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| author | Patrick Palka <ppalka@redhat.com> | 2025-06-06 09:34:17 -0400 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2025-06-06 09:35:11 -0400 |
| commit | e75e42f315e1e8bb4befee8ed242bd241c182091 (patch) | |
| tree | f49bdd8de85ec639f6d0ab34b71f0463e0798cf3 | |
| parent | b2338ebf3e698589c69a521b4b4a7908dd959751 (diff) | |
| download | gcc-e75e42f315e1e8bb4befee8ed242bd241c182091.zip gcc-e75e42f315e1e8bb4befee8ed242bd241c182091.tar.gz gcc-e75e42f315e1e8bb4befee8ed242bd241c182091.tar.bz2 | |
libstdc++: Fix flat_map::operator[] for const lvalue keys [PR120432]
The const lvalue operator[] overload wasn't properly forwarding the key
type to the generic overload, causing a hard error for const keys.
Rather than correcting the forwarded type this patch just makes the
non-template overloads call try_emplace directly instead. That way we
can remove the non-standard same_as constraint on the generic overload
and match the spec more closely.
PR libstdc++/120432
libstdc++-v3/ChangeLog:
* include/std/flat_map (flat_map::operator[]): Make the
non-template overloads call try_emplace directly. Remove
non-standard same_as constraint on the template overload.
* testsuite/23_containers/flat_map/1.cc (test08): New test.
Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
(cherry picked from commit 91ed3248ce26aaaee4d7471aa4edbc07b3f1a90e)
| -rw-r--r-- | libstdc++-v3/include/std/flat_map | 6 | ||||
| -rw-r--r-- | libstdc++-v3/testsuite/23_containers/flat_map/1.cc | 10 |
2 files changed, 13 insertions, 3 deletions
diff --git a/libstdc++-v3/include/std/flat_map b/libstdc++-v3/include/std/flat_map index 4bd4963..de006ad 100644 --- a/libstdc++-v3/include/std/flat_map +++ b/libstdc++-v3/include/std/flat_map @@ -1148,14 +1148,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // element access mapped_type& operator[](const key_type& __x) - { return operator[]<const key_type>(__x); } + { return try_emplace(__x).first->second; } mapped_type& operator[](key_type&& __x) - { return operator[]<key_type>(std::move(__x)); } + { return try_emplace(std::move(__x)).first->second; } template<typename _Key2> - requires same_as<remove_cvref_t<_Key2>, _Key> || __transparent_comparator<_Compare> + requires __transparent_comparator<_Compare> mapped_type& operator[](_Key2&& __x) { return try_emplace(std::forward<_Key2>(__x)).first->second; } diff --git a/libstdc++-v3/testsuite/23_containers/flat_map/1.cc b/libstdc++-v3/testsuite/23_containers/flat_map/1.cc index 9d99796..d7f27a0 100644 --- a/libstdc++-v3/testsuite/23_containers/flat_map/1.cc +++ b/libstdc++-v3/testsuite/23_containers/flat_map/1.cc @@ -252,6 +252,15 @@ test07() VERIFY( std::ranges::equal(m, (std::pair<int,int>[]){{3,4}}) ); } +void +test08() +{ + // PR libstdc++/120432 - flat_map operator[] is broken for const lvalue keys + std::flat_map<int, int> m; + const int k = 42; + m[k] = 0; +} + int main() { @@ -265,4 +274,5 @@ main() test05(); test06(); test07(); + test08(); } |