use rustc::hir::*;
use rustc::hir::map::NodeItem;
use rustc::lint::*;
use rustc::ty;
use syntax::ast::NodeId;
use utils::{match_type, paths, span_lint};
declare_lint! {
pub PTR_ARG,
Warn,
"arguments of the type `&Vec<...>` (instead of `&[...]`) or `&String` (instead of `&str`)"
}
#[derive(Copy,Clone)]
pub struct PtrArg;
impl LintPass for PtrArg {
fn get_lints(&self) -> LintArray {
lint_array!(PTR_ARG)
}
}
impl LateLintPass for PtrArg {
fn check_item(&mut self, cx: &LateContext, item: &Item) {
if let ItemFn(ref decl, _, _, _, _, _) = item.node {
check_fn(cx, decl, item.id);
}
}
fn check_impl_item(&mut self, cx: &LateContext, item: &ImplItem) {
if let ImplItemKind::Method(ref sig, _) = item.node {
if let Some(NodeItem(it)) = cx.tcx.map.find(cx.tcx.map.get_parent(item.id)) {
if let ItemImpl(_, _, _, Some(_), _, _) = it.node {
return; }
}
check_fn(cx, &sig.decl, item.id);
}
}
fn check_trait_item(&mut self, cx: &LateContext, item: &TraitItem) {
if let MethodTraitItem(ref sig, _) = item.node {
check_fn(cx, &sig.decl, item.id);
}
}
}
fn check_fn(cx: &LateContext, decl: &FnDecl, fn_id: NodeId) {
let fn_ty = cx.tcx.node_id_to_type(fn_id).fn_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 {
if match_type(cx, ty, &paths::VEC) {
span_lint(cx,
PTR_ARG,
arg.ty.span,
"writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used \
with non-Vec-based slices. Consider changing the type to `&[...]`");
} else if match_type(cx, ty, &paths::STRING) {
span_lint(cx,
PTR_ARG,
arg.ty.span,
"writing `&String` instead of `&str` involves a new object where a slice will do. \
Consider changing the type to `&str`");
}
}
}
}