clang/test/Parser/cxx2b-auto-x.cpp

   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
   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 *;
  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; }