diff options
| -rw-r--r-- | third_party/nix/src/libexpr/attr-set.cc | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/third_party/nix/src/libexpr/attr-set.cc b/third_party/nix/src/libexpr/attr-set.cc index e961156487a9..55b1d0ccd540 100644 --- a/third_party/nix/src/libexpr/attr-set.cc +++ b/third_party/nix/src/libexpr/attr-set.cc @@ -4,15 +4,29 @@ #include <absl/container/btree_map.h> #include <gc/gc_cpp.h> +#include <glog/logging.h> #include "eval-inline.hh" namespace nix { -// TODO: using insert_or_assign might break existing Nix code because -// of the weird ordering situation. Need to investigate. +// This function inherits its name from previous implementations, in +// which Bindings was backed by an array of elements which was scanned +// linearly. +// +// In that setup, inserting duplicate elements would always yield the +// first element (until the next sort, which wasn't stable, after +// which things are more or less undefined). +// +// This behaviour is mimicked by using .insert(), which will *not* +// override existing values. void Bindings::push_back(const Attr& attr) { - attributes_.insert_or_assign(attr.name, attr); + auto [_, inserted] = attributes_.insert_or_assign(attr.name, attr); + + if (!inserted) { + DLOG(WARNING) << "attempted to insert duplicate attribute for key '" + << attr.name << "'"; + } } size_t Bindings::size() { return attributes_.size(); } |