72 lines
2.3 KiB
Rust
72 lines
2.3 KiB
Rust
//! Checks for usage of &Vec[_] and &String
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//!
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//! This lint is **warn** by default
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use rustc::lint::*;
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use rustc_front::hir::*;
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use rustc::middle::ty;
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use rustc::front::map::Node;
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use utils::{span_lint, match_type};
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use utils::{STRING_PATH, VEC_PATH};
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declare_lint! {
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pub PTR_ARG,
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Warn,
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"fn arguments of the type `&Vec<...>` or `&String`, suggesting to use `&[...]` or `&str` \
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instead, respectively"
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}
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#[derive(Copy,Clone)]
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pub struct PtrArg;
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impl LintPass for PtrArg {
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fn get_lints(&self) -> LintArray {
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lint_array!(PTR_ARG)
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}
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}
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impl LateLintPass for PtrArg {
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fn check_item(&mut self, cx: &LateContext, item: &Item) {
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if let &ItemFn(ref decl, _, _, _, _, _) = &item.node {
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check_fn(cx, decl);
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}
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}
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fn check_impl_item(&mut self, cx: &LateContext, item: &ImplItem) {
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if let &MethodImplItem(ref sig, _) = &item.node {
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if let Some(Node::NodeItem(it)) = cx.tcx.map.find(cx.tcx.map.get_parent(item.id)) {
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if let ItemImpl(_, _, _, Some(_), _, _) = it.node {
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return; // ignore trait impls
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}
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}
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check_fn(cx, &sig.decl);
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}
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}
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fn check_trait_item(&mut self, cx: &LateContext, item: &TraitItem) {
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if let &MethodTraitItem(ref sig, _) = &item.node {
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check_fn(cx, &sig.decl);
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}
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}
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}
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fn check_fn(cx: &LateContext, decl: &FnDecl) {
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for arg in &decl.inputs {
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if let Some(ty) = cx.tcx.ast_ty_to_ty_cache.borrow().get(&arg.ty.id) {
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if let ty::TyRef(_, ty::TypeAndMut { ty, mutbl: MutImmutable }) = ty.sty {
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if match_type(cx, ty, &VEC_PATH) {
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span_lint(cx, PTR_ARG, arg.ty.span,
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"writing `&Vec<_>` instead of `&[_]` involves one more reference \
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and cannot be used with non-Vec-based slices. Consider changing \
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the type to `&[...]`");
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} else if match_type(cx, ty, &STRING_PATH) {
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span_lint(cx, PTR_ARG, arg.ty.span,
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"writing `&String` instead of `&str` involves a new object \
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where a slice will do. Consider changing the type to `&str`");
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}
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}
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}
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}
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}
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