rust-clippy/src/ptr_arg.rs

70 lines
2 KiB
Rust
Raw Normal View History

//! Checks for usage of &Vec[_] and &String
//!
//! This lint is **warn** by default
use rustc::plugin::Registry;
use rustc::lint::*;
use rustc::middle::const_eval::lookup_const_by_id;
use rustc::middle::def::*;
use syntax::ast::*;
use syntax::ast_util::{is_comparison_binop, binop_to_string};
use syntax::ptr::P;
use syntax::codemap::Span;
use types::match_ty_unwrap;
2015-07-26 14:53:11 +00:00
use utils::span_lint;
declare_lint! {
pub PTR_ARG,
Allow,
"Warn on declaration of a &Vec- or &String-typed method argument"
}
#[derive(Copy,Clone)]
pub struct PtrArg;
impl LintPass for PtrArg {
fn get_lints(&self) -> LintArray {
lint_array!(PTR_ARG)
}
fn check_item(&mut self, cx: &Context, item: &Item) {
if let &ItemFn(ref decl, _, _, _, _, _) = &item.node {
check_fn(cx, decl);
}
}
fn check_impl_item(&mut self, cx: &Context, item: &ImplItem) {
if let &MethodImplItem(ref sig, _) = &item.node {
check_fn(cx, &sig.decl);
}
}
fn check_trait_item(&mut self, cx: &Context, item: &TraitItem) {
if let &MethodTraitItem(ref sig, _) = &item.node {
check_fn(cx, &sig.decl);
}
}
}
fn check_fn(cx: &Context, decl: &FnDecl) {
for arg in &decl.inputs {
match &arg.ty.node {
&TyPtr(ref p) | &TyRptr(_, ref p) =>
check_ptr_subtype(cx, arg.ty.span, &p.ty),
_ => ()
}
}
}
fn check_ptr_subtype(cx: &Context, span: Span, ty: &Ty) {
match_ty_unwrap(ty, &["Vec"]).map_or_else(|| match_ty_unwrap(ty,
&["String"]).map_or((), |_| {
span_lint(cx, PTR_ARG, span,
"writing `&String` instead of `&str` involves a new object \
where a slice will do. Consider changing the type to `&str`")
}), |_| span_lint(cx, PTR_ARG, span,
"writing `&Vec<_>` instead of \
`&[_]` involves one more reference and cannot be used with \
non-Vec-based slices. Consider changing the type to `&[...]`"))
}