elided_named_lifetimes: add suggestions

compiler/rustc_lint/src/context/diagnostics.rs

@@ -7,6 +7,7 @@ use rustc_ast::util::unicode::TEXT_FLOW_CONTROL_CHARS;
 use rustc_errors::{
     elided_lifetime_in_path_suggestion, Applicability, Diag, DiagArgValue, LintDiagnostic,
 };
+use rustc_hir::MissingLifetimeKind;
 use rustc_middle::middle::stability;
 use rustc_session::lint::{BuiltinLintDiag, ElidedLifetimeResolution};
 use rustc_session::Session;
@@ -14,7 +15,8 @@ use rustc_span::symbol::kw;
 use rustc_span::BytePos;
 use tracing::debug;
 
-use crate::lints;
+use crate::fluent_generated;
+use crate::lints::{self, ElidedNamedLifetime};
 
 mod check_cfg;
 
@@ -442,20 +444,32 @@ pub(super) fn decorate_lint(sess: &Session, diagnostic: BuiltinLintDiag, diag: &
         BuiltinLintDiag::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by } => {
             lints::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by }.decorate_lint(diag)
         }
-        BuiltinLintDiag::ElidedNamedLifetimes { elided: (elided, _kind), resolution } => {
-            match resolution {
-                ElidedLifetimeResolution::Static => lints::ElidedNamedLifetime {
-                    elided,
-                    name: kw::StaticLifetime,
-                    named_declaration: None,
-                },
-                ElidedLifetimeResolution::Param(name, declaration) => lints::ElidedNamedLifetime {
-                    elided,
-                    name,
-                    named_declaration: Some(declaration),
-                },
-            }
-            .decorate_lint(diag)
+        BuiltinLintDiag::ElidedNamedLifetimes { elided: (span, kind), resolution } => {
+            let (name, named_declaration) = match resolution {
+                ElidedLifetimeResolution::Static => (kw::StaticLifetime, None),
+                ElidedLifetimeResolution::Param(name, declaration) => (name, Some(declaration)),
+            };
+            ElidedNamedLifetime { span, name, named_declaration }.decorate_lint(diag);
+
+            let (applicability, suggestion) = match kind {
+                MissingLifetimeKind::Underscore => {
+                    (Applicability::MachineApplicable, format!("{name}"))
+                }
+                MissingLifetimeKind::Ampersand => {
+                    (Applicability::MachineApplicable, format!("&{name} "))
+                }
+                MissingLifetimeKind::Comma => (Applicability::Unspecified, format!("<{name}, ")),
+                MissingLifetimeKind::Brackets => (
+                    Applicability::Unspecified,
+                    format!("{}<{name}>", sess.source_map().span_to_snippet(span).unwrap()),
+                ),
+            };
+            diag.span_suggestion_verbose(
+                span,
+                fluent_generated::lint_elided_named_lifetime_suggestion,
+                suggestion,
+                applicability,
+            );
         }
     }
 }

compiler/rustc_lint/src/lints.rs

@@ -2627,7 +2627,7 @@ pub(crate) struct ElidedLifetimesInPaths {
 #[diag(lint_elided_named_lifetime)]
 pub(crate) struct ElidedNamedLifetime {
     #[label(lint_label_elided)]
-    pub elided: Span,
+    pub span: Span,
     pub name: Symbol,
     #[label(lint_label_named)]
     pub named_declaration: Option<Span>,