diff --git a/clippy_lints/src/lifetimes.rs b/clippy_lints/src/lifetimes.rs index 1de7e9e47f7..6bfcc475841 100644 --- a/clippy_lints/src/lifetimes.rs +++ b/clippy_lints/src/lifetimes.rs @@ -6,6 +6,7 @@ use rustc::hir::intravisit::{Visitor, walk_ty, walk_ty_param_bound, walk_fn_decl use std::collections::{HashSet, HashMap}; use syntax::codemap::Span; use utils::{in_external_macro, span_lint, last_path_segment}; +use syntax::symbol::keywords; /// **What it does:** Checks for lifetime annotations which can be removed by /// relying on lifetime elision. @@ -58,20 +59,24 @@ impl LintPass for LifetimePass { impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LifetimePass { fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) { - if let ItemFn(ref decl, _, _, _, ref generics, _) = item.node { - check_fn_inner(cx, decl, generics, item.span); + if let ItemFn(ref decl, _, _, _, ref generics, id) = item.node { + check_fn_inner(cx, decl, Some(id), generics, item.span); } } fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx ImplItem) { - if let ImplItemKind::Method(ref sig, _) = item.node { - check_fn_inner(cx, &sig.decl, &sig.generics, item.span); + if let ImplItemKind::Method(ref sig, id) = item.node { + check_fn_inner(cx, &sig.decl, Some(id), &sig.generics, item.span); } } fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx TraitItem) { - if let TraitItemKind::Method(ref sig, _) = item.node { - check_fn_inner(cx, &sig.decl, &sig.generics, item.span); + if let TraitItemKind::Method(ref sig, ref body) = item.node { + let body = match *body { + TraitMethod::Required(_) => None, + TraitMethod::Provided(id) => Some(id), + }; + check_fn_inner(cx, &sig.decl, body, &sig.generics, item.span); } } } @@ -98,7 +103,7 @@ fn bound_lifetimes(bound: &TyParamBound) -> HirVec<&Lifetime> { } } -fn check_fn_inner<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, decl: &'tcx FnDecl, generics: &'tcx Generics, span: Span) { +fn check_fn_inner<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, decl: &'tcx FnDecl, body: Option, generics: &'tcx Generics, span: Span) { if in_external_macro(cx, span) || has_where_lifetimes(cx, &generics.where_clause) { return; } @@ -107,7 +112,7 @@ fn check_fn_inner<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, decl: &'tcx FnDecl, gene .iter() .flat_map(|typ| typ.bounds.iter().flat_map(bound_lifetimes)); - if could_use_elision(cx, decl, &generics.lifetimes, bounds_lts) { + if could_use_elision(cx, decl, body, &generics.lifetimes, bounds_lts) { span_lint(cx, NEEDLESS_LIFETIMES, span, @@ -119,6 +124,7 @@ fn check_fn_inner<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, decl: &'tcx FnDecl, gene fn could_use_elision<'a, 'tcx: 'a, T: Iterator>( cx: &LateContext<'a, 'tcx>, func: &'tcx FnDecl, + body: Option, named_lts: &'tcx [LifetimeDef], bounds_lts: T ) -> bool { @@ -147,6 +153,14 @@ fn could_use_elision<'a, 'tcx: 'a, T: Iterator>( let input_lts = lts_from_bounds(input_visitor.into_vec(), bounds_lts); let output_lts = output_visitor.into_vec(); + if let Some(body_id) = body { + let mut checker = BodyLifetimeChecker { lifetimes_used_in_body: false }; + checker.visit_expr(&cx.tcx.hir.body(body_id).value); + if checker.lifetimes_used_in_body { + return false; + } + } + // check for lifetimes from higher scopes for lt in input_lts.iter().chain(output_lts.iter()) { if !allowed_lts.contains(lt) { @@ -384,3 +398,20 @@ fn report_extra_lifetimes<'a, 'tcx: 'a>(cx: &LateContext<'a, 'tcx>, func: &'tcx span_lint(cx, UNUSED_LIFETIMES, v, "this lifetime isn't used in the function definition"); } } + +struct BodyLifetimeChecker { + lifetimes_used_in_body: bool, +} + +impl<'tcx> Visitor<'tcx> for BodyLifetimeChecker { + // for lifetimes as parameters of generics + fn visit_lifetime(&mut self, lifetime: &'tcx Lifetime) { + if lifetime.name != keywords::Invalid.name() && lifetime.name != "'static" { + self.lifetimes_used_in_body = true; + } + } + + fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> { + NestedVisitorMap::None + } +} \ No newline at end of file diff --git a/tests/ui/lifetimes.rs b/tests/ui/lifetimes.rs index f953c0ad3d2..620ceafdba2 100644 --- a/tests/ui/lifetimes.rs +++ b/tests/ui/lifetimes.rs @@ -128,5 +128,29 @@ fn elided_input_named_output<'a>(_arg: &str) -> &'a str { unimplemented!() } fn trait_bound_ok<'a, T: WithLifetime<'static>>(_: &'a u8, _: T) { unimplemented!() } fn trait_bound<'a, T: WithLifetime<'a>>(_: &'a u8, _: T) { unimplemented!() } +// don't warn on these, see #292 +fn trait_bound_bug<'a, T: WithLifetime<'a>>() { unimplemented!() } + +// #740 +struct Test { + vec: Vec, +} + +impl Test { + fn iter<'a>(&'a self) -> Box + 'a> { + unimplemented!() + } +} + + +trait LintContext<'a> {} + +fn f<'a, T: LintContext<'a>>(cx: &T) {} + +fn test<'a>(x: &'a [u8]) -> u8 { + let y: &'a u8 = &x[5]; + *y +} + fn main() { } diff --git a/tests/ui/lifetimes.stderr b/tests/ui/lifetimes.stderr index 6d213ad45f2..aa12547bb20 100644 --- a/tests/ui/lifetimes.stderr +++ b/tests/ui/lifetimes.stderr @@ -91,5 +91,28 @@ error: explicit lifetimes given in parameter types where they could be elided 128 | fn trait_bound_ok<'a, T: WithLifetime<'static>>(_: &'a u8, _: T) { unimplemented!() } | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -error: aborting due to 14 previous errors +error: explicit lifetimes given in parameter types where they could be elided + --> $DIR/lifetimes.rs:132:1 + | +132 | fn trait_bound_bug<'a, T: WithLifetime<'a>>() { unimplemented!() } + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: explicit lifetimes given in parameter types where they could be elided + --> $DIR/lifetimes.rs:140:5 + | +140 | fn iter<'a>(&'a self) -> Box + 'a> { + | _____^ starting here... +141 | | unimplemented!() +142 | | } + | |_____^ ...ending here + +warning: unused variable: `cx` + --> $DIR/lifetimes.rs:148:30 + | +148 | fn f<'a, T: LintContext<'a>>(cx: &T) {} + | ^^ + | + = note: #[warn(unused_variables)] on by default + +error: aborting due to 16 previous errors