File: concepts-requires6.C

package info (click to toggle)
gcc-arm-none-eabi 15%3A14.2.rel1-1
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid, trixie
  • size: 1,099,328 kB
  • sloc: cpp: 3,627,108; ansic: 2,571,498; ada: 834,230; f90: 235,082; makefile: 79,231; asm: 74,984; xml: 51,692; exp: 39,736; sh: 33,298; objc: 15,629; python: 15,069; fortran: 14,429; pascal: 7,003; awk: 5,070; perl: 3,106; ml: 285; lisp: 253; lex: 204; haskell: 135
file content (34 lines) | stat: -rw-r--r-- 809 bytes parent folder | download | duplicates (2) 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
 
// { dg-do compile { target c++20 } }

// Test deduction requirements.

// req12.C

template <typename T, typename U>
concept SameAs = __is_same_as(T, U);

template <typename T>
concept C1 = requires(T t) { // { dg-message "in requirements" }
  { t } -> SameAs<T>; // NOTE: t deduced as decltype((t))
  // { dg-message "does not satisfy" "" { target *-*-* } .-1 }
};

template <typename T>
  requires C1<T>
constexpr bool f1() { return true; }

static_assert(f1<char>()); // { dg-error "" }
static_assert(f1<int>()); // { dg-error "" }
static_assert(f1<double>()); // { dg-error "" }


template <typename T>
concept C2 = requires(T t) {
  { t } -> SameAs<T&>; // NOTE: t deduced as decltype((t))
};

template <typename T>
  requires C2<T>
constexpr bool f2() { return true; }

static_assert(f2<int>()); // OK