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Split new_without_default and new_without_default_derive.

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This is still very slow, because we do a trait lookup for each field.
Perhaps storing the visited types in a set to reuse types would improve
performance somewhat. Also we may want to pre-decide some known types
(e.g. `Vec<T>`, `Option<T>`).
This commit is contained in:
Andre Bogus 2016-05-17 08:33:57 +02:00
parent 84098f56b6
commit 9cfc42275d
6 changed files with 93 additions and 26 deletions
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1
CHANGELOG.md
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@ -174,6 +174,7 @@ All notable changes to this project will be documented in this file.
[`neg_multiply`]: https://github.com/Manishearth/rust-clippy/wiki#neg_multiply
[`new_ret_no_self`]: https://github.com/Manishearth/rust-clippy/wiki#new_ret_no_self
[`new_without_default`]: https://github.com/Manishearth/rust-clippy/wiki#new_without_default
[`new_without_default_derive`]: https://github.com/Manishearth/rust-clippy/wiki#new_without_default_derive
[`no_effect`]: https://github.com/Manishearth/rust-clippy/wiki#no_effect
[`non_ascii_literal`]: https://github.com/Manishearth/rust-clippy/wiki#non_ascii_literal
[`nonminimal_bool`]: https://github.com/Manishearth/rust-clippy/wiki#nonminimal_bool

3
README.md
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@ -17,7 +17,7 @@ Table of contents:
## Lints
There are 150 lints included in this crate:
There are 151 lints included in this crate:
name | default | meaning
---------------------------------------------------------------------------------------------------------------------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
@ -107,6 +107,7 @@ name
[neg_multiply](https://github.com/Manishearth/rust-clippy/wiki#neg_multiply) | warn | Warns on multiplying integers with -1
[new_ret_no_self](https://github.com/Manishearth/rust-clippy/wiki#new_ret_no_self) | warn | not returning `Self` in a `new` method
[new_without_default](https://github.com/Manishearth/rust-clippy/wiki#new_without_default) | warn | `fn new() -> Self` method without `Default` implementation
[new_without_default_derive](https://github.com/Manishearth/rust-clippy/wiki#new_without_default_derive) | warn | `fn new() -> Self` without `#[derive]`able `Default` implementation
[no_effect](https://github.com/Manishearth/rust-clippy/wiki#no_effect) | warn | statements with no effect
[non_ascii_literal](https://github.com/Manishearth/rust-clippy/wiki#non_ascii_literal) | allow | using any literal non-ASCII chars in a string literal; suggests using the \\u escape instead
[nonminimal_bool](https://github.com/Manishearth/rust-clippy/wiki#nonminimal_bool) | allow | checks for boolean expressions that can be written more concisely

1
src/lib.rs
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@ -527,6 +527,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
needless_update::NEEDLESS_UPDATE,
neg_multiply::NEG_MULTIPLY,
new_without_default::NEW_WITHOUT_DEFAULT,
new_without_default::NEW_WITHOUT_DEFAULT_DERIVE,
no_effect::NO_EFFECT,
no_effect::UNNECESSARY_OPERATION,
non_expressive_names::MANY_SINGLE_CHAR_NAMES,

106
src/new_without_default.rs
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@ -1,11 +1,55 @@
use rustc::hir::intravisit::FnKind;
use rustc::hir::def_id::DefId;
use rustc::hir;
use rustc::lint::*;
use rustc::ty;
use syntax::ast;
use syntax::codemap::Span;
use utils::paths;
use utils::{get_trait_def_id, implements_trait, in_external_macro, return_ty, same_tys, span_lint};
/// **What it does:** This lints about type with a `fn new() -> Self` method
/// and no implementation of
/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html)
///
/// **Why is this bad?** User might expect to be able to use
/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html)
/// as the type can be
/// constructed without arguments.
///
/// **Known problems:** Hopefully none.
///
/// **Example:**
///
/// ```rust,ignore
/// struct Foo(Bar);
///
/// impl Foo {
/// fn new() -> Self {
/// Foo(Bar::new())
/// }
/// }
/// ```
///
/// Instead, use:
///
/// ```rust
/// struct Foo(Bar);
///
/// impl Default for Foo {
/// fn default() -> Self {
/// Foo(Bar::new())
/// }
/// }
/// ```
///
/// You can also have `new()` call `Default::default()`
declare_lint! {
pub NEW_WITHOUT_DEFAULT,
Warn,
"`fn new() -> Self` method without `Default` implementation"
}
/// **What it does:** This lints about type with a `fn new() -> Self` method
/// and no implementation of
/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html)
@ -29,24 +73,11 @@ use utils::{get_trait_def_id, implements_trait, in_external_macro, return_ty, sa
/// }
/// ```
///
/// Instead, use:
///
/// ```rust
/// struct Foo;
///
/// impl Default for Foo {
/// fn default() -> Self {
/// Foo
/// }
/// }
/// ```
///
/// You can also have `new()` call `Default::default()`
///
/// Just prepend `#[derive(Default)]` before the `struct` definition
declare_lint! {
pub NEW_WITHOUT_DEFAULT,
pub NEW_WITHOUT_DEFAULT_DERIVE,
Warn,
"`fn new() -> Self` method without `Default` implementation"
"`fn new() -> Self` without `#[derive]`able `Default` implementation"
}
#[derive(Copy,Clone)]
@ -54,7 +85,7 @@ pub struct NewWithoutDefault;
impl LintPass for NewWithoutDefault {
fn get_lints(&self) -> LintArray {
lint_array!(NEW_WITHOUT_DEFAULT)
lint_array!(NEW_WITHOUT_DEFAULT, NEW_WITHOUT_DEFAULT_DERIVE)
}
}
@ -66,8 +97,8 @@ impl LateLintPass for NewWithoutDefault {
if let FnKind::Method(name, _, _, _) = kind {
if decl.inputs.is_empty() && name.as_str() == "new" {
let self_ty = cx.tcx.lookup_item_type(cx.tcx.map.local_def_id(cx.tcx.map.get_parent(id))).ty;
let self_ty = cx.tcx.lookup_item_type(cx.tcx.map.local_def_id(
cx.tcx.map.get_parent(id))).ty;
if_let_chain!{[
self_ty.walk_shallow().next().is_none(), // implements_trait does not work with generics
let Some(ret_ty) = return_ty(cx, id),
@ -75,10 +106,43 @@ impl LateLintPass for NewWithoutDefault {
let Some(default_trait_id) = get_trait_def_id(cx, &paths::DEFAULT_TRAIT),
!implements_trait(cx, self_ty, default_trait_id, Vec::new())
], {
span_lint(cx, NEW_WITHOUT_DEFAULT, span,
&format!("you should consider adding a `Default` implementation for `{}`", self_ty));
if can_derive_default(self_ty, cx, default_trait_id) {
span_lint(cx,
NEW_WITHOUT_DEFAULT_DERIVE, span,
&format!("you should consider deriving a \
`Default` implementation for `{}`",
self_ty)).
span_suggestion(span,
"try this",
"#[derive(Default)]".into());
} else {
span_lint(cx,
NEW_WITHOUT_DEFAULT, span,
&format!("you should consider adding a \
`Default` implementation for `{}`",
self_ty)).
span_suggestion(span,
"try this",
format!("impl Default for {} {{ fn default() -> \
Self {{ {}::new() }} }}", self_ty, self_ty));
}
}}
}
}
}
}
fn can_derive_default<'t, 'c>(ty: ty::Ty<'t>, cx: &LateContext<'c, 't>, default_trait_id: DefId) -> bool {
match ty.sty {
ty::TyStruct(ref adt_def, ref substs) => {
for field in adt_def.all_fields() {
let f_ty = field.ty(cx.tcx, substs);
if !implements_trait(cx, f_ty, default_trait_id, Vec::new()) {
return false
}
}
true
},
_ => false
}
}

2
tests/compile-fail/methods.rs
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@ -3,7 +3,7 @@
#![plugin(clippy)]
#![deny(clippy, clippy_pedantic)]
#![allow(blacklisted_name, unused, print_stdout, non_ascii_literal, new_without_default)]
#![allow(blacklisted_name, unused, print_stdout, non_ascii_literal, new_without_default, new_without_default_derive)]
use std::collections::BTreeMap;
use std::collections::HashMap;

6
tests/compile-fail/new_without_default.rs
View file

@ -2,18 +2,18 @@
#![plugin(clippy)]
#![allow(dead_code)]
#![deny(new_without_default)]
#![deny(new_without_default, new_without_default_derive)]
struct Foo;
impl Foo {
fn new() -> Foo { Foo } //~ERROR: you should consider adding a `Default` implementation for `Foo`
fn new() -> Foo { Foo } //~ERROR: you should consider deriving a `Default` implementation for `Foo`
}
struct Bar;
impl Bar {
fn new() -> Self { Bar } //~ERROR: you should consider adding a `Default` implementation for `Bar`
fn new() -> Self { Bar } //~ERROR: you should consider deriving a `Default` implementation for `Bar`
}
struct Ok;