elided_named_lifetimes: improve the message a bit

Author: GrigorenkoPV

compiler/rustc_ast_lowering/src/lib.rs

@@ -1643,7 +1643,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         for lifetime in captured_lifetimes_to_duplicate {
             let res = self.resolver.get_lifetime_res(lifetime.id).unwrap_or(LifetimeRes::Error);
             let (old_def_id, missing_kind) = match res {
-                LifetimeRes::Param { param: old_def_id, binder: _ } => (old_def_id, None),
+                LifetimeRes::Param { param: (old_def_id, _), binder: _ } => (old_def_id, None),
 
                 LifetimeRes::Fresh { param, kind, .. } => {
                     debug_assert_eq!(lifetime.ident.name, kw::UnderscoreLifetime);
@@ -2061,7 +2061,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         res: LifetimeRes,
     ) -> &'hir hir::Lifetime {
         let res = match res {
-            LifetimeRes::Param { param, .. } => {
+            LifetimeRes::Param { param: (param, _), .. } => {
                 let param = self.get_remapped_def_id(param);
                 hir::LifetimeName::Param(param)
             }

compiler/rustc_hir/src/def.rs

@@ -8,7 +8,7 @@ use rustc_data_structures::unord::UnordMap;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::hygiene::MacroKind;
-use rustc_span::symbol::kw;
+use rustc_span::symbol::{kw, Ident};
 use rustc_span::Symbol;
 
 use crate::definitions::DefPathData;
@@ -796,8 +796,8 @@ impl<Id> Res<Id> {
 pub enum LifetimeRes {
     /// Successfully linked the lifetime to a generic parameter.
     Param {
-        /// Id of the generic parameter that introduced it.
-        param: LocalDefId,
+        /// `LocalDefId` & `Ident` of the generic parameter that introduced it.
+        param: (LocalDefId, Ident),
         /// Id of the introducing place. That can be:
         /// - an item's id, for the item's generic parameters;
         /// - a TraitRef's ref_id, identifying the `for<...>` binder;

compiler/rustc_lint/messages.ftl

@@ -253,9 +253,8 @@ lint_duplicate_macro_attribute =
 lint_duplicate_matcher_binding = duplicate matcher binding
 
 lint_elided_named_lifetime = elided lifetime has a name
-    .label_static = this elided lifetime gets resolved as `'static`
-    .label_this = this elided lifetime
-    .label_that = gets resolved as this named lifetime
+    .label_elided = this elided lifetime gets resolved as `{$name}`
+    .label_named = lifetime `{$name}` declared here
 
 lint_enum_intrinsics_mem_discriminant =
     the return value of `mem::discriminant` is unspecified when called with a non-enum type

compiler/rustc_lint/src/context/diagnostics.rs

@@ -10,6 +10,7 @@ use rustc_errors::{
 use rustc_middle::middle::stability;
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::Session;
+use rustc_span::symbol::kw;
 use rustc_span::BytePos;
 use tracing::debug;
 
@@ -442,10 +443,14 @@ pub(super) fn decorate_lint(sess: &Session, diagnostic: BuiltinLintDiag, diag: &
             lints::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by }.decorate_lint(diag)
         }
         BuiltinLintDiag::ElidedIsStatic { elided } => {
-            lints::ElidedNamedLifetime::Static { elided }.decorate_lint(diag)
+            lints::ElidedNamedLifetime { elided, name: kw::StaticLifetime, named_declaration: None }
+                .decorate_lint(diag)
         }
-        BuiltinLintDiag::ElidedIsParam { elided, param } => {
-            lints::ElidedNamedLifetime::Param { elided, param }.decorate_lint(diag)
+        BuiltinLintDiag::ElidedIsParam { elided, param } => lints::ElidedNamedLifetime {
+            elided,
+            name: param.name,
+            named_declaration: Some(param.span),
         }
+        .decorate_lint(diag),
     }
 }

compiler/rustc_lint/src/lints.rs

@@ -2612,19 +2612,13 @@ pub struct ElidedLifetimesInPaths {
 }
 
 #[derive(LintDiagnostic)]
-pub enum ElidedNamedLifetime {
-    #[diag(lint_elided_named_lifetime)]
-    Static {
-        #[label(lint_label_static)]
-        elided: Span,
-    },
-    #[diag(lint_elided_named_lifetime)]
-    Param {
-        #[label(lint_label_this)]
-        elided: Span,
-        #[label(lint_label_that)]
-        param: Span,
-    },
+#[diag(lint_elided_named_lifetime)]
+pub struct ElidedNamedLifetime {
+    #[label(lint_label_elided)]
+    pub elided: Span,
+    pub name: Symbol,
+    #[label(lint_label_named)]
+    pub named_declaration: Option<Span>,
 }
 
 #[derive(LintDiagnostic)]

compiler/rustc_lint_defs/src/lib.rs

@@ -590,7 +590,7 @@ pub enum BuiltinLintDiag {
     },
     ElidedIsParam {
         elided: Span,
-        param: Span,
+        param: Ident,
     },
     UnknownCrateTypes {
         span: Span,

compiler/rustc_resolve/src/late.rs

@@ -1597,7 +1597,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             if let Some(&(_, res)) = rib.bindings.get(&normalized_ident) {
                 self.record_lifetime_res(lifetime.id, res, LifetimeElisionCandidate::Named);
 
-                if let LifetimeRes::Param { param, binder } = res {
+                if let LifetimeRes::Param { param: (param, _), binder } = res {
                     match self.lifetime_uses.entry(param) {
                         Entry::Vacant(v) => {
                             debug!("First use of {:?} at {:?}", res, ident.span);
@@ -2065,7 +2065,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
         }
 
         match candidate {
-            LifetimeElisionCandidate::Missing(missing) => {
+            LifetimeElisionCandidate::Missing(missing @ MissingLifetime { span: elided, .. }) => {
                 debug_assert_eq!(id, missing.id);
                 match res {
                     LifetimeRes::Static => {
@@ -2074,11 +2074,11 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                                 lint::builtin::ELIDED_NAMED_LIFETIMES,
                                 missing.id_if_not_fake_or(self.crate_node_id),
                                 missing.span,
-                                BuiltinLintDiag::ElidedIsStatic { elided: missing.span },
+                                BuiltinLintDiag::ElidedIsStatic { elided },
                             );
                         }
                     }
-                    LifetimeRes::Param { param, binder } => {
+                    LifetimeRes::Param { param: (_, param), binder } => {
                         self.r.lint_buffer.buffer_lint(
                             lint::builtin::ELIDED_NAMED_LIFETIMES,
                             // It should be possible to use `self.crate_node_id`
@@ -2088,10 +2088,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                             // we would have to do some additional work.
                             missing.id_if_not_fake_or(binder),
                             missing.span,
-                            BuiltinLintDiag::ElidedIsParam {
-                                elided: missing.span,
-                                param: self.r.tcx().source_span(param),
-                            },
+                            BuiltinLintDiag::ElidedIsParam { elided, param },
                         );
                     }
                     LifetimeRes::Fresh { .. }
@@ -2826,7 +2823,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                         (&mut function_value_rib, DefKind::ConstParam)
                     }
                     GenericParamKind::Lifetime => {
-                        let res = LifetimeRes::Param { param: def_id, binder };
+                        let res = LifetimeRes::Param { param: (def_id, param.ident), binder };
                         self.record_lifetime_param(param.id, res);
                         function_lifetime_rib.bindings.insert(ident, (param.id, res));
                         continue;