use rustc::lint::*;
use rustc_front::hir::*;
use rustc::middle::ty;
use rustc::front::map::Node;
use utils::{span_lint, match_type};
use utils::{STRING_PATH, VEC_PATH};
declare_lint! {
pub PTR_ARG,
Warn,
"fn arguments of the type `&Vec<...>` or `&String`, suggesting to use `&[...]` or `&str` \
instead, respectively"
}
#[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);
}
}
fn check_impl_item(&mut self, cx: &LateContext, item: &ImplItem) {
if let ImplItemKind::Method(ref sig, _) = item.node {
if let Some(Node::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);
}
}
fn check_trait_item(&mut self, cx: &LateContext, item: &TraitItem) {
if let MethodTraitItem(ref sig, _) = item.node {
check_fn(cx, &sig.decl);
}
}
}
fn check_fn(cx: &LateContext, decl: &FnDecl) {
for arg in &decl.inputs {
if let Some(ty) = cx.tcx.ast_ty_to_ty_cache.borrow().get(&arg.ty.id) {
if let ty::TyRef(_, ty::TypeAndMut { ty, mutbl: MutImmutable }) = ty.sty {
if match_type(cx, ty, &VEC_PATH) {
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, &STRING_PATH) {
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`");
}
}
}
}
}