fix #22842, dispatch confusion with Type{T} vs. typeof(T) (#23831)

(cherry picked from commit f4619d0)

Author: JeffBezanson

src/jltypes.c

@@ -588,8 +588,13 @@ static int typekey_eq(jl_datatype_t *tt, jl_value_t **key, size_t n)
     }
     for(j=0; j < n; j++) {
         jl_value_t *kj = key[j], *tj = jl_svecref(tt->parameters,j);
-        if (tj != kj && !jl_types_equal(tj, kj))
-            return 0;
+        if (tj != kj) {
+            // require exact same Type{T}. see e.g. issue #22842
+            if (jl_is_type_type(tj) || jl_is_type_type(kj))
+                return 0;
+            if (!jl_types_equal(tj, kj))
+                return 0;
+        }
     }
     return 1;
 }

test/core.jl

@@ -907,6 +907,12 @@ let
     @test_throws MethodError foor(StridedArray)
 end
 
+# issue #22842
+f22842(x::UnionAll) = UnionAll
+f22842(x::DataType) = length(x.parameters)
+@test f22842(Tuple{Vararg{Int64,N} where N}) == 1
+@test f22842(Tuple{Vararg{Int64,N}} where N) === UnionAll
+
 # issue #1153
 mutable struct SI{m, s, kg}
     value::AbstractFloat