cxx1y-deduced-return-type.cpp revision 4384712b3a0aedd7c68d6abdb0407850f7b46c8b
160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith// RUN: %clang_cc1 -std=c++1y -verify -fsyntax-only %s 260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 360e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto f(); // expected-note {{previous}} 460e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint f(); // expected-error {{differ only in their return type}} 560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 660e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto &g(); 760e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto g() -> auto &; 860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 960e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto h() -> auto *; 1060e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto *h(); 1160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 1260e141e1f87211ca831de6821003d80fe20a06f3Richard Smithstruct Conv1 { 1360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith operator auto(); // expected-note {{declared here}} 1460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} conv1; 1560e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint conv1a = conv1; // expected-error {{function 'operator auto' with deduced return type cannot be used before it is defined}} 1660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith// expected-error@-1 {{no viable conversion}} 1760e141e1f87211ca831de6821003d80fe20a06f3Richard SmithConv1::operator auto() { return 123; } 1860e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint conv1b = conv1; 1960e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint conv1c = conv1.operator auto(); 2060e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint conv1d = conv1.operator int(); // expected-error {{no member named 'operator int'}} 2160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 2260e141e1f87211ca831de6821003d80fe20a06f3Richard Smithstruct Conv2 { 2360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith operator auto() { return 0; } // expected-note 2{{previous}} 2460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith operator auto() { return 0.; } // expected-error {{cannot be redeclared}} expected-error {{redefinition of 'operator auto'}} 2560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith}; 2660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 2760e141e1f87211ca831de6821003d80fe20a06f3Richard Smithstruct Conv3 { 2860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith operator auto() { int *p = nullptr; return p; } // expected-note {{candidate}} 2960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith operator auto*() { int *p = nullptr; return p; } // expected-note {{candidate}} 3060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} conv3; 3160e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint *conv3a = conv3; // expected-error {{ambiguous}} 3260e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint *conv3b = conv3.operator auto(); 3360e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint *conv3c = conv3.operator auto*(); 3460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 3560e141e1f87211ca831de6821003d80fe20a06f3Richard Smithtemplate<typename T> 3660e141e1f87211ca831de6821003d80fe20a06f3Richard Smithstruct Conv4 { 3760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith operator auto() { return T(); } 3860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith}; 3960e141e1f87211ca831de6821003d80fe20a06f3Richard SmithConv4<int> conv4int; 4060e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint conv4a = conv4int; 4160e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint conv4b = conv4int.operator auto(); 4260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 4360e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto a(); 4460e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto a() { return 0; } 4560e141e1f87211ca831de6821003d80fe20a06f3Richard Smithusing T = decltype(a()); 4660e141e1f87211ca831de6821003d80fe20a06f3Richard Smithusing T = int; 4760e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto a(); // expected-note {{previous}} 4860e141e1f87211ca831de6821003d80fe20a06f3Richard Smithusing T = decltype(a()); 4960e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto *a(); // expected-error {{differ only in their return type}} 5060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 5160e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto b(bool k) { 5260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith if (k) 5360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return "hello"; 5460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return "goodbye"; 5560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 5660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 5760e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto *ptr_1() { 5860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return 100; // expected-error {{cannot deduce return type 'auto *' from returned value of type 'int'}} 5960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 6060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 6160e141e1f87211ca831de6821003d80fe20a06f3Richard Smithconst auto &ref_1() { 6260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return 0; // expected-warning {{returning reference to local temporary}} 6360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 6460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 6560e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto init_list() { 6660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return { 1, 2, 3 }; // expected-error {{cannot deduce return type from initializer list}} 6760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 6860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 6960e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto fwd_decl(); // expected-note 2{{here}} 7060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 7160e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint n = fwd_decl(); // expected-error {{function 'fwd_decl' with deduced return type cannot be used before it is defined}} 7260e141e1f87211ca831de6821003d80fe20a06f3Richard Smithint k = sizeof(fwd_decl()); // expected-error {{used before it is defined}} 7360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 7460e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto fac(int n) { 7560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith if (n <= 2) 7660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return n; 7760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return n * fac(n-1); // ok 7860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 7960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 8060e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto fac_2(int n) { // expected-note {{declared here}} 8160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith if (n > 2) 8260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return n * fac_2(n-1); // expected-error {{cannot be used before it is defined}} 8360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return n; 8460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 8560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 8660e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto void_ret() {} 8760e141e1f87211ca831de6821003d80fe20a06f3Richard Smithusing Void = void; 8860e141e1f87211ca831de6821003d80fe20a06f3Richard Smithusing Void = decltype(void_ret()); 8960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 9060e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto &void_ret_2() {} // expected-error {{cannot deduce return type 'auto &' for function with no return statements}} 9160e141e1f87211ca831de6821003d80fe20a06f3Richard Smithconst auto void_ret_3() {} // ok, return type 'const void' is adjusted to 'void' 9260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 9360e141e1f87211ca831de6821003d80fe20a06f3Richard Smithconst auto void_ret_4() { 9460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith if (false) 9560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return void(); 9660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith if (false) 9760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return; 9860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return 0; // expected-error {{'auto' in return type deduced as 'int' here but deduced as 'void' in earlier return statement}} 9960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 10060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 10160e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace Templates { 10260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto f1() { 10360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return T() + 1; 10460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 10560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto &f2(T &&v) { return v; } 10660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int a = f1<int>(); 10760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith const int &b = f2(0); 10860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith double d; 10960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith float &c = f2(0.0); // expected-error {{non-const lvalue reference to type 'float' cannot bind to a value of unrelated type 'double'}} 11060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 11160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto fwd_decl(); // expected-note {{declared here}} 11260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int e = fwd_decl<int>(); // expected-error {{cannot be used before it is defined}} 11360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto fwd_decl() { return 0; } 11460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int f = fwd_decl<int>(); 1154384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo template <typename T> 1164384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo auto fwd_decl(); // expected-note {{candidate template ignored: could not match 'auto ()' against 'int ()'}} 11760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int g = fwd_decl<char>(); 11860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 11960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto (*p)() = f1; // expected-error {{incompatible initializer}} 12060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto (*q)() = f1<int>; // ok 12160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 12260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith typedef decltype(f2(1.2)) dbl; // expected-note {{previous}} 12360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith typedef float dbl; // expected-error {{typedef redefinition with different types ('float' vs 'decltype(f2(1.2))' (aka 'double &'))}} 12460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 12560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith extern template auto fwd_decl<double>(); 12660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int k1 = fwd_decl<double>(); 12760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith extern template int fwd_decl<char>(); // expected-error {{does not refer to a function template}} 12860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int k2 = fwd_decl<char>(); 12960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 1304384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo template <typename T> auto instantiate() { T::error; } // expected-error {{has no members}} \ 1314384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo // expected-note {{candidate template ignored: could not match 'auto ()' against 'void ()'}} 13260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith extern template auto instantiate<int>(); // ok 13360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int k = instantiate<int>(); // expected-note {{in instantiation of}} 13460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<> auto instantiate<char>() {} // ok 13560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<> void instantiate<double>() {} // expected-error {{no function template matches}} 13660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 13760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto arg_single() { return 0; } 13860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto arg_multi() { return 0l; } 13960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto arg_multi(int) { return "bad"; } 14060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> struct Outer { 14160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith static auto arg_single() { return 0.f; } 14260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith static auto arg_multi() { return 0.; } 14360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith static auto arg_multi(int) { return "bad"; } 14460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith }; 14560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> T &take_fn(T (*p)()); 14660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 14760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &check1 = take_fn(arg_single); // expected-error {{no matching}} expected-note@-2 {{couldn't infer}} 14860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &check2 = take_fn(arg_single<int>); 14960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &check3 = take_fn<int>(arg_single); // expected-error {{no matching}} expected-note@-4{{no overload of 'arg_single'}} 15060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &check4 = take_fn<int>(arg_single<int>); 15160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith long &check5 = take_fn(arg_multi); // expected-error {{no matching}} expected-note@-6 {{couldn't infer}} 15260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith long &check6 = take_fn(arg_multi<int>); 15360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith long &check7 = take_fn<long>(arg_multi); // expected-error {{no matching}} expected-note@-8{{no overload of 'arg_multi'}} 15460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith long &check8 = take_fn<long>(arg_multi<int>); 15560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 15660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith float &mem_check1 = take_fn(Outer<int>::arg_single); 15760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith float &mem_check2 = take_fn<float>(Outer<char>::arg_single); 15860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith double &mem_check3 = take_fn(Outer<long>::arg_multi); 15960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith double &mem_check4 = take_fn<double>(Outer<double>::arg_multi); 16060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 16160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith namespace Deduce1 { 1624384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo template <typename T> auto f() { return 0; } // expected-note {{candidate}} \ 1634384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo // expected-note {{candidate function has different return type ('int' expected but has 'auto')}} 16460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> void g(T(*)()); // expected-note 2{{candidate}} 16560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith void h() { 16660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto p = f<int>; 16760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto (*q)() = f<int>; 16860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int (*r)() = f; // expected-error {{does not match}} 16960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g(f<int>); 17060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g<int>(f); // expected-error {{no matching function}} 17160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g(f); // expected-error {{no matching function}} 17260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 17360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 17460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 17560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith namespace Deduce2 { 1764384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo template <typename T> auto f(int) { return 0; } // expected-note {{candidate}} \ 1774384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo // expected-note {{candidate function has different return type ('int' expected but has 'auto')}} 17860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> void g(T(*)(int)); // expected-note 2{{candidate}} 17960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith void h() { 18060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto p = f<int>; 18160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto (*q)(int) = f<int>; 18260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int (*r)(int) = f; // expected-error {{does not match}} 18360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g(f<int>); 18460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g<int>(f); // expected-error {{no matching function}} 18560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g(f); // expected-error {{no matching function}} 18660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 18760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 18860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 18960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith namespace Deduce3 { 19060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto f(T) { return 0; } 19160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> void g(T(*)(int)); // expected-note {{couldn't infer}} 19260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith void h() { 19360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto p = f<int>; 19460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto (*q)(int) = f<int>; 19560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int (*r)(int) = f; // ok 19660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g(f<int>); 19760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g<int>(f); // ok 19860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith g(f); // expected-error {{no matching function}} 19960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 20060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 20160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 20260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith namespace DeduceInDeducedReturnType { 20360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T, typename U> auto f() -> auto (T::*)(U) { 20460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int (T::*result)(U) = nullptr; 20560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return result; 20660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 20760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith struct S {}; 20860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int (S::*(*p)())(double) = f; 20960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int (S::*(*q)())(double) = f<S, double>; 21060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 21160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 21260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 21360e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto fwd_decl_using(); 21460e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace N { using ::fwd_decl_using; } 21560e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto fwd_decl_using() { return 0; } 21660e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace N { int k = N::fwd_decl_using(); } 21760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 21860e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace OverloadResolutionNonTemplate { 21960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f(); 22060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f(int); // expected-note {{here}} 22160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 22260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &g(int (*f)()); // expected-note {{not viable: no overload of 'f' matching 'int (*)()'}} 22360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith char &g(int (*f)(int)); // expected-note {{not viable: no overload of 'f' matching 'int (*)(int)'}} 22460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 22560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int a = g(f); // expected-error {{no matching function}} 22660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 22760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f() { return 0; } 22860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 22960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith // FIXME: It's not completely clear whether this should be ill-formed. 23060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &b = g(f); // expected-error {{used before it is defined}} 23160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 23260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f(int) { return 0.0; } 23360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 23460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &c = g(f); // ok 23560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 23660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 23760e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace OverloadResolutionTemplate { 23860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f(); 23960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto f(T); 24060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 24160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &g(int (*f)()); // expected-note {{not viable: no overload of 'f' matching 'int (*)()'}} expected-note {{candidate}} 24260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith char &g(int (*f)(int)); // expected-note {{not viable: no overload of 'f' matching 'int (*)(int)'}} expected-note {{candidate}} 24360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 24460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int a = g(f); // expected-error {{no matching function}} 24560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 24660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f() { return 0; } 24760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 24860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &b = g(f); // ok (presumably), due to deduction failure forming type of 'f<int>' 24960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 25060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto f(T) { return 0; } 25160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 25260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int &c = g(f); // expected-error {{ambiguous}} 25360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 25460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 25560e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace DefaultedMethods { 25660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith struct A { 25760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto operator=(const A&) = default; // expected-error {{must return 'DefaultedMethods::A &'}} 25860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith A &operator=(A&&); // expected-note {{previous}} 25960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith }; 26060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto A::operator=(A&&) = default; // expected-error {{differs from the declaration in the return type}} 26160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 26260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 26360e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace Constexpr { 26460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith constexpr auto f1(int n) { return n; } 26560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith struct NonLiteral { ~NonLiteral(); } nl; // expected-note {{user-provided destructor}} 26660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith constexpr auto f2(int n) { return nl; } // expected-error {{return type 'Constexpr::NonLiteral' is not a literal type}} 26760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 26860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 26960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith// It's not really clear whether these are valid, but this matches g++. 27060e141e1f87211ca831de6821003d80fe20a06f3Richard Smithusing size_t = decltype(sizeof(0)); 27160e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto operator new(size_t n, const char*); // expected-error {{must return type 'void *'}} 27260e141e1f87211ca831de6821003d80fe20a06f3Richard Smithauto operator delete(void *, const char*); // expected-error {{must return type 'void'}} 27360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 27460e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace Virtual { 27560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith struct S { 27660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith virtual auto f() { return 0; } // expected-error {{function with deduced return type cannot be virtual}} expected-note {{here}} 27760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith }; 27860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith // Allow 'auto' anyway for error recovery. 27960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith struct T : S { 28060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int f(); 28160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith }; 28260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith struct U : S { 28360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f(); // expected-error {{different return}} 28460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith }; 28560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 28660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith // And here's why... 28760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith struct V { virtual auto f(); }; // expected-error {{cannot be virtual}} 28860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith struct W : V { virtual auto f(); }; // expected-error {{cannot be virtual}} 28960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto V::f() { return 0; } // in tu1.cpp 29060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto W::f() { return 0.0; } // in tu2.cpp 29160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith W w; 29260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int k1 = w.f(); 29360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int k2 = ((V&)w).f(); 29460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 29560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 29660e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace std_examples { 29760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 29860e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace NoReturn { 29960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f() {} 30060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith void (*p)() = &f; 30160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 30225d8c856681120581315edcdb48257c99af6b45cRichard Smith auto f(); // ok 30325d8c856681120581315edcdb48257c99af6b45cRichard Smith 30460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto *g() {} // expected-error {{cannot deduce return type 'auto *' for function with no return statements}} 30525d8c856681120581315edcdb48257c99af6b45cRichard Smith 30625d8c856681120581315edcdb48257c99af6b45cRichard Smith auto h() = delete; // expected-note {{explicitly deleted}} 30725d8c856681120581315edcdb48257c99af6b45cRichard Smith auto x = h(); // expected-error {{call to deleted}} 30860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 30960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 31060e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace UseBeforeComplete { 31160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto n = n; // expected-error {{variable 'n' declared with 'auto' type cannot appear in its own initializer}} 31260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f(); // expected-note {{declared here}} 31360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith void g() { &f; } // expected-error {{function 'f' with deduced return type cannot be used before it is defined}} 31460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto sum(int i) { 31560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith if (i == 1) 31660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return i; 31760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith else 31860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith return sum(i - 1) + i; 31960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith } 32060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 32160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 32260e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace Redecl { 32360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f(); 32460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f() { return 42; } 32560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith auto f(); // expected-note 2{{previous}} 32660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int f(); // expected-error {{functions that differ only in their return type cannot be overloaded}} 32760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith decltype(auto) f(); // expected-error {{cannot be overloaded}} 32860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 3294384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo template <typename T> auto g(T t) { return t; } // expected-note {{candidate}} \ 3304384712b3a0aedd7c68d6abdb0407850f7b46c8bLarisse Voufo // expected-note {{candidate function [with T = int]}} 33160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template auto g(int); 33260e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template char g(char); // expected-error {{does not refer to a function}} 33360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<> auto g(double); 33460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 33560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> T g(T t) { return t; } // expected-note {{candidate}} 33660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template char g(char); 33760e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template auto g(float); 33860e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 33960e141e1f87211ca831de6821003d80fe20a06f3Richard Smith void h() { return g(42); } // expected-error {{ambiguous}} 34060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 34160e141e1f87211ca831de6821003d80fe20a06f3Richard Smith 34260e141e1f87211ca831de6821003d80fe20a06f3Richard Smithnamespace ExplicitInstantiationDecl { 34360e141e1f87211ca831de6821003d80fe20a06f3Richard Smith template<typename T> auto f(T t) { return t; } 34460e141e1f87211ca831de6821003d80fe20a06f3Richard Smith extern template auto f(int); 34560e141e1f87211ca831de6821003d80fe20a06f3Richard Smith int (*p)(int) = f; 34660e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 347d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Valinamespace MemberTemplatesWithDeduction { 348d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali struct M { 349d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali template<class T> auto foo(T t) { return t; } 350d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali template<class T> auto operator()(T t) const { return t; } 351d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali template<class T> static __attribute__((unused)) int static_foo(T) { 352d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali return 5; 353d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali } 354d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali template<class T> operator T() { return T{}; } 355d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali operator auto() { return &static_foo<int>; } 356d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali }; 357d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali struct N : M { 358d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali using M::foo; 359d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali using M::operator(); 360d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali using M::static_foo; 361d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali using M::operator auto; 362d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali }; 363d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali 364d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali template <class T> int test() { 365d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali int i = T{}.foo(3); 366d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali T m = T{}.foo(M{}); 367d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali int j = T{}(3); 368d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali M m2 = M{}(M{}); 369d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali int k = T{}.static_foo(4); 370d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali int l = T::static_foo(5); 371d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali int l2 = T{}; 372d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali struct X { }; 373d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali X x = T{}; 374d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali return 0; 375d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali } 376d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali int Minst = test<M>(); 377d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali int Ninst = test<N>(); 378d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali 379d570a9282fd1793cbf21c090d80cb0b6b4b89982Faisal Vali} 38060e141e1f87211ca831de6821003d80fe20a06f3Richard Smith} 381