fix #33270; stack overflow in named tuple ctor with Type{T} (#33303)

base/namedtuple.jl

@@ -69,11 +69,13 @@ if nameof(@__MODULE__) === :Base
 Construct a named tuple with the given `names` (a tuple of Symbols) and field types `T`
 (a `Tuple` type) from a tuple of values.
 """
-function NamedTuple{names,T}(args::Tuple) where {names, T <: Tuple}
+@eval function NamedTuple{names,T}(args::Tuple) where {names, T <: Tuple}
     if length(args) != length(names)
         throw(ArgumentError("Wrong number of arguments to named tuple constructor."))
     end
-    NamedTuple{names,T}(T(args))
+    # Note T(args) might not return something of type T; e.g.
+    # Tuple{Type{Float64}}((Float64,)) returns a Tuple{DataType}
+    $(Expr(:splatnew, :(NamedTuple{names,T}), :(T(args))))
 end
 
 """

test/namedtuple.jl

@@ -261,3 +261,9 @@ y = map(v -> (a=v.a, b=v.a + v.b), [(a=1, b=missing), (a=1, b=2)])
 @test merge((a=1, b=2), (b=3, c=4), (c=5,)) === (a=1, b=3, c=5)
 @test merge((a=1, b=2), (b=3, c=(d=1,)), (c=(d=2,),)) === (a=1, b=3, c=(d=2,))
 @test merge((a=1, b=2)) === (a=1, b=2)
+
+# issue #33270
+let n = NamedTuple{(:T,), Tuple{Type{Float64}}}((Float64,))
+    @test n isa NamedTuple{(:T,), Tuple{Type{Float64}}}
+    @test n.T === Float64
+end