Auto merge of #127936 - matthiaskrgr:rollup-ci0eg7k, r=tgross35

Rollup of 8 pull requests

Successful merges:

 - #127418 (Wrap too long type name)
 - #127594 (Fuchsia status code match arm)
 - #127835 (Fix ICE in suggestion caused by `⩵` being recovered as `==`)
 - #127858 (match lowering: Rename `MatchPair` to `MatchPairTree`)
 - #127871 (Mention that type parameters are used recursively on bivariance error)
 - #127913 (remove `debug-logging` default from tools profile)
 - #127925 (Remove tag field from `Relation`s)
 - #127929 (Use more accurate span for `addr_of!` suggestion)

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

4 files changed, 177 insertions, 61 deletions

diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index bf8ef18c04f..dbc265ad3ff 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -1572,6 +1572,7 @@ fn check_type_alias_type_params_are_used<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalD
                 param_name,
                 param_def_kind: tcx.def_descr(param.def_id),
                 help: errors::UnusedGenericParameterHelp::TyAlias { param_name },
+                usage_spans: vec![],
                 const_param_help,
             });
             diag.code(E0091);
diff --git a/compiler/rustc_hir_analysis/src/check/errs.rs b/compiler/rustc_hir_analysis/src/check/errs.rs
index 17cb20df754..19a0476e630 100644
--- a/compiler/rustc_hir_analysis/src/check/errs.rs
+++ b/compiler/rustc_hir_analysis/src/check/errs.rs
@@ -1,5 +1,4 @@
 use rustc_hir as hir;
-use rustc_hir_pretty::qpath_to_string;
 use rustc_lint_defs::builtin::STATIC_MUT_REFS;
 use rustc_middle::ty::{Mutability, TyCtxt};
 use rustc_span::Span;
@@ -12,9 +11,17 @@ pub fn maybe_expr_static_mut(tcx: TyCtxt<'_>, expr: hir::Expr<'_>) {
     let hir_id = expr.hir_id;
     if let hir::ExprKind::AddrOf(borrow_kind, m, expr) = expr.kind
         && matches!(borrow_kind, hir::BorrowKind::Ref)
-        && let Some(var) = path_if_static_mut(tcx, expr)
+        && path_if_static_mut(expr)
     {
-        handle_static_mut_ref(tcx, span, var, span.edition().at_least_rust_2024(), m, hir_id);
+        handle_static_mut_ref(
+            tcx,
+            span,
+            span.with_hi(expr.span.lo()),
+            span.shrink_to_hi(),
+            span.edition().at_least_rust_2024(),
+            m,
+            hir_id,
+        );
     }
 }
 
@@ -24,12 +31,13 @@ pub fn maybe_stmt_static_mut(tcx: TyCtxt<'_>, stmt: hir::Stmt<'_>) {
         && let hir::PatKind::Binding(ba, _, _, _) = loc.pat.kind
         && let hir::ByRef::Yes(rmutbl) = ba.0
         && let Some(init) = loc.init
-        && let Some(var) = path_if_static_mut(tcx, init)
+        && path_if_static_mut(init)
     {
         handle_static_mut_ref(
             tcx,
             init.span,
-            var,
+            init.span.shrink_to_lo(),
+            init.span.shrink_to_hi(),
             loc.span.edition().at_least_rust_2024(),
             rmutbl,
             stmt.hir_id,
@@ -37,38 +45,39 @@ pub fn maybe_stmt_static_mut(tcx: TyCtxt<'_>, stmt: hir::Stmt<'_>) {
     }
 }
 
-fn path_if_static_mut(tcx: TyCtxt<'_>, expr: &hir::Expr<'_>) -> Option<String> {
+fn path_if_static_mut(expr: &hir::Expr<'_>) -> bool {
     if let hir::ExprKind::Path(qpath) = expr.kind
         && let hir::QPath::Resolved(_, path) = qpath
         && let hir::def::Res::Def(def_kind, _) = path.res
         && let hir::def::DefKind::Static { safety: _, mutability: Mutability::Mut, nested: false } =
             def_kind
     {
-        return Some(qpath_to_string(&tcx, &qpath));
+        return true;
     }
-    None
+    false
 }
 
 fn handle_static_mut_ref(
     tcx: TyCtxt<'_>,
     span: Span,
-    var: String,
+    lo: Span,
+    hi: Span,
     e2024: bool,
     mutable: Mutability,
     hir_id: hir::HirId,
 ) {
     if e2024 {
         let (sugg, shared) = if mutable == Mutability::Mut {
-            (errors::StaticMutRefSugg::Mut { span, var }, "mutable")
+            (errors::MutRefSugg::Mut { lo, hi }, "mutable")
         } else {
-            (errors::StaticMutRefSugg::Shared { span, var }, "shared")
+            (errors::MutRefSugg::Shared { lo, hi }, "shared")
         };
         tcx.dcx().emit_err(errors::StaticMutRef { span, sugg, shared });
     } else {
         let (sugg, shared) = if mutable == Mutability::Mut {
-            (errors::RefOfMutStaticSugg::Mut { span, var }, "mutable")
+            (errors::MutRefSugg::Mut { lo, hi }, "mutable")
         } else {
-            (errors::RefOfMutStaticSugg::Shared { span, var }, "shared")
+            (errors::MutRefSugg::Shared { lo, hi }, "shared")
         };
         tcx.emit_node_span_lint(
             STATIC_MUT_REFS,
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index b2ef07d65c5..809427f86ee 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -4,12 +4,12 @@ use crate::constrained_generic_params::{identify_constrained_generic_params, Par
 use crate::errors;
 use crate::fluent_generated as fluent;
 
-use hir::intravisit::Visitor;
+use hir::intravisit::{self, Visitor};
 use rustc_ast as ast;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
 use rustc_errors::{codes::*, pluralize, struct_span_code_err, Applicability, ErrorGuaranteed};
 use rustc_hir as hir;
-use rustc_hir::def::DefKind;
+use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId, LocalModDefId};
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::ItemKind;
@@ -1799,7 +1799,7 @@ fn receiver_is_implemented<'tcx>(
 
 fn check_variances_for_type_defn<'tcx>(
     tcx: TyCtxt<'tcx>,
-    item: &hir::Item<'tcx>,
+    item: &'tcx hir::Item<'tcx>,
     hir_generics: &hir::Generics<'tcx>,
 ) {
     let identity_args = ty::GenericArgs::identity_for_item(tcx, item.owner_id);
@@ -1886,21 +1886,21 @@ fn check_variances_for_type_defn<'tcx>(
             hir::ParamName::Error => {}
             _ => {
                 let has_explicit_bounds = explicitly_bounded_params.contains(&parameter);
-                report_bivariance(tcx, hir_param, has_explicit_bounds, item.kind);
+                report_bivariance(tcx, hir_param, has_explicit_bounds, item);
             }
         }
     }
 }
 
-fn report_bivariance(
-    tcx: TyCtxt<'_>,
-    param: &rustc_hir::GenericParam<'_>,
+fn report_bivariance<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    param: &'tcx hir::GenericParam<'tcx>,
     has_explicit_bounds: bool,
-    item_kind: ItemKind<'_>,
+    item: &'tcx hir::Item<'tcx>,
 ) -> ErrorGuaranteed {
     let param_name = param.name.ident();
 
-    let help = match item_kind {
+    let help = match item.kind {
         ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
             if let Some(def_id) = tcx.lang_items().phantom_data() {
                 errors::UnusedGenericParameterHelp::Adt {
@@ -1915,6 +1915,49 @@ fn report_bivariance(
         item_kind => bug!("report_bivariance: unexpected item kind: {item_kind:?}"),
     };
 
+    let mut usage_spans = vec![];
+    intravisit::walk_item(
+        &mut CollectUsageSpans { spans: &mut usage_spans, param_def_id: param.def_id.to_def_id() },
+        item,
+    );
+
+    if !usage_spans.is_empty() {
+        // First, check if the ADT is (probably) cyclical. We say probably here, since
+        // we're not actually looking into substitutions, just walking through fields.
+        // And we only recurse into the fields of ADTs, and not the hidden types of
+        // opaques or anything else fancy.
+        let item_def_id = item.owner_id.to_def_id();
+        let is_probably_cyclical = if matches!(
+            tcx.def_kind(item_def_id),
+            DefKind::Struct | DefKind::Union | DefKind::Enum
+        ) {
+            IsProbablyCyclical { tcx, adt_def_id: item_def_id, seen: Default::default() }
+                .visit_all_fields(tcx.adt_def(item_def_id))
+                .is_break()
+        } else {
+            false
+        };
+        // If the ADT is cyclical, then if at least one usage of the type parameter or
+        // the `Self` alias is present in the, then it's probably a cyclical struct, and
+        // we should call those parameter usages recursive rather than just saying they're
+        // unused...
+        //
+        // We currently report *all* of the parameter usages, since computing the exact
+        // subset is very involved, and the fact we're mentioning recursion at all is
+        // likely to guide the user in the right direction.
+        if is_probably_cyclical {
+            let diag = tcx.dcx().create_err(errors::RecursiveGenericParameter {
+                spans: usage_spans,
+                param_span: param.span,
+                param_name,
+                param_def_kind: tcx.def_descr(param.def_id.to_def_id()),
+                help,
+                note: (),
+            });
+            return diag.emit();
+        }
+    }
+
     let const_param_help =
         matches!(param.kind, hir::GenericParamKind::Type { .. } if !has_explicit_bounds)
             .then_some(());
@@ -1923,6 +1966,7 @@ fn report_bivariance(
         span: param.span,
         param_name,
         param_def_kind: tcx.def_descr(param.def_id.to_def_id()),
+        usage_spans,
         help,
         const_param_help,
     });
@@ -1930,6 +1974,77 @@ fn report_bivariance(
     diag.emit()
 }
 
+/// Detects cases where an ADT is trivially cyclical -- we want to detect this so
+/// /we only mention that its parameters are used cyclically if the ADT is truly
+/// cyclical.
+///
+/// Notably, we don't consider substitutions here, so this may have false positives.
+struct IsProbablyCyclical<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    adt_def_id: DefId,
+    seen: FxHashSet<DefId>,
+}
+
+impl<'tcx> IsProbablyCyclical<'tcx> {
+    fn visit_all_fields(&mut self, adt_def: ty::AdtDef<'tcx>) -> ControlFlow<(), ()> {
+        for field in adt_def.all_fields() {
+            self.tcx.type_of(field.did).instantiate_identity().visit_with(self)?;
+        }
+
+        ControlFlow::Continue(())
+    }
+}
+
+impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for IsProbablyCyclical<'tcx> {
+    type Result = ControlFlow<(), ()>;
+
+    fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<(), ()> {
+        if let Some(adt_def) = t.ty_adt_def() {
+            if adt_def.did() == self.adt_def_id {
+                return ControlFlow::Break(());
+            }
+
+            if self.seen.insert(adt_def.did()) {
+                self.visit_all_fields(adt_def)?;
+            }
+        }
+
+        t.super_visit_with(self)
+    }
+}
+
+/// Collect usages of the `param_def_id` and `Res::SelfTyAlias` in the HIR.
+///
+/// This is used to report places where the user has used parameters in a
+/// non-variance-constraining way for better bivariance errors.
+struct CollectUsageSpans<'a> {
+    spans: &'a mut Vec<Span>,
+    param_def_id: DefId,
+}
+
+impl<'tcx> Visitor<'tcx> for CollectUsageSpans<'_> {
+    type Result = ();
+
+    fn visit_generics(&mut self, _g: &'tcx rustc_hir::Generics<'tcx>) -> Self::Result {
+        // Skip the generics. We only care about fields, not where clause/param bounds.
+    }
+
+    fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) -> Self::Result {
+        if let hir::TyKind::Path(hir::QPath::Resolved(None, qpath)) = t.kind {
+            if let Res::Def(DefKind::TyParam, def_id) = qpath.res
+                && def_id == self.param_def_id
+            {
+                self.spans.push(t.span);
+                return;
+            } else if let Res::SelfTyAlias { .. } = qpath.res {
+                self.spans.push(t.span);
+                return;
+            }
+        }
+        intravisit::walk_ty(self, t);
+    }
+}
+
 impl<'tcx> WfCheckingCtxt<'_, 'tcx> {
     /// Feature gates RFC 2056 -- trivial bounds, checking for global bounds that
     /// aren't true.
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index 0ee87a13e9e..03311fed396 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -1500,33 +1500,33 @@ pub struct StaticMutRef<'a> {
     #[label]
     pub span: Span,
     #[subdiagnostic]
-    pub sugg: StaticMutRefSugg,
+    pub sugg: MutRefSugg,
     pub shared: &'a str,
 }
 
 #[derive(Subdiagnostic)]
-pub enum StaticMutRefSugg {
-    #[suggestion(
+pub enum MutRefSugg {
+    #[multipart_suggestion(
         hir_analysis_suggestion,
         style = "verbose",
-        code = "addr_of!({var})",
         applicability = "maybe-incorrect"
     )]
     Shared {
-        #[primary_span]
-        span: Span,
-        var: String,
+        #[suggestion_part(code = "addr_of!(")]
+        lo: Span,
+        #[suggestion_part(code = ")")]
+        hi: Span,
     },
-    #[suggestion(
+    #[multipart_suggestion(
         hir_analysis_suggestion_mut,
         style = "verbose",
-        code = "addr_of_mut!({var})",
         applicability = "maybe-incorrect"
     )]
     Mut {
-        #[primary_span]
-        span: Span,
-        var: String,
+        #[suggestion_part(code = "addr_of_mut!(")]
+        lo: Span,
+        #[suggestion_part(code = ")")]
+        hi: Span,
     },
 }
 
@@ -1539,36 +1539,10 @@ pub struct RefOfMutStatic<'a> {
     #[label]
     pub span: Span,
     #[subdiagnostic]
-    pub sugg: RefOfMutStaticSugg,
+    pub sugg: MutRefSugg,
     pub shared: &'a str,
 }
 
-#[derive(Subdiagnostic)]
-pub enum RefOfMutStaticSugg {
-    #[suggestion(
-        hir_analysis_suggestion,
-        style = "verbose",
-        code = "addr_of!({var})",
-        applicability = "maybe-incorrect"
-    )]
-    Shared {
-        #[primary_span]
-        span: Span,
-        var: String,
-    },
-    #[suggestion(
-        hir_analysis_suggestion_mut,
-        style = "verbose",
-        code = "addr_of_mut!({var})",
-        applicability = "maybe-incorrect"
-    )]
-    Mut {
-        #[primary_span]
-        span: Span,
-        var: String,
-    },
-}
-
 #[derive(Diagnostic)]
 #[diag(hir_analysis_not_supported_delegation)]
 pub struct NotSupportedDelegation<'a> {
@@ -1597,12 +1571,29 @@ pub(crate) struct UnusedGenericParameter {
     pub span: Span,
     pub param_name: Ident,
     pub param_def_kind: &'static str,
+    #[label(hir_analysis_usage_spans)]
+    pub usage_spans: Vec<Span>,
     #[subdiagnostic]
     pub help: UnusedGenericParameterHelp,
     #[help(hir_analysis_const_param_help)]
     pub const_param_help: Option<()>,
 }
 
+#[derive(Diagnostic)]
+#[diag(hir_analysis_recursive_generic_parameter)]
+pub(crate) struct RecursiveGenericParameter {
+    #[primary_span]
+    pub spans: Vec<Span>,
+    #[label]
+    pub param_span: Span,
+    pub param_name: Ident,
+    pub param_def_kind: &'static str,
+    #[subdiagnostic]
+    pub help: UnusedGenericParameterHelp,
+    #[note]
+    pub note: (),
+}
+
 #[derive(Subdiagnostic)]
 pub(crate) enum UnusedGenericParameterHelp {
     #[help(hir_analysis_unused_generic_parameter_adt_help)]