https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112934
Bug ID: 112934
Summary: excessive code for std::map::erase(key)
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: pobrn at protonmail dot com
Target Milestone: ---
It is probably expected that calling erase(key) is equivalent to or better than
auto it = m.find(k);
if (it != m.end())
m.erase(it);
However, currently that is not the case: https://gcc.godbolt.org/z/f1Mh3bodf
This is because std::map::erase(key) calls erase(key) on the underlying tree,
which then uses equal_range() and tries to delete a range of iterators. This is
unnecessary since a map enforces unique keys.
libc++ has an __erase_unique() method on the underlying tree type to handle
this, which does essentially what - I assume - most people expect erase(key) to
do:
https://github.com/llvm/llvm-project/blob/b88b480640f173582ffbfd2faae690f2bc895d14/libcxx/include/__tree#L2453
I believe the same applies to std::set.
