Auto merge of rust-lang#127924 - matthiaskrgr:rollup-1gn6afv, r=matth…

…iaskrgr

Rollup of 6 pull requests

Successful merges:

 - rust-lang#124881 (Use ThreadId instead of TLS-address in `ReentrantLock`)
 - rust-lang#127656 (make pub_use_of_private_extern_crate show up in cargo's future breakage reports)
 - rust-lang#127748 (Use Option's discriminant as its size hint)
 - rust-lang#127854 (Add internal lint for detecting non-glob imports of `rustc_type_ir::inherent`)
 - rust-lang#127908 (Update extern linking documentation)
 - rust-lang#127919 (Allow a git command for getting the current branch in bootstrap to fail)

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

compiler/rustc_lint/messages.ftl

@@ -556,6 +556,9 @@ lint_non_fmt_panic_unused =
     }
     .add_fmt_suggestion = or add a "{"{"}{"}"}" format string to use the message literally
 
+lint_non_glob_import_type_ir_inherent = non-glob import of `rustc_type_ir::inherent`
+    .suggestion = try using a glob import instead
+
 lint_non_local_definitions_cargo_update = the {$macro_kind} `{$macro_name}` may come from an old version of the `{$crate_name}` crate, try updating your dependency with `cargo update -p {$crate_name}`
 
 lint_non_local_definitions_deprecation = this lint may become deny-by-default in the edition 2024 and higher, see the tracking issue <https://github.com/rust-lang/rust/issues/120363>

compiler/rustc_lint/src/internal.rs

@@ -3,7 +3,8 @@
 
 use crate::lints::{
     BadOptAccessDiag, DefaultHashTypesDiag, DiagOutOfImpl, LintPassByHand, NonExistentDocKeyword,
-    QueryInstability, SpanUseEqCtxtDiag, TyQualified, TykindDiag, TykindKind, UntranslatableDiag,
+    NonGlobImportTypeIrInherent, QueryInstability, SpanUseEqCtxtDiag, TyQualified, TykindDiag,
+    TykindKind, UntranslatableDiag,
 };
 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
 use rustc_ast as ast;
@@ -263,6 +264,49 @@ fn gen_args(segment: &PathSegment<'_>) -> String {
     String::new()
 }
 
+declare_tool_lint! {
+    /// The `non_glob_import_of_type_ir_inherent_item` lint detects
+    /// non-glob imports of module `rustc_type_ir::inherent`.
+    pub rustc::NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT,
+    Allow,
+    "non-glob import of `rustc_type_ir::inherent`",
+    report_in_external_macro: true
+}
+
+declare_lint_pass!(TypeIr => [NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT]);
+
+impl<'tcx> LateLintPass<'tcx> for TypeIr {
+    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
+        let rustc_hir::ItemKind::Use(path, kind) = item.kind else { return };
+
+        let is_mod_inherent = |def_id| cx.tcx.is_diagnostic_item(sym::type_ir_inherent, def_id);
+        let (lo, hi, snippet) = match path.segments {
+            [.., penultimate, segment]
+                if penultimate.res.opt_def_id().is_some_and(is_mod_inherent) =>
+            {
+                (segment.ident.span, item.ident.span, "*")
+            }
+            [.., segment]
+                if path.res.iter().flat_map(Res::opt_def_id).any(is_mod_inherent)
+                    && let rustc_hir::UseKind::Single = kind =>
+            {
+                let (lo, snippet) =
+                    match cx.tcx.sess.source_map().span_to_snippet(path.span).as_deref() {
+                        Ok("self") => (path.span, "*"),
+                        _ => (segment.ident.span.shrink_to_hi(), "::*"),
+                    };
+                (lo, if segment.ident == item.ident { lo } else { item.ident.span }, snippet)
+            }
+            _ => return,
+        };
+        cx.emit_span_lint(
+            NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT,
+            path.span,
+            NonGlobImportTypeIrInherent { suggestion: lo.eq_ctxt(hi).then(|| lo.to(hi)), snippet },
+        );
+    }
+}
+
 declare_tool_lint! {
     /// The `lint_pass_impl_without_macro` detects manual implementations of a lint
     /// pass, without using [`declare_lint_pass`] or [`impl_lint_pass`].

compiler/rustc_lint/src/lib.rs

@@ -572,6 +572,8 @@ fn register_internals(store: &mut LintStore) {
     store.register_late_mod_pass(|_| Box::new(ExistingDocKeyword));
     store.register_lints(&TyTyKind::get_lints());
     store.register_late_mod_pass(|_| Box::new(TyTyKind));
+    store.register_lints(&TypeIr::get_lints());
+    store.register_late_mod_pass(|_| Box::new(TypeIr));
     store.register_lints(&Diagnostics::get_lints());
     store.register_late_mod_pass(|_| Box::new(Diagnostics));
     store.register_lints(&BadOptAccess::get_lints());
@@ -595,6 +597,7 @@ fn register_internals(store: &mut LintStore) {
             LintId::of(PASS_BY_VALUE),
             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
             LintId::of(USAGE_OF_QUALIFIED_TY),
+            LintId::of(NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT),
             LintId::of(EXISTING_DOC_KEYWORD),
             LintId::of(BAD_OPT_ACCESS),
             LintId::of(SPAN_USE_EQ_CTXT),

compiler/rustc_lint/src/lints.rs

@@ -926,6 +926,14 @@ pub struct TyQualified {
     pub suggestion: Span,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(lint_non_glob_import_type_ir_inherent)]
+pub struct NonGlobImportTypeIrInherent {
+    #[suggestion(code = "{snippet}", applicability = "maybe-incorrect")]
+    pub suggestion: Option<Span>,
+    pub snippet: &'static str,
+}
+
 #[derive(LintDiagnostic)]
 #[diag(lint_lintpass_by_hand)]
 #[help]

compiler/rustc_lint_defs/src/builtin.rs

@@ -1203,16 +1203,16 @@ declare_lint! {
     /// This was historically allowed, but is not the intended behavior
     /// according to the visibility rules. This is a [future-incompatible]
     /// lint to transition this to a hard error in the future. See [issue
-    /// #34537] for more details.
+    /// #127909] for more details.
     ///
-    /// [issue #34537]: https://github.com/rust-lang/rust/issues/34537
+    /// [issue #127909]: https://github.com/rust-lang/rust/issues/127909
     /// [future-incompatible]: ../index.md#future-incompatible-lints
     pub PUB_USE_OF_PRIVATE_EXTERN_CRATE,
     Deny,
     "detect public re-exports of private extern crates",
     @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
-        reference: "issue #34537 <https://github.com/rust-lang/rust/issues/34537>",
+        reason: FutureIncompatibilityReason::FutureReleaseErrorReportInDeps,
+        reference: "issue #127909 <https://github.com/rust-lang/rust/issues/127909>",
     };
 }
 

compiler/rustc_span/src/symbol.rs

@@ -1926,6 +1926,7 @@ symbols! {
         type_ascription,
         type_changing_struct_update,
         type_id,
+        type_ir_inherent,
         type_length_limit,
         type_macros,
         type_name,

compiler/rustc_type_ir/src/effects.rs

@@ -1,4 +1,4 @@
-use crate::inherent::{AdtDef, IntoKind, Ty};
+use crate::inherent::*;
 use crate::lang_items::TraitSolverLangItem::{EffectsMaybe, EffectsNoRuntime, EffectsRuntime};
 use crate::Interner;
 

compiler/rustc_type_ir/src/lib.rs

@@ -24,6 +24,7 @@ pub mod elaborate;
 pub mod error;
 pub mod fast_reject;
 pub mod fold;
+#[cfg_attr(feature = "nightly", rustc_diagnostic_item = "type_ir_inherent")]
 pub mod inherent;
 pub mod ir_print;
 pub mod lang_items;

library/core/src/option.rs

@@ -770,6 +770,13 @@ impl<T> Option<T> {
         }
     }
 
+    #[inline]
+    const fn len(&self) -> usize {
+        // Using the intrinsic avoids emitting a branch to get the 0 or 1.
+        let discriminant: isize = crate::intrinsics::discriminant_value(self);
+        discriminant as usize
+    }
+
     /// Returns a slice of the contained value, if any. If this is `None`, an
     /// empty slice is returned. This can be useful to have a single type of
     /// iterator over an `Option` or slice.
@@ -812,7 +819,7 @@ impl<T> Option<T> {
         unsafe {
             slice::from_raw_parts(
                 (self as *const Self).byte_add(core::mem::offset_of!(Self, Some.0)).cast(),
-                self.is_some() as usize,
+                self.len(),
             )
         }
     }
@@ -869,7 +876,7 @@ impl<T> Option<T> {
         unsafe {
             slice::from_raw_parts_mut(
                 (self as *mut Self).byte_add(core::mem::offset_of!(Self, Some.0)).cast(),
-                self.is_some() as usize,
+                self.len(),
             )
         }
     }
@@ -2242,10 +2249,8 @@ impl<A> Iterator for Item<A> {
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        match self.opt {
-            Some(_) => (1, Some(1)),
-            None => (0, Some(0)),
-        }
+        let len = self.len();
+        (len, Some(len))
     }
 }
 
@@ -2256,7 +2261,12 @@ impl<A> DoubleEndedIterator for Item<A> {
     }
 }
 
-impl<A> ExactSizeIterator for Item<A> {}
+impl<A> ExactSizeIterator for Item<A> {
+    #[inline]
+    fn len(&self) -> usize {
+        self.opt.len()
+    }
+}
 impl<A> FusedIterator for Item<A> {}
 unsafe impl<A> TrustedLen for Item<A> {}