From 984542c4e229bbb5be070d1e276022f0b68513ec Mon Sep 17 00:00:00 2001
From: pommicket <pommicket@gmail.com>
Date: Wed, 15 Oct 2025 15:43:43 -0400
Subject: [PATCH] Don't highlight `let` expressions as having type `bool`

---
 compiler/rustc_hir_typeck/src/demand.rs           | 4 +++-
 tests/ui/binop/let-chain-type-issue-147665.rs     | 7 +++++++
 tests/ui/binop/let-chain-type-issue-147665.stderr | 9 +++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/binop/let-chain-type-issue-147665.rs
 create mode 100644 tests/ui/binop/let-chain-type-issue-147665.stderr

diff --git a/compiler/rustc_hir_typeck/src/demand.rs b/compiler/rustc_hir_typeck/src/demand.rs
index fb6ebe066a8f2..880b0ca2fb1fe 100644
--- a/compiler/rustc_hir_typeck/src/demand.rs
+++ b/compiler/rustc_hir_typeck/src/demand.rs
@@ -792,7 +792,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Binary(_, lhs, rhs), .. }),
                 Some(TypeError::Sorts(ExpectedFound { expected, .. })),
             ) if rhs.hir_id == expr.hir_id
-                && self.typeck_results.borrow().expr_ty_adjusted_opt(lhs) == Some(expected) =>
+                && self.typeck_results.borrow().expr_ty_adjusted_opt(lhs) == Some(expected)
+                // let expressions being marked as `bool` is confusing (see issue #147665)
+                && !matches!(lhs.kind, hir::ExprKind::Let(..)) =>
             {
                 err.span_label(lhs.span, format!("expected because this is `{expected}`"));
             }
diff --git a/tests/ui/binop/let-chain-type-issue-147665.rs b/tests/ui/binop/let-chain-type-issue-147665.rs
new file mode 100644
index 0000000000000..4a6b40c6f9877
--- /dev/null
+++ b/tests/ui/binop/let-chain-type-issue-147665.rs
@@ -0,0 +1,7 @@
+// Shouldn't highlight `let x = 1` as having type bool.
+//@ edition:2024
+
+fn main() {
+    if let x = 1 && 2 {}
+    //~^ ERROR mismatched types
+}
diff --git a/tests/ui/binop/let-chain-type-issue-147665.stderr b/tests/ui/binop/let-chain-type-issue-147665.stderr
new file mode 100644
index 0000000000000..b2b82228eaebf
--- /dev/null
+++ b/tests/ui/binop/let-chain-type-issue-147665.stderr
@@ -0,0 +1,9 @@
+error[E0308]: mismatched types
+  --> $DIR/let-chain-type-issue-147665.rs:5:21
+   |
+LL |     if let x = 1 && 2 {}
+   |                     ^ expected `bool`, found integer
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.