Rework `redundant_closure`

* Better track when a early-bound region appears when a late-bound region is required
* Don't lint when the closure gives explicit types.

3 files changed, 38 insertions, 23 deletions

diff --git a/clippy_utils/src/ty.rs b/clippy_utils/src/ty.rs
index dbb6b986952..d0e15aa8bb3 100644
--- a/clippy_utils/src/ty.rs
+++ b/clippy_utils/src/ty.rs
@@ -419,6 +419,11 @@ pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangI
     }
 }
 
+/// Gets the diagnostic name of the type, if it has one
+pub fn type_diagnostic_name(cx: &LateContext<'_>, ty: Ty<'_>) -> Option<Symbol> {
+    ty.ty_adt_def().and_then(|adt| cx.tcx.get_diagnostic_name(adt.did()))
+}
+
 /// Return `true` if the passed `typ` is `isize` or `usize`.
 pub fn is_isize_or_usize(typ: Ty<'_>) -> bool {
     matches!(typ.kind(), ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize))
diff --git a/clippy_utils/src/usage.rs b/clippy_utils/src/usage.rs
index 8a7ea1e6cad..39ef76348d7 100644
--- a/clippy_utils/src/usage.rs
+++ b/clippy_utils/src/usage.rs
@@ -1,15 +1,15 @@
-use crate::visitors::{for_each_expr, for_each_expr_with_closures, Descend};
+use crate::visitors::{for_each_expr, for_each_expr_with_closures, Descend, Visitable};
+use crate::{self as utils, get_enclosing_loop_or_multi_call_closure};
 use core::ops::ControlFlow;
 use hir::def::Res;
 use rustc_hir::intravisit::{self, Visitor};
-use rustc_hir::{Expr, ExprKind, HirId, HirIdSet, Node};
+use rustc_hir::{self as hir, Expr, ExprKind, HirId, HirIdSet};
 use rustc_hir_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::LateContext;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::mir::FakeReadCause;
 use rustc_middle::ty;
-use {crate as utils, rustc_hir as hir};
 
 /// Returns a set of mutated local variable IDs, or `None` if mutations could not be determined.
 pub fn mutated_variables<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) -> Option<HirIdSet> {
@@ -154,6 +154,17 @@ pub fn contains_return_break_continue_macro(expression: &Expr<'_>) -> bool {
     .is_some()
 }
 
+pub fn local_used_in<'tcx>(cx: &LateContext<'tcx>, local_id: HirId, v: impl Visitable<'tcx>) -> bool {
+    for_each_expr_with_closures(cx, v, |e| {
+        if utils::path_to_local_id(e, local_id) {
+            ControlFlow::Break(())
+        } else {
+            ControlFlow::Continue(())
+        }
+    })
+    .is_some()
+}
+
 pub fn local_used_after_expr(cx: &LateContext<'_>, local_id: HirId, after: &Expr<'_>) -> bool {
     let Some(block) = utils::get_enclosing_block(cx, local_id) else {
         return false;
@@ -166,32 +177,21 @@ pub fn local_used_after_expr(cx: &LateContext<'_>, local_id: HirId, after: &Expr
     // let closure = || local;
     // closure();
     // closure();
-    let in_loop_or_closure = cx
-        .tcx
-        .hir()
-        .parent_iter(after.hir_id)
-        .take_while(|&(id, _)| id != block.hir_id)
-        .any(|(_, node)| {
-            matches!(
-                node,
-                Node::Expr(Expr {
-                    kind: ExprKind::Loop(..) | ExprKind::Closure { .. },
-                    ..
-                })
-            )
-        });
-    if in_loop_or_closure {
-        return true;
-    }
+    let loop_start = get_enclosing_loop_or_multi_call_closure(cx, after).map(|e| e.hir_id);
 
     let mut past_expr = false;
     for_each_expr_with_closures(cx, block, |e| {
-        if e.hir_id == after.hir_id {
+        if past_expr {
+            if utils::path_to_local_id(e, local_id) {
+                ControlFlow::Break(())
+            } else {
+                ControlFlow::Continue(Descend::Yes)
+            }
+        } else if e.hir_id == after.hir_id {
             past_expr = true;
             ControlFlow::Continue(Descend::No)
-        } else if past_expr && utils::path_to_local_id(e, local_id) {
-            ControlFlow::Break(())
         } else {
+            past_expr = Some(e.hir_id) == loop_start;
             ControlFlow::Continue(Descend::Yes)
         }
     })
diff --git a/clippy_utils/src/visitors.rs b/clippy_utils/src/visitors.rs
index 8dafa723afa..09f447b27eb 100644
--- a/clippy_utils/src/visitors.rs
+++ b/clippy_utils/src/visitors.rs
@@ -52,6 +52,16 @@ pub trait Visitable<'tcx> {
     /// Calls the corresponding `visit_*` function on the visitor.
     fn visit<V: Visitor<'tcx>>(self, visitor: &mut V);
 }
+impl<'tcx, T> Visitable<'tcx> for &'tcx [T]
+where
+    &'tcx T: Visitable<'tcx>,
+{
+    fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) {
+        for x in self {
+            x.visit(visitor);
+        }
+    }
+}
 macro_rules! visitable_ref {
     ($t:ident, $f:ident) => {
         impl<'tcx> Visitable<'tcx> for &'tcx $t<'tcx> {