mirror of https://github.com/rust-lang/rust.git
70 lines
2.0 KiB
Rust
70 lines
2.0 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::plugin::Registry;
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use rustc::lint::*;
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use rustc::middle::const_eval::lookup_const_by_id;
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use rustc::middle::def::*;
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use syntax::ast::*;
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use syntax::ast_util::{is_comparison_binop, binop_to_string};
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use syntax::ptr::P;
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use syntax::codemap::Span;
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use types::match_ty_unwrap;
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use utils::span_lint;
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declare_lint! {
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pub PTR_ARG,
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Allow,
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"Warn on declaration of a &Vec- or &String-typed method argument"
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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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fn check_item(&mut self, cx: &Context, 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: &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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}
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fn check_fn(cx: &Context, decl: &FnDecl) {
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for arg in &decl.inputs {
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match &arg.ty.node {
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&TyPtr(ref p) | &TyRptr(_, ref p) =>
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check_ptr_subtype(cx, arg.ty.span, &p.ty),
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_ => ()
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}
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}
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}
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fn check_ptr_subtype(cx: &Context, span: Span, ty: &Ty) {
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match_ty_unwrap(ty, &["Vec"]).map_or_else(|| match_ty_unwrap(ty,
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&["String"]).map_or((), |_| {
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span_lint(cx, PTR_ARG, 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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}), |_| span_lint(cx, PTR_ARG, span,
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"writing `&Vec<_>` instead of \
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`&[_]` involves one more reference and cannot be used with \
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non-Vec-based slices. Consider changing the type to `&[...]`."))
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}
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