Rollup of 11 pull requests

compiler/rustc_ast/Cargo.toml

@@ -4,10 +4,9 @@ version = "0.0.0"
 edition = "2021"
 
 [dependencies]
-# FIXME: bumping memchr to 2.7.1 causes linker errors in MSVC thin-lto
 # tidy-alphabetical-start
 bitflags = "2.4.1"
-memchr = "=2.5.0"
+memchr = "2.7.4"
 rustc_ast_ir = { path = "../rustc_ast_ir" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_index = { path = "../rustc_index" }

compiler/rustc_lint/messages.ftl

@@ -783,6 +783,9 @@ lint_tykind = usage of `ty::TyKind`
 lint_tykind_kind = usage of `ty::TyKind::<kind>`
     .suggestion = try using `ty::<kind>` directly
 
+lint_type_ir_inherent_usage = do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
+    .note = the method or struct you're looking for is likely defined somewhere else downstream in the compiler
+
 lint_undropped_manually_drops = calls to `std::mem::drop` with `std::mem::ManuallyDrop` instead of the inner value does nothing
     .label = argument has type `{$arg_ty}`
     .suggestion = use `std::mem::ManuallyDrop::into_inner` to get the inner value

compiler/rustc_lint/src/internal.rs

@@ -18,7 +18,7 @@ use tracing::debug;
 use crate::lints::{
     BadOptAccessDiag, DefaultHashTypesDiag, DiagOutOfImpl, LintPassByHand, NonExistentDocKeyword,
     NonGlobImportTypeIrInherent, QueryInstability, SpanUseEqCtxtDiag, TyQualified, TykindDiag,
-    TykindKind, UntranslatableDiag,
+    TykindKind, TypeIrInherentUsage, UntranslatableDiag,
 };
 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
 
@@ -277,13 +277,39 @@ declare_tool_lint! {
     report_in_external_macro: true
 }
 
-declare_lint_pass!(TypeIr => [NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT]);
+declare_tool_lint! {
+    /// The `usage_of_type_ir_inherent` lint detects usage `rustc_type_ir::inherent`.
+    ///
+    /// This module should only be used within the trait solver.
+    pub rustc::USAGE_OF_TYPE_IR_INHERENT,
+    Allow,
+    "usage `rustc_type_ir::inherent` outside of trait system",
+    report_in_external_macro: true
+}
+
+declare_lint_pass!(TypeIr => [NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT, USAGE_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);
+
+        // Path segments except for the final.
+        if let Some(seg) =
+            path.segments.iter().find(|seg| seg.res.opt_def_id().is_some_and(is_mod_inherent))
+        {
+            cx.emit_span_lint(USAGE_OF_TYPE_IR_INHERENT, seg.ident.span, TypeIrInherentUsage);
+        }
+        // Final path resolutions, like `use rustc_type_ir::inherent`
+        else if path.res.iter().any(|res| res.opt_def_id().is_some_and(is_mod_inherent)) {
+            cx.emit_span_lint(
+                USAGE_OF_TYPE_IR_INHERENT,
+                path.segments.last().unwrap().ident.span,
+                TypeIrInherentUsage,
+            );
+        }
+
         let (lo, hi, snippet) = match path.segments {
             [.., penultimate, segment]
                 if penultimate.res.opt_def_id().is_some_and(is_mod_inherent) =>

compiler/rustc_lint/src/lints.rs

@@ -918,6 +918,11 @@ pub(crate) struct TyQualified {
     pub suggestion: Span,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(lint_type_ir_inherent_usage)]
+#[note]
+pub(crate) struct TypeIrInherentUsage;
+
 #[derive(LintDiagnostic)]
 #[diag(lint_non_glob_import_type_ir_inherent)]
 pub(crate) struct NonGlobImportTypeIrInherent {

compiler/rustc_mir_transform/src/add_moves_for_packed_drops.rs

@@ -86,7 +86,7 @@ fn add_move_for_packed_drop<'tcx>(
 
     let source_info = terminator.source_info;
     let ty = place.ty(body, tcx).ty;
-    let temp = patch.new_temp(ty, terminator.source_info.span);
+    let temp = patch.new_temp(ty, source_info.span);
 
     let storage_dead_block = patch.new_block(BasicBlockData {
         statements: vec![Statement { source_info, kind: StatementKind::StorageDead(temp) }],

compiler/rustc_mir_transform/src/check_packed_ref.rs

@@ -37,24 +37,17 @@ impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
     }
 
     fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, _location: Location) {
-        if context.is_borrow() {
-            if util::is_disaligned(self.tcx, self.body, self.param_env, *place) {
-                let def_id = self.body.source.instance.def_id();
-                if let Some(impl_def_id) = self.tcx.impl_of_method(def_id)
-                    && self.tcx.is_builtin_derived(impl_def_id)
-                {
-                    // If we ever reach here it means that the generated derive
-                    // code is somehow doing an unaligned reference, which it
-                    // shouldn't do.
-                    span_bug!(
-                        self.source_info.span,
-                        "builtin derive created an unaligned reference"
-                    );
-                } else {
-                    self.tcx
-                        .dcx()
-                        .emit_err(errors::UnalignedPackedRef { span: self.source_info.span });
-                }
+        if context.is_borrow() && util::is_disaligned(self.tcx, self.body, self.param_env, *place) {
+            let def_id = self.body.source.instance.def_id();
+            if let Some(impl_def_id) = self.tcx.impl_of_method(def_id)
+                && self.tcx.is_builtin_derived(impl_def_id)
+            {
+                // If we ever reach here it means that the generated derive
+                // code is somehow doing an unaligned reference, which it
+                // shouldn't do.
+                span_bug!(self.source_info.span, "builtin derive created an unaligned reference");
+            } else {
+                self.tcx.dcx().emit_err(errors::UnalignedPackedRef { span: self.source_info.span });
             }
         }
     }