added IO to broadcastable (#42070)

Author: ArunS-tack

base/broadcast.jl

@@ -697,7 +697,7 @@ julia> Broadcast.broadcastable("hello") # Strings break convention of matching i
 Base.RefValue{String}("hello")
 ```
 """
-broadcastable(x::Union{Symbol,AbstractString,Function,UndefInitializer,Nothing,RoundingMode,Missing,Val,Ptr,AbstractPattern,Pair}) = Ref(x)
+broadcastable(x::Union{Symbol,AbstractString,Function,UndefInitializer,Nothing,RoundingMode,Missing,Val,Ptr,AbstractPattern,Pair,IO}) = Ref(x)
 broadcastable(::Type{T}) where {T} = Ref{Type{T}}(T)
 broadcastable(x::Union{AbstractArray,Number,AbstractChar,Ref,Tuple,Broadcasted}) = x
 # Default to collecting iterables — which will error for non-iterables

test/broadcast.jl

@@ -1052,3 +1052,9 @@ end
     @test Broadcast.BroadcastFunction(+)(2:3, 2:3) == 4:2:6
     @test Broadcast.BroadcastFunction(+)(2:3, 2:3) isa AbstractRange
 end
+
+@testset "#42063" begin
+    buf = IOBuffer()
+    @test println.(buf, [1,2,3]) == [nothing, nothing, nothing]
+    @test String(take!(buf)) == "1\n2\n3\n"
+end