Auto merge of #111380 - Dylan-DPC:rollup-xiptbhn, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - #110304 (Add GNU Property Note)
 - #110504 (Tweak borrow suggestion span)
 - #110583 (tweak "make mut" spans when assigning to locals)
 - #110694 (Implement builtin # syntax and use it for offset_of!(...))
 - #111120 (Suggest let for possible binding with ty)
 - #111252 (Min specialization improvements)
 - #111361 (Update books)

Failed merges:

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

Author: bors

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -603,6 +603,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
     gate_all!(yeet_expr, "`do yeet` expression is experimental");
     gate_all!(dyn_star, "`dyn*` trait objects are experimental");
     gate_all!(const_closures, "const closures are experimental");
+    gate_all!(builtin_syntax, "`builtin #` syntax is unstable");
 
     if !visitor.features.negative_bounds {
         for &span in spans.get(&sym::negative_bounds).iter().copied().flatten() {

compiler/rustc_ast_pretty/src/pprust/state/expr.rs

@@ -556,8 +556,7 @@ impl<'a> State<'a> {
                 self.pclose();
             }
             ast::ExprKind::OffsetOf(container, fields) => {
-                // FIXME: This should have its own syntax, distinct from a macro invocation.
-                self.word("offset_of!");
+                self.word("builtin # offset_of");
                 self.popen();
                 self.rbox(0, Inconsistent);
                 self.print_type(container);

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -150,10 +150,6 @@ builtin_macros_format_pos_mismatch = {$n} positional {$n ->
     *[more] arguments
     } in format string, but {$desc}
 
-builtin_macros_offset_of_expected_field = expected field
-
-builtin_macros_offset_of_expected_two_args = expected 2 arguments
-
 builtin_macros_test_case_non_item = `#[test_case]` attribute is only allowed on items
 
 builtin_macros_test_bad_fn = {$kind} functions cannot be used for tests

compiler/rustc_builtin_macros/messages.ftl

@@ -44,7 +44,6 @@ mod format;
 mod format_foreign;
 mod global_allocator;
 mod log_syntax;
-mod offset_of;
 mod source_util;
 mod test;
 mod trace_macros;
@@ -92,7 +91,6 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand) {
         line: source_util::expand_line,
         log_syntax: log_syntax::expand_log_syntax,
         module_path: source_util::expand_mod,
-        offset_of: offset_of::expand_offset_of,
         option_env: env::expand_option_env,
         core_panic: edition_panic::expand_panic,
         std_panic: edition_panic::expand_panic,

compiler/rustc_builtin_macros/src/lib.rs

@@ -12,6 +12,7 @@ use object::{
 
 use snap::write::FrameEncoder;
 
+use object::elf::NT_GNU_PROPERTY_TYPE_0;
 use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::owned_slice::try_slice_owned;
 use rustc_data_structures::sync::MetadataRef;
@@ -93,6 +94,54 @@ pub(super) fn search_for_section<'a>(
         .map_err(|e| format!("failed to read {} section in '{}': {}", section, path.display(), e))
 }
 
+fn add_gnu_property_note(
+    file: &mut write::Object<'static>,
+    architecture: Architecture,
+    binary_format: BinaryFormat,
+    endianness: Endianness,
+) {
+    // check bti protection
+    if binary_format != BinaryFormat::Elf
+        || !matches!(architecture, Architecture::X86_64 | Architecture::Aarch64)
+    {
+        return;
+    }
+
+    let section = file.add_section(
+        file.segment_name(StandardSegment::Data).to_vec(),
+        b".note.gnu.property".to_vec(),
+        SectionKind::Note,
+    );
+    let mut data: Vec<u8> = Vec::new();
+    let n_namsz: u32 = 4; // Size of the n_name field
+    let n_descsz: u32 = 16; // Size of the n_desc field
+    let n_type: u32 = NT_GNU_PROPERTY_TYPE_0; // Type of note descriptor
+    let header_values = [n_namsz, n_descsz, n_type];
+    header_values.iter().for_each(|v| {
+        data.extend_from_slice(&match endianness {
+            Endianness::Little => v.to_le_bytes(),
+            Endianness::Big => v.to_be_bytes(),
+        })
+    });
+    data.extend_from_slice(b"GNU\0"); // Owner of the program property note
+    let pr_type: u32 = match architecture {
+        Architecture::X86_64 => 0xc0000002,
+        Architecture::Aarch64 => 0xc0000000,
+        _ => unreachable!(),
+    };
+    let pr_datasz: u32 = 4; //size of the pr_data field
+    let pr_data: u32 = 3; //program property descriptor
+    let pr_padding: u32 = 0;
+    let property_values = [pr_type, pr_datasz, pr_data, pr_padding];
+    property_values.iter().for_each(|v| {
+        data.extend_from_slice(&match endianness {
+            Endianness::Little => v.to_le_bytes(),
+            Endianness::Big => v.to_be_bytes(),
+        })
+    });
+    file.append_section_data(section, &data, 8);
+}
+
 pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static>> {
     let endianness = match sess.target.options.endian {
         Endian::Little => Endianness::Little,
@@ -205,6 +254,7 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
         _ => elf::ELFOSABI_NONE,
     };
     let abi_version = 0;
+    add_gnu_property_note(&mut file, architecture, binary_format, endianness);
     file.flags = FileFlags::Elf { os_abi, abi_version, e_flags };
     Some(file)
 }

compiler/rustc_builtin_macros/src/offset_of.rs

@@ -109,9 +109,11 @@ impl Borrow<[u8]> for OwnedSlice {
 }
 
 // Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Box<dyn Send + Sync>)`, which is `Send`
+#[cfg(parallel_compiler)]
 unsafe impl Send for OwnedSlice {}
 
 // Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Box<dyn Send + Sync>)`, which is `Sync`
+#[cfg(parallel_compiler)]
 unsafe impl Sync for OwnedSlice {}
 
 #[cfg(test)]

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -313,6 +313,8 @@ declare_features! (
     (active, async_closure, "1.37.0", Some(62290), None),
     /// Allows async functions to be declared, implemented, and used in traits.
     (active, async_fn_in_trait, "1.66.0", Some(91611), None),
+    /// Allows builtin # foo() syntax
+    (active, builtin_syntax, "CURRENT_RUSTC_VERSION", Some(110680), None),
     /// Allows `c"foo"` literals.
     (active, c_str_literals, "CURRENT_RUSTC_VERSION", Some(105723), None),
     /// Treat `extern "C"` function as nounwind.

compiler/rustc_data_structures/src/owned_slice.rs

@@ -279,6 +279,9 @@ hir_analysis_specialization_trait = implementing `rustc_specialization_trait` tr
 hir_analysis_closure_implicit_hrtb = implicit types in closure signatures are forbidden when `for<...>` is present
     .label = `for<...>` is here
 
+hir_analysis_empty_specialization = specialization impl does not specialize any associated items
+    .note = impl is a specialization of this impl
+
 hir_analysis_const_specialize = cannot specialize on const impl with non-const impl
 
 hir_analysis_static_specialize = cannot specialize on `'static` lifetime

compiler/rustc_feature/src/active.rs

@@ -814,6 +814,15 @@ pub(crate) struct ClosureImplicitHrtb {
     pub for_sp: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(hir_analysis_empty_specialization)]
+pub(crate) struct EmptySpecialization {
+    #[primary_span]
+    pub span: Span,
+    #[note]
+    pub base_impl_span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(hir_analysis_const_specialize)]
 pub(crate) struct ConstSpecialize {

compiler/rustc_hir_analysis/messages.ftl

@@ -80,7 +80,7 @@ use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
 use rustc_span::Span;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
-use rustc_trait_selection::traits::{self, translate_substs, wf, ObligationCtxt};
+use rustc_trait_selection::traits::{self, translate_substs_with_cause, wf, ObligationCtxt};
 
 pub(super) fn check_min_specialization(tcx: TyCtxt<'_>, impl_def_id: LocalDefId) {
     if let Some(node) = parent_specialization_node(tcx, impl_def_id) {
@@ -100,12 +100,19 @@ fn parent_specialization_node(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId) -> Opti
         // Implementing a normal trait isn't a specialization.
         return None;
     }
+    if trait_def.is_marker {
+        // Overlapping marker implementations are not really specializations.
+        return None;
+    }
     Some(impl2_node)
 }
 
 /// Check that `impl1` is a sound specialization
 #[instrument(level = "debug", skip(tcx))]
 fn check_always_applicable(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId, impl2_node: Node) {
+    let span = tcx.def_span(impl1_def_id);
+    check_has_items(tcx, impl1_def_id, impl2_node, span);
+
     if let Some((impl1_substs, impl2_substs)) = get_impl_substs(tcx, impl1_def_id, impl2_node) {
         let impl2_def_id = impl2_node.def_id();
         debug!(?impl2_def_id, ?impl2_substs);
@@ -116,14 +123,20 @@ fn check_always_applicable(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId, impl2_node
             unconstrained_parent_impl_substs(tcx, impl2_def_id, impl2_substs)
         };
 
-        let span = tcx.def_span(impl1_def_id);
         check_constness(tcx, impl1_def_id, impl2_node, span);
         check_static_lifetimes(tcx, &parent_substs, span);
         check_duplicate_params(tcx, impl1_substs, &parent_substs, span);
         check_predicates(tcx, impl1_def_id, impl1_substs, impl2_node, impl2_substs, span);
     }
 }
 
+fn check_has_items(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId, impl2_node: Node, span: Span) {
+    if let Node::Impl(impl2_id) = impl2_node && tcx.associated_item_def_ids(impl1_def_id).is_empty() {
+        let base_impl_span = tcx.def_span(impl2_id);
+        tcx.sess.emit_err(errors::EmptySpecialization { span, base_impl_span });
+    }
+}
+
 /// Check that the specializing impl `impl1` is at least as const as the base
 /// impl `impl2`
 fn check_constness(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId, impl2_node: Node, span: Span) {
@@ -167,8 +180,21 @@ fn get_impl_substs(
         ocx.assumed_wf_types(param_env, tcx.def_span(impl1_def_id), impl1_def_id);
 
     let impl1_substs = InternalSubsts::identity_for_item(tcx, impl1_def_id);
-    let impl2_substs =
-        translate_substs(infcx, param_env, impl1_def_id.to_def_id(), impl1_substs, impl2_node);
+    let impl1_span = tcx.def_span(impl1_def_id);
+    let impl2_substs = translate_substs_with_cause(
+        infcx,
+        param_env,
+        impl1_def_id.to_def_id(),
+        impl1_substs,
+        impl2_node,
+        |_, span| {
+            traits::ObligationCause::new(
+                impl1_span,
+                impl1_def_id,
+                traits::ObligationCauseCode::BindingObligation(impl2_node.def_id(), span),
+            )
+        },
+    );
 
     let errors = ocx.select_all_or_error();
     if !errors.is_empty() {