namespace ParameterScopes {
const int k = 42;
constexpr const int &ObscureTheTruth(const int &a) { return a; } // expected-note 3{{reference to 'a' cannot be returned from a constexpr function}}
constexpr const int &MaybeReturnJunk(bool b, const int a) { // expected-note 2{{declared here}}
return ObscureTheTruth(b ? a : k); // expected-note 2{{in call to 'ObscureTheTruth(a)'}}
}
static_assert(MaybeReturnJunk(false, 0) == 42, ""); // ok
constexpr int a = MaybeReturnJunk(true, 0); // expected-error {{constant expression}} expected-note {{in call to 'MaybeReturnJunk(1, 0)'}}
constexpr const int MaybeReturnNonstaticRef(bool b, const int a) { // expected-note {{here}}
// If ObscureTheTruth returns a reference to 'a', the result is not a
// constant expression even though 'a' is still in scope.
return ObscureTheTruth(b ? a : k); // expected-note {{in call to 'ObscureTheTruth(a)'}}
}
static_assert(MaybeReturnNonstaticRef(false, 0) == 42, ""); // ok
constexpr int b = MaybeReturnNonstaticRef(true, 0); // expected-error {{constant expression}} expected-note {{in call to 'MaybeReturnNonstaticRef(1, 0)'}}
constexpr int InternalReturnJunk(int n) {
// FIXME: We should reject this: it never produces a constant expression.
return MaybeReturnJunk(true, n); // expected-note {{in call to 'MaybeReturnJunk(1, 0)'}}
}
constexpr int n3 = InternalReturnJunk(0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'InternalReturnJunk(0)'}}
constexpr int LToR(int &n) { return n; }
constexpr int GrabCallersArgument(bool which, int a, int b) {
return LToR(which ? b : a);
}
static_assert(GrabCallersArgument(false, 1, 2) == 1, "");
static_assert(GrabCallersArgument(true, 4, 8) == 8, "");
}
namespace ParameterScopes {
const int k = 42;
constexpr const int &ObscureTheTruth(const int &a) { return a; }
constexpr const int &MaybeReturnJunk(bool b, const int a) { // expected-note 2{{declared here}}
return ObscureTheTruth(b ? a : k);
}
static_assert(MaybeReturnJunk(false, 0) == 42, ""); // ok
constexpr int a = MaybeReturnJunk(true, 0); // expected-error {{constant expression}} expected-note {{read of variable whose lifetime has ended}}
constexpr const int MaybeReturnNonstaticRef(bool b, const int a) {
return ObscureTheTruth(b ? a : k);
}
static_assert(MaybeReturnNonstaticRef(false, 0) == 42, ""); // ok
constexpr int b = MaybeReturnNonstaticRef(true, 0); // ok
constexpr int InternalReturnJunk(int n) {
return MaybeReturnJunk(true, n); // expected-note {{read of variable whose lifetime has ended}}
}
constexpr int n3 = InternalReturnJunk(0); // expected-error {{must be initialized by a constant expression}} expected-note {{in call to 'InternalReturnJunk(0)'}}
constexpr int LToR(int &n) { return n; }
constexpr int GrabCallersArgument(bool which, int a, int b) {
return LToR(which ? b : a);
}
static_assert(GrabCallersArgument(false, 1, 2) == 1, "");
static_assert(GrabCallersArgument(true, 4, 8) == 8, "");
}