2015-05-04 05:17:15 +00:00
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//! 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 syntax::ast::*;
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2015-08-21 16:28:17 +00:00
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use rustc::middle::ty;
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2015-08-16 06:54:43 +00:00
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2015-08-21 16:28:17 +00:00
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use utils::{span_lint, match_def_path};
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2015-05-04 05:17:15 +00:00
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declare_lint! {
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2015-05-04 06:15:24 +00:00
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pub PTR_ARG,
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2015-05-04 05:17:15 +00:00
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Allow,
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2015-08-13 08:32:35 +00:00
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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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2015-05-04 05:17:15 +00:00
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}
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#[derive(Copy,Clone)]
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2015-05-04 06:15:24 +00:00
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pub struct PtrArg;
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2015-05-04 05:17:15 +00:00
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2015-05-04 06:15:24 +00:00
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impl LintPass for PtrArg {
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2015-05-04 05:17:15 +00:00
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fn get_lints(&self) -> LintArray {
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2015-05-04 06:15:24 +00:00
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lint_array!(PTR_ARG)
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2015-05-04 05:17:15 +00:00
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}
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2015-08-11 18:22:20 +00:00
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2015-05-04 05:17:15 +00:00
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fn check_item(&mut self, cx: &Context, item: &Item) {
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2015-08-11 18:22:20 +00:00
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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: &Context, item: &ImplItem) {
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if let &MethodImplItem(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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fn check_trait_item(&mut self, cx: &Context, 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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2015-05-04 05:17:15 +00:00
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}
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2015-08-21 16:28:17 +00:00
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#[allow(unused_imports)]
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2015-05-04 05:17:15 +00:00
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fn check_fn(cx: &Context, decl: &FnDecl) {
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2015-08-21 16:28:17 +00:00
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{
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// In case stuff gets moved around
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use collections::vec::Vec;
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use collections::string::String;
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}
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2015-08-11 18:22:20 +00:00
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for arg in &decl.inputs {
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2015-08-21 16:28:17 +00:00
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if arg.ty.node == TyInfer { // "self" arguments
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continue;
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}
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let ref sty = cx.tcx.pat_ty(&*arg.pat).sty;
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if let &ty::TyRef(_, ty::TypeAndMut { ty, mutbl: MutImmutable }) = sty {
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if let ty::TyStruct(did, _) = ty.sty {
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if match_def_path(cx, did.did, &["collections", "vec", "Vec"]) {
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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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}
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else if match_def_path(cx, did.did, &["collections", "string", "String"]) {
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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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2015-08-11 18:22:20 +00:00
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}
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}
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2015-05-04 05:17:15 +00:00
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}
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