Auto merge of rust-lang#133329 - jhpratt:rollup-8ndpkzx, r=jhpratt

Rollup of 13 pull requests

Successful merges:

 - rust-lang#130867 (distinguish overflow and unimplemented in Step::steps_between)
 - rust-lang#131859 (Update TRPL to add new Chapter 17: Async and Await)
 - rust-lang#132090 (Stop being so bail-y in candidate assembly)
 - rust-lang#132658 (Detect const in pattern with typo)
 - rust-lang#133041 (Print name of env var in `--print=deployment-target`)
 - rust-lang#133102 (aarch64 softfloat target: always pass floats in int registers)
 - rust-lang#133159 (Don't allow `-Zunstable-options` to take a value )
 - rust-lang#133217 ([AIX] Add option -X32_64 to the "strip" command)
 - rust-lang#133237 (Minimally constify `Add`)
 - rust-lang#133238 (re-export `is_loongarch_feature_detected`)
 - rust-lang#133286 (Re-delay a resolve `bug` related to `Self`-ctor in patterns)
 - rust-lang#133301 (Add code example for `wrapping_neg` method for signed integers)
 - rust-lang#133313 (Use arc4random of libc for RTEMS target)

Failed merges:

 - rust-lang#133215 (Fix missing submodule in `./x vendor`)

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

compiler/rustc_abi/src/lib.rs

@@ -638,7 +638,7 @@ impl AddAssign for Size {
 #[cfg(feature = "nightly")]
 impl Step for Size {
     #[inline]
-    fn steps_between(start: &Self, end: &Self) -> Option<usize> {
+    fn steps_between(start: &Self, end: &Self) -> (usize, Option<usize>) {
         u64::steps_between(&start.bytes(), &end.bytes())
     }
 

compiler/rustc_codegen_ssa/src/back/apple.rs

@@ -97,7 +97,7 @@ fn minimum_deployment_target(target: &Target) -> OSVersion {
 }
 
 /// Name of the environment variable used to fetch the deployment target on the given OS.
-fn deployment_target_env_var(os: &str) -> &'static str {
+pub fn deployment_target_env_var(os: &str) -> &'static str {
     match os {
         "macos" => "MACOSX_DEPLOYMENT_TARGET",
         "ios" => "IPHONEOS_DEPLOYMENT_TARGET",

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1117,14 +1117,14 @@ fn link_natively(
         let stripcmd = "rust-objcopy";
         match (strip, crate_type) {
             (Strip::Debuginfo, _) => {
-                strip_symbols_with_external_utility(sess, stripcmd, out_filename, Some("-S"))
+                strip_symbols_with_external_utility(sess, stripcmd, out_filename, &["-S"])
             }
             // Per the manpage, `-x` is the maximum safe strip level for dynamic libraries. (#93988)
             (Strip::Symbols, CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro) => {
-                strip_symbols_with_external_utility(sess, stripcmd, out_filename, Some("-x"))
+                strip_symbols_with_external_utility(sess, stripcmd, out_filename, &["-x"])
             }
             (Strip::Symbols, _) => {
-                strip_symbols_with_external_utility(sess, stripcmd, out_filename, None)
+                strip_symbols_with_external_utility(sess, stripcmd, out_filename, &[])
             }
             (Strip::None, _) => {}
         }
@@ -1141,7 +1141,7 @@ fn link_natively(
         match strip {
             // Always preserve the symbol table (-x).
             Strip::Debuginfo => {
-                strip_symbols_with_external_utility(sess, stripcmd, out_filename, Some("-x"))
+                strip_symbols_with_external_utility(sess, stripcmd, out_filename, &["-x"])
             }
             // Strip::Symbols is handled via the --strip-all linker option.
             Strip::Symbols => {}
@@ -1158,11 +1158,15 @@ fn link_natively(
         match strip {
             Strip::Debuginfo => {
                 // FIXME: AIX's strip utility only offers option to strip line number information.
-                strip_symbols_with_external_utility(sess, stripcmd, out_filename, Some("-l"))
+                strip_symbols_with_external_utility(sess, stripcmd, out_filename, &[
+                    "-X32_64", "-l",
+                ])
             }
             Strip::Symbols => {
                 // Must be noted this option might remove symbol __aix_rust_metadata and thus removes .info section which contains metadata.
-                strip_symbols_with_external_utility(sess, stripcmd, out_filename, Some("-r"))
+                strip_symbols_with_external_utility(sess, stripcmd, out_filename, &[
+                    "-X32_64", "-r",
+                ])
             }
             Strip::None => {}
         }
@@ -1181,12 +1185,10 @@ fn strip_symbols_with_external_utility(
     sess: &Session,
     util: &str,
     out_filename: &Path,
-    option: Option<&str>,
+    options: &[&str],
 ) {
     let mut cmd = Command::new(util);
-    if let Some(option) = option {
-        cmd.arg(option);
-    }
+    cmd.args(options);
 
     let mut new_path = sess.get_tools_search_paths(false);
     if let Some(path) = env::var_os("PATH") {

compiler/rustc_driver_impl/src/lib.rs

@@ -875,8 +875,9 @@ fn print_crate_info(
             DeploymentTarget => {
                 if sess.target.is_like_osx {
                     println_info!(
-                        "deployment_target={}",
-                        apple::pretty_version(apple::deployment_target(sess))
+                        "{}={}",
+                        apple::deployment_target_env_var(&sess.target.os),
+                        apple::pretty_version(apple::deployment_target(sess)),
                     )
                 } else {
                     #[allow(rustc::diagnostic_outside_of_impl)]

compiler/rustc_hir_typeck/src/lib.rs

@@ -364,7 +364,7 @@ fn report_unexpected_variant_res(
         .with_code(err_code);
     match res {
         Res::Def(DefKind::Fn | DefKind::AssocFn, _) if err_code == E0164 => {
-            let patterns_url = "https://doc.rust-lang.org/book/ch18-00-patterns.html";
+            let patterns_url = "https://doc.rust-lang.org/book/ch19-00-patterns.html";
             err.with_span_label(span, "`fn` calls are not allowed in patterns")
                 .with_help(format!("for more information, visit {patterns_url}"))
         }

compiler/rustc_index_macros/src/newtype.rs

@@ -122,7 +122,7 @@ impl Parse for Newtype {
                 #gate_rustc_only
                 impl ::std::iter::Step for #name {
                     #[inline]
-                    fn steps_between(start: &Self, end: &Self) -> Option<usize> {
+                    fn steps_between(start: &Self, end: &Self) -> (usize, Option<usize>) {
                         <usize as ::std::iter::Step>::steps_between(
                             &Self::index(*start),
                             &Self::index(*end),

compiler/rustc_mir_build/messages.ftl

@@ -203,7 +203,7 @@ mir_build_lower_range_bound_must_be_less_than_or_equal_to_upper =
 
 mir_build_lower_range_bound_must_be_less_than_upper = lower range bound must be less than upper
 
-mir_build_more_information = for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html
+mir_build_more_information = for more information, visit https://doc.rust-lang.org/book/ch19-02-refutability.html
 
 mir_build_moved = value is moved into `{$name}` here
 
@@ -338,6 +338,13 @@ mir_build_unreachable_pattern = unreachable pattern
     .unreachable_covered_by_catchall = matches any value
     .unreachable_covered_by_one = matches all the relevant values
     .unreachable_covered_by_many = multiple earlier patterns match some of the same values
+    .unreachable_pattern_const_reexport_accessible = there is a constant of the same name imported in another scope, which could have been used to pattern match against its value instead of introducing a new catch-all binding, but it needs to be imported in the pattern's scope
+    .unreachable_pattern_wanted_const = you might have meant to pattern match against the value of {$is_typo ->
+        [true] similarly named constant
+        *[false] constant
+        } `{$const_name}` instead of introducing a new catch-all binding
+    .unreachable_pattern_const_inaccessible = there is a constant of the same name, which could have been used to pattern match against its value instead of introducing a new catch-all binding, but it is not accessible from this scope
+    .unreachable_pattern_let_binding = there is a binding of the same name; if you meant to pattern match against the value of that binding, that is a feature of constants that is not available for `let` bindings
     .suggestion = remove the match arm
 
 mir_build_unsafe_fn_safe_body = an unsafe function restricts its caller, but its body is safe by default

compiler/rustc_mir_build/src/errors.rs

@@ -593,6 +593,14 @@ pub(crate) struct UnreachablePattern<'tcx> {
     pub(crate) uninhabited_note: Option<()>,
     #[label(mir_build_unreachable_covered_by_catchall)]
     pub(crate) covered_by_catchall: Option<Span>,
+    #[subdiagnostic]
+    pub(crate) wanted_constant: Option<WantedConstant>,
+    #[note(mir_build_unreachable_pattern_const_reexport_accessible)]
+    pub(crate) accessible_constant: Option<Span>,
+    #[note(mir_build_unreachable_pattern_const_inaccessible)]
+    pub(crate) inaccessible_constant: Option<Span>,
+    #[note(mir_build_unreachable_pattern_let_binding)]
+    pub(crate) pattern_let_binding: Option<Span>,
     #[label(mir_build_unreachable_covered_by_one)]
     pub(crate) covered_by_one: Option<Span>,
     #[note(mir_build_unreachable_covered_by_many)]
@@ -602,6 +610,20 @@ pub(crate) struct UnreachablePattern<'tcx> {
     pub(crate) suggest_remove: Option<Span>,
 }
 
+#[derive(Subdiagnostic)]
+#[suggestion(
+    mir_build_unreachable_pattern_wanted_const,
+    code = "{const_path}",
+    applicability = "machine-applicable"
+)]
+pub(crate) struct WantedConstant {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) is_typo: bool,
+    pub(crate) const_name: String,
+    pub(crate) const_path: String,
+}
+
 #[derive(Diagnostic)]
 #[diag(mir_build_const_pattern_depends_on_generic_parameter, code = E0158)]
 pub(crate) struct ConstPatternDependsOnGenericParameter {

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -7,7 +7,9 @@ use rustc_errors::{Applicability, ErrorGuaranteed, MultiSpan, struct_span_code_e
 use rustc_hir::def::*;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::{self as hir, BindingMode, ByRef, HirId};
+use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::traits::Reveal;
+use rustc_lint::Level;
 use rustc_middle::bug;
 use rustc_middle::middle::limits::get_limit_size;
 use rustc_middle::thir::visit::Visitor;
@@ -22,8 +24,10 @@ use rustc_pattern_analysis::rustc::{
 use rustc_session::lint::builtin::{
     BINDINGS_WITH_VARIANT_NAME, IRREFUTABLE_LET_PATTERNS, UNREACHABLE_PATTERNS,
 };
+use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::{Span, sym};
+use rustc_trait_selection::infer::InferCtxtExt;
 use tracing::instrument;
 
 use crate::errors::*;
@@ -969,6 +973,10 @@ fn report_unreachable_pattern<'p, 'tcx>(
         covered_by_one: None,
         covered_by_many: None,
         covered_by_many_n_more_count: 0,
+        wanted_constant: None,
+        accessible_constant: None,
+        inaccessible_constant: None,
+        pattern_let_binding: None,
         suggest_remove: None,
     };
     match explanation.covered_by.as_slice() {
@@ -991,7 +999,10 @@ fn report_unreachable_pattern<'p, 'tcx>(
             });
         }
         [covering_pat] if pat_is_catchall(covering_pat) => {
-            lint.covered_by_catchall = Some(covering_pat.data().span);
+            // A binding pattern that matches all, a single binding name.
+            let pat = covering_pat.data();
+            lint.covered_by_catchall = Some(pat.span);
+            find_fallback_pattern_typo(cx, hir_id, pat, &mut lint);
         }
         [covering_pat] => {
             lint.covered_by_one = Some(covering_pat.data().span);
@@ -1024,6 +1035,157 @@ fn report_unreachable_pattern<'p, 'tcx>(
     cx.tcx.emit_node_span_lint(UNREACHABLE_PATTERNS, hir_id, pat_span, lint);
 }
 
+/// Detect typos that were meant to be a `const` but were interpreted as a new pattern binding.
+fn find_fallback_pattern_typo<'tcx>(
+    cx: &PatCtxt<'_, 'tcx>,
+    hir_id: HirId,
+    pat: &Pat<'tcx>,
+    lint: &mut UnreachablePattern<'_>,
+) {
+    if let (Level::Allow, _) = cx.tcx.lint_level_at_node(UNREACHABLE_PATTERNS, hir_id) {
+        // This is because we use `with_no_trimmed_paths` later, so if we never emit the lint we'd
+        // ICE. At the same time, we don't really need to do all of this if we won't emit anything.
+        return;
+    }
+    if let PatKind::Binding { name, subpattern: None, ty, .. } = pat.kind {
+        // See if the binding might have been a `const` that was mistyped or out of scope.
+        let mut accessible = vec![];
+        let mut accessible_path = vec![];
+        let mut inaccessible = vec![];
+        let mut imported = vec![];
+        let mut imported_spans = vec![];
+        let infcx = cx.tcx.infer_ctxt().build(ty::TypingMode::non_body_analysis());
+        let parent = cx.tcx.hir().get_parent_item(hir_id);
+
+        for item in cx.tcx.hir_crate_items(()).free_items() {
+            if let DefKind::Use = cx.tcx.def_kind(item.owner_id) {
+                // Look for consts being re-exported.
+                let item = cx.tcx.hir().expect_item(item.owner_id.def_id);
+                let use_name = item.ident.name;
+                let hir::ItemKind::Use(path, _) = item.kind else {
+                    continue;
+                };
+                for res in &path.res {
+                    if let Res::Def(DefKind::Const, id) = res
+                        && infcx.can_eq(cx.param_env, ty, cx.tcx.type_of(id).instantiate_identity())
+                    {
+                        if cx.tcx.visibility(id).is_accessible_from(parent, cx.tcx) {
+                            // The original const is accessible, suggest using it directly.
+                            let item_name = cx.tcx.item_name(*id);
+                            accessible.push(item_name);
+                            accessible_path.push(with_no_trimmed_paths!(cx.tcx.def_path_str(id)));
+                        } else if cx
+                            .tcx
+                            .visibility(item.owner_id)
+                            .is_accessible_from(parent, cx.tcx)
+                        {
+                            // The const is accessible only through the re-export, point at
+                            // the `use`.
+                            imported.push(use_name);
+                            imported_spans.push(item.ident.span);
+                        }
+                    }
+                }
+            }
+            if let DefKind::Const = cx.tcx.def_kind(item.owner_id)
+                && infcx.can_eq(
+                    cx.param_env,
+                    ty,
+                    cx.tcx.type_of(item.owner_id).instantiate_identity(),
+                )
+            {
+                // Look for local consts.
+                let item_name = cx.tcx.item_name(item.owner_id.into());
+                let vis = cx.tcx.visibility(item.owner_id);
+                if vis.is_accessible_from(parent, cx.tcx) {
+                    accessible.push(item_name);
+                    let path = if item_name == name {
+                        // We know that the const wasn't in scope because it has the exact
+                        // same name, so we suggest the full path.
+                        with_no_trimmed_paths!(cx.tcx.def_path_str(item.owner_id))
+                    } else {
+                        // The const is likely just typoed, and nothing else.
+                        cx.tcx.def_path_str(item.owner_id)
+                    };
+                    accessible_path.push(path);
+                } else if name == item_name {
+                    // The const exists somewhere in this crate, but it can't be imported
+                    // from this pattern's scope. We'll just point at its definition.
+                    inaccessible.push(cx.tcx.def_span(item.owner_id));
+                }
+            }
+        }
+        if let Some((i, &const_name)) =
+            accessible.iter().enumerate().find(|(_, &const_name)| const_name == name)
+        {
+            // The pattern name is an exact match, so the pattern needed to be imported.
+            lint.wanted_constant = Some(WantedConstant {
+                span: pat.span,
+                is_typo: false,
+                const_name: const_name.to_string(),
+                const_path: accessible_path[i].clone(),
+            });
+        } else if let Some(name) = find_best_match_for_name(&accessible, name, None) {
+            // The pattern name is likely a typo.
+            lint.wanted_constant = Some(WantedConstant {
+                span: pat.span,
+                is_typo: true,
+                const_name: name.to_string(),
+                const_path: name.to_string(),
+            });
+        } else if let Some(i) =
+            imported.iter().enumerate().find(|(_, &const_name)| const_name == name).map(|(i, _)| i)
+        {
+            // The const with the exact name wasn't re-exported from an import in this
+            // crate, we point at the import.
+            lint.accessible_constant = Some(imported_spans[i]);
+        } else if let Some(name) = find_best_match_for_name(&imported, name, None) {
+            // The typoed const wasn't re-exported by an import in this crate, we suggest
+            // the right name (which will likely require another follow up suggestion).
+            lint.wanted_constant = Some(WantedConstant {
+                span: pat.span,
+                is_typo: true,
+                const_path: name.to_string(),
+                const_name: name.to_string(),
+            });
+        } else if !inaccessible.is_empty() {
+            for span in inaccessible {
+                // The const with the exact name match isn't accessible, we just point at it.
+                lint.inaccessible_constant = Some(span);
+            }
+        } else {
+            // Look for local bindings for people that might have gotten confused with how
+            // `let` and `const` works.
+            for (_, node) in cx.tcx.hir().parent_iter(hir_id) {
+                match node {
+                    hir::Node::Stmt(hir::Stmt { kind: hir::StmtKind::Let(let_stmt), .. }) => {
+                        if let hir::PatKind::Binding(_, _, binding_name, _) = let_stmt.pat.kind {
+                            if name == binding_name.name {
+                                lint.pattern_let_binding = Some(binding_name.span);
+                            }
+                        }
+                    }
+                    hir::Node::Block(hir::Block { stmts, .. }) => {
+                        for stmt in *stmts {
+                            if let hir::StmtKind::Let(let_stmt) = stmt.kind {
+                                if let hir::PatKind::Binding(_, _, binding_name, _) =
+                                    let_stmt.pat.kind
+                                {
+                                    if name == binding_name.name {
+                                        lint.pattern_let_binding = Some(binding_name.span);
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    hir::Node::Item(_) => break,
+                    _ => {}
+                }
+            }
+        }
+    }
+}
+
 /// Report unreachable arms, if any.
 fn report_arm_reachability<'p, 'tcx>(
     cx: &PatCtxt<'p, 'tcx>,

compiler/rustc_parse/messages.ftl

@@ -827,7 +827,7 @@ parse_unexpected_expr_in_pat =
     }, found an expression
 
     .label = not a pattern
-    .note = arbitrary expressions are not allowed in patterns: <https://doc.rust-lang.org/book/ch18-00-patterns.html>
+    .note = arbitrary expressions are not allowed in patterns: <https://doc.rust-lang.org/book/ch19-00-patterns.html>
 
 parse_unexpected_expr_in_pat_const_sugg = consider extracting the expression into a `const`
 

compiler/rustc_passes/src/stability.rs

@@ -590,16 +590,7 @@ impl<'tcx> MissingStabilityAnnotations<'tcx> {
     }
 
     fn check_missing_const_stability(&self, def_id: LocalDefId, span: Span) {
-        // if the const impl is derived using the `derive_const` attribute,
-        // then it would be "stable" at least for the impl.
-        // We gate usages of it using `feature(const_trait_impl)` anyways
-        // so there is no unstable leakage
-        if self.tcx.is_automatically_derived(def_id.to_def_id()) {
-            return;
-        }
-
-        let is_const = self.tcx.is_const_fn(def_id.to_def_id())
-            || self.tcx.is_const_trait_impl(def_id.to_def_id());
+        let is_const = self.tcx.is_const_fn(def_id.to_def_id());
 
         // Reachable const fn must have a stability attribute.
         if is_const