to their own
 directory

---
 .../{ => naked-functions}/aarch64-naked-fn-no-bti-prolog.rs       | 0
 tests/assembly/{wasm32-naked-fn.rs => naked-functions/wasm32.rs}  | 0
 .../{ => naked-functions}/x86_64-naked-fn-no-cet-prolog.rs        | 0
 3 files changed, 0 insertions(+), 0 deletions(-)
 rename tests/assembly/{ => naked-functions}/aarch64-naked-fn-no-bti-prolog.rs (100%)
 rename tests/assembly/{wasm32-naked-fn.rs => naked-functions/wasm32.rs} (100%)
 rename tests/assembly/{ => naked-functions}/x86_64-naked-fn-no-cet-prolog.rs (100%)

diff --git a/tests/assembly/aarch64-naked-fn-no-bti-prolog.rs b/tests/assembly/naked-functions/aarch64-naked-fn-no-bti-prolog.rs
similarity index 100%
rename from tests/assembly/aarch64-naked-fn-no-bti-prolog.rs
rename to tests/assembly/naked-functions/aarch64-naked-fn-no-bti-prolog.rs
diff --git a/tests/assembly/wasm32-naked-fn.rs b/tests/assembly/naked-functions/wasm32.rs
similarity index 100%
rename from tests/assembly/wasm32-naked-fn.rs
rename to tests/assembly/naked-functions/wasm32.rs
diff --git a/tests/assembly/x86_64-naked-fn-no-cet-prolog.rs b/tests/assembly/naked-functions/x86_64-naked-fn-no-cet-prolog.rs
similarity index 100%
rename from tests/assembly/x86_64-naked-fn-no-cet-prolog.rs
rename to tests/assembly/naked-functions/x86_64-naked-fn-no-cet-prolog.rs

From f35bda3997d285618b267f1b25eebff2ff467387 Mon Sep 17 00:00:00 2001
From: Folkert de Vries <folkert@folkertdev.nl>
Date: Fri, 28 Feb 2025 19:30:01 +0100
Subject: [PATCH 02/12] support XCOFF in `naked_asm!`

---
 .../rustc_codegen_ssa/src/mir/naked_asm.rs    | 50 +++++++++++++++----
 tests/assembly/naked-functions/aix.rs         | 35 +++++++++++++
 2 files changed, 76 insertions(+), 9 deletions(-)
 create mode 100644 tests/assembly/naked-functions/aix.rs

diff --git a/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs b/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
index 0593fb420c306..cfe96c45cbd9c 100644
--- a/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
@@ -125,7 +125,8 @@ fn prefix_and_suffix<'tcx>(
     // the alignment from a `#[repr(align(<n>))]` is used if it specifies a higher alignment.
     // if no alignment is specified, an alignment of 4 bytes is used.
     let min_function_alignment = tcx.sess.opts.unstable_opts.min_function_alignment;
-    let align = Ord::max(min_function_alignment, attrs.alignment).map(|a| a.bytes()).unwrap_or(4);
+    let align_bytes =
+        Ord::max(min_function_alignment, attrs.alignment).map(|a| a.bytes()).unwrap_or(4);
 
     // In particular, `.arm` can also be written `.code 32` and `.thumb` as `.code 16`.
     let (arch_prefix, arch_suffix) = if is_arm {
@@ -157,12 +158,16 @@ fn prefix_and_suffix<'tcx>(
             }
             Linkage::LinkOnceAny | Linkage::LinkOnceODR | Linkage::WeakAny | Linkage::WeakODR => {
                 match asm_binary_format {
-                    BinaryFormat::Elf
-                    | BinaryFormat::Coff
-                    | BinaryFormat::Wasm
-                    | BinaryFormat::Xcoff => {
+                    BinaryFormat::Elf | BinaryFormat::Coff | BinaryFormat::Wasm => {
                         writeln!(w, ".weak {asm_name}")?;
                     }
+                    BinaryFormat::Xcoff => {
+                        // FIXME: there is currently no way of defining a weak symbol in inline assembly
+                        // for AIX. See https://github.com/llvm/llvm-project/issues/130269
+                        emit_fatal(
+                            "cannot create weak symbols from inline assembly for this target",
+                        )
+                    }
                     BinaryFormat::MachO => {
                         writeln!(w, ".globl {asm_name}")?;
                         writeln!(w, ".weak_definition {asm_name}")?;
@@ -189,7 +194,7 @@ fn prefix_and_suffix<'tcx>(
     let mut begin = String::new();
     let mut end = String::new();
     match asm_binary_format {
-        BinaryFormat::Elf | BinaryFormat::Xcoff => {
+        BinaryFormat::Elf => {
             let section = link_section.unwrap_or(format!(".text.{asm_name}"));
 
             let progbits = match is_arm {
@@ -203,7 +208,7 @@ fn prefix_and_suffix<'tcx>(
             };
 
             writeln!(begin, ".pushsection {section},\"ax\", {progbits}").unwrap();
-            writeln!(begin, ".balign {align}").unwrap();
+            writeln!(begin, ".balign {align_bytes}").unwrap();
             write_linkage(&mut begin).unwrap();
             if let Visibility::Hidden = item_data.visibility {
                 writeln!(begin, ".hidden {asm_name}").unwrap();
@@ -224,7 +229,7 @@ fn prefix_and_suffix<'tcx>(
         BinaryFormat::MachO => {
             let section = link_section.unwrap_or("__TEXT,__text".to_string());
             writeln!(begin, ".pushsection {},regular,pure_instructions", section).unwrap();
-            writeln!(begin, ".balign {align}").unwrap();
+            writeln!(begin, ".balign {align_bytes}").unwrap();
             write_linkage(&mut begin).unwrap();
             if let Visibility::Hidden = item_data.visibility {
                 writeln!(begin, ".private_extern {asm_name}").unwrap();
@@ -240,7 +245,7 @@ fn prefix_and_suffix<'tcx>(
         BinaryFormat::Coff => {
             let section = link_section.unwrap_or(format!(".text.{asm_name}"));
             writeln!(begin, ".pushsection {},\"xr\"", section).unwrap();
-            writeln!(begin, ".balign {align}").unwrap();
+            writeln!(begin, ".balign {align_bytes}").unwrap();
             write_linkage(&mut begin).unwrap();
             writeln!(begin, ".def {asm_name}").unwrap();
             writeln!(begin, ".scl 2").unwrap();
@@ -279,6 +284,33 @@ fn prefix_and_suffix<'tcx>(
             // .size is ignored for function symbols, so we can skip it
             writeln!(end, "end_function").unwrap();
         }
+        BinaryFormat::Xcoff => {
+            // the LLVM XCOFFAsmParser is extremely incomplete and does not implement many of the
+            // documented directives.
+            //
+            // - https://github.com/llvm/llvm-project/blob/1b25c0c4da968fe78921ce77736e5baef4db75e3/llvm/lib/MC/MCParser/XCOFFAsmParser.cpp
+            // - https://www.ibm.com/docs/en/ssw_aix_71/assembler/assembler_pdf.pdf
+            //
+            // Consequently, we try our best here but cannot do as good a job as for other binary
+            // formats.
+
+            // FIXME: start a section. `.csect` is not currently implemented in LLVM
+
+            // fun fact: according to the assembler documentation, .align takes an exponent,
+            // but LLVM only accepts powers of 2 (but does emit the exponent)
+            // so when we hand `.align 32` to LLVM, the assembly output will contain `.align 5`
+            writeln!(begin, ".align {}", align_bytes).unwrap();
+
+            write_linkage(&mut begin).unwrap();
+            if let Visibility::Hidden = item_data.visibility {
+                // FIXME apparently `.globl {asm_name}, hidden` is valid
+                // but due to limitations with `.weak` (see above) we can't really use that in general yet
+            }
+            writeln!(begin, "{asm_name}:").unwrap();
+
+            writeln!(end).unwrap();
+            // FIXME: end the section?
+        }
     }
 
     (begin, end)
diff --git a/tests/assembly/naked-functions/aix.rs b/tests/assembly/naked-functions/aix.rs
new file mode 100644
index 0000000000000..cc0825b37387c
--- /dev/null
+++ b/tests/assembly/naked-functions/aix.rs
@@ -0,0 +1,35 @@
+//@ revisions: elfv1-be aix
+//@ add-core-stubs
+//@ assembly-output: emit-asm
+//
+//@[elfv1-be] compile-flags: --target powerpc64-unknown-linux-gnu
+//@[elfv1-be] needs-llvm-components: powerpc
+//
+//@[aix] compile-flags: --target powerpc64-ibm-aix
+//@[aix] needs-llvm-components: powerpc
+
+#![crate_type = "lib"]
+#![feature(no_core, naked_functions, asm_experimental_arch, f128, linkage, fn_align)]
+#![no_core]
+
+// tests that naked functions work for the `powerpc64-ibm-aix` target.
+//
+// This target is special because it uses the XCOFF binary format
+// It is tested alongside an elf powerpc target to pin down commonalities and differences.
+//
+// https://doc.rust-lang.org/rustc/platform-support/aix.html
+// https://www.ibm.com/docs/en/aix/7.2?topic=formats-xcoff-object-file-format
+
+extern crate minicore;
+use minicore::*;
+
+// elfv1-be: .p2align 2
+// aix: .align 2
+// CHECK: .globl blr
+// CHECK-LABEL: blr:
+// CHECK: blr
+#[no_mangle]
+#[naked]
+unsafe extern "C" fn blr() {
+    naked_asm!("blr")
+}

From 112f7b01a1b25035cd8b288d6936c6be48a3d845 Mon Sep 17 00:00:00 2001
From: morine0122 <k0000.m000.job@gmail.com>
Date: Sun, 2 Mar 2025 18:06:06 +0900
Subject: [PATCH 03/12] make precise capturing args in rustdoc Json typed

---
 compiler/rustc_hir/src/hir.rs                 | 11 +++++---
 compiler/rustc_hir_analysis/src/collect.rs    | 11 +++++---
 compiler/rustc_metadata/src/rmeta/mod.rs      |  3 ++-
 compiler/rustc_middle/src/query/mod.rs        |  4 +--
 compiler/rustc_middle/src/ty/parameterized.rs |  2 ++
 src/librustdoc/clean/mod.rs                   | 27 +++++++++++++++++--
 src/librustdoc/clean/types.rs                 | 17 +++++++++++-
 src/librustdoc/html/format.rs                 |  2 +-
 src/librustdoc/json/conversions.rs            | 13 ++++++++-
 src/rustdoc-json-types/lib.rs                 | 20 ++++++++++++--
 .../impl-trait-precise-capturing.rs           |  6 ++---
 11 files changed, 96 insertions(+), 20 deletions(-)

diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 928455ace8562..69327ca3c0083 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -3368,13 +3368,16 @@ pub struct OpaqueTy<'hir> {
     pub span: Span,
 }
 
-#[derive(Debug, Clone, Copy, HashStable_Generic)]
-pub enum PreciseCapturingArg<'hir> {
-    Lifetime(&'hir Lifetime),
+#[derive(Debug, Clone, Copy, HashStable_Generic, Encodable, Decodable)]
+pub enum PreciseCapturingArgKind<T, U> {
+    Lifetime(T),
     /// Non-lifetime argument (type or const)
-    Param(PreciseCapturingNonLifetimeArg),
+    Param(U),
 }
 
+pub type PreciseCapturingArg<'hir> =
+    PreciseCapturingArgKind<&'hir Lifetime, PreciseCapturingNonLifetimeArg>;
+
 impl PreciseCapturingArg<'_> {
     pub fn hir_id(self) -> HirId {
         match self {
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 49523912b14d3..33921547bbb4f 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -28,7 +28,7 @@ use rustc_errors::{
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::{self, InferKind, Visitor, VisitorExt, walk_generics};
-use rustc_hir::{self as hir, GenericParamKind, HirId, Node};
+use rustc_hir::{self as hir, GenericParamKind, HirId, Node, PreciseCapturingArgKind};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::ObligationCause;
 use rustc_middle::hir::nested_filter;
@@ -1792,7 +1792,7 @@ fn opaque_ty_origin<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> hir::OpaqueT
 fn rendered_precise_capturing_args<'tcx>(
     tcx: TyCtxt<'tcx>,
     def_id: LocalDefId,
-) -> Option<&'tcx [Symbol]> {
+) -> Option<&'tcx [PreciseCapturingArgKind<Symbol, Symbol>]> {
     if let Some(ty::ImplTraitInTraitData::Trait { opaque_def_id, .. }) =
         tcx.opt_rpitit_info(def_id.to_def_id())
     {
@@ -1801,7 +1801,12 @@ fn rendered_precise_capturing_args<'tcx>(
 
     tcx.hir_node_by_def_id(def_id).expect_opaque_ty().bounds.iter().find_map(|bound| match bound {
         hir::GenericBound::Use(args, ..) => {
-            Some(&*tcx.arena.alloc_from_iter(args.iter().map(|arg| arg.name())))
+            Some(&*tcx.arena.alloc_from_iter(args.iter().map(|arg| match arg {
+                PreciseCapturingArgKind::Lifetime(_) => {
+                    PreciseCapturingArgKind::Lifetime(arg.name())
+                }
+                PreciseCapturingArgKind::Param(_) => PreciseCapturingArgKind::Param(arg.name()),
+            })))
         }
         _ => None,
     })
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index 7b34e605c5307..5536c93f84a43 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -10,6 +10,7 @@ use rustc_abi::{FieldIdx, ReprOptions, VariantIdx};
 use rustc_ast::expand::StrippedCfgItem;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::svh::Svh;
+use rustc_hir::PreciseCapturingArgKind;
 use rustc_hir::def::{CtorKind, DefKind, DocLinkResMap};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIndex, DefPathHash, StableCrateId};
 use rustc_hir::definitions::DefKey;
@@ -440,7 +441,7 @@ define_tables! {
     coerce_unsized_info: Table<DefIndex, LazyValue<ty::adjustment::CoerceUnsizedInfo>>,
     mir_const_qualif: Table<DefIndex, LazyValue<mir::ConstQualifs>>,
     rendered_const: Table<DefIndex, LazyValue<String>>,
-    rendered_precise_capturing_args: Table<DefIndex, LazyArray<Symbol>>,
+    rendered_precise_capturing_args: Table<DefIndex, LazyArray<PreciseCapturingArgKind<Symbol, Symbol>>>,
     asyncness: Table<DefIndex, ty::Asyncness>,
     fn_arg_names: Table<DefIndex, LazyArray<Ident>>,
     coroutine_kind: Table<DefIndex, hir::CoroutineKind>,
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 3ad9201dd6f8e..86719766eacc1 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -25,7 +25,7 @@ use rustc_hir::def_id::{
     CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap, LocalDefIdSet, LocalModDefId,
 };
 use rustc_hir::lang_items::{LangItem, LanguageItems};
-use rustc_hir::{Crate, ItemLocalId, ItemLocalMap, TraitCandidate};
+use rustc_hir::{Crate, ItemLocalId, ItemLocalMap, PreciseCapturingArgKind, TraitCandidate};
 use rustc_index::IndexVec;
 use rustc_lint_defs::LintId;
 use rustc_macros::rustc_queries;
@@ -1430,7 +1430,7 @@ rustc_queries! {
     }
 
     /// Gets the rendered precise capturing args for an opaque for use in rustdoc.
-    query rendered_precise_capturing_args(def_id: DefId) -> Option<&'tcx [Symbol]> {
+    query rendered_precise_capturing_args(def_id: DefId) -> Option<&'tcx [PreciseCapturingArgKind<Symbol, Symbol>]> {
         desc { |tcx| "rendering precise capturing args for `{}`", tcx.def_path_str(def_id) }
         separate_provide_extern
     }
diff --git a/compiler/rustc_middle/src/ty/parameterized.rs b/compiler/rustc_middle/src/ty/parameterized.rs
index 8eaf0a58f7086..1b495a85a5fbd 100644
--- a/compiler/rustc_middle/src/ty/parameterized.rs
+++ b/compiler/rustc_middle/src/ty/parameterized.rs
@@ -3,6 +3,7 @@ use std::hash::Hash;
 use rustc_data_structures::unord::UnordMap;
 use rustc_hir::def_id::DefIndex;
 use rustc_index::{Idx, IndexVec};
+use rustc_span::Symbol;
 
 use crate::ty;
 
@@ -96,6 +97,7 @@ trivially_parameterized_over_tcx! {
     rustc_hir::def_id::DefIndex,
     rustc_hir::definitions::DefKey,
     rustc_hir::OpaqueTyOrigin<rustc_hir::def_id::DefId>,
+    rustc_hir::PreciseCapturingArgKind<Symbol, Symbol>,
     rustc_index::bit_set::DenseBitSet<u32>,
     rustc_index::bit_set::FiniteBitSet<u32>,
     rustc_session::cstore::ForeignModule,
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 97ff4c2ef4096..c0e37179e95ec 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -231,7 +231,7 @@ fn clean_generic_bound<'tcx>(
             GenericBound::TraitBound(clean_poly_trait_ref(t, cx), t.modifiers)
         }
         hir::GenericBound::Use(args, ..) => {
-            GenericBound::Use(args.iter().map(|arg| arg.name()).collect())
+            GenericBound::Use(args.iter().map(|arg| clean_precise_capturing_arg(arg, cx)).collect())
         }
     })
 }
@@ -286,6 +286,18 @@ fn clean_lifetime(lifetime: &hir::Lifetime, cx: &DocContext<'_>) -> Lifetime {
     Lifetime(lifetime.ident.name)
 }
 
+pub(crate) fn clean_precise_capturing_arg(
+    arg: &hir::PreciseCapturingArg<'_>,
+    cx: &DocContext<'_>,
+) -> PreciseCapturingArg {
+    match arg {
+        hir::PreciseCapturingArg::Lifetime(lt) => {
+            PreciseCapturingArg::Lifetime(clean_lifetime(lt, cx))
+        }
+        hir::PreciseCapturingArg::Param(param) => PreciseCapturingArg::Param(param.ident.name),
+    }
+}
+
 pub(crate) fn clean_const<'tcx>(
     constant: &hir::ConstArg<'tcx>,
     _cx: &mut DocContext<'tcx>,
@@ -2364,7 +2376,18 @@ fn clean_middle_opaque_bounds<'tcx>(
     }
 
     if let Some(args) = cx.tcx.rendered_precise_capturing_args(impl_trait_def_id) {
-        bounds.push(GenericBound::Use(args.to_vec()));
+        bounds.push(GenericBound::Use(
+            args.iter()
+                .map(|arg| match arg {
+                    hir::PreciseCapturingArgKind::Lifetime(lt) => {
+                        PreciseCapturingArg::Lifetime(Lifetime(*lt))
+                    }
+                    hir::PreciseCapturingArgKind::Param(param) => {
+                        PreciseCapturingArg::Param(*param)
+                    }
+                })
+                .collect(),
+        ));
     }
 
     ImplTrait(bounds)
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 9e9cd52883491..228d9108e4eb6 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1240,7 +1240,7 @@ pub(crate) enum GenericBound {
     TraitBound(PolyTrait, hir::TraitBoundModifiers),
     Outlives(Lifetime),
     /// `use<'a, T>` precise-capturing bound syntax
-    Use(Vec<Symbol>),
+    Use(Vec<PreciseCapturingArg>),
 }
 
 impl GenericBound {
@@ -1304,6 +1304,21 @@ impl Lifetime {
     }
 }
 
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
+pub(crate) enum PreciseCapturingArg {
+    Lifetime(Lifetime),
+    Param(Symbol),
+}
+
+impl PreciseCapturingArg {
+    pub(crate) fn name(self) -> Symbol {
+        match self {
+            PreciseCapturingArg::Lifetime(lt) => lt.0,
+            PreciseCapturingArg::Param(param) => param,
+        }
+    }
+}
+
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub(crate) enum WherePredicate {
     BoundPredicate { ty: Type, bounds: Vec<GenericBound>, bound_params: Vec<GenericParamDef> },
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 8b8439a253527..e93b9eb272a47 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -283,7 +283,7 @@ impl clean::GenericBound {
                 } else {
                     f.write_str("use&lt;")?;
                 }
-                args.iter().joined(", ", f)?;
+                args.iter().map(|arg| arg.name()).joined(", ", f)?;
                 if f.alternate() { f.write_str(">") } else { f.write_str("&gt;") }
             }
         })
diff --git a/src/librustdoc/json/conversions.rs b/src/librustdoc/json/conversions.rs
index 9606ba76991a7..d65c13b2b6313 100644
--- a/src/librustdoc/json/conversions.rs
+++ b/src/librustdoc/json/conversions.rs
@@ -548,7 +548,18 @@ impl FromClean<clean::GenericBound> for GenericBound {
                 }
             }
             Outlives(lifetime) => GenericBound::Outlives(convert_lifetime(lifetime)),
-            Use(args) => GenericBound::Use(args.into_iter().map(|arg| arg.to_string()).collect()),
+            Use(args) => GenericBound::Use(
+                args.iter()
+                    .map(|arg| match arg {
+                        clean::PreciseCapturingArg::Lifetime(lt) => {
+                            PreciseCapturingArg::Lifetime(convert_lifetime(*lt))
+                        }
+                        clean::PreciseCapturingArg::Param(param) => {
+                            PreciseCapturingArg::Param(param.to_string())
+                        }
+                    })
+                    .collect(),
+            ),
         }
     }
 }
diff --git a/src/rustdoc-json-types/lib.rs b/src/rustdoc-json-types/lib.rs
index 8f6496e9626c8..8ec7cffe06620 100644
--- a/src/rustdoc-json-types/lib.rs
+++ b/src/rustdoc-json-types/lib.rs
@@ -30,7 +30,7 @@ pub type FxHashMap<K, V> = HashMap<K, V>; // re-export for use in src/librustdoc
 /// This integer is incremented with every breaking change to the API,
 /// and is returned along with the JSON blob as [`Crate::format_version`].
 /// Consuming code should assert that this value matches the format version(s) that it supports.
-pub const FORMAT_VERSION: u32 = 40;
+pub const FORMAT_VERSION: u32 = 41;
 
 /// The root of the emitted JSON blob.
 ///
@@ -909,7 +909,7 @@ pub enum GenericBound {
     /// ```
     Outlives(String),
     /// `use<'a, T>` precise-capturing bound syntax
-    Use(Vec<String>),
+    Use(Vec<PreciseCapturingArg>),
 }
 
 /// A set of modifiers applied to a trait.
@@ -927,6 +927,22 @@ pub enum TraitBoundModifier {
     MaybeConst,
 }
 
+/// One precise capturing argument. See [the rust reference](https://doc.rust-lang.org/reference/types/impl-trait.html#precise-capturing).
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum PreciseCapturingArg {
+    /// A lifetime.
+    /// ```rust
+    /// pub fn hello<'a, T, const N: usize>() -> impl Sized + use<'a, T, N> {}
+    /// //                                                        ^^
+    Lifetime(String),
+    /// A type or constant parameter.
+    /// ```rust
+    /// pub fn hello<'a, T, const N: usize>() -> impl Sized + use<'a, T, N> {}
+    /// //                                                            ^  ^
+    Param(String),
+}
+
 /// Either a type or a constant, usually stored as the right-hand side of an equation in places like
 /// [`AssocItemConstraint`]
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
diff --git a/tests/rustdoc-json/impl-trait-precise-capturing.rs b/tests/rustdoc-json/impl-trait-precise-capturing.rs
index 52252560e6fda..06be95099b4d5 100644
--- a/tests/rustdoc-json/impl-trait-precise-capturing.rs
+++ b/tests/rustdoc-json/impl-trait-precise-capturing.rs
@@ -1,4 +1,4 @@
-//@ is "$.index[*][?(@.name=='hello')].inner.function.sig.output.impl_trait[1].use[0]" \"\'a\"
-//@ is "$.index[*][?(@.name=='hello')].inner.function.sig.output.impl_trait[1].use[1]" \"T\"
-//@ is "$.index[*][?(@.name=='hello')].inner.function.sig.output.impl_trait[1].use[2]" \"N\"
+//@ is "$.index[*][?(@.name=='hello')].inner.function.sig.output.impl_trait[1].use[0].lifetime" \"\'a\"
+//@ is "$.index[*][?(@.name=='hello')].inner.function.sig.output.impl_trait[1].use[1].param" \"T\"
+//@ is "$.index[*][?(@.name=='hello')].inner.function.sig.output.impl_trait[1].use[2].param" \"N\"
 pub fn hello<'a, T, const N: usize>() -> impl Sized + use<'a, T, N> {}

From 47ba5bd41ec58207896aaf54623eb53f15876cbe Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Tue, 11 Mar 2025 07:56:49 +0000
Subject: [PATCH 04/12] Enable `f16` tests for `powf`

The LLVM issue [1] was fixed with [2], which is included in the LLVM20
upgrade. Tests no longer fail, so enable them here.

[1]: https://github.com/llvm/llvm-project/pull/98681
[2]: https://github.com/llvm/llvm-project/pull/98681
---
 library/std/tests/floats/f16.rs | 84 ++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 43 deletions(-)

diff --git a/library/std/tests/floats/f16.rs b/library/std/tests/floats/f16.rs
index 5180f3d40f3a7..19389a9178e91 100644
--- a/library/std/tests/floats/f16.rs
+++ b/library/std/tests/floats/f16.rs
@@ -461,18 +461,16 @@ fn test_recip() {
 #[test]
 #[cfg(reliable_f16_math)]
 fn test_powi() {
-    // FIXME(llvm19): LLVM misoptimizes `powi.f16`
-    // <https://github.com/llvm/llvm-project/issues/98665>
-    // let nan: f16 = f16::NAN;
-    // let inf: f16 = f16::INFINITY;
-    // let neg_inf: f16 = f16::NEG_INFINITY;
-    // assert_eq!(1.0f16.powi(1), 1.0);
-    // assert_approx_eq!((-3.1f16).powi(2), 9.61, TOL_0);
-    // assert_approx_eq!(5.9f16.powi(-2), 0.028727, TOL_N2);
-    // assert_eq!(8.3f16.powi(0), 1.0);
-    // assert!(nan.powi(2).is_nan());
-    // assert_eq!(inf.powi(3), inf);
-    // assert_eq!(neg_inf.powi(2), inf);
+    let nan: f16 = f16::NAN;
+    let inf: f16 = f16::INFINITY;
+    let neg_inf: f16 = f16::NEG_INFINITY;
+    assert_eq!(1.0f16.powi(1), 1.0);
+    assert_approx_eq!((-3.1f16).powi(2), 9.61, TOL_0);
+    assert_approx_eq!(5.9f16.powi(-2), 0.028727, TOL_N2);
+    assert_eq!(8.3f16.powi(0), 1.0);
+    assert!(nan.powi(2).is_nan());
+    assert_eq!(inf.powi(3), inf);
+    assert_eq!(neg_inf.powi(2), inf);
 }
 
 #[test]
@@ -813,6 +811,7 @@ fn test_clamp_max_is_nan() {
 }
 
 #[test]
+#[cfg(reliable_f16_math)]
 fn test_total_cmp() {
     use core::cmp::Ordering;
 
@@ -820,14 +819,13 @@ fn test_total_cmp() {
         1 << (f16::MANTISSA_DIGITS - 2)
     }
 
-    // FIXME(f16_f128): test subnormals when powf is available
-    // fn min_subnorm() -> f16 {
-    //     f16::MIN_POSITIVE / f16::powf(2.0, f16::MANTISSA_DIGITS as f16 - 1.0)
-    // }
+    fn min_subnorm() -> f16 {
+        f16::MIN_POSITIVE / f16::powf(2.0, f16::MANTISSA_DIGITS as f16 - 1.0)
+    }
 
-    // fn max_subnorm() -> f16 {
-    //     f16::MIN_POSITIVE - min_subnorm()
-    // }
+    fn max_subnorm() -> f16 {
+        f16::MIN_POSITIVE - min_subnorm()
+    }
 
     fn q_nan() -> f16 {
         f16::from_bits(f16::NAN.to_bits() | quiet_bit_mask())
@@ -846,12 +844,12 @@ fn test_total_cmp() {
     assert_eq!(Ordering::Equal, (-1.5_f16).total_cmp(&-1.5));
     assert_eq!(Ordering::Equal, (-0.5_f16).total_cmp(&-0.5));
     assert_eq!(Ordering::Equal, (-f16::MIN_POSITIVE).total_cmp(&-f16::MIN_POSITIVE));
-    // assert_eq!(Ordering::Equal, (-max_subnorm()).total_cmp(&-max_subnorm()));
-    // assert_eq!(Ordering::Equal, (-min_subnorm()).total_cmp(&-min_subnorm()));
+    assert_eq!(Ordering::Equal, (-max_subnorm()).total_cmp(&-max_subnorm()));
+    assert_eq!(Ordering::Equal, (-min_subnorm()).total_cmp(&-min_subnorm()));
     assert_eq!(Ordering::Equal, (-0.0_f16).total_cmp(&-0.0));
     assert_eq!(Ordering::Equal, 0.0_f16.total_cmp(&0.0));
-    // assert_eq!(Ordering::Equal, min_subnorm().total_cmp(&min_subnorm()));
-    // assert_eq!(Ordering::Equal, max_subnorm().total_cmp(&max_subnorm()));
+    assert_eq!(Ordering::Equal, min_subnorm().total_cmp(&min_subnorm()));
+    assert_eq!(Ordering::Equal, max_subnorm().total_cmp(&max_subnorm()));
     assert_eq!(Ordering::Equal, f16::MIN_POSITIVE.total_cmp(&f16::MIN_POSITIVE));
     assert_eq!(Ordering::Equal, 0.5_f16.total_cmp(&0.5));
     assert_eq!(Ordering::Equal, 1.0_f16.total_cmp(&1.0));
@@ -870,13 +868,13 @@ fn test_total_cmp() {
     assert_eq!(Ordering::Less, (-1.5_f16).total_cmp(&-1.0));
     assert_eq!(Ordering::Less, (-1.0_f16).total_cmp(&-0.5));
     assert_eq!(Ordering::Less, (-0.5_f16).total_cmp(&-f16::MIN_POSITIVE));
-    // assert_eq!(Ordering::Less, (-f16::MIN_POSITIVE).total_cmp(&-max_subnorm()));
-    // assert_eq!(Ordering::Less, (-max_subnorm()).total_cmp(&-min_subnorm()));
-    // assert_eq!(Ordering::Less, (-min_subnorm()).total_cmp(&-0.0));
+    assert_eq!(Ordering::Less, (-f16::MIN_POSITIVE).total_cmp(&-max_subnorm()));
+    assert_eq!(Ordering::Less, (-max_subnorm()).total_cmp(&-min_subnorm()));
+    assert_eq!(Ordering::Less, (-min_subnorm()).total_cmp(&-0.0));
     assert_eq!(Ordering::Less, (-0.0_f16).total_cmp(&0.0));
-    // assert_eq!(Ordering::Less, 0.0_f16.total_cmp(&min_subnorm()));
-    // assert_eq!(Ordering::Less, min_subnorm().total_cmp(&max_subnorm()));
-    // assert_eq!(Ordering::Less, max_subnorm().total_cmp(&f16::MIN_POSITIVE));
+    assert_eq!(Ordering::Less, 0.0_f16.total_cmp(&min_subnorm()));
+    assert_eq!(Ordering::Less, min_subnorm().total_cmp(&max_subnorm()));
+    assert_eq!(Ordering::Less, max_subnorm().total_cmp(&f16::MIN_POSITIVE));
     assert_eq!(Ordering::Less, f16::MIN_POSITIVE.total_cmp(&0.5));
     assert_eq!(Ordering::Less, 0.5_f16.total_cmp(&1.0));
     assert_eq!(Ordering::Less, 1.0_f16.total_cmp(&1.5));
@@ -894,13 +892,13 @@ fn test_total_cmp() {
     assert_eq!(Ordering::Greater, (-1.0_f16).total_cmp(&-1.5));
     assert_eq!(Ordering::Greater, (-0.5_f16).total_cmp(&-1.0));
     assert_eq!(Ordering::Greater, (-f16::MIN_POSITIVE).total_cmp(&-0.5));
-    // assert_eq!(Ordering::Greater, (-max_subnorm()).total_cmp(&-f16::MIN_POSITIVE));
-    // assert_eq!(Ordering::Greater, (-min_subnorm()).total_cmp(&-max_subnorm()));
-    // assert_eq!(Ordering::Greater, (-0.0_f16).total_cmp(&-min_subnorm()));
+    assert_eq!(Ordering::Greater, (-max_subnorm()).total_cmp(&-f16::MIN_POSITIVE));
+    assert_eq!(Ordering::Greater, (-min_subnorm()).total_cmp(&-max_subnorm()));
+    assert_eq!(Ordering::Greater, (-0.0_f16).total_cmp(&-min_subnorm()));
     assert_eq!(Ordering::Greater, 0.0_f16.total_cmp(&-0.0));
-    // assert_eq!(Ordering::Greater, min_subnorm().total_cmp(&0.0));
-    // assert_eq!(Ordering::Greater, max_subnorm().total_cmp(&min_subnorm()));
-    // assert_eq!(Ordering::Greater, f16::MIN_POSITIVE.total_cmp(&max_subnorm()));
+    assert_eq!(Ordering::Greater, min_subnorm().total_cmp(&0.0));
+    assert_eq!(Ordering::Greater, max_subnorm().total_cmp(&min_subnorm()));
+    assert_eq!(Ordering::Greater, f16::MIN_POSITIVE.total_cmp(&max_subnorm()));
     assert_eq!(Ordering::Greater, 0.5_f16.total_cmp(&f16::MIN_POSITIVE));
     assert_eq!(Ordering::Greater, 1.0_f16.total_cmp(&0.5));
     assert_eq!(Ordering::Greater, 1.5_f16.total_cmp(&1.0));
@@ -918,12 +916,12 @@ fn test_total_cmp() {
     assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&-1.0));
     assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&-0.5));
     assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&-f16::MIN_POSITIVE));
-    // assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&-max_subnorm()));
-    // assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&-min_subnorm()));
+    assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&-max_subnorm()));
+    assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&-min_subnorm()));
     assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&-0.0));
     assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&0.0));
-    // assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&min_subnorm()));
-    // assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&max_subnorm()));
+    assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&min_subnorm()));
+    assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&max_subnorm()));
     assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&f16::MIN_POSITIVE));
     assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&0.5));
     assert_eq!(Ordering::Less, (-q_nan()).total_cmp(&1.0));
@@ -940,12 +938,12 @@ fn test_total_cmp() {
     assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&-1.0));
     assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&-0.5));
     assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&-f16::MIN_POSITIVE));
-    // assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&-max_subnorm()));
-    // assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&-min_subnorm()));
+    assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&-max_subnorm()));
+    assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&-min_subnorm()));
     assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&-0.0));
     assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&0.0));
-    // assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&min_subnorm()));
-    // assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&max_subnorm()));
+    assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&min_subnorm()));
+    assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&max_subnorm()));
     assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&f16::MIN_POSITIVE));
     assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&0.5));
     assert_eq!(Ordering::Less, (-s_nan()).total_cmp(&1.0));

From e1854933d8b0bdbbf692c9c9e28c0cd694f34e4b Mon Sep 17 00:00:00 2001
From: Sean Cross <sean@xobs.io>
Date: Tue, 11 Mar 2025 22:50:57 +0800
Subject: [PATCH 05/12] bump libc to 0.2.171 to fix xous

Due to a reorganization in the `libc` crate, the `xous` target broke
with version `0.2.170`. Bump libc to `0.2.171` to fix nightly.

Signed-off-by: Sean Cross <sean@xobs.io>
---
 library/Cargo.lock     | 4 ++--
 library/std/Cargo.toml | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/library/Cargo.lock b/library/Cargo.lock
index 405c69d95686e..c9f14d0b6ae45 100644
--- a/library/Cargo.lock
+++ b/library/Cargo.lock
@@ -157,9 +157,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.170"
+version = "0.2.171"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "875b3680cb2f8f71bdcf9a30f38d48282f5d3c95cbf9b3fa57269bb5d5c06828"
+checksum = "c19937216e9d3aa9956d9bb8dfc0b0c8beb6058fc4f7a4dc4d850edf86a237d6"
 dependencies = [
  "rustc-std-workspace-core",
 ]
diff --git a/library/std/Cargo.toml b/library/std/Cargo.toml
index 0ec167c2d1618..3bea2b47e257a 100644
--- a/library/std/Cargo.toml
+++ b/library/std/Cargo.toml
@@ -35,7 +35,7 @@ miniz_oxide = { version = "0.8.0", optional = true, default-features = false }
 addr2line = { version = "0.24.0", optional = true, default-features = false }
 
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
-libc = { version = "0.2.170", default-features = false, features = [
+libc = { version = "0.2.171", default-features = false, features = [
     'rustc-dep-of-std',
 ], public = true }
 

From 576bcfcd4e094fa59aff6efe8c27c871a135c805 Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Tue, 11 Mar 2025 13:48:08 -0700
Subject: [PATCH 06/12] Update compiletest's `has_asm_support` to match rustc

The list of `ASM_SUPPORTED_ARCHS` was missing a few from the compiler's
actual stable list.
---
 compiler/rustc_ast_lowering/src/asm.rs |  1 +
 src/tools/compiletest/src/common.rs    | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_ast_lowering/src/asm.rs b/compiler/rustc_ast_lowering/src/asm.rs
index 87af7959a884d..65784af92c7ca 100644
--- a/compiler/rustc_ast_lowering/src/asm.rs
+++ b/compiler/rustc_ast_lowering/src/asm.rs
@@ -38,6 +38,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
         if let Some(asm_arch) = asm_arch {
             // Inline assembly is currently only stable for these architectures.
+            // (See also compiletest's `has_asm_support`.)
             let is_stable = matches!(
                 asm_arch,
                 asm::InlineAsmArch::X86
diff --git a/src/tools/compiletest/src/common.rs b/src/tools/compiletest/src/common.rs
index 978836cb6636a..08d3c1c343e08 100644
--- a/src/tools/compiletest/src/common.rs
+++ b/src/tools/compiletest/src/common.rs
@@ -481,9 +481,17 @@ impl Config {
     }
 
     pub fn has_asm_support(&self) -> bool {
+        // This should match the stable list in `LoweringContext::lower_inline_asm`.
         static ASM_SUPPORTED_ARCHS: &[&str] = &[
-            "x86", "x86_64", "arm", "aarch64", "riscv32",
+            "x86",
+            "x86_64",
+            "arm",
+            "aarch64",
+            "arm64ec",
+            "riscv32",
             "riscv64",
+            "loongarch64",
+            "s390x",
             // These targets require an additional asm_experimental_arch feature.
             // "nvptx64", "hexagon", "mips", "mips64", "spirv", "wasm32",
         ];

From b54398e4ea9188b0ccf60105e15ea5f2ed723edd Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Fri, 7 Mar 2025 16:55:28 +0100
Subject: [PATCH 07/12] Make opts.maybe_sysroot non-optional

build_session_options always uses materialize_sysroot anyway.
---
 compiler/rustc_error_messages/src/lib.rs  | 6 ++++--
 compiler/rustc_interface/src/interface.rs | 6 +++---
 compiler/rustc_interface/src/tests.rs     | 4 ++--
 compiler/rustc_session/src/config.rs      | 4 ++--
 compiler/rustc_session/src/options.rs     | 2 +-
 src/librustdoc/config.rs                  | 4 ++++
 src/librustdoc/core.rs                    | 4 ++--
 src/librustdoc/doctest.rs                 | 2 +-
 tests/ui-fulldeps/run-compiler-twice.rs   | 2 +-
 9 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 6d02d6370fc13..56adc583ac4a4 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -107,7 +107,7 @@ impl From<Vec<FluentError>> for TranslationBundleError {
 /// (overriding any conflicting messages).
 #[instrument(level = "trace")]
 pub fn fluent_bundle(
-    mut user_provided_sysroot: Option<PathBuf>,
+    mut user_provided_sysroot: PathBuf,
     mut sysroot_candidates: Vec<PathBuf>,
     requested_locale: Option<LanguageIdentifier>,
     additional_ftl_path: Option<&Path>,
@@ -142,7 +142,9 @@ pub fn fluent_bundle(
     // If the user requests the default locale then don't try to load anything.
     if let Some(requested_locale) = requested_locale {
         let mut found_resources = false;
-        for sysroot in user_provided_sysroot.iter_mut().chain(sysroot_candidates.iter_mut()) {
+        for sysroot in
+            Some(&mut user_provided_sysroot).into_iter().chain(sysroot_candidates.iter_mut())
+        {
             sysroot.push("share");
             sysroot.push("locale");
             sysroot.push(requested_locale.to_string());
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index b35703d8e737b..3f87b1a547be5 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -18,7 +18,7 @@ use rustc_parse::parser::attr::AllowLeadingUnsafe;
 use rustc_query_impl::QueryCtxt;
 use rustc_query_system::query::print_query_stack;
 use rustc_session::config::{self, Cfg, CheckCfg, ExpectedValues, Input, OutFileName};
-use rustc_session::filesearch::{self, sysroot_candidates};
+use rustc_session::filesearch::sysroot_candidates;
 use rustc_session::parse::ParseSess;
 use rustc_session::{CompilerIO, EarlyDiagCtxt, Session, lint};
 use rustc_span::source_map::{FileLoader, RealFileLoader, SourceMapInputs};
@@ -390,7 +390,7 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
 
     crate::callbacks::setup_callbacks();
 
-    let sysroot = filesearch::materialize_sysroot(config.opts.maybe_sysroot.clone());
+    let sysroot = config.opts.sysroot.clone();
     let target = config::build_target_config(&early_dcx, &config.opts.target_triple, &sysroot);
     let file_loader = config.file_loader.unwrap_or_else(|| Box::new(RealFileLoader));
     let path_mapping = config.opts.file_path_mapping();
@@ -424,7 +424,7 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             let temps_dir = config.opts.unstable_opts.temps_dir.as_deref().map(PathBuf::from);
 
             let bundle = match rustc_errors::fluent_bundle(
-                config.opts.maybe_sysroot.clone(),
+                config.opts.sysroot.clone(),
                 sysroot_candidates().to_vec(),
                 config.opts.unstable_opts.translate_lang.clone(),
                 config.opts.unstable_opts.translate_additional_ftl.as_deref(),
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index aabd235bcabed..b44be1710edf7 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -21,7 +21,7 @@ use rustc_session::config::{
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
 use rustc_session::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
-use rustc_session::{CompilerIO, EarlyDiagCtxt, Session, build_session, filesearch, getopts};
+use rustc_session::{CompilerIO, EarlyDiagCtxt, Session, build_session, getopts};
 use rustc_span::edition::{DEFAULT_EDITION, Edition};
 use rustc_span::source_map::{RealFileLoader, SourceMapInputs};
 use rustc_span::{FileName, SourceFileHashAlgorithm, sym};
@@ -41,7 +41,7 @@ where
 
     let matches = optgroups().parse(args).unwrap();
     let sessopts = build_session_options(&mut early_dcx, &matches);
-    let sysroot = filesearch::materialize_sysroot(sessopts.maybe_sysroot.clone());
+    let sysroot = sessopts.sysroot.clone();
     let target =
         rustc_session::config::build_target_config(&early_dcx, &sessopts.target_triple, &sysroot);
     let hash_kind = sessopts.unstable_opts.src_hash_algorithm(&target);
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 7af221c960757..dcdb7fa9c1054 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -1214,7 +1214,7 @@ impl Default for Options {
             describe_lints: false,
             output_types: OutputTypes(BTreeMap::new()),
             search_paths: vec![],
-            maybe_sysroot: None,
+            sysroot: filesearch::materialize_sysroot(None),
             target_triple: TargetTuple::from_tuple(host_tuple()),
             test: false,
             incremental: None,
@@ -2618,7 +2618,7 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         describe_lints,
         output_types,
         search_paths,
-        maybe_sysroot: Some(sysroot),
+        sysroot,
         target_triple,
         test,
         incremental,
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 8977365ee73d9..804b46a9bec41 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -333,7 +333,7 @@ top_level_options!(
         output_types: OutputTypes [TRACKED],
         search_paths: Vec<SearchPath> [UNTRACKED],
         libs: Vec<NativeLib> [TRACKED],
-        maybe_sysroot: Option<PathBuf> [UNTRACKED],
+        sysroot: PathBuf [UNTRACKED],
 
         target_triple: TargetTuple [TRACKED],
 
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 9cf471733f94a..eeabf07f42377 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -103,6 +103,8 @@ pub(crate) struct Options {
     /// compiling doctests from the crate.
     pub(crate) edition: Edition,
     /// The path to the sysroot. Used during the compilation process.
+    pub(crate) sysroot: PathBuf,
+    /// Has the same value as `sysroot` except is `None` when the user didn't pass `---sysroot`.
     pub(crate) maybe_sysroot: Option<PathBuf>,
     /// Lint information passed over the command-line.
     pub(crate) lint_opts: Vec<(String, Level)>,
@@ -202,6 +204,7 @@ impl fmt::Debug for Options {
             .field("unstable_options", &"...")
             .field("target", &self.target)
             .field("edition", &self.edition)
+            .field("sysroot", &self.sysroot)
             .field("maybe_sysroot", &self.maybe_sysroot)
             .field("lint_opts", &self.lint_opts)
             .field("describe_lints", &self.describe_lints)
@@ -834,6 +837,7 @@ impl Options {
             unstable_opts_strs,
             target,
             edition,
+            sysroot,
             maybe_sysroot,
             lint_opts,
             describe_lints,
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 719f1f978feca..c47e42670c909 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -210,7 +210,7 @@ pub(crate) fn create_config(
         unstable_opts,
         target,
         edition,
-        maybe_sysroot,
+        sysroot,
         lint_opts,
         describe_lints,
         lint_cap,
@@ -253,7 +253,7 @@ pub(crate) fn create_config(
     let test = scrape_examples_options.map(|opts| opts.scrape_tests).unwrap_or(false);
     // plays with error output here!
     let sessopts = config::Options {
-        maybe_sysroot,
+        sysroot,
         search_paths: libs,
         crate_types,
         lint_opts,
diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
index 88af9a7388cea..7a9e42933cacb 100644
--- a/src/librustdoc/doctest.rs
+++ b/src/librustdoc/doctest.rs
@@ -158,7 +158,7 @@ pub(crate) fn run(dcx: DiagCtxtHandle<'_>, input: Input, options: RustdocOptions
         if options.proc_macro_crate { vec![CrateType::ProcMacro] } else { vec![CrateType::Rlib] };
 
     let sessopts = config::Options {
-        maybe_sysroot: options.maybe_sysroot.clone(),
+        sysroot: options.sysroot.clone(),
         search_paths: options.libs.clone(),
         crate_types,
         lint_opts,
diff --git a/tests/ui-fulldeps/run-compiler-twice.rs b/tests/ui-fulldeps/run-compiler-twice.rs
index f414c961627dd..ffc19b138a573 100644
--- a/tests/ui-fulldeps/run-compiler-twice.rs
+++ b/tests/ui-fulldeps/run-compiler-twice.rs
@@ -46,7 +46,7 @@ fn main() {
 fn compile(code: String, output: PathBuf, sysroot: PathBuf, linker: Option<&Path>) {
     let mut opts = Options::default();
     opts.output_types = OutputTypes::new(&[(OutputType::Exe, None)]);
-    opts.maybe_sysroot = Some(sysroot);
+    opts.sysroot = sysroot;
 
     if let Some(linker) = linker {
         opts.cg.linker = Some(linker.to_owned());

From 0a679514d41443329c183110a4142e6813bc4307 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Fri, 7 Mar 2025 16:58:01 +0100
Subject: [PATCH 08/12] Avoid unnecessary argument mutation in fluent_bundle

---
 compiler/rustc_error_messages/src/lib.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 56adc583ac4a4..aa83ddf8d1fa3 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -107,8 +107,8 @@ impl From<Vec<FluentError>> for TranslationBundleError {
 /// (overriding any conflicting messages).
 #[instrument(level = "trace")]
 pub fn fluent_bundle(
-    mut user_provided_sysroot: PathBuf,
-    mut sysroot_candidates: Vec<PathBuf>,
+    user_provided_sysroot: PathBuf,
+    sysroot_candidates: Vec<PathBuf>,
     requested_locale: Option<LanguageIdentifier>,
     additional_ftl_path: Option<&Path>,
     with_directionality_markers: bool,
@@ -142,8 +142,8 @@ pub fn fluent_bundle(
     // If the user requests the default locale then don't try to load anything.
     if let Some(requested_locale) = requested_locale {
         let mut found_resources = false;
-        for sysroot in
-            Some(&mut user_provided_sysroot).into_iter().chain(sysroot_candidates.iter_mut())
+        for mut sysroot in
+            Some(user_provided_sysroot).into_iter().chain(sysroot_candidates.into_iter())
         {
             sysroot.push("share");
             sysroot.push("locale");

From 7e8494f0a511d9374d96fb741efebb3ea71957fd Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Fri, 7 Mar 2025 17:09:20 +0100
Subject: [PATCH 09/12] Don't return an error from get_or_default_sysroot

All callers unwrap the result.
---
 compiler/rustc_codegen_ssa/src/back/link.rs |  3 +-
 compiler/rustc_session/src/filesearch.rs    | 48 +++++++++------------
 src/librustdoc/config.rs                    |  4 +-
 3 files changed, 23 insertions(+), 32 deletions(-)

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 7d9971c021db3..62ed880478b5e 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1286,8 +1286,7 @@ fn link_sanitizer_runtime(
         if path.exists() {
             sess.target_tlib_path.dir.clone()
         } else {
-            let default_sysroot =
-                filesearch::get_or_default_sysroot().expect("Failed finding sysroot");
+            let default_sysroot = filesearch::get_or_default_sysroot();
             let default_tlib =
                 filesearch::make_target_lib_path(&default_sysroot, sess.opts.target_triple.tuple());
             default_tlib
diff --git a/compiler/rustc_session/src/filesearch.rs b/compiler/rustc_session/src/filesearch.rs
index cc2decc2fe4b3..50f09c57107e6 100644
--- a/compiler/rustc_session/src/filesearch.rs
+++ b/compiler/rustc_session/src/filesearch.rs
@@ -160,8 +160,7 @@ fn current_dll_path() -> Result<PathBuf, String> {
 
 pub fn sysroot_candidates() -> SmallVec<[PathBuf; 2]> {
     let target = crate::config::host_tuple();
-    let mut sysroot_candidates: SmallVec<[PathBuf; 2]> =
-        smallvec![get_or_default_sysroot().expect("Failed finding sysroot")];
+    let mut sysroot_candidates: SmallVec<[PathBuf; 2]> = smallvec![get_or_default_sysroot()];
     let path = current_dll_path().and_then(|s| try_canonicalize(s).map_err(|e| e.to_string()));
     if let Ok(dll) = path {
         // use `parent` twice to chop off the file name and then also the
@@ -195,12 +194,12 @@ pub fn sysroot_candidates() -> SmallVec<[PathBuf; 2]> {
 /// Returns the provided sysroot or calls [`get_or_default_sysroot`] if it's none.
 /// Panics if [`get_or_default_sysroot`]  returns an error.
 pub fn materialize_sysroot(maybe_sysroot: Option<PathBuf>) -> PathBuf {
-    maybe_sysroot.unwrap_or_else(|| get_or_default_sysroot().expect("Failed finding sysroot"))
+    maybe_sysroot.unwrap_or_else(|| get_or_default_sysroot())
 }
 
 /// This function checks if sysroot is found using env::args().next(), and if it
 /// is not found, finds sysroot from current rustc_driver dll.
-pub fn get_or_default_sysroot() -> Result<PathBuf, String> {
+pub fn get_or_default_sysroot() -> PathBuf {
     // Follow symlinks. If the resolved path is relative, make it absolute.
     fn canonicalize(path: PathBuf) -> PathBuf {
         let path = try_canonicalize(&path).unwrap_or(path);
@@ -255,30 +254,25 @@ pub fn get_or_default_sysroot() -> Result<PathBuf, String> {
     // binary able to locate Rust libraries in systems using content-addressable
     // storage (CAS).
     fn from_env_args_next() -> Option<PathBuf> {
-        match env::args_os().next() {
-            Some(first_arg) => {
-                let mut p = PathBuf::from(first_arg);
-
-                // Check if sysroot is found using env::args().next() only if the rustc in argv[0]
-                // is a symlink (see #79253). We might want to change/remove it to conform with
-                // https://www.gnu.org/prep/standards/standards.html#Finding-Program-Files in the
-                // future.
-                if fs::read_link(&p).is_err() {
-                    // Path is not a symbolic link or does not exist.
-                    return None;
-                }
-
-                // Pop off `bin/rustc`, obtaining the suspected sysroot.
-                p.pop();
-                p.pop();
-                // Look for the target rustlib directory in the suspected sysroot.
-                let mut rustlib_path = rustc_target::relative_target_rustlib_path(&p, "dummy");
-                rustlib_path.pop(); // pop off the dummy target.
-                rustlib_path.exists().then_some(p)
-            }
-            None => None,
+        let mut p = PathBuf::from(env::args_os().next()?);
+
+        // Check if sysroot is found using env::args().next() only if the rustc in argv[0]
+        // is a symlink (see #79253). We might want to change/remove it to conform with
+        // https://www.gnu.org/prep/standards/standards.html#Finding-Program-Files in the
+        // future.
+        if fs::read_link(&p).is_err() {
+            // Path is not a symbolic link or does not exist.
+            return None;
         }
+
+        // Pop off `bin/rustc`, obtaining the suspected sysroot.
+        p.pop();
+        p.pop();
+        // Look for the target rustlib directory in the suspected sysroot.
+        let mut rustlib_path = rustc_target::relative_target_rustlib_path(&p, "dummy");
+        rustlib_path.pop(); // pop off the dummy target.
+        rustlib_path.exists().then_some(p)
     }
 
-    Ok(from_env_args_next().unwrap_or(default_from_rustc_driver_dll()?))
+    from_env_args_next().unwrap_or(default_from_rustc_driver_dll().expect("Failed finding sysroot"))
 }
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index eeabf07f42377..8161fb102ea9d 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -734,9 +734,7 @@ impl Options {
 
         let sysroot = match &maybe_sysroot {
             Some(s) => s.clone(),
-            None => {
-                rustc_session::filesearch::get_or_default_sysroot().expect("Failed finding sysroot")
-            }
+            None => rustc_session::filesearch::get_or_default_sysroot(),
         };
 
         let libs = matches

From 926b5d2e4f8cbd6c5807efb18823e49e793002e3 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Fri, 7 Mar 2025 17:12:42 +0100
Subject: [PATCH 10/12] Use materialize_sysroot in rustdoc

---
 src/librustdoc/config.rs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 8161fb102ea9d..23a2bcd9011ee 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -732,10 +732,7 @@ impl Options {
         let target = parse_target_triple(early_dcx, matches);
         let maybe_sysroot = matches.opt_str("sysroot").map(PathBuf::from);
 
-        let sysroot = match &maybe_sysroot {
-            Some(s) => s.clone(),
-            None => rustc_session::filesearch::get_or_default_sysroot(),
-        };
+        let sysroot = rustc_session::filesearch::materialize_sysroot(maybe_sysroot.clone());
 
         let libs = matches
             .opt_strs("L")

From f51d1d29f7776cc887971a890f8faf6e46aa3acd Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Wed, 12 Mar 2025 13:54:41 +0000
Subject: [PATCH 11/12] Rename user_provided_sysroot argument of fluent_bundle

---
 compiler/rustc_error_messages/src/lib.rs | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index aa83ddf8d1fa3..fe0bf7df0b7f6 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -107,7 +107,7 @@ impl From<Vec<FluentError>> for TranslationBundleError {
 /// (overriding any conflicting messages).
 #[instrument(level = "trace")]
 pub fn fluent_bundle(
-    user_provided_sysroot: PathBuf,
+    sysroot: PathBuf,
     sysroot_candidates: Vec<PathBuf>,
     requested_locale: Option<LanguageIdentifier>,
     additional_ftl_path: Option<&Path>,
@@ -142,9 +142,7 @@ pub fn fluent_bundle(
     // If the user requests the default locale then don't try to load anything.
     if let Some(requested_locale) = requested_locale {
         let mut found_resources = false;
-        for mut sysroot in
-            Some(user_provided_sysroot).into_iter().chain(sysroot_candidates.into_iter())
-        {
+        for mut sysroot in Some(sysroot).into_iter().chain(sysroot_candidates.into_iter()) {
             sysroot.push("share");
             sysroot.push("locale");
             sysroot.push(requested_locale.to_string());

From 1543256e6f5f8a46e5acbee7bcb39354ece10010 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Wed, 12 Mar 2025 14:15:19 +0000
Subject: [PATCH 12/12] Remove unused host_tlib_path field

---
 compiler/rustc_session/src/session.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index bcd9a73d9d30a..1c9adea281dc7 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -143,7 +143,6 @@ pub struct Session {
     pub target: Target,
     pub host: Target,
     pub opts: config::Options,
-    pub host_tlib_path: Arc<SearchPath>,
     pub target_tlib_path: Arc<SearchPath>,
     pub psess: ParseSess,
     pub sysroot: PathBuf,
@@ -1042,6 +1041,7 @@ pub fn build_session(
 
     let host_triple = config::host_tuple();
     let target_triple = sopts.target_triple.tuple();
+    // FIXME use host sysroot?
     let host_tlib_path = Arc::new(SearchPath::from_sysroot_and_triple(&sysroot, host_triple));
     let target_tlib_path = if host_triple == target_triple {
         // Use the same `SearchPath` if host and target triple are identical to avoid unnecessary
@@ -1070,7 +1070,6 @@ pub fn build_session(
         target,
         host,
         opts: sopts,
-        host_tlib_path,
         target_tlib_path,
         psess,
         sysroot,