src/Sema.zig                                                                                                         | 109 ++++++++++++++++++++++++--------
 test/cases/compile_errors/direct_struct_loop.zig                                                                     |   9 +++
 test/cases/compile_errors/indirect_struct_loop.zig                                                                   |  13 ++++
 test/cases/compile_errors/instantiating_an_undefined_value_for_an_invalid_struct_that_contains_itself.zig            |  16 +++++
 test/cases/compile_errors/instantiating_an_undefined_value_for_an_invalid_union_that_contains_itself.zig             |  16 +++++
 test/cases/compile_errors/stage1/obj/direct_struct_loop.zig                                                          |   8 ---
 test/cases/compile_errors/stage1/obj/indirect_struct_loop.zig                                                        |  10 ---
 test/cases/compile_errors/stage1/obj/instantiating_an_undefined_value_for_an_invalid_struct_that_contains_itself.zig |  15 -----
 test/cases/compile_errors/stage1/obj/struct_depends_on_itself_via_optional_field.zig                                 |  19 ------
 test/cases/compile_errors/struct_depends_on_itself_via_optional_field.zig                                            |  19 ++++++
 10 files changed, 156 insertions(+), 78 deletions(-)