Add redundant_method_names lint

clippy_lints/src/lib.rs

@@ -330,6 +330,7 @@ mod regex;
 mod repeat_once;
 mod returns;
 mod self_assignment;
+mod self_named_constructor;
 mod semicolon_if_nothing_returned;
 mod serde_api;
 mod shadow;
@@ -900,6 +901,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         returns::LET_AND_RETURN,
         returns::NEEDLESS_RETURN,
         self_assignment::SELF_ASSIGNMENT,
+        self_named_constructor::SELF_NAMED_CONSTRUCTOR,
         semicolon_if_nothing_returned::SEMICOLON_IF_NOTHING_RETURNED,
         serde_api::SERDE_API_MISUSE,
         shadow::SHADOW_REUSE,
@@ -1406,6 +1408,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(returns::LET_AND_RETURN),
         LintId::of(returns::NEEDLESS_RETURN),
         LintId::of(self_assignment::SELF_ASSIGNMENT),
+        LintId::of(self_named_constructor::SELF_NAMED_CONSTRUCTOR),
         LintId::of(serde_api::SERDE_API_MISUSE),
         LintId::of(single_component_path_imports::SINGLE_COMPONENT_PATH_IMPORTS),
         LintId::of(size_of_in_element_count::SIZE_OF_IN_ELEMENT_COUNT),
@@ -1559,6 +1562,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES),
         LintId::of(returns::LET_AND_RETURN),
         LintId::of(returns::NEEDLESS_RETURN),
+        LintId::of(self_named_constructor::SELF_NAMED_CONSTRUCTOR),
         LintId::of(single_component_path_imports::SINGLE_COMPONENT_PATH_IMPORTS),
         LintId::of(tabs_in_doc_comments::TABS_IN_DOC_COMMENTS),
         LintId::of(to_digit_is_some::TO_DIGIT_IS_SOME),
@@ -2101,6 +2105,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     let scripts = conf.allowed_scripts.clone();
     store.register_early_pass(move || box disallowed_script_idents::DisallowedScriptIdents::new(&scripts));
     store.register_late_pass(|| box strlen_on_c_strings::StrlenOnCStrings);
+    store.register_late_pass(move || box self_named_constructor::SelfNamedConstructor);
+
 }
 
 #[rustfmt::skip]

clippy_lints/src/self_named_constructor.rs

@@ -0,0 +1,91 @@
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::return_ty;
+use clippy_utils::ty::{contains_adt_constructor, contains_ty};
+use rustc_hir::{Impl, ImplItem, ImplItemKind, ItemKind, Node};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// **What it does:** Warns when constructors have the same name as their types.
+    ///
+    /// **Why is this bad?** Repeating the name of the type is redundant.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust,ignore
+    /// struct Foo {}
+    ///
+    /// impl Foo {
+    ///     pub fn foo() -> Foo {
+    ///         Foo {}
+    ///     }
+    /// }
+    /// ```
+    /// Use instead:
+    /// ```rust,ignore
+    /// struct Foo {}
+    ///
+    /// impl Foo {
+    ///     pub fn new() -> Foo {
+    ///         Foo {}
+    ///     }
+    /// }
+    /// ```
+    pub SELF_NAMED_CONSTRUCTOR,
+    style,
+    "method should not have the same name as the type it is implemented for"
+}
+
+declare_lint_pass!(SelfNamedConstructor => [SELF_NAMED_CONSTRUCTOR]);
+
+impl<'tcx> LateLintPass<'tcx> for SelfNamedConstructor {
+    fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx ImplItem<'_>) {
+        match impl_item.kind {
+            ImplItemKind::Fn(ref sig, _) => {
+                if sig.decl.implicit_self.has_implicit_self() {
+                    return;
+                }
+            },
+            _ => return,
+        }
+
+        let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id());
+        let item = cx.tcx.hir().expect_item(parent);
+        let self_ty = cx.tcx.type_of(item.def_id);
+        let ret_ty = return_ty(cx, impl_item.hir_id());
+
+        // Do not check trait impls
+        if matches!(item.kind, ItemKind::Impl(Impl { of_trait: Some(_), .. })) {
+            return;
+        }
+
+        // Ensure method is constructor-like
+        if let Some(self_adt) = self_ty.ty_adt_def() {
+            if !contains_adt_constructor(ret_ty, self_adt) {
+                return;
+            }
+        } else if !contains_ty(ret_ty, self_ty) {
+            return;
+        }
+
+        if_chain! {
+            if let Some(self_def) = self_ty.ty_adt_def();
+            if let Some(self_local_did) = self_def.did.as_local();
+            let self_id = cx.tcx.hir().local_def_id_to_hir_id(self_local_did);
+            if let Some(Node::Item(x)) = cx.tcx.hir().find(self_id);
+            let type_name = x.ident.name.as_str().to_lowercase();
+            if impl_item.ident.name.as_str() == type_name || impl_item.ident.name.as_str().replace("_", "") == type_name;
+
+            then {
+                span_lint(
+                    cx,
+                    SELF_NAMED_CONSTRUCTOR,
+                    impl_item.span,
+                    &format!("constructor `{}` has the same name as the type", impl_item.ident.name),
+                );
+            }
+        }
+    }
+}