From cd241b33cb8379311286f53c4afc6e671ddfded1 Mon Sep 17 00:00:00 2001
From: ThibsG <thibsg@pm.me>
Date: Thu, 13 May 2021 10:24:29 +0200
Subject: [PATCH] Trigger `wrong_self_convention` only if it has implicit self

---
 clippy_lints/src/methods/mod.rs        | 24 ++++++++++++++----------
 tests/ui/wrong_self_convention2.rs     | 23 +++++++++++++++++++++++
 tests/ui/wrong_self_convention2.stderr | 19 +++++++++++++++++++
 3 files changed, 56 insertions(+), 10 deletions(-)
 create mode 100644 tests/ui/wrong_self_convention2.stderr

diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
index 0b1b6304def..e0d29682146 100644
--- a/clippy_lints/src/methods/mod.rs
+++ b/clippy_lints/src/methods/mod.rs
@@ -1838,16 +1838,18 @@ fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx hir::Impl
                     }
                 }
 
-                wrong_self_convention::check(
-                    cx,
-                    &name,
-                    item.vis.node.is_pub(),
-                    self_ty,
-                    first_arg_ty,
-                    first_arg.pat.span,
-                    implements_trait,
-                    false
-                );
+                if sig.decl.implicit_self.has_implicit_self() {
+                    wrong_self_convention::check(
+                        cx,
+                        &name,
+                        item.vis.node.is_pub(),
+                        self_ty,
+                        first_arg_ty,
+                        first_arg.pat.span,
+                        implements_trait,
+                        false
+                    );
+                }
             }
         }
 
@@ -1903,7 +1905,9 @@ fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>
 
         if_chain! {
             if let TraitItemKind::Fn(ref sig, _) = item.kind;
+            if sig.decl.implicit_self.has_implicit_self();
             if let Some(first_arg_ty) = sig.decl.inputs.iter().next();
+
             then {
                 let first_arg_span = first_arg_ty.span;
                 let first_arg_ty = hir_ty_to_ty(cx.tcx, first_arg_ty);
diff --git a/tests/ui/wrong_self_convention2.rs b/tests/ui/wrong_self_convention2.rs
index 18202ef2989..b2c6503de49 100644
--- a/tests/ui/wrong_self_convention2.rs
+++ b/tests/ui/wrong_self_convention2.rs
@@ -42,3 +42,26 @@ fn from_usize(x: usize) -> Self {
         }
     }
 }
+
+mod issue7179 {
+    pub struct S(i32);
+
+    impl S {
+        // don't trigger (`s` is not `self`)
+        pub fn from_be(s: Self) -> Self {
+            S(i32::from_be(s.0))
+        }
+
+        // lint
+        pub fn from_be_self(self) -> Self {
+            S(i32::from_be(self.0))
+        }
+    }
+
+    trait T {
+        // don't trigger (`s` is not `self`)
+        fn from_be(s: Self) -> Self;
+        // lint
+        fn from_be_self(self) -> Self;
+    }
+}
diff --git a/tests/ui/wrong_self_convention2.stderr b/tests/ui/wrong_self_convention2.stderr
new file mode 100644
index 00000000000..d2d74ce099e
--- /dev/null
+++ b/tests/ui/wrong_self_convention2.stderr
@@ -0,0 +1,19 @@
+error: methods called `from_*` usually take no `self`
+  --> $DIR/wrong_self_convention2.rs:56:29
+   |
+LL |         pub fn from_be_self(self) -> Self {
+   |                             ^^^^
+   |
+   = note: `-D clippy::wrong-self-convention` implied by `-D warnings`
+   = help: consider choosing a less ambiguous name
+
+error: methods called `from_*` usually take no `self`
+  --> $DIR/wrong_self_convention2.rs:65:25
+   |
+LL |         fn from_be_self(self) -> Self;
+   |                         ^^^^
+   |
+   = help: consider choosing a less ambiguous name
+
+error: aborting due to 2 previous errors
+