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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,118 @@ | ||
| use rustc_hir::def_id::LocalDefId; | ||
| use rustc_hir::intravisit::{walk_fn_decl, FnKind, Visitor}; | ||
| use rustc_hir::{ | ||
| Body, FnDecl, FnSig, ImplItem, ImplItemKind, Lifetime, LifetimeName, TraitItem, TraitItemKind, | ||
| }; | ||
| use rustc_middle::ty::layout::HasTyCtxt; | ||
| use rustc_session::{declare_lint, declare_lint_pass}; | ||
| use rustc_span::symbol::kw; | ||
| use rustc_span::Span; | ||
|
|
||
| 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" | ||
| } | ||
|
|
||
| declare_lint_pass!(ElidedNamedLifetimes => [ELIDED_NAMED_LIFETIMES]); | ||
|
|
||
| impl<'tcx> LateLintPass<'tcx> for ElidedNamedLifetimes { | ||
| fn check_fn( | ||
| &mut self, | ||
| cx: &LateContext<'tcx>, | ||
| _: FnKind<'tcx>, | ||
| decl: &'tcx FnDecl<'tcx>, | ||
| _: &'tcx Body<'tcx>, | ||
| _: Span, | ||
| _: LocalDefId, | ||
| ) { | ||
| self.check_decl(cx, decl) | ||
| } | ||
|
|
||
| fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'tcx>) { | ||
| if let TraitItemKind::Fn(FnSig { decl, .. }, _) = item.kind { | ||
| self.check_decl(cx, decl) | ||
| } | ||
| } | ||
|
|
||
| fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'tcx>) { | ||
| if let ImplItemKind::Fn(FnSig { decl, .. }, _) = item.kind { | ||
| self.check_decl(cx, decl) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl ElidedNamedLifetimes { | ||
| fn check_decl<'tcx>(&self, cx: &LateContext<'tcx>, decl: &'tcx FnDecl<'tcx>) { | ||
| walk_fn_decl(&mut LifetimeVisitor { cx }, decl) | ||
| } | ||
| } | ||
| struct LifetimeVisitor<'a, 'tcx> { | ||
| cx: &'a LateContext<'tcx>, | ||
| } | ||
|
|
||
| impl<'tcx> Visitor<'tcx> for LifetimeVisitor<'_, 'tcx> { | ||
| fn visit_lifetime(&mut self, lifetime: &'tcx Lifetime) -> Self::Result { | ||
| // `.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 tcx = self.cx.tcx(); | ||
| let name = tcx.item_name(param.into()); | ||
| if name == kw::UnderscoreLifetime { | ||
| return; | ||
| } | ||
| let span = tcx.source_span(param); | ||
| (name, Some(span)) | ||
| } | ||
| LifetimeName::Static => (kw::StaticLifetime, None), | ||
| LifetimeName::ImplicitObjectLifetimeDefault | ||
| | LifetimeName::Error | ||
| | LifetimeName::Infer => return, | ||
| }; | ||
| self.cx.emit_lint( | ||
| ELIDED_NAMED_LIFETIMES, | ||
| ElidedNamedLifetime { | ||
| span: lifetime.ident.span, | ||
| sugg: { | ||
| let (span, code) = lifetime.suggestion(); | ||
| ElidedNamedLifetimeSuggestion { span, code } | ||
| }, | ||
| name, | ||
| declaration, | ||
| }, | ||
| ) | ||
| } | ||
| } |
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