[WIP] Add getter prefix name lint

CHANGELOG.md

@@ -698,6 +698,7 @@ All notable changes to this project will be documented in this file.
 [`forget_copy`]: https://rust-lang.github.io/rust-clippy/master/index.html#forget_copy
 [`forget_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#forget_ref
 [`get_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
+[`getter_prefix`]: https://rust-lang.github.io/rust-clippy/master/index.html#getter_prefix
 [`identity_conversion`]: https://rust-lang.github.io/rust-clippy/master/index.html#identity_conversion
 [`identity_op`]: https://rust-lang.github.io/rust-clippy/master/index.html#identity_op
 [`if_let_redundant_pattern_matching`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_let_redundant_pattern_matching

README.md

@@ -7,7 +7,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are 290 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 291 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
 

clippy_lints/src/lib.rs

@@ -159,6 +159,7 @@ pub mod multiple_crate_versions;
 pub mod mut_mut;
 pub mod mut_reference;
 pub mod mutex_atomic;
+pub mod naming;
 pub mod needless_bool;
 pub mod needless_borrow;
 pub mod needless_borrowed_ref;
@@ -486,6 +487,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
     reg.register_late_lint_pass(box ptr_offset_with_cast::Pass);
     reg.register_late_lint_pass(box redundant_clone::RedundantClone);
     reg.register_late_lint_pass(box slow_vector_initialization::Pass);
+    reg.register_early_lint_pass(box naming::GetterPrefix);
 
     reg.register_lint_group("clippy::restriction", Some("clippy_restriction"), vec![
         arithmetic::FLOAT_ARITHMETIC,
@@ -697,6 +699,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
         misc_early::ZERO_PREFIXED_LITERAL,
         mut_reference::UNNECESSARY_MUT_PASSED,
         mutex_atomic::MUTEX_ATOMIC,
+        naming::GETTER_PREFIX,
         needless_bool::BOOL_COMPARISON,
         needless_bool::NEEDLESS_BOOL,
         needless_borrowed_ref::NEEDLESS_BORROWED_REFERENCE,
@@ -837,6 +840,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
         misc_early::MIXED_CASE_HEX_LITERALS,
         misc_early::UNNEEDED_FIELD_PATTERN,
         mut_reference::UNNECESSARY_MUT_PASSED,
+        naming::GETTER_PREFIX,
         neg_multiply::NEG_MULTIPLY,
         new_without_default::NEW_WITHOUT_DEFAULT,
         non_expressive_names::JUST_UNDERSCORES_AND_DIGITS,

clippy_lints/src/naming.rs

@@ -0,0 +1,95 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use crate::rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
+use crate::rustc::{declare_tool_lint, lint_array};
+use crate::syntax::ast;
+use crate::utils::span_lint;
+
+/// **What it does:** Checks for the `get_` prefix on getters.
+///
+/// **Why is this bad?** The Rust API Guidelines section on naming
+/// [specifies](https://rust-lang-nursery.github.io/api-guidelines/naming.html#getter-names-follow-rust-convention-c-getter)
+/// that the `get_` prefix is not used for getters in Rust code unless
+/// there is a single and obvious thing that could reasonably be gotten by
+/// a getter.
+///
+/// The exceptions to this naming convention are as follows:
+/// - `get` (such as in
+///   [`std::cell::Cell::get`](https://doc.rust-lang.org/std/cell/struct.Cell.html#method.get))
+/// - `get_mut`
+/// - `get_unchecked`
+/// - `get_unchecked_mut`
+/// - `get_ref`
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+///
+/// ```rust
+/// // Bad
+/// impl B {
+///     fn get_id(&self) -> usize {
+///         ..
+///     }
+/// }
+///
+/// // Good
+/// impl G {
+///     fn id(&self) -> usize {
+///         ..
+///     }
+/// }
+///
+/// // Also allowed
+/// impl A {
+///     fn get(&self) -> usize {
+///         ..
+///     }
+/// }
+/// ```
+declare_clippy_lint! {
+    pub GETTER_PREFIX,
+    style,
+    "prefixing a getter with `get_`, which does not follow convention"
+}
+
+#[derive(Copy, Clone)]
+pub struct GetterPrefix;
+
+#[rustfmt::skip]
+const ALLOWED_METHOD_NAMES: [&'static str; 5] = [
+    "get",
+    "get_mut",
+    "get_unchecked",
+    "get_unchecked_mut",
+    "get_ref"
+];
+
+impl LintPass for GetterPrefix {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(GETTER_PREFIX)
+    }
+}
+
+impl EarlyLintPass for GetterPrefix {
+    fn check_impl_item(&mut self, cx: &EarlyContext<'_>, implitem: &ast::ImplItem) {
+        if let ast::ImplItemKind::Method(..) = implitem.node {
+            let name = implitem.ident.name.as_str().get();
+            if name.starts_with("get_") && !ALLOWED_METHOD_NAMES.contains(&name) {
+                span_lint(
+                    cx,
+                    GETTER_PREFIX,
+                    implitem.span,
+                    "prefixing a getter with `get_` does not follow naming conventions",
+                );
+            }
+        }
+    }
+}

tests/ui/naming.rs

@@ -0,0 +1,48 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub struct MyStruct {
+    id: usize
+}
+
+impl MyStruct {
+    pub fn get_id(&self) -> usize {
+        self.id
+    }
+
+    pub fn get(&self) -> usize {
+        self.id
+    }
+
+    pub fn get_mut(&mut self) -> usize {
+        self.id
+    }
+
+    pub fn get_unchecked(&self) -> usize {
+        self.id
+    }
+
+    pub fn get_unchecked_mut(&mut self) -> usize {
+        self.id
+    }
+
+    pub fn get_ref(&self) -> usize {
+        self.id
+    }
+}
+
+fn main() {
+   let mut s = MyStruct { id: 42 };
+   s.get_id();
+   s.get();
+   s.get_mut();
+   s.get_unchecked();
+   s.get_unchecked_mut();
+   s.get_ref();
+}

tests/ui/naming.stderr

@@ -0,0 +1,12 @@
+error: prefixing a getter with `get_` does not follow naming conventions
+  --> $DIR/naming.rs:15:5
+   |
+LL | /     pub fn get_id(&self) -> usize {
+LL | |         self.id
+LL | |     }
+   | |_____^
+   |
+   = note: `-D clippy::getter-prefix` implied by `-D warnings`
+
+error: aborting due to previous error
+

tests/ui/unused_unit.rs

@@ -22,7 +22,7 @@
 struct Unitter;
 impl Unitter {
     // try to disorient the lint with multiple unit returns and newlines
-    pub fn get_unit<F: Fn() -> (), G>(&self, f: F, _g: G) ->
+    pub fn get<F: Fn() -> (), G>(&self, f: F, _g: G) ->
         ()
     where G: Fn() -> () {
         let _y: &Fn() -> () = &f;
@@ -41,7 +41,7 @@ fn return_unit() -> () { () }
 
 fn main() {
     let u = Unitter;
-    assert_eq!(u.get_unit(|| {}, return_unit), u.into());
+    assert_eq!(u.get(|| {}, return_unit), u.into());
     return_unit();
     loop {
         break();

tests/ui/unused_unit.stderr

@@ -1,8 +1,8 @@
 error: unneeded unit return type
-  --> $DIR/unused_unit.rs:25:59
+  --> $DIR/unused_unit.rs:25:54
    |
-LL |       pub fn get_unit<F: Fn() -> (), G>(&self, f: F, _g: G) ->
-   |  ___________________________________________________________^
+LL |       pub fn get<F: Fn() -> (), G>(&self, f: F, _g: G) ->
+   |  ______________________________________________________^
 LL | |         ()
    | |__________^ help: remove the `-> ()`
    |