From c433d542cf64304d2f701c42165bbb4ae55c0309 Mon Sep 17 00:00:00 2001
From: kraktus <kraktus@users.noreply.github.com>
Date: Sat, 10 Sep 2022 11:36:31 +0200
Subject: [PATCH 1/2] Do not lint `use_self` in proc macro expansion

---
 clippy_lints/src/use_self.rs | 5 +++--
 tests/ui/use_self.fixed      | 9 +++++++++
 tests/ui/use_self.rs         | 9 +++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/clippy_lints/src/use_self.rs b/clippy_lints/src/use_self.rs
index 486ea5e5ccfa..d1c00341818c 100644
--- a/clippy_lints/src/use_self.rs
+++ b/clippy_lints/src/use_self.rs
@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::ty::same_type_and_consts;
-use clippy_utils::{meets_msrv, msrvs};
+use clippy_utils::{is_from_proc_macro, meets_msrv, msrvs};
 use if_chain::if_chain;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
@@ -87,7 +87,7 @@ impl_lint_pass!(UseSelf => [USE_SELF]);
 const SEGMENTS_MSG: &str = "segments should be composed of at least 1 element";
 
 impl<'tcx> LateLintPass<'tcx> for UseSelf {
-    fn check_item(&mut self, _cx: &LateContext<'_>, item: &Item<'_>) {
+    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &Item<'tcx>) {
         if matches!(item.kind, ItemKind::OpaqueTy(_)) {
             // skip over `ItemKind::OpaqueTy` in order to lint `foo() -> impl <..>`
             return;
@@ -103,6 +103,7 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
             if parameters.as_ref().map_or(true, |params| {
                 !params.parenthesized && !params.args.iter().any(|arg| matches!(arg, GenericArg::Lifetime(_)))
             });
+            if !is_from_proc_macro(cx, item); // expensive, should be last check
             then {
                 StackItem::Check {
                     impl_id: item.def_id,
diff --git a/tests/ui/use_self.fixed b/tests/ui/use_self.fixed
index 4f80aaecc902..37986187da17 100644
--- a/tests/ui/use_self.fixed
+++ b/tests/ui/use_self.fixed
@@ -608,3 +608,12 @@ mod issue8845 {
         }
     }
 }
+
+mod issue6902 {
+    use serde::Serialize;
+
+    #[derive(Serialize)]
+    pub enum Foo {
+        Bar = 1,
+    }
+}
diff --git a/tests/ui/use_self.rs b/tests/ui/use_self.rs
index 52da72db53ce..1b2b3337c92e 100644
--- a/tests/ui/use_self.rs
+++ b/tests/ui/use_self.rs
@@ -608,3 +608,12 @@ mod issue8845 {
         }
     }
 }
+
+mod issue6902 {
+    use serde::Serialize;
+
+    #[derive(Serialize)]
+    pub enum Foo {
+        Bar = 1,
+    }
+}

From 59ee6a89a3e6dc9547002e014470573647f22a8f Mon Sep 17 00:00:00 2001
From: kraktus <kraktus@users.noreply.github.com>
Date: Sat, 10 Sep 2022 11:47:07 +0200
Subject: [PATCH 2/2] Remove duplicate context check

---
 clippy_lints/src/use_self.rs | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/clippy_lints/src/use_self.rs b/clippy_lints/src/use_self.rs
index d1c00341818c..44ab9bca7959 100644
--- a/clippy_lints/src/use_self.rs
+++ b/clippy_lints/src/use_self.rs
@@ -214,9 +214,6 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
                 hir_ty_to_ty(cx.tcx, hir_ty)
             };
             if same_type_and_consts(ty, cx.tcx.type_of(impl_id));
-            let hir = cx.tcx.hir();
-            // prevents false positive on `#[derive(serde::Deserialize)]`
-            if !hir.span(hir.get_parent_node(hir_ty.hir_id)).in_derive_expansion();
             then {
                 span_lint(cx, hir_ty.span);
             }