broadcast: use recursion rather than ntuple to map over a tuple (#51154)

Inference seems to have trouble with the anonymous function version, so
go back to the recursive version.

Fixes #51129
Probably also fixes #50859

(cherry picked from commit d949bb4)

Author: vtjnash

base/broadcast.jl

@@ -750,8 +750,8 @@ _broadcast_getindex_eltype(A) = eltype(A)  # Tuple, Array, etc.
 eltypes(::Tuple{}) = Tuple{}
 eltypes(t::Tuple{Any}) = Iterators.TupleOrBottom(_broadcast_getindex_eltype(t[1]))
 eltypes(t::Tuple{Any,Any}) = Iterators.TupleOrBottom(_broadcast_getindex_eltype(t[1]), _broadcast_getindex_eltype(t[2]))
-# eltypes(t::Tuple) = (TT = eltypes(tail(t)); TT === Union{} ? Union{} : Iterators.TupleOrBottom(_broadcast_getindex_eltype(t[1]), TT.parameters...))
-eltypes(t::Tuple) = Iterators.TupleOrBottom(ntuple(i -> _broadcast_getindex_eltype(t[i]), Val(length(t)))...)
+eltypes(t::Tuple) = (TT = eltypes(tail(t)); TT === Union{} ? Union{} : Iterators.TupleOrBottom(_broadcast_getindex_eltype(t[1]), TT.parameters...))
+# eltypes(t::Tuple) = Iterators.TupleOrBottom(ntuple(i -> _broadcast_getindex_eltype(t[i]), Val(length(t)))...)
 
 # Inferred eltype of result of broadcast(f, args...)
 function combine_eltypes(f, args::Tuple)

test/broadcast.jl

@@ -1133,3 +1133,6 @@ end
 import Base.Broadcast: BroadcastStyle, DefaultArrayStyle
 @test Base.infer_effects(BroadcastStyle, (DefaultArrayStyle{1},DefaultArrayStyle{2},)) |>
     Core.Compiler.is_foldable
+
+f51129(v, x) = (1 .- (v ./ x) .^ 2)
+@test @inferred(f51129([13.0], 6.5)) == [-3.0]