Don't fire rust_2021_incompatible_closure_captures in edition = 2021

compiler/rustc_lint_defs/src/builtin.rs

@@ -3407,7 +3407,7 @@ declare_lint! {
     ///
     /// ### Example of drop reorder
     ///
-    /// ```rust,compile_fail
+    /// ```rust,edition2018,compile_fail
     /// #![deny(rust_2021_incompatible_closure_captures)]
     /// # #![allow(unused)]
     ///
@@ -3443,7 +3443,7 @@ declare_lint! {
     ///
     /// ### Example of auto-trait
     ///
-    /// ```rust,compile_fail
+    /// ```rust,edition2018,compile_fail
     /// #![deny(rust_2021_incompatible_closure_captures)]
     /// use std::thread;
     ///

compiler/rustc_typeck/src/check/upvar.rs

@@ -2024,6 +2024,10 @@ fn should_do_rust_2021_incompatible_closure_captures_analysis(
     tcx: TyCtxt<'_>,
     closure_id: hir::HirId,
 ) -> bool {
+    if tcx.sess.rust_2021() {
+        return false;
+    }
+
     let (level, _) =
         tcx.lint_level_at_node(lint::builtin::RUST_2021_INCOMPATIBLE_CLOSURE_CAPTURES, closure_id);
 

src/test/ui/lint/issue-101284.rs

@@ -0,0 +1,15 @@
+// check-pass
+// edition:2021
+#![deny(rust_2021_compatibility)]
+
+pub struct Warns {
+    // `Arc` has significant drop
+    _significant_drop: std::sync::Arc<()>,
+    field: String,
+}
+
+pub fn test(w: Warns) {
+    _ = || drop(w.field);
+}
+
+fn main() {}