clang/test/CXX/dcl.decl/dcl.init/p5.cpp

   1 // RUN: %clang_cc1 -fsyntax-only -verify -Wno-deprecated-builtins -std=c++98 %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify -Wno-deprecated-builtins -std=c++11 %s
   3 // RUN: %clang_cc1 -fsyntax-only -verify -Wno-deprecated-builtins %s
   4
   5 //   A program that calls for default-initialization or value-initialization of
   6 //   an entity of reference type is illformed. If T is a cv-qualified type, the
   7 //   cv-unqualified version of T is used for these definitions of
   8 //   zero-initialization, default-initialization, and value-initialization.
   9
  10 typedef int &IR;
  11 IR r; // expected-error {{declaration of reference variable 'r' requires an initializer}}
  12 int n = IR(); // expected-error {{reference to type 'int' requires an initializer}}
  13
  14 #if __cplusplus < 201103L
  15 struct S { // expected-error {{implicit default constructor for 'S' must explicitly initialize the reference member}}
  16   int &x; // expected-note {{declared here}} expected-error 3{{reference to type 'int' requires an initializer}}
  17 };
  18 S s; // expected-note {{implicit default constructor for 'S' first required here}}
  19 S f() {
  20   return S(); // expected-note {{in value-initialization of type 'S' here}}
  21 }
  22
  23 struct T
  24   : S { // expected-note 2{{in value-initialization of type 'S' here}}
  25 };
  26 T t = T(); // expected-note {{in value-initialization of type 'T' here}}
  27
  28 struct U {
  29   T t[3]; // expected-note {{in value-initialization of type 'T' here}}
  30 };
  31 U u = U(); // expected-note {{in value-initialization of type 'U' here}}
  32 #else
  33 struct S {
  34   int &x; // expected-note 4{{because field 'x' of reference type 'int &' would not be initialized}}
  35 };
  36 S s; // expected-error {{deleted default constructor}}
  37 S f() {
  38   return S(); // expected-error {{deleted default constructor}}
  39 }
  40
  41 struct T
  42   : S { // expected-note 2{{because base class 'S' has a deleted default constructor}}
  43 };
  44 T t = T(); // expected-error {{deleted default constructor}}
  45
  46 struct U {
  47   T t[3]; // expected-note {{because field 't' has a deleted default constructor}}
  48 };
  49 U u = U(); // expected-error {{deleted default constructor}}
  50 #endif
  51
  52 // Ensure that we handle C++11 in-class initializers properly as an extension.
  53 // In this case, there is no user-declared default constructor, so we
  54 // recursively apply the value-initialization checks, but we will emit a
  55 // constructor call anyway, because the default constructor is not trivial.
  56 struct V {
  57   int n;
  58   int &r = n; // expected-warning 0-1{{C++11}}
  59 };
  60 V v = V(); // ok
  61 struct W {
  62   int n;
  63   S s = { n }; // expected-warning 0-1{{C++11}}
  64 };
  65 W w = W(); // ok
  66
  67 // Ensure we're not faking this up by making the default constructor
  68 // non-trivial.
  69 _Static_assert(__has_trivial_constructor(S), "");
  70 _Static_assert(__has_trivial_constructor(T), "");
  71 _Static_assert(__has_trivial_constructor(U), "");
  72 _Static_assert(!__has_trivial_constructor(V), "");
  73 _Static_assert(!__has_trivial_constructor(W), "");