src/Sema.zig                          | 113 +++++++++++++++++++++++++-------
 src/Zcu/PerThread.zig                 |  14 ++--
 test/behavior/union.zig               |  19 ++++++
 test/incremental/change_enum_tag_type |  59 +++++++++++++++++
 4 files changed, 177 insertions(+), 28 deletions(-)