https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102623
Bug ID: 102623
Summary: Failure to detect destructed scalar objects in
consteval function
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
using T = int;
consteval bool f()
{
T t = 42;
t.~T();
return (t == 42);
}
bool x = f();
This code should not compile, as `f` invokes undefined behavior during constant
evaluation, as Clang diagnoses:
<source>:9:10: error: call to consteval function 'f' is not a constant
expression
bool x = f();
^
<source>:6:11: note: read of object outside its lifetime is not allowed in a
constant expression
return (t == 42);
^
The specific usage with `int` here was not UB until C++20 (although
pseudo-destructors weren't allowed in constant expressions until C++20 anyway),
but as of
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p0593r6.html#pseudo-destructor-calls
pseudo-destructors end the lifetime of the operand.
