https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121024
Bug ID: 121024
Summary: ranges::destroy and ranges::destroy_n do not end
lifetime of trivial types
Product: gcc
Version: 15.1.0
Status: UNCONFIRMED
Keywords: accepts-invalid
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
CC: daniel.kruegler at googlemail dot com, de34 at live dot cn,
tkaminsk at gcc dot gnu.org, unassigned at gcc dot gnu.org,
webrown.cpp at gmail dot com
Target Milestone: ---
+++ This bug was initially created as a clone of Bug #119754 comment 6 +++
Consider this example (https://godbolt.org/z/dGGE6o5qY):
```
#include <memory>
using namespace std;
template <auto>
struct require_valid_constant;
template <class Fn>
constexpr int consteval_validate_destruction(Fn op) {
struct S {
int n;
};
S arr[1]{{42}};
op(arr);
return arr[0].n;
}
template <auto Fn>
constexpr bool CanWellDefinedlyAccessAfterOperation =
requires { typename
require_valid_constant<consteval_validate_destruction(Fn)>; };
static_assert(CanWellDefinedlyAccessAfterOperation<[](auto&) {}>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) { destroy(arr
+ 0, arr + 1); }>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) {
destroy_at(arr + 0); }>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) {
destroy_at(&arr); }>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) {
destroy_n(arr + 0, 1); }>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) {
ranges::destroy(arr + 0, arr + 1); }>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) {
ranges::destroy(arr); }>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) {
ranges::destroy_at(arr + 0); }>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) {
ranges::destroy_at(&arr); }>);
static_assert(!CanWellDefinedlyAccessAfterOperation<[](auto& arr) {
ranges::destroy_n(arr + 0, 1); }>);
```
It seems that algorithms in std properly destroy trivially destructible
objects, but those in std::ranges don't.
Although the difference is only observable by Clang due to Bug 102284.
