X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_lints%2Fsrc%2Fptr.rs;h=2ecdf983e6bdafd76ad6f91d7a4bdd1bc9d00e69;hb=5d4102ee786dea507dc42e1c4968b959767abdbd;hp=f7017dfc5c3373c1c1b896ffb420ae3a1defed3d;hpb=b8ecdc1cefa8fbdefc8128d4592e8a2e39d71219;p=rust.git diff --git a/clippy_lints/src/ptr.rs b/clippy_lints/src/ptr.rs index f7017dfc5c3..2ecdf983e6b 100644 --- a/clippy_lints/src/ptr.rs +++ b/clippy_lints/src/ptr.rs @@ -1,37 +1,58 @@ //! Checks for usage of `&Vec[_]` and `&String`. +use std::borrow::Cow; use rustc::hir::*; use rustc::hir::map::NodeItem; +use rustc::hir::QPath; use rustc::lint::*; use rustc::ty; use syntax::ast::NodeId; use syntax::codemap::Span; use syntax_pos::MultiSpan; -use utils::{match_path, match_type, paths, span_lint, span_lint_and_then}; +use crate::utils::{match_qpath, match_type, paths, snippet_opt, span_lint, span_lint_and_then, walk_ptrs_hir_ty}; +use crate::utils::ptr::get_spans; -/// **What it does:** This lint checks for function arguments of type `&String` or `&Vec` unless -/// the references are mutable. +/// **What it does:** This lint checks for function arguments of type `&String` +/// or `&Vec` unless the references are mutable. It will also suggest you +/// replace `.clone()` calls with the appropriate `.to_owned()`/`to_string()` +/// calls. /// -/// **Why is this bad?** Requiring the argument to be of the specific size makes the function less -/// useful for no benefit; slices in the form of `&[T]` or `&str` usually suffice and can be -/// obtained from other types, too. +/// **Why is this bad?** Requiring the argument to be of the specific size +/// makes the function less useful for no benefit; slices in the form of `&[T]` +/// or `&str` usually suffice and can be obtained from other types, too. /// -/// **Known problems:** None. +/// **Known problems:** The lint does not follow data. So if you have an +/// argument `x` and write `let y = x; y.clone()` the lint will not suggest +/// changing that `.clone()` to `.to_owned()`. +/// +/// Other functions called from this function taking a `&String` or `&Vec` +/// argument may also fail to compile if you change the argument. Applying +/// this lint on them will fix the problem, but they may be in other crates. +/// +/// Also there may be `fn(&Vec)`-typed references pointing to your function. +/// If you have them, you will get a compiler error after applying this lint's +/// suggestions. You then have the choice to undo your changes or change the +/// type of the reference. +/// +/// Note that if the function is part of your public interface, there may be +/// other crates referencing it you may not be aware. Carefully deprecate the +/// function before applying the lint suggestions in this case. /// /// **Example:** /// ```rust /// fn foo(&Vec) { .. } /// ``` -declare_lint! { +declare_clippy_lint! { pub PTR_ARG, - Warn, + style, "fn arguments of the type `&Vec<...>` or `&String`, suggesting to use `&[...]` or `&str` \ instead, respectively" } /// **What it does:** This lint checks for equality comparisons with `ptr::null` /// -/// **Why is this bad?** It's easier and more readable to use the inherent `.is_null()` +/// **Why is this bad?** It's easier and more readable to use the inherent +/// `.is_null()` /// method instead /// /// **Known problems:** None. @@ -40,33 +61,38 @@ /// ```rust /// if x == ptr::null { .. } /// ``` -declare_lint! { +declare_clippy_lint! { pub CMP_NULL, - Warn, + style, "comparing a pointer to a null pointer, suggesting to use `.is_null()` instead." } -/// **What it does:** This lint checks for functions that take immutable references and return +/// **What it does:** This lint checks for functions that take immutable +/// references and return /// mutable ones. /// -/// **Why is this bad?** This is trivially unsound, as one can create two mutable references -/// from the same (immutable!) source. This [error](https://github.com/rust-lang/rust/issues/39465) +/// **Why is this bad?** This is trivially unsound, as one can create two +/// mutable references +/// from the same (immutable!) source. This +/// [error](https://github.com/rust-lang/rust/issues/39465) /// actually lead to an interim Rust release 1.15.1. /// -/// **Known problems:** To be on the conservative side, if there's at least one mutable reference -/// with the output lifetime, this lint will not trigger. In practice, this case is unlikely anyway. +/// **Known problems:** To be on the conservative side, if there's at least one +/// mutable reference +/// with the output lifetime, this lint will not trigger. In practice, this +/// case is unlikely anyway. /// /// **Example:** /// ```rust /// fn foo(&Foo) -> &mut Bar { .. } /// ``` -declare_lint! { +declare_clippy_lint! { pub MUT_FROM_REF, - Warn, + correctness, "fns that create mutable refs from immutable ref args" } -#[derive(Copy,Clone)] +#[derive(Copy, Clone)] pub struct PointerPass; impl LintPass for PointerPass { @@ -77,59 +103,147 @@ fn get_lints(&self) -> LintArray { impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PointerPass { fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) { - if let ItemFn(ref decl, _, _, _, _, _) = item.node { - check_fn(cx, decl, item.id); + if let ItemFn(ref decl, _, _, body_id) = item.node { + check_fn(cx, decl, item.id, Some(body_id)); } } fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx ImplItem) { - if let ImplItemKind::Method(ref sig, _) = item.node { + if let ImplItemKind::Method(ref sig, body_id) = item.node { if let Some(NodeItem(it)) = cx.tcx.hir.find(cx.tcx.hir.get_parent(item.id)) { if let ItemImpl(_, _, _, _, Some(_), _, _) = it.node { return; // ignore trait impls } } - check_fn(cx, &sig.decl, item.id); + check_fn(cx, &sig.decl, item.id, Some(body_id)); } } fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx TraitItem) { - if let TraitItemKind::Method(ref sig, _) = item.node { - check_fn(cx, &sig.decl, item.id); + if let TraitItemKind::Method(ref sig, ref trait_method) = item.node { + let body_id = if let TraitMethod::Provided(b) = *trait_method { + Some(b) + } else { + None + }; + check_fn(cx, &sig.decl, item.id, body_id); } } fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) { - if let ExprBinary(ref op, ref l, ref r) = expr.node { - if (op.node == BiEq || op.node == BiNe) && (is_null_path(l) || is_null_path(r)) { - span_lint(cx, - CMP_NULL, - expr.span, - "Comparing with null is better expressed by the .is_null() method"); + if let ExprKind::Binary(ref op, ref l, ref r) = expr.node { + if (op.node == BinOpKind::Eq || op.node == BinOpKind::Ne) && (is_null_path(l) || is_null_path(r)) { + span_lint( + cx, + CMP_NULL, + expr.span, + "Comparing with null is better expressed by the .is_null() method", + ); } } } } -fn check_fn(cx: &LateContext, decl: &FnDecl, fn_id: NodeId) { +fn check_fn(cx: &LateContext, decl: &FnDecl, fn_id: NodeId, opt_body_id: Option) { let fn_def_id = cx.tcx.hir.local_def_id(fn_id); let sig = cx.tcx.fn_sig(fn_def_id); let fn_ty = sig.skip_binder(); - for (arg, ty) in decl.inputs.iter().zip(fn_ty.inputs()) { - if let ty::TyRef(_, ty::TypeAndMut { ty, mutbl: MutImmutable }) = ty.sty { + for (idx, (arg, ty)) in decl.inputs.iter().zip(fn_ty.inputs()).enumerate() { + if let ty::TyRef( + _, + ty, + MutImmutable + ) = ty.sty + { if match_type(cx, ty, &paths::VEC) { - span_lint(cx, - PTR_ARG, - arg.span, - "writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used \ - with non-Vec-based slices. Consider changing the type to `&[...]`"); + let mut ty_snippet = None; + if_chain! { + if let TyPath(QPath::Resolved(_, ref path)) = walk_ptrs_hir_ty(arg).node; + if let Some(&PathSegment{args: Some(ref parameters), ..}) = path.segments.last(); + then { + let types: Vec<_> = parameters.args.iter().filter_map(|arg| match arg { + GenericArg::Type(ty) => Some(ty), + _ => None, + }).collect(); + if types.len() == 1 { + ty_snippet = snippet_opt(cx, types[0].span); + } + } + }; + if let Some(spans) = get_spans(cx, opt_body_id, idx, &[("clone", ".to_owned()")]) { + span_lint_and_then( + cx, + PTR_ARG, + arg.span, + "writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used \ + with non-Vec-based slices.", + |db| { + if let Some(ref snippet) = ty_snippet { + db.span_suggestion(arg.span, "change this to", format!("&[{}]", snippet)); + } + for (clonespan, suggestion) in spans { + db.span_suggestion( + clonespan, + &snippet_opt(cx, clonespan).map_or( + "change the call to".into(), + |x| Cow::Owned(format!("change `{}` to", x)), + ), + suggestion.into(), + ); + } + }, + ); + } } else if match_type(cx, ty, &paths::STRING) { - span_lint(cx, - PTR_ARG, - arg.span, - "writing `&String` instead of `&str` involves a new object where a slice will do. \ - Consider changing the type to `&str`"); + if let Some(spans) = get_spans(cx, opt_body_id, idx, &[("clone", ".to_string()"), ("as_str", "")]) { + span_lint_and_then( + cx, + PTR_ARG, + arg.span, + "writing `&String` instead of `&str` involves a new object where a slice will do.", + |db| { + db.span_suggestion(arg.span, "change this to", "&str".into()); + for (clonespan, suggestion) in spans { + db.span_suggestion_short( + clonespan, + &snippet_opt(cx, clonespan).map_or( + "change the call to".into(), + |x| Cow::Owned(format!("change `{}` to", x)), + ), + suggestion.into(), + ); + } + }, + ); + } + } else if match_type(cx, ty, &paths::COW) { + if_chain! { + if let TyRptr(_, MutTy { ref ty, ..} ) = arg.node; + if let TyPath(ref path) = ty.node; + if let QPath::Resolved(None, ref pp) = *path; + if let [ref bx] = *pp.segments; + if let Some(ref params) = bx.args; + if !params.parenthesized; + if let Some(inner) = params.args.iter().find_map(|arg| match arg { + GenericArg::Type(ty) => Some(ty), + GenericArg::Lifetime(_) => None, + }); + then { + let replacement = snippet_opt(cx, inner.span); + if let Some(r) = replacement { + span_lint_and_then( + cx, + PTR_ARG, + arg.span, + "using a reference to `Cow` is not recommended.", + |db| { + db.span_suggestion(arg.span, "change this to", "&".to_owned() + &r); + }, + ); + } + } + } } } } @@ -137,11 +251,11 @@ fn check_fn(cx: &LateContext, decl: &FnDecl, fn_id: NodeId) { if let FunctionRetTy::Return(ref ty) = decl.output { if let Some((out, MutMutable, _)) = get_rptr_lm(ty) { let mut immutables = vec![]; - for (_, ref mutbl, ref argspan) in - decl.inputs - .iter() - .filter_map(|ty| get_rptr_lm(ty)) - .filter(|&(lt, _, _)| lt.name == out.name) { + for (_, ref mutbl, ref argspan) in decl.inputs + .iter() + .filter_map(|ty| get_rptr_lm(ty)) + .filter(|&(lt, _, _)| lt.name == out.name) + { if *mutbl == MutMutable { return; } @@ -167,10 +281,10 @@ fn get_rptr_lm(ty: &Ty) -> Option<(&Lifetime, Mutability, Span)> { } fn is_null_path(expr: &Expr) -> bool { - if let ExprCall(ref pathexp, ref args) = expr.node { + if let ExprKind::Call(ref pathexp, ref args) = expr.node { if args.is_empty() { - if let ExprPath(ref path) = pathexp.node { - return match_path(path, &paths::PTR_NULL) || match_path(path, &paths::PTR_NULL_MUT); + if let ExprKind::Path(ref path) = pathexp.node { + return match_qpath(path, &paths::PTR_NULL) || match_qpath(path, &paths::PTR_NULL_MUT); } } }