WIP

Author: GrigorenkoPV

compiler/rustc_hir/src/def.rs

@@ -829,12 +829,7 @@ pub enum LifetimeRes {
     /// late resolution. Those lifetimes will be inferred by typechecking.
     Infer,
     /// `'static` lifetime.
-    Static {
-        /// We do not want to emit `elided_named_lifetimes`
-        /// when we are inside of a const item or a static,
-        /// because it would get too annoying.
-        suppress_elision_warning: bool,
-    },
+    Static,
     /// Resolution failure.
     Error,
     /// HACK: This is used to recover the NodeId of an elided lifetime.

compiler/rustc_lint/src/context/diagnostics.rs

@@ -8,13 +8,12 @@ use rustc_errors::{
     elided_lifetime_in_path_suggestion, Applicability, Diag, DiagArgValue, LintDiagnostic,
 };
 use rustc_middle::middle::stability;
-use rustc_session::lint::{BuiltinLintDiag, ElidedLifetimeResolution};
+use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::Session;
-use rustc_span::symbol::kw;
 use rustc_span::BytePos;
 use tracing::debug;
 
-use crate::lints::{self, ElidedNamedLifetime};
+use crate::lints::{self};
 
 mod check_cfg;
 
@@ -446,16 +445,5 @@ 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: (span, kind), resolution } => {
-            match resolution {
-                ElidedLifetimeResolution::Static => {
-                    ElidedNamedLifetime { span, kind, name: kw::StaticLifetime, declaration: None }
-                }
-                ElidedLifetimeResolution::Param(name, declaration) => {
-                    ElidedNamedLifetime { span, kind, name, declaration: Some(declaration) }
-                }
-            }
-            .decorate_lint(diag)
-        }
     }
 }

compiler/rustc_lint/src/elided.rs

@@ -0,0 +1,116 @@
+use rustc_hir::{
+    ImplItem, ImplItemKind, Item, ItemKind, Lifetime, LifetimeName, TraitItem, TraitItemKind,
+};
+use rustc_middle::ty::layout::HasTyCtxt;
+use rustc_session::{declare_lint, impl_lint_pass};
+use rustc_span::symbol::kw;
+
+use crate::lints::{ElidedNamedLifetime, ElidedNamedLifetimeSuggestion};
+use crate::{LateContext, LateLintPass, LintContext};
+
+declare_lint! {
+    /// The `elided_named_lifetimes` lint detects when an elided
+    /// lifetime ends up being a named lifetime, such as `'static`
+    /// or some lifetime parameter `'a`.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![deny(elided_named_lifetimes)]
+    /// struct Foo;
+    /// impl Foo {
+    ///     pub fn get_mut(&'static self, x: &mut u8) -> &mut u8 {
+    ///         unsafe { &mut *(x as *mut _) }
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Lifetime elision is quite useful, because it frees you from having
+    /// to give each lifetime its own name, but sometimes it can produce
+    /// somewhat surprising resolutions. In safe code, it is mostly okay,
+    /// because the borrow checker prevents any unsoundness, so the worst
+    /// case scenario is you get a confusing error message in some other place.
+    /// But with `unsafe` code, such unexpected resolutions may lead to unsound code.
+    pub ELIDED_NAMED_LIFETIMES,
+    Warn,
+    "detects when an elided lifetime gets resolved to be `'static` or some named parameter"
+}
+
+#[derive(Clone, Debug, Default)]
+pub(crate) struct ElidedNamedLifetimes {
+    allow_static: bool,
+}
+
+impl_lint_pass!(ElidedNamedLifetimes => [ELIDED_NAMED_LIFETIMES]);
+
+impl<'tcx> LateLintPass<'tcx> for ElidedNamedLifetimes {
+    fn check_trait_item(&mut self, _: &LateContext<'tcx>, item: &'tcx TraitItem<'tcx>) {
+        if let TraitItemKind::Const(..) = item.kind {
+            self.allow_static = true;
+        }
+    }
+    fn check_trait_item_post(&mut self, _: &LateContext<'tcx>, _: &'tcx TraitItem<'tcx>) {
+        self.allow_static = false;
+    }
+
+    fn check_impl_item(&mut self, _: &LateContext<'tcx>, item: &'tcx ImplItem<'tcx>) {
+        if let ImplItemKind::Const(..) = item.kind {
+            self.allow_static = true;
+        }
+    }
+    fn check_impl_item_post(&mut self, _: &LateContext<'tcx>, _: &'tcx ImplItem<'tcx>) {
+        self.allow_static = false;
+    }
+
+    fn check_item(&mut self, _: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
+        if let ItemKind::Const(..) | ItemKind::Static(..) = item.kind {
+            self.allow_static = true;
+        }
+    }
+    fn check_item_post(&mut self, _: &LateContext<'tcx>, _: &'tcx Item<'tcx>) {
+        self.allow_static = false;
+    }
+
+    fn check_lifetime(&mut self, cx: &LateContext<'tcx>, lifetime: &'tcx Lifetime) {
+        // `.is_elided()` should probably be called `.resolves_to_elided()`,
+        // and `.is_anonymous()` is actually the thing that we need here.
+        if !lifetime.is_anonymous() {
+            return;
+        }
+        let (name, declaration) = match lifetime.res {
+            LifetimeName::Param(param) => {
+                let name = cx.tcx().item_name(param.into());
+                if name == kw::UnderscoreLifetime {
+                    return;
+                }
+                let span = cx.tcx().def_span(param);
+                (name, Some(span))
+            }
+            LifetimeName::Static => {
+                if self.allow_static {
+                    return;
+                }
+                (kw::StaticLifetime, None)
+            }
+            LifetimeName::ImplicitObjectLifetimeDefault
+            | LifetimeName::Error
+            | LifetimeName::Infer => return,
+        };
+        cx.emit_lint(
+            ELIDED_NAMED_LIFETIMES,
+            ElidedNamedLifetime {
+                span: lifetime.ident.span,
+                sugg: {
+                    let (span, code) = lifetime.suggestion(name.as_str());
+                    ElidedNamedLifetimeSuggestion { span, code }
+                },
+                name,
+                declaration,
+            },
+        )
+    }
+}

compiler/rustc_lint/src/late.rs

@@ -286,6 +286,7 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
             cx.with_param_env(trait_item.owner_id, |cx| {
                 lint_callback!(cx, check_trait_item, trait_item);
                 hir_visit::walk_trait_item(cx, trait_item);
+                lint_callback!(cx, check_trait_item_post, trait_item);
             });
         });
         self.context.generics = generics;
@@ -305,6 +306,7 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
     }
 
     fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
+        lint_callback!(self, check_lifetime, lt);
         hir_visit::walk_lifetime(self, lt);
     }
 

compiler/rustc_lint/src/lib.rs

@@ -50,6 +50,7 @@ mod context;
 mod deref_into_dyn_supertrait;
 mod drop_forget_useless;
 mod early;
+mod elided;
 mod enum_intrinsics_non_enums;
 mod errors;
 mod expect;
@@ -91,6 +92,7 @@ use async_fn_in_trait::AsyncFnInTrait;
 use builtin::*;
 use deref_into_dyn_supertrait::*;
 use drop_forget_useless::*;
+use elided::ElidedNamedLifetimes;
 use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
 use for_loops_over_fallibles::*;
 use hidden_unicode_codepoints::*;
@@ -243,6 +245,7 @@ late_lint_methods!(
             NonLocalDefinitions: NonLocalDefinitions::default(),
             ImplTraitOvercaptures: ImplTraitOvercaptures,
             TailExprDropOrder: TailExprDropOrder,
+            ElidedNamedLifetimes: ElidedNamedLifetimes::default(),
         ]
     ]
 );

compiler/rustc_lint/src/lints.rs

@@ -7,9 +7,9 @@ use rustc_errors::{
     Applicability, Diag, DiagArgValue, DiagMessage, DiagStyledString, ElidedLifetimeInPathSubdiag,
     EmissionGuarantee, LintDiagnostic, MultiSpan, SubdiagMessageOp, Subdiagnostic, SuggestionStyle,
 };
+use rustc_hir as hir;
 use rustc_hir::def::Namespace;
 use rustc_hir::def_id::DefId;
-use rustc_hir::{self as hir, MissingLifetimeKind};
 use rustc_macros::{LintDiagnostic, Subdiagnostic};
 use rustc_middle::ty::inhabitedness::InhabitedPredicate;
 use rustc_middle::ty::{Clause, PolyExistentialTraitRef, Ty, TyCtxt};
@@ -2624,16 +2624,23 @@ pub(crate) struct ElidedLifetimesInPaths {
     pub subdiag: ElidedLifetimeInPathSubdiag,
 }
 
+#[allow(unused)]
 pub(crate) struct ElidedNamedLifetime {
     pub span: Span,
-    pub kind: MissingLifetimeKind,
     pub name: Symbol,
     pub declaration: Option<Span>,
+    pub sugg: ElidedNamedLifetimeSuggestion,
+}
+
+pub(crate) struct ElidedNamedLifetimeSuggestion {
+    pub span: Span,
+    pub code: String,
 }
 
 impl<G: EmissionGuarantee> LintDiagnostic<'_, G> for ElidedNamedLifetime {
     fn decorate_lint(self, diag: &mut rustc_errors::Diag<'_, G>) {
-        let Self { span, kind, name, declaration } = self;
+        let Self { span, name, declaration, sugg } = self;
+        diag.span(span);
         diag.primary_message(fluent::lint_elided_named_lifetime);
         diag.arg("name", name);
         diag.span_label(span, fluent::lint_label_elided);
@@ -2647,32 +2654,12 @@ impl<G: EmissionGuarantee> LintDiagnostic<'_, G> for ElidedNamedLifetime {
         if name != rustc_span::symbol::kw::StaticLifetime {
             return;
         }
-        match kind {
-            MissingLifetimeKind::Underscore => diag.span_suggestion_verbose(
-                span,
-                fluent::lint_suggestion,
-                format!("{name}"),
-                Applicability::MachineApplicable,
-            ),
-            MissingLifetimeKind::Ampersand => diag.span_suggestion_verbose(
-                span.shrink_to_hi(),
-                fluent::lint_suggestion,
-                format!("{name} "),
-                Applicability::MachineApplicable,
-            ),
-            MissingLifetimeKind::Comma => diag.span_suggestion_verbose(
-                span.shrink_to_hi(),
-                fluent::lint_suggestion,
-                format!("{name}, "),
-                Applicability::MachineApplicable,
-            ),
-            MissingLifetimeKind::Brackets => diag.span_suggestion_verbose(
-                span.shrink_to_hi(),
-                fluent::lint_suggestion,
-                format!("<{name}>"),
-                Applicability::MachineApplicable,
-            ),
-        };
+        diag.span_suggestion_verbose(
+            sugg.span,
+            fluent::lint_suggestion,
+            sugg.code,
+            Applicability::MachineApplicable,
+        );
     }
 }
 

compiler/rustc_lint/src/passes.rs

@@ -34,6 +34,7 @@ macro_rules! late_lint_methods {
                 d: rustc_span::Span,
                 e: rustc_span::def_id::LocalDefId);
             fn check_trait_item(a: &'tcx rustc_hir::TraitItem<'tcx>);
+            fn check_trait_item_post(a: &'tcx rustc_hir::TraitItem<'tcx>);
             fn check_impl_item(a: &'tcx rustc_hir::ImplItem<'tcx>);
             fn check_impl_item_post(a: &'tcx rustc_hir::ImplItem<'tcx>);
             fn check_struct_def(a: &'tcx rustc_hir::VariantData<'tcx>);
@@ -43,6 +44,7 @@ macro_rules! late_lint_methods {
             fn check_attribute(a: &'tcx rustc_ast::Attribute);
             fn check_attributes(a: &'tcx [rustc_ast::Attribute]);
             fn check_attributes_post(a: &'tcx [rustc_ast::Attribute]);
+            fn check_lifetime(lt: &'tcx rustc_hir::Lifetime);
         ]);
     )
 }

compiler/rustc_lint_defs/src/builtin.rs

@@ -42,7 +42,6 @@ declare_lint_pass! {
         DUPLICATE_MACRO_ATTRIBUTES,
         ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
         ELIDED_LIFETIMES_IN_PATHS,
-        ELIDED_NAMED_LIFETIMES,
         EXPLICIT_BUILTIN_CFGS_IN_FLAGS,
         EXPORTED_PRIVATE_DEPENDENCIES,
         FFI_UNWIND_CALLS,
@@ -1863,38 +1862,6 @@ declare_lint! {
     "hidden lifetime parameters in types are deprecated"
 }
 
-declare_lint! {
-    /// The `elided_named_lifetimes` lint detects when an elided
-    /// lifetime ends up being a named lifetime, such as `'static`
-    /// or some lifetime parameter `'a`.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,compile_fail
-    /// #![deny(elided_named_lifetimes)]
-    /// struct Foo;
-    /// impl Foo {
-    ///     pub fn get_mut(&'static self, x: &mut u8) -> &mut u8 {
-    ///         unsafe { &mut *(x as *mut _) }
-    ///     }
-    /// }
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// Lifetime elision is quite useful, because it frees you from having
-    /// to give each lifetime its own name, but sometimes it can produce
-    /// somewhat surprising resolutions. In safe code, it is mostly okay,
-    /// because the borrow checker prevents any unsoundness, so the worst
-    /// case scenario is you get a confusing error message in some other place.
-    /// But with `unsafe` code, such unexpected resolutions may lead to unsound code.
-    pub ELIDED_NAMED_LIFETIMES,
-    Warn,
-    "detects when an elided lifetime gets resolved to be `'static` or some named parameter"
-}
-
 declare_lint! {
     /// The `bare_trait_objects` lint suggests using `dyn Trait` for trait
     /// objects.

compiler/rustc_lint_defs/src/lib.rs

@@ -10,7 +10,7 @@ use rustc_data_structures::stable_hasher::{
 };
 use rustc_error_messages::{DiagMessage, MultiSpan};
 use rustc_hir::def::Namespace;
-use rustc_hir::{HashStableContext, HirId, MissingLifetimeKind};
+use rustc_hir::{HashStableContext, HirId};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::edition::Edition;
 use rustc_span::symbol::{Ident, MacroRulesNormalizedIdent};
@@ -556,12 +556,6 @@ pub enum DeprecatedSinceKind {
     InVersion(String),
 }
 
-#[derive(Debug)]
-pub enum ElidedLifetimeResolution {
-    Static,
-    Param(Symbol, Span),
-}
-
 // This could be a closure, but then implementing derive trait
 // becomes hacky (and it gets allocated).
 #[derive(Debug)]
@@ -574,10 +568,6 @@ pub enum BuiltinLintDiag {
     },
     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
     ElidedLifetimesInPaths(usize, Span, bool, Span),
-    ElidedNamedLifetimes {
-        elided: (Span, MissingLifetimeKind),
-        resolution: ElidedLifetimeResolution,
-    },
     UnknownCrateTypes {
         span: Span,
         candidate: Option<Symbol>,