+
+ /// Identify when the type error is because `()` is found in a binding that was assigned a
+ /// block without a tail expression.
+ fn check_for_binding_assigned_block_without_tail_expression(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ checked_ty: Ty<'tcx>,
+ expected_ty: Ty<'tcx>,
+ ) {
+ if !checked_ty.is_unit() {
+ return;
+ }
+ let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind else { return; };
+ let hir::def::Res::Local(hir_id) = path.res else { return; };
+ let Some(hir::Node::Pat(pat)) = self.tcx.hir().find(hir_id) else {
+ return;
+ };
+ let Some(hir::Node::Local(hir::Local {
+ ty: None,
+ init: Some(init),
+ ..
+ })) = self.tcx.hir().find_parent(pat.hir_id) else { return; };
+ let hir::ExprKind::Block(block, None) = init.kind else { return; };
+ if block.expr.is_some() {
+ return;
+ }
+ let [.., stmt] = block.stmts else {
+ err.span_label(block.span, "this empty block is missing a tail expression");
+ return;
+ };
+ let hir::StmtKind::Semi(tail_expr) = stmt.kind else { return; };
+ let Some(ty) = self.node_ty_opt(tail_expr.hir_id) else { return; };
+ if self.can_eq(self.param_env, expected_ty, ty).is_ok() {
+ err.span_suggestion_short(
+ stmt.span.with_lo(tail_expr.span.hi()),
+ "remove this semicolon",
+ "",
+ Applicability::MachineApplicable,
+ );
+ } else {
+ err.span_label(block.span, "this block is missing a tail expression");
+ }
+ }