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// PR c++/91353 - P1331R2: Allow trivial default init in constexpr contexts.
// { dg-do compile { target c++20 } }
// Test basic use.
struct S {
int i;
constexpr S(bool b) {
if (b)
i = 42;
}
};
constexpr S s1(true);
constexpr S s2(false); // { dg-error "not a constant expression" }
constexpr int
fn1 (int x)
{
int a;
a = 5;
return x + a;
}
static_assert (fn1 (2) == 7);
constexpr int
fn2 (int x)
{
const int a; // { dg-error "uninitialized .const a." }
constexpr int b; // { dg-error "uninitialized .const b." }
return x;
}
constexpr int
fn3 (int x)
{
int a; // { dg-message ".int a. is not const" }
return x + a; // { dg-error "the value of .a. is not usable in a constant expression" }
}
constexpr int a = fn3 (5); // { dg-message "in .constexpr. expansion of" }
constexpr int
fn4 ()
{
struct S { int a = -5; int b; } s;
return s.a;
}
static_assert (fn4 () == -5);
constexpr int
fn5 ()
{
struct S { int a = 9; int b; } s;
return s.b; // { dg-error "accessing uninitialized member" }
}
constexpr int b = fn5 (); // { dg-message "in .constexpr. expansion of" }
constexpr int
fn6 ()
{
int a;
return 42;
}
static_assert (fn6 () == 42);
constexpr int
fn7 (bool b)
{
int a; // { dg-message ".int a. is not const" }
if (b)
a = 42;
return a; // { dg-error "the value of .a. is not usable" }
}
static_assert (fn7 (true) == 42);
static_assert (fn7 (false) == 42); // { dg-error "non-constant condition" }
// { dg-message "in .constexpr. expansion of" "" { target *-*-* } .-1 }
constexpr int
fn8 (int n)
{
int r;
switch (n)
{
case 1:
r = n;
return r;
case 42:
r = n;
return r;
}
}
static_assert (fn8 (1) == 1);
static_assert (fn8 (42) == 42);
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