Define ==/isequal/hash for Some by forwarding to the wrapped …

…value (#52421)

The equality of two `Some` depends on the equality of the wrapped 
value, once the `Some` is unwrapped.
---------

Co-authored-by: Alex Arslan <ararslan@comcast.net>
Co-authored-by: Lilith Orion Hafner <lilithhafner@gmail.com>

base/some.jl

@@ -166,3 +166,8 @@ macro something(args...)
     end
     return expr
 end
+
+==(a::Some, b::Some) = a.value == b.value
+isequal(a::Some, b::Some)::Bool = isequal(a.value, b.value)
+const hash_some_seed = UInt == UInt64 ? 0xde5c997007a4ca3a : 0x78c29c09
+hash(s::Some, h::UInt) = hash(s.value, hash_some_seed + h)

test/some.jl

@@ -49,6 +49,32 @@
 @test !isequal(Some(1), nothing)
 @test !isequal(Some(nothing), nothing)
 
+# Some with something else is false
+@test !=(Some(nothing), nothing)
+@test !=(nothing, Some(nothing))
+
+# Two `Some`s forward to their wrapped things
+@test ==(Some([0x1]), Some([1]))
+
+# propagate wrapped missings
+@test !=(Some(1), Some(missing)) isa Missing
+@test !=(Some(missing), Some(1)) isa Missing
+@test ==(Some(missing), Some(missing)) isa Missing
+
+# Make sure to still propagate non-wrapped Missing
+@test ==(Some(1), missing) isa Missing
+@test ==(missing, Some(1)) isa Missing
+
+@test isequal(Some([0x1]), Some([1]))
+@test !isequal(missing, Some(missing))
+@test !isequal(Some(missing), missing)
+@test isequal(Some(missing), Some(missing))
+
+# hashing implications
+@test hash(Some(0x1)) != hash(0x1)
+@test hash(Some(0x1)) == hash(Some(1))
+@test hash((Some(1),)) != hash((1, Some))
+
 @testset "something" begin
     @test_throws ArgumentError something()
     @test something(1) === 1