https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96439
Bug ID: 96439
Summary: [concepts] nested requirement allows calling a method
of a local parameter
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: src at andyf dot de
Target Milestone: ---
Hello,
the following code is accepted by GCC 10.2.0 and trunk (as of 20200802):
template<int N>
struct array {
constexpr auto size() const { return N; }
};
template<typename T>
concept C2 = requires(T a) {
requires a.size() > 2; // "a" is a local parameter and should be allowed
only a an unevaluated operand
};
static_assert(C2< array<5> >);
My reading of [expr.prim.req.nested] p2 is, that is should be ill-formed, "a"
is a local parameter. The following code is (correctly in my opinion) rejected
by GCC:
template<typename T>
constexpr bool Fun(T& t)
{
return true;
}
template<typename T>
concept C1 = requires(T a) {
requires true == Func(a);
};
static_assert(C1<int>);
It looks to me, that in the case of calling a member function on a local
parameter the check is missing. Clang rejects both examples. MSVC 19.24 shows
the same behavior as GCC, so I might be misreading something.
Here is a godbolt link: https://godbolt.org/z/TeTdoK
Cheers,
Andreas
