Check if method is constructor

Author: Anthony Huang

clippy_lints/src/self_named_constructor.rs

@@ -1,9 +1,9 @@
 use clippy_utils::diagnostics::span_lint_and_then;
-use clippy_utils::get_parent_as_impl;
-use rustc_hir::{ImplItem, ImplItemKind, Node, TyKind};
+use clippy_utils::ty::{contains_adt_constructor, contains_ty};
+use clippy_utils::return_ty;
+use rustc_hir::{ImplItem, ImplItemKind, Node};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::Symbol;
 
 declare_clippy_lint! {
     /// **What it does:** Warns when constructors have the same name as their types.
@@ -42,18 +42,30 @@ 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(_, _) => {},
+            _ => 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());
+        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! {
-            // Get type name
-            if let Some(imp) = get_parent_as_impl(cx.tcx, impl_item.hir_id());
-            if let TyKind::Path(ty_path) = &imp.self_ty.kind;
-            if let Some(ty_id) = cx.qpath_res(ty_path, imp.self_ty.hir_id).opt_def_id();
-            if let Some(local_id) = ty_id.as_local();
-            let ty_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_id);
-            if let Some(Node::Item(x)) = cx.tcx.hir().find(ty_hir_id);
+            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;
 
-            // Get constructor name
-            if let ImplItemKind::Fn(_, _) = impl_item.kind;
-            if impl_item.ident.name == Symbol::intern(&x.ident.name.as_str().to_lowercase());
             then {
                 span_lint_and_then(
                     cx,

tests/ui/self_named_constructor.rs

@@ -1,36 +1,50 @@
 #![warn(clippy::self_named_constructor)]
 
-struct Foo {}
+struct Q;
 
-impl Foo {
-    pub fn foo() -> Foo {
-        Foo {}
+impl Q {
+    pub fn q() -> Q {
+        Q
+    }
+
+    fn r() -> R {
+        R
     }
 }
 
-struct Bar {}
+struct R;
 
-impl Bar {
-    pub fn new() -> Bar {
-        Bar {}
+impl R {
+    pub fn new() -> R {
+        R
     }
 }
 
-struct FooBar {}
+struct V;
 
-impl FooBar {
-    pub fn foobar() -> FooBar {
-        FooBar {}
+impl V {
+    pub fn v() -> R {
+        R
     }
 }
 
-#[derive(Default)]
-pub struct Default {}
+struct U;
+
+trait T {
+    type Item;
+}
 
-impl Foo {
-    fn bar() -> Bar {
-        Bar {}
+impl T for U {
+    type Item = Self;
+}
+
+impl U {
+    pub fn u() -> impl T<Item = Self> {
+        U
     }
 }
 
+#[derive(Default)]
+pub struct Default;
+
 fn main() {}

tests/ui/self_named_constructor.stderr

@@ -1,48 +1,32 @@
-error: constructor `foo` has the same name as the type
+error: constructor `q` has the same name as the type
   --> $DIR/self_named_constructor.rs:6:5
    |
-LL | /     pub fn foo() -> Foo {
-LL | |         Foo {}
+LL | /     pub fn q() -> Q {
+LL | |         Q
 LL | |     }
    | |_____^
    |
    = note: `-D clippy::self-named-constructor` implied by `-D warnings`
-help: consider renaming `foo()` to `new()`
+help: consider renaming `q()` to `new()`
   --> $DIR/self_named_constructor.rs:6:5
    |
-LL | /     pub fn foo() -> Foo {
-LL | |         Foo {}
-LL | |     }
-   | |_____^
-
-error: constructor `foobar` has the same name as the type
-  --> $DIR/self_named_constructor.rs:22:5
-   |
-LL | /     pub fn foobar() -> FooBar {
-LL | |         FooBar {}
-LL | |     }
-   | |_____^
-   |
-help: consider renaming `foobar()` to `new()`
-  --> $DIR/self_named_constructor.rs:22:5
-   |
-LL | /     pub fn foobar() -> FooBar {
-LL | |         FooBar {}
+LL | /     pub fn q() -> Q {
+LL | |         Q
 LL | |     }
    | |_____^
 
 error: constructor `default` has the same name as the type
-  --> $DIR/self_named_constructor.rs:27:10
+  --> $DIR/self_named_constructor.rs:47:10
    |
 LL | #[derive(Default)]
    |          ^^^^^^^
    |
 help: consider renaming `default()` to `new()`
-  --> $DIR/self_named_constructor.rs:27:10
+  --> $DIR/self_named_constructor.rs:47:10
    |
 LL | #[derive(Default)]
    |          ^^^^^^^
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors