https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97790
Bug ID: 97790
Summary: constexpr evaluation reports false positive memory
leak
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ldalessandro at gmail dot com
Target Milestone: ---
The constexpr evaluator seems to lose track of dynamic allocations in some
contexts, resulting in false-positive leaks and rejected valid code.
This particular example uses an immediately invoked function expression
referencing an NTTP, which seems like a corner case but is actually extremely
common in two-pass constexpr algorithms (i.e., compute constexpr size of
result, then compute result to return).
https://godbolt.org/z/Tnn6xh
```
struct vector {
int *data;
int n;
constexpr vector() : data(new int[1]{}), n(1) {}
constexpr ~vector() { delete [] data; }
};
struct Foo {
constexpr auto foo() const {
return vector();
}
};
template <auto& f>
constexpr static auto bar() {
[] { return f.foo().n; }();
return true;
}
constexpr Foo foo;
constexpr auto dd = bar<foo>();
```
