From c6d10d24c1d45bc4dbbc53d83a1648e02a1d65c6 Mon Sep 17 00:00:00 2001
From: Dilum Aluthge <dilum@aluthge.com>
Date: Sat, 21 Feb 2026 03:18:15 -0500
Subject: [PATCH] Fix a JET error around matching methods for `push!(...)`
 (#173)
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This is a forward-port of https://github.com/JuliaLang/Distributed.jl/pull/173 (https://github.com/JuliaLang/Distributed.jl/commit/b7c43b235a963d19ec1c5e5aa9b8a565b6e49c34).

```
┌  @ Distributed /workpath/Distributed.jl/src/process_messages.jl:387
│ no matching method found `push!(::Nothing, ::Any)` (1/2 union split): Distributed.push!(default_worker_pool()::Union{Nothing, Distributed.AbstractWorkerPool}, w.id::Any)
└────────────────────
```

(cherry picked from commit b7c43b235a963d19ec1c5e5aa9b8a565b6e49c34)
---
 src/workerpool.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/workerpool.jl b/src/workerpool.jl
index 6d03bc9..881e4bf 100644
--- a/src/workerpool.jl
+++ b/src/workerpool.jl
@@ -288,7 +288,7 @@ julia> default_worker_pool()
 WorkerPool(Channel{Int64}(sz_max:9223372036854775807,sz_curr:3), Set([4, 2, 3]), RemoteChannel{Channel{Any}}(1, 1, 4))
 ```
 """
-function default_worker_pool()
+function default_worker_pool()::AbstractWorkerPool
     # On workers retrieve the default worker pool from the master when accessed
     # for the first time
     if _default_worker_pool[] === nothing
@@ -298,7 +298,7 @@ function default_worker_pool()
             _default_worker_pool[] = remotecall_fetch(()->default_worker_pool(), 1)
         end
     end
-    return _default_worker_pool[]
+    return _default_worker_pool[]::AbstractWorkerPool
 end
 
 """