1 // RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify=expected,cxx23 %s
2 // RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx14_20 %s
3 // RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14_20 %s
4
5 int a;
6 int &b = [] (int &r) -> decltype(auto) { return r; } (a);
7 int &c = [] (int &r) -> decltype(auto) { return (r); } (a);
__anon1c1d34e60102(int &r) 8 int &d = [] (int &r) -> auto & { return r; } (a);
__anon1c1d34e60202(int &r) 9 int &e = [] (int &r) -> auto { return r; } (a); // expected-error {{cannot bind to a temporary}}
10 int &f = [] (int r) -> decltype(auto) { return r; } (a); // expected-error {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
11 int &g = [] (int r) -> decltype(auto) { return (r); } (a); // expected-warning {{reference to stack}}
12 // cxx23-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
13
test_explicit_auto_return()14 int test_explicit_auto_return()
15 {
16 struct X {};
17 auto L = [](auto F, auto a) { return F(a); };
18 auto M = [](auto a) -> auto { return a; }; // OK
19 auto MRef = [](auto b) -> auto & { return b; }; //cxx14_20-warning{{reference to stack}}
20 // cxx23-error@-1 {{non-const lvalue reference to type 'X' cannot bind to a temporary of type 'X'}}
21 auto MPtr = [](auto c) -> auto* { return &c; }; //expected-warning{{address of stack}}
22 auto MDeclType = [](auto&& d) -> decltype(auto) { return static_cast<decltype(d)>(d); }; //OK
23 M(3);
24
25 auto &&x = MDeclType(X{});
26 auto &&x1 = M(X{});
27 auto &&x2 = MRef(X{});//expected-note{{in instantiation of}}
28 auto &&x3 = MPtr(X{}); //expected-note{{in instantiation of}}
29 return 0;
30 }
31
test_implicit_auto_return()32 int test_implicit_auto_return()
33 {
34 {
35 auto M = [](auto a) { return a; };
36 struct X {};
37 X x = M(X{});
38
39 }
40 }
41
test_multiple_returns()42 int test_multiple_returns() {
43 auto M = [](auto a) {
44 bool k;
45 if (k)
46 return a;
47 else
48 return 5; //expected-error{{deduced as 'int' here}}
49 };
50 M(3); // OK
51 M('a'); //expected-note{{in instantiation of}}
52 return 0;
53 }
test_no_parameter_list()54 int test_no_parameter_list()
55 {
56 static int si = 0;
57 auto M = [] { return 5; }; // OK
58 auto M2 = [] -> auto && { return si; };
59 #if __cplusplus <= 202002L
60 // expected-warning@-2{{is a C++23 extension}}
61 #endif
62 M();
63 }
64
test_conditional_in_return()65 int test_conditional_in_return() {
66 auto Fac = [](auto f, auto n) {
67 return n <= 0 ? n : f(f, n - 1) * n;
68 };
69 // FIXME: this test causes a recursive limit - need to error more gracefully.
70 //Fac(Fac, 3);
71
72 }
73