1 // RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx2b -std=c++2b -Wpre-c++2b-compat %s
2 // RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx20 -std=c++20 %s
3 
looks_like_decltype_auto()4 void looks_like_decltype_auto() {
5   decltype(auto(42)) b = 42; // cxx20-error {{'auto' not allowed here}} \
6                                 cxx2b-warning {{'auto' as a functional-style cast is incompatible with C++ standards before C++2b}}
7   decltype(long *) a = 42;   // expected-error {{expected '(' for function-style cast or type construction}} \
8                                 expected-error {{expected expression}}
9   decltype(auto *) a = 42;   // expected-error {{expected '(' for function-style cast or type construction}} \
10                                 expected-error {{expected expression}}
11   decltype(auto()) c = 42;   // cxx2b-error {{initializer for functional-style cast to 'auto' is empty}} \
12                                 cxx20-error {{'auto' not allowed here}}
13 }
14 
15 struct looks_like_declaration {
16   int n;
17 } a;
18 
19 using T = looks_like_declaration *;
f()20 void f() { T(&a)->n = 1; }
21 // FIXME: They should be deemed expressions without breaking function pointer
22 //        parameter declarations with trailing return types.
23 // void g() { auto(&a)->n = 0; }
24 // void h() { auto{&a}->n = 0; }
25