use afoldl instead of tail recursion for tuples

It is easy to accidentally call these functions (they are used by vcat,
which is syntax) with very long lists of values, causing inference to
crash and take a long time. The `afoldl` function can handle that very
well however, while naive recursion did not.

Fixes #53585

base/abstractarray.jl

@@ -1650,13 +1650,15 @@ eltypeof(x::AbstractArray) = eltype(x)
 
 promote_eltypeof() = error()
 promote_eltypeof(v1) = eltypeof(v1)
-promote_eltypeof(v1, vs...) = promote_type(eltypeof(v1), promote_eltypeof(vs...))
+promote_eltypeof(v1, v2) = promote_type(eltypeof(v1), eltypeof(v2))
+promote_eltypeof(v1, v2, vs...) = (@inline; afoldl(((::Type{T}, y) where {T}) -> promote_type(T, eltypeof(y)), promote_eltypeof(v1, v2), vs...))
 promote_eltypeof(v1::T, vs::T...) where {T} = eltypeof(v1)
 promote_eltypeof(v1::AbstractArray{T}, vs::AbstractArray{T}...) where {T} = T
 
 promote_eltype() = error()
 promote_eltype(v1) = eltype(v1)
-promote_eltype(v1, vs...) = promote_type(eltype(v1), promote_eltype(vs...))
+promote_eltype(v1, v2) = promote_type(eltype(v1), eltype(v2))
+promote_eltype(v1, v2, vs...) = (@inline; afoldl(((::Type{T}, y) where {T}) -> promote_type(T, eltype(y)), promote_eltype(v1, v2), vs...))
 promote_eltype(v1::T, vs::T...) where {T} = eltype(T)
 promote_eltype(v1::AbstractArray{T}, vs::AbstractArray{T}...) where {T} = T
 

base/promotion.jl

@@ -19,7 +19,8 @@ Number
 """
 typejoin() = Bottom
 typejoin(@nospecialize(t)) = (@_nospecializeinfer_meta; t)
-typejoin(@nospecialize(t), ts...) = (@_foldable_meta; @_nospecializeinfer_meta; typejoin(t, typejoin(ts...)))
+typejoin(@nospecialize(t), @nospecialize(s), @nospecialize(u)) = (@_foldable_meta; @_nospecializeinfer_meta; typejoin(typejoin(t, s), u))
+typejoin(@nospecialize(t), @nospecialize(s), @nospecialize(u), ts...) = (@_foldable_meta; @_nospecializeinfer_meta; afoldl(typejoin, typejoin(t, s, u), ts...))
 function typejoin(@nospecialize(a), @nospecialize(b))
     @_foldable_meta
     @_nospecializeinfer_meta
@@ -299,7 +300,8 @@ function promote_type end
 
 promote_type()  = Bottom
 promote_type(T) = T
-promote_type(T, S, U, V...) = (@inline; promote_type(T, promote_type(S, U, V...)))
+promote_type(T, S, U) = (@inline; promote_type(promote_type(T, S), U))
+promote_type(T, S, U, V...) = (@inline; afoldl(promote_type, promote_type(T, S, U), V...))
 
 promote_type(::Type{Bottom}, ::Type{Bottom}) = Bottom
 promote_type(::Type{T}, ::Type{T}) where {T} = T
@@ -373,7 +375,9 @@ function _promote(x::T, y::S) where {T,S}
     return (convert(R, x), convert(R, y))
 end
 promote_typeof(x) = typeof(x)
-promote_typeof(x, xs...) = (@inline; promote_type(typeof(x), promote_typeof(xs...)))
+promote_typeof(x, y) = (@inline; promote_type(typeof(x), typeof(y)))
+promote_typeof(x, y, z) = (@inline; promote_type(typeof(x), typeof(y), typeof(z)))
+promote_typeof(x, y, z, a...) = (@inline; afoldl(((::Type{T}, y) where {T}) -> promote_type(T, typeof(y)), promote_typeof(x, y, z), a...))
 function _promote(x, y, z)
     @inline
     R = promote_typeof(x, y, z)

test/compiler/inference.jl

@@ -5639,3 +5639,9 @@ end
 @test issue53590(true, false) == Real
 @test issue53590(false, false) == Float64
 @test issue53590(false, true) == Real
+
+# issue #53585
+let t = ntuple(i -> i % 8 == 1 ? Int64 : Float64, 4000)
+    @test only(Base.return_types(Base.promote_typeof, t)) == Type{Float64}
+    @test only(Base.return_types(vcat, t)) == Vector{Float64}
+end