The `var_name` string was built on the stack and then added to the `IdentifierStore`. This lead to use-after-free, since `IdentifierStore` just stores a `llvm::StringRef`. Add it to `ast_context().Idents` to provide a longer-lived reference.
Carbon::
check
cpp
--target-cpu
--target-cpu-tune
--target-cpu-features
IndirectIndexWith.Ref
Core.Array
array