Correctly set the variant bits of uuid1 (#59428)

Author: GunnarFarneback

stdlib/UUIDs/src/UUIDs.jl

@@ -74,8 +74,8 @@ function _build_uuid1(rng::AbstractRNG, timestamp::UInt64)
     # mask off clock sequence and node
     u &= 0x00000000000000003fffffffffffffff
 
-    # set the unicast/multicast bit and version
-    u |= 0x00000000000010000000010000000000
+    # set the version, variant, and unicast/multicast bit
+    u |= 0x00000000000010008000010000000000
 
     ts_low = timestamp & typemax(UInt32)
     ts_mid = (timestamp >> 32) & typemax(UInt16)

stdlib/UUIDs/test/runtests.jl

@@ -42,6 +42,15 @@ u7 = uuid7()
     @test uuid_version(u7) == 7
 end
 
+@testset "Extraction of variant bits" begin
+    # RFC 4122, section 4.1.1
+    uuid_variant(u::UUID) = Int((u.value >> 62) & 0x3)
+    @test uuid_variant(u1) == 2
+    @test uuid_variant(u4) == 2
+    @test uuid_variant(u5) == 2
+    @test uuid_variant(u7) == 2
+end
+
 @testset "Parsing from string" begin
     @test u1 == UUID(string(u1)) == UUID(GenericString(string(u1)))
     @test u4 == UUID(string(u4)) == UUID(GenericString(string(u4)))