1 // RUN: %clang_cc1 -std=c++20 -verify %s
2
3 template <class T>
4 requires(sizeof(T) > 2) || T::value // #FOO_REQ
5 void Foo(T){}; // #FOO
6
7 template <class T>
8 void TrailingReturn(T) // #TRAILING
9 requires(sizeof(T) > 2) || // #TRAILING_REQ
10 T::value // #TRAILING_REQ_VAL
11 {};
12 template <bool B>
13 struct HasValue {
14 static constexpr bool value = B;
15 };
16 static_assert(sizeof(HasValue<true>) <= 2);
17
18 template <bool B>
19 struct HasValueLarge {
20 static constexpr bool value = B;
21 int I;
22 };
23 static_assert(sizeof(HasValueLarge<true>) > 2);
24
usage()25 void usage() {
26 // Passes the 1st check, short-circuit so the 2nd ::value is not evaluated.
27 Foo(1.0);
28 TrailingReturn(1.0);
29
30 // Fails the 1st check, but has a ::value, so the check happens correctly.
31 Foo(HasValue<true>{});
32 TrailingReturn(HasValue<true>{});
33
34 // Passes the 1st check, but would have passed the 2nd one.
35 Foo(HasValueLarge<true>{});
36 TrailingReturn(HasValueLarge<true>{});
37
38 // Fails the 1st check, fails 2nd because there is no ::value.
39 Foo(true);
40 // expected-error@-1{{no matching function for call to 'Foo'}}
41 // expected-note@#FOO{{candidate template ignored: constraints not satisfied [with T = bool]}}
42 // expected-note@#FOO_REQ{{because 'sizeof(_Bool) > 2' (1 > 2) evaluated to false}}
43 // expected-note@#FOO_REQ{{because substituted constraint expression is ill-formed: type 'bool' cannot be used prior to '::' because it has no members}}
44
45 TrailingReturn(true);
46 // expected-error@-1{{no matching function for call to 'TrailingReturn'}}
47 // expected-note@#TRAILING{{candidate template ignored: constraints not satisfied [with T = bool]}}
48 // expected-note@#TRAILING_REQ{{because 'sizeof(_Bool) > 2' (1 > 2) evaluated to false}}
49 // expected-note@#TRAILING_REQ_VAL{{because substituted constraint expression is ill-formed: type 'bool' cannot be used prior to '::' because it has no members}}
50
51 // Fails the 1st check, fails 2nd because ::value is false.
52 Foo(HasValue<false>{});
53 // expected-error@-1 {{no matching function for call to 'Foo'}}
54 // expected-note@#FOO{{candidate template ignored: constraints not satisfied [with T = HasValue<false>]}}
55 // expected-note@#FOO_REQ{{because 'sizeof(HasValue<false>) > 2' (1 > 2) evaluated to false}}
56 // expected-note@#FOO_REQ{{and 'HasValue<false>::value' evaluated to false}}
57 TrailingReturn(HasValue<false>{});
58 // expected-error@-1 {{no matching function for call to 'TrailingReturn'}}
59 // expected-note@#TRAILING{{candidate template ignored: constraints not satisfied [with T = HasValue<false>]}}
60 // expected-note@#TRAILING_REQ{{because 'sizeof(HasValue<false>) > 2' (1 > 2) evaluated to false}}
61 // expected-note@#TRAILING_REQ_VAL{{and 'HasValue<false>::value' evaluated to false}}
62 }
63