Auto merge of #137046 - workingjubilee:rollup-u56aw1m, r=workingjubilee

Rollup of 10 pull requests

Successful merges:

 - #133312 (triagebot: automatically add more rustdoc related labels)
 - #134016 (Stabilize `const_is_char_boundary` and `const_str_split_at`.)
 - #136971 (Add a new check-pass UI test for returning `impl Fn(T) -> impl Trait`)
 - #136983 (Prepare standard library for Rust 2024 migration)
 - #137002 (Fix early lint check desc in query)
 - #137006 (borrowck diagnostics cleanup: remove an unused and a barely-used field)
 - #137032 (Decode metadata buffer in one go)
 - #137035 (Normalize closure instance before eagerly monomorphizing it)
 - #137037 (add x86-sse2 (32bit) ABI that requires SSE2 target feature)
 - #137038 (llvm: Tolerate captures in tests)

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

Author: bors

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -147,9 +147,7 @@ pub(crate) enum RegionErrorKind<'tcx> {
 pub(crate) struct ErrorConstraintInfo<'tcx> {
     // fr: outlived_fr
     pub(super) fr: RegionVid,
-    pub(super) fr_is_local: bool,
     pub(super) outlived_fr: RegionVid,
-    pub(super) outlived_fr_is_local: bool,
 
     // Category and span for best blame constraint
     pub(super) category: ConstraintCategory<'tcx>,
@@ -471,14 +469,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             fr_is_local, outlived_fr_is_local, category
         );
 
-        let errci = ErrorConstraintInfo {
-            fr,
-            outlived_fr,
-            fr_is_local,
-            outlived_fr_is_local,
-            category,
-            span: cause.span,
-        };
+        let errci = ErrorConstraintInfo { fr, outlived_fr, category, span: cause.span };
 
         let mut diag = match (category, fr_is_local, outlived_fr_is_local) {
             (ConstraintCategory::Return(kind), true, false) if self.is_closure_fn_mut(fr) => {
@@ -680,11 +671,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 && self.regioncx.universal_regions().defining_ty.is_fn_def())
             || self.regioncx.universal_regions().defining_ty.is_const()
         {
-            return self.report_general_error(&ErrorConstraintInfo {
-                fr_is_local: true,
-                outlived_fr_is_local: false,
-                ..*errci
-            });
+            return self.report_general_error(errci);
         }
 
         let mut diag =
@@ -762,15 +749,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     /// ```
     #[allow(rustc::diagnostic_outside_of_impl)] // FIXME
     fn report_general_error(&self, errci: &ErrorConstraintInfo<'tcx>) -> Diag<'infcx> {
-        let ErrorConstraintInfo {
-            fr,
-            fr_is_local,
-            outlived_fr,
-            outlived_fr_is_local,
-            span,
-            category,
-            ..
-        } = errci;
+        let ErrorConstraintInfo { fr, outlived_fr, span, category, .. } = errci;
 
         let mir_def_name = self.infcx.tcx.def_descr(self.mir_def_id().to_def_id());
 
@@ -789,19 +768,22 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let outlived_fr_name = self.give_region_a_name(*outlived_fr).unwrap();
         outlived_fr_name.highlight_region_name(&mut diag);
 
-        let err_category = match (category, outlived_fr_is_local, fr_is_local) {
-            (ConstraintCategory::Return(_), true, _) => LifetimeReturnCategoryErr::WrongReturn {
+        let err_category = if matches!(category, ConstraintCategory::Return(_))
+            && self.regioncx.universal_regions().is_local_free_region(*outlived_fr)
+        {
+            LifetimeReturnCategoryErr::WrongReturn {
                 span: *span,
                 mir_def_name,
                 outlived_fr_name,
                 fr_name: &fr_name,
-            },
-            _ => LifetimeReturnCategoryErr::ShortReturn {
+            }
+        } else {
+            LifetimeReturnCategoryErr::ShortReturn {
                 span: *span,
                 category_desc: category.description(),
                 free_region_name: &fr_name,
                 outlived_fr_name,
-            },
+            }
         };
 
         diag.subdiagnostic(err_category);

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -2272,10 +2272,7 @@ impl<D: Decoder> Decodable<D> for EncodedMetadata {
         let len = d.read_usize();
         let mmap = if len > 0 {
             let mut mmap = MmapMut::map_anon(len).unwrap();
-            for _ in 0..len {
-                (&mut mmap[..]).write_all(&[d.read_u8()]).unwrap();
-            }
-            mmap.flush().unwrap();
+            mmap.copy_from_slice(d.read_raw_bytes(len));
             Some(mmap.make_read_only().unwrap())
         } else {
             None

compiler/rustc_middle/src/query/mod.rs

@@ -116,7 +116,7 @@ rustc_queries! {
     }
 
     query early_lint_checks(_: ()) {
-        desc { "perform lints prior to macro expansion" }
+        desc { "perform lints prior to AST lowering" }
     }
 
     query resolutions(_: ()) -> &'tcx ty::ResolverGlobalCtxt {

compiler/rustc_monomorphize/src/collector.rs

@@ -1509,6 +1509,13 @@ impl<'v> RootCollector<'_, 'v> {
                         }
                         _ => unreachable!(),
                     };
+                    let Ok(instance) = self.tcx.try_normalize_erasing_regions(
+                        ty::TypingEnv::fully_monomorphized(),
+                        instance,
+                    ) else {
+                        // Don't ICE on an impossible-to-normalize closure.
+                        return;
+                    };
                     let mono_item = create_fn_mono_item(self.tcx, instance, DUMMY_SP);
                     if mono_item.node.is_instantiable(self.tcx) {
                         self.output.push(mono_item);

compiler/rustc_target/src/spec/base/apple/mod.rs

@@ -2,8 +2,8 @@ use std::borrow::Cow;
 use std::env;
 
 use crate::spec::{
-    Cc, DebuginfoKind, FloatAbi, FramePointer, LinkerFlavor, Lld, SplitDebuginfo, StackProbeType,
-    StaticCow, TargetOptions, cvs,
+    Cc, DebuginfoKind, FloatAbi, FramePointer, LinkerFlavor, Lld, RustcAbi, SplitDebuginfo,
+    StackProbeType, StaticCow, TargetOptions, cvs,
 };
 
 #[cfg(test)]
@@ -103,7 +103,7 @@ pub(crate) fn base(
     arch: Arch,
     abi: TargetAbi,
 ) -> (TargetOptions, StaticCow<str>, StaticCow<str>) {
-    let opts = TargetOptions {
+    let mut opts = TargetOptions {
         abi: abi.target_abi().into(),
         llvm_floatabi: Some(FloatAbi::Hard),
         os: os.into(),
@@ -154,6 +154,10 @@ pub(crate) fn base(
 
         ..Default::default()
     };
+    if matches!(arch, Arch::I386 | Arch::I686) {
+        // All Apple x86-32 targets have SSE2.
+        opts.rustc_abi = Some(RustcAbi::X86Sse2);
+    }
     (opts, unversioned_llvm_target(os, arch, abi), arch.target_arch())
 }
 

compiler/rustc_target/src/spec/mod.rs

@@ -1109,6 +1109,8 @@ impl ToJson for FloatAbi {
 /// The Rustc-specific variant of the ABI used for this target.
 #[derive(Clone, Copy, PartialEq, Hash, Debug)]
 pub enum RustcAbi {
+    /// On x86-32 only: make use of SSE and SSE2 for ABI purposes.
+    X86Sse2,
     /// On x86-32/64 only: do not use any FPU or SIMD registers for the ABI.
     X86Softfloat,
 }
@@ -1118,6 +1120,7 @@ impl FromStr for RustcAbi {
 
     fn from_str(s: &str) -> Result<RustcAbi, ()> {
         Ok(match s {
+            "x86-sse2" => RustcAbi::X86Sse2,
             "x86-softfloat" => RustcAbi::X86Softfloat,
             _ => return Err(()),
         })
@@ -1127,6 +1130,7 @@ impl FromStr for RustcAbi {
 impl ToJson for RustcAbi {
     fn to_json(&self) -> Json {
         match *self {
+            RustcAbi::X86Sse2 => "x86-sse2",
             RustcAbi::X86Softfloat => "x86-softfloat",
         }
         .to_json()
@@ -3264,6 +3268,11 @@ impl Target {
         // Check consistency of Rust ABI declaration.
         if let Some(rust_abi) = self.rustc_abi {
             match rust_abi {
+                RustcAbi::X86Sse2 => check_matches!(
+                    &*self.arch,
+                    "x86",
+                    "`x86-sse2` ABI is only valid for x86-32 targets"
+                ),
                 RustcAbi::X86Softfloat => check_matches!(
                     &*self.arch,
                     "x86" | "x86_64",

compiler/rustc_target/src/spec/targets/i586_pc_nto_qnx700.rs

@@ -1,5 +1,5 @@
 use crate::spec::base::nto_qnx;
-use crate::spec::{StackProbeType, Target, TargetOptions, base};
+use crate::spec::{RustcAbi, StackProbeType, Target, TargetOptions, base};
 
 pub(crate) fn target() -> Target {
     let mut meta = nto_qnx::meta();
@@ -14,6 +14,7 @@ pub(crate) fn target() -> Target {
             .into(),
         arch: "x86".into(),
         options: TargetOptions {
+            rustc_abi: Some(RustcAbi::X86Sse2),
             cpu: "pentium4".into(),
             max_atomic_width: Some(64),
             pre_link_args: nto_qnx::pre_link_args(

compiler/rustc_target/src/spec/targets/i586_unknown_linux_gnu.rs

@@ -2,6 +2,7 @@ use crate::spec::Target;
 
 pub(crate) fn target() -> Target {
     let mut base = super::i686_unknown_linux_gnu::target();
+    base.rustc_abi = None; // overwrite the SSE2 ABI set by the base target
     base.cpu = "pentium".into();
     base.llvm_target = "i586-unknown-linux-gnu".into();
     base

compiler/rustc_target/src/spec/targets/i586_unknown_linux_musl.rs

@@ -2,6 +2,7 @@ use crate::spec::Target;
 
 pub(crate) fn target() -> Target {
     let mut base = super::i686_unknown_linux_musl::target();
+    base.rustc_abi = None; // overwrite the SSE2 ABI set by the base target
     base.cpu = "pentium".into();
     base.llvm_target = "i586-unknown-linux-musl".into();
     // FIXME(compiler-team#422): musl targets should be dynamically linked by default.

compiler/rustc_target/src/spec/targets/i686_linux_android.rs

@@ -1,4 +1,4 @@
-use crate::spec::{SanitizerSet, StackProbeType, Target, TargetOptions, base};
+use crate::spec::{RustcAbi, SanitizerSet, StackProbeType, Target, TargetOptions, base};
 
 // See https://developer.android.com/ndk/guides/abis.html#x86
 // for target ABI requirements.
@@ -8,6 +8,7 @@ pub(crate) fn target() -> Target {
 
     base.max_atomic_width = Some(64);
 
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     // https://developer.android.com/ndk/guides/abis.html#x86
     base.cpu = "pentium4".into();
     base.features = "+mmx,+sse,+sse2,+sse3,+ssse3".into();

compiler/rustc_target/src/spec/targets/i686_pc_windows_gnu.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, Target, base};
+use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, RustcAbi, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::windows_gnu::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.frame_pointer = FramePointer::Always; // Required for backtraces

compiler/rustc_target/src/spec/targets/i686_pc_windows_gnullvm.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, Target, base};
+use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, RustcAbi, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::windows_gnullvm::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.frame_pointer = FramePointer::Always; // Required for backtraces

compiler/rustc_target/src/spec/targets/i686_pc_windows_msvc.rs

@@ -1,7 +1,8 @@
-use crate::spec::{LinkerFlavor, Lld, SanitizerSet, Target, base};
+use crate::spec::{LinkerFlavor, Lld, RustcAbi, SanitizerSet, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::windows_msvc::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.supported_sanitizers = SanitizerSet::ADDRESS;

compiler/rustc_target/src/spec/targets/i686_unknown_freebsd.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target, base};
+use crate::spec::{Cc, LinkerFlavor, Lld, RustcAbi, StackProbeType, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::freebsd::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32", "-Wl,-znotext"]);

compiler/rustc_target/src/spec/targets/i686_unknown_haiku.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target, base};
+use crate::spec::{Cc, LinkerFlavor, Lld, RustcAbi, StackProbeType, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::haiku::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32"]);

compiler/rustc_target/src/spec/targets/i686_unknown_linux_gnu.rs

@@ -1,7 +1,19 @@
-use crate::spec::{Cc, LinkerFlavor, Lld, SanitizerSet, StackProbeType, Target, base};
+use crate::spec::{Cc, LinkerFlavor, Lld, RustcAbi, SanitizerSet, StackProbeType, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::linux_gnu::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
+    // Dear distribution packager, if you are changing the base CPU model with the goal of removing
+    // the SSE2 requirement, make sure to also set the `rustc_abi` to `None` above or else the compiler
+    // will complain that the chosen ABI cannot be realized with the given CPU features.
+    // Also note that x86 without SSE2 is *not* considered a Tier 1 target by the Rust project, and
+    // it has some known floating-point correctness issues mostly caused by a lack of people caring
+    // for LLVM's x87 support (double-rounding, value truncation; see
+    // <https://github.com/rust-lang/rust/issues/114479> for details). This can lead to incorrect
+    // math (Rust generally promises exact math, so this can break code in unexpected ways) and it
+    // can lead to memory safety violations if floating-point values are used e.g. to access an
+    // array. If users run into such issues and report bugs upstream and then it turns out that the
+    // bugs are caused by distribution patches, that leads to confusion and frustration.
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.supported_sanitizers = SanitizerSet::ADDRESS;

compiler/rustc_target/src/spec/targets/i686_unknown_linux_musl.rs

@@ -1,7 +1,10 @@
-use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, StackProbeType, Target, base};
+use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, RustcAbi, StackProbeType, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::linux_musl::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
+    // If you want to change the base CPU, please see `i686_unknown_linux_gnu.rs`
+    // for an important comment.
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32", "-Wl,-melf_i386"]);

compiler/rustc_target/src/spec/targets/i686_unknown_netbsd.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target, TargetOptions, base};
+use crate::spec::{Cc, LinkerFlavor, Lld, RustcAbi, StackProbeType, Target, TargetOptions, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::netbsd::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32"]);

compiler/rustc_target/src/spec/targets/i686_unknown_openbsd.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target, base};
+use crate::spec::{Cc, LinkerFlavor, Lld, RustcAbi, StackProbeType, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::openbsd::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32", "-fuse-ld=lld"]);

compiler/rustc_target/src/spec/targets/i686_uwp_windows_gnu.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, Target, base};
+use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, RustcAbi, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::windows_uwp_gnu::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.frame_pointer = FramePointer::Always; // Required for backtraces

compiler/rustc_target/src/spec/targets/i686_uwp_windows_msvc.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Target, base};
+use crate::spec::{RustcAbi, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::windows_uwp_msvc::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
 

compiler/rustc_target/src/spec/targets/i686_win7_windows_gnu.rs

@@ -1,8 +1,9 @@
-use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, Target, base};
+use crate::spec::{Cc, FramePointer, LinkerFlavor, Lld, RustcAbi, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::windows_gnu::opts();
     base.vendor = "win7".into();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.frame_pointer = FramePointer::Always; // Required for backtraces

compiler/rustc_target/src/spec/targets/i686_win7_windows_msvc.rs

@@ -1,8 +1,9 @@
-use crate::spec::{LinkerFlavor, Lld, SanitizerSet, Target, base};
+use crate::spec::{LinkerFlavor, Lld, RustcAbi, SanitizerSet, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::windows_msvc::opts();
     base.vendor = "win7".into();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.supported_sanitizers = SanitizerSet::ADDRESS;

compiler/rustc_target/src/spec/targets/i686_wrs_vxworks.rs

@@ -1,7 +1,8 @@
-use crate::spec::{Cc, LinkerFlavor, Lld, StackProbeType, Target, base};
+use crate::spec::{Cc, LinkerFlavor, Lld, RustcAbi, StackProbeType, Target, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::vxworks::opts();
+    base.rustc_abi = Some(RustcAbi::X86Sse2);
     base.cpu = "pentium4".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32"]);