Cannot combine @simd and @threads on a loop

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Description

julia> import Base: Threads

julia> @simd Threads.@threads for i in 1:10 end
ERROR: LoadError: Base.SimdLoop.SimdError("for loop expected")
Stacktrace:
 [1] compile(::Expr, ::Bool) at ./simdloop.jl:54
 [2] @simd(::LineNumberNode, ::Module, ::Any) at ./simdloop.jl:124
in expression starting at REPL[2]:1

julia> Threads.@threads @simd for i in 1:10 end
ERROR: LoadError: ArgumentError: unrecognized argument to @threads
Stacktrace:
 [1] @threads(::LineNumberNode, ::Module, ::Vararg{Any,N} where N) at ./threadingconstructs.jl:101
in expression starting at REPL[4]:1

Contributor guide

Research direction

Investigate the macro expansion order and how @simd and @threads interact. Check the source files simdloop.jl and threadingconstructs.jl to understand the macro logic.

Tech stack

None

Domain

backend

Issue type

Bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

2

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

Active

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

Clear

Prerequisites

Julia

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

60