Auto merge of rust-lang#129936 - matthiaskrgr:rollup-0s8xycb, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - rust-lang#127692 (Suggest `impl Trait` for References to Bare Trait in Function Header)
 - rust-lang#128701 (Don't Suggest Labeling `const` and `unsafe` Blocks )
 - rust-lang#128934 (Non-exhaustive structs may be empty)
 - rust-lang#129630 (Document the broken C ABI of `wasm32-unknown-unknown`)
 - rust-lang#129863 (update comment regarding TargetOptions.features)
 - rust-lang#129896 (do not attempt to prove unknowable goals)
 - rust-lang#129926 (Move `SanityCheck` and `MirPass`)
 - rust-lang#129928 (rustc_driver_impl: remove some old dead logic)
 - rust-lang#129930 (include 1.80.1 release notes on master)

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

Author: bors

Diff for: RELEASES.md

@@ -112,6 +112,14 @@ tools.
 
 - [Add a Rust-for Linux `auto` CI job to check kernel builds.](https://github.com/rust-lang/rust/pull/125209/)
 
+Version 1.80.1 (2024-08-08)
+===========================
+
+<a id="1.80.1"></a>
+
+- [Fix miscompilation in the jump threading MIR optimization when comparing floats](https://github.com/rust-lang/rust/pull/128271)
+- [Revert changes to the `dead_code` lint from 1.80.0](https://github.com/rust-lang/rust/pull/128618)
+
 Version 1.80.0 (2024-07-25)
 ==========================
 

Diff for: compiler/rustc_driver_impl/src/lib.rs

@@ -61,7 +61,6 @@ use rustc_session::lint::{Lint, LintId};
 use rustc_session::output::collect_crate_types;
 use rustc_session::{config, filesearch, EarlyDiagCtxt, Session};
 use rustc_span::source_map::FileLoader;
-use rustc_span::symbol::sym;
 use rustc_span::FileName;
 use rustc_target::json::ToJson;
 use rustc_target::spec::{Target, TargetTriple};
@@ -777,16 +776,8 @@ fn print_crate_info(
                     .config
                     .iter()
                     .filter_map(|&(name, value)| {
-                        // Note that crt-static is a specially recognized cfg
-                        // directive that's printed out here as part of
-                        // rust-lang/rust#37406, but in general the
-                        // `target_feature` cfg is gated under
-                        // rust-lang/rust#29717. For now this is just
-                        // specifically allowing the crt-static cfg and that's
-                        // it, this is intended to get into Cargo and then go
-                        // through to build scripts.
-                        if (name != sym::target_feature || value != Some(sym::crt_dash_static))
-                            && !sess.is_nightly_build()
+                        // On stable, exclude unstable flags.
+                        if !sess.is_nightly_build()
                             && find_gated_cfg(|cfg_sym| cfg_sym == name).is_some()
                         {
                             return None;

Diff for: compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs

@@ -133,9 +133,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 return;
             };
             let sugg = self.add_generic_param_suggestion(generics, self_ty.span, &impl_trait_name);
-            if sugg.is_empty() {
-                return;
-            };
             diag.multipart_suggestion(
                 format!(
                     "alternatively use a blanket implementation to implement `{of_trait_name}` for \
@@ -170,6 +167,10 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         let parent_id = tcx.hir().get_parent_item(self_ty.hir_id).def_id;
         // FIXME: If `type_alias_impl_trait` is enabled, also look for `Trait0<Ty = Trait1>`
         //        and suggest `Trait0<Ty = impl Trait1>`.
+        // Functions are found in three different contexts.
+        // 1. Independent functions
+        // 2. Functions inside trait blocks
+        // 3. Functions inside impl blocks
         let (sig, generics, owner) = match tcx.hir_node_by_def_id(parent_id) {
             hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(sig, generics, _), .. }) => {
                 (sig, generics, None)
@@ -180,13 +181,21 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 owner_id,
                 ..
             }) => (sig, generics, Some(tcx.parent(owner_id.to_def_id()))),
+            hir::Node::ImplItem(hir::ImplItem {
+                kind: hir::ImplItemKind::Fn(sig, _),
+                generics,
+                owner_id,
+                ..
+            }) => (sig, generics, Some(tcx.parent(owner_id.to_def_id()))),
             _ => return false,
         };
         let Ok(trait_name) = tcx.sess.source_map().span_to_snippet(self_ty.span) else {
             return false;
         };
         let impl_sugg = vec![(self_ty.span.shrink_to_lo(), "impl ".to_string())];
         let mut is_downgradable = true;
+
+        // Check if trait object is safe for suggesting dynamic dispatch.
         let is_object_safe = match self_ty.kind {
             hir::TyKind::TraitObject(objects, ..) => {
                 objects.iter().all(|(o, _)| match o.trait_ref.path.res {
@@ -202,8 +211,15 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
             _ => false,
         };
+
+        let borrowed = matches!(
+            tcx.parent_hir_node(self_ty.hir_id),
+            hir::Node::Ty(hir::Ty { kind: hir::TyKind::Ref(..), .. })
+        );
+
+        // Suggestions for function return type.
         if let hir::FnRetTy::Return(ty) = sig.decl.output
-            && ty.hir_id == self_ty.hir_id
+            && ty.peel_refs().hir_id == self_ty.hir_id
         {
             let pre = if !is_object_safe {
                 format!("`{trait_name}` is not object safe, ")
@@ -214,14 +230,26 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 "{pre}use `impl {trait_name}` to return an opaque type, as long as you return a \
                  single underlying type",
             );
+
             diag.multipart_suggestion_verbose(msg, impl_sugg, Applicability::MachineApplicable);
+
+            // Suggest `Box<dyn Trait>` for return type
             if is_object_safe {
-                diag.multipart_suggestion_verbose(
-                    "alternatively, you can return an owned trait object",
+                // If the return type is `&Trait`, we don't want
+                // the ampersand to be displayed in the `Box<dyn Trait>`
+                // suggestion.
+                let suggestion = if borrowed {
+                    vec![(ty.span, format!("Box<dyn {trait_name}>"))]
+                } else {
                     vec![
                         (ty.span.shrink_to_lo(), "Box<dyn ".to_string()),
                         (ty.span.shrink_to_hi(), ">".to_string()),
-                    ],
+                    ]
+                };
+
+                diag.multipart_suggestion_verbose(
+                    "alternatively, you can return an owned trait object",
+                    suggestion,
                     Applicability::MachineApplicable,
                 );
             } else if is_downgradable {
@@ -230,39 +258,43 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
             return true;
         }
+
+        // Suggestions for function parameters.
         for ty in sig.decl.inputs {
-            if ty.hir_id != self_ty.hir_id {
+            if ty.peel_refs().hir_id != self_ty.hir_id {
                 continue;
             }
             let sugg = self.add_generic_param_suggestion(generics, self_ty.span, &trait_name);
-            if !sugg.is_empty() {
-                diag.multipart_suggestion_verbose(
-                    format!("use a new generic type parameter, constrained by `{trait_name}`"),
-                    sugg,
-                    Applicability::MachineApplicable,
-                );
-                diag.multipart_suggestion_verbose(
-                    "you can also use an opaque type, but users won't be able to specify the type \
-                     parameter when calling the `fn`, having to rely exclusively on type inference",
-                    impl_sugg,
-                    Applicability::MachineApplicable,
-                );
-            }
+            diag.multipart_suggestion_verbose(
+                format!("use a new generic type parameter, constrained by `{trait_name}`"),
+                sugg,
+                Applicability::MachineApplicable,
+            );
+            diag.multipart_suggestion_verbose(
+                "you can also use an opaque type, but users won't be able to specify the type \
+                 parameter when calling the `fn`, having to rely exclusively on type inference",
+                impl_sugg,
+                Applicability::MachineApplicable,
+            );
             if !is_object_safe {
                 diag.note(format!("`{trait_name}` it is not object safe, so it can't be `dyn`"));
                 if is_downgradable {
                     // We'll emit the object safety error already, with a structured suggestion.
                     diag.downgrade_to_delayed_bug();
                 }
             } else {
+                // No ampersand in suggestion if it's borrowed already
+                let (dyn_str, paren_dyn_str) =
+                    if borrowed { ("dyn ", "(dyn ") } else { ("&dyn ", "&(dyn ") };
+
                 let sugg = if let hir::TyKind::TraitObject([_, _, ..], _, _) = self_ty.kind {
                     // There are more than one trait bound, we need surrounding parentheses.
                     vec![
-                        (self_ty.span.shrink_to_lo(), "&(dyn ".to_string()),
+                        (self_ty.span.shrink_to_lo(), paren_dyn_str.to_string()),
                         (self_ty.span.shrink_to_hi(), ")".to_string()),
                     ]
                 } else {
-                    vec![(self_ty.span.shrink_to_lo(), "&dyn ".to_string())]
+                    vec![(self_ty.span.shrink_to_lo(), dyn_str.to_string())]
                 };
                 diag.multipart_suggestion_verbose(
                     format!(

Diff for: compiler/rustc_middle/src/mir/mod.rs

@@ -3,8 +3,6 @@
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/index.html
 
 use std::borrow::Cow;
-use std::cell::RefCell;
-use std::collections::hash_map::Entry;
 use std::fmt::{self, Debug, Formatter};
 use std::ops::{Index, IndexMut};
 use std::{iter, mem};
@@ -26,7 +24,6 @@ use rustc_index::bit_set::BitSet;
 use rustc_index::{Idx, IndexSlice, IndexVec};
 use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
 use rustc_serialize::{Decodable, Encodable};
-use rustc_session::Session;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::Symbol;
 use rustc_span::{Span, DUMMY_SP};
@@ -106,65 +103,6 @@ impl<'tcx> HasLocalDecls<'tcx> for Body<'tcx> {
     }
 }
 
-thread_local! {
-    static PASS_NAMES: RefCell<FxHashMap<&'static str, &'static str>> = {
-        RefCell::new(FxHashMap::default())
-    };
-}
-
-/// Converts a MIR pass name into a snake case form to match the profiling naming style.
-fn to_profiler_name(type_name: &'static str) -> &'static str {
-    PASS_NAMES.with(|names| match names.borrow_mut().entry(type_name) {
-        Entry::Occupied(e) => *e.get(),
-        Entry::Vacant(e) => {
-            let snake_case: String = type_name
-                .chars()
-                .flat_map(|c| {
-                    if c.is_ascii_uppercase() {
-                        vec!['_', c.to_ascii_lowercase()]
-                    } else if c == '-' {
-                        vec!['_']
-                    } else {
-                        vec![c]
-                    }
-                })
-                .collect();
-            let result = &*String::leak(format!("mir_pass{}", snake_case));
-            e.insert(result);
-            result
-        }
-    })
-}
-
-/// A streamlined trait that you can implement to create a pass; the
-/// pass will be named after the type, and it will consist of a main
-/// loop that goes over each available MIR and applies `run_pass`.
-pub trait MirPass<'tcx> {
-    fn name(&self) -> &'static str {
-        // FIXME Simplify the implementation once more `str` methods get const-stable.
-        // See copypaste in `MirLint`
-        const {
-            let name = std::any::type_name::<Self>();
-            crate::util::common::c_name(name)
-        }
-    }
-
-    fn profiler_name(&self) -> &'static str {
-        to_profiler_name(self.name())
-    }
-
-    /// Returns `true` if this pass is enabled with the current combination of compiler flags.
-    fn is_enabled(&self, _sess: &Session) -> bool {
-        true
-    }
-
-    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>);
-
-    fn is_mir_dump_enabled(&self) -> bool {
-        true
-    }
-}
-
 impl MirPhase {
     /// Gets the index of the current MirPhase within the set of all `MirPhase`s.
     ///

Diff for: compiler/rustc_middle/src/ty/inhabitedness/mod.rs

@@ -81,10 +81,6 @@ impl<'tcx> VariantDef {
         adt: ty::AdtDef<'_>,
     ) -> InhabitedPredicate<'tcx> {
         debug_assert!(!adt.is_union());
-        if self.is_field_list_non_exhaustive() && !self.def_id.is_local() {
-            // Non-exhaustive variants from other crates are always considered inhabited.
-            return InhabitedPredicate::True;
-        }
         InhabitedPredicate::all(
             tcx,
             self.fields.iter().map(|field| {

Diff for: compiler/rustc_middle/src/util/common.rs

@@ -20,19 +20,3 @@ pub fn to_readable_str(mut val: usize) -> String {
 
     groups.join("_")
 }
-
-// const wrapper for `if let Some((_, tail)) = name.rsplit_once(':') { tail } else { name }`
-pub const fn c_name(name: &'static str) -> &'static str {
-    // FIXME Simplify the implementation once more `str` methods get const-stable.
-    // and inline into call site
-    let bytes = name.as_bytes();
-    let mut i = bytes.len();
-    while i > 0 && bytes[i - 1] != b':' {
-        i = i - 1;
-    }
-    let (_, bytes) = bytes.split_at(i);
-    match std::str::from_utf8(bytes) {
-        Ok(name) => name,
-        Err(_) => name,
-    }
-}