Implement C++11 [expr.call]p11: If the operand to a decltype-specifier is a

function call (or a comma expression with a function call on its right-hand
side), possibly parenthesized, then the return type is not required to be
complete and a temporary is not bound. Other subexpressions inside a decltype
expression do not get this treatment.

This is implemented by deferring the relevant checks for all calls immediately
within a decltype expression, then, when the expression is fully-parsed,
checking the relevant constraints and stripping off any top-level temporary
binding.

Deferring the completion of the return type exposed a bug in overload
resolution where completion of the argument types was not attempted, which
is also fixed by this change.

llvm-svn: 151117

1 files changed, 108 insertions, 0 deletions

diff --git a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.type.simple/p5-cxx0x.cpp b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.type.simple/p5-cxx0x.cpp
new file mode 100644
index 00000000000..2bd5d234ce7
--- /dev/null
+++ b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.type.simple/p5-cxx0x.cpp
@@ -0,0 +1,108 @@
+// RUN: %clang_cc1 -std=c++11 -verify %s
+
+namespace std_example {
+
+template<class T> struct A { ~A() = delete; }; // expected-note {{deleted here}}
+template<class T> auto h() -> A<T>;
+template<class T> auto i(T) -> T;
+template<class T> auto f(T) -> decltype(i(h<T>())); // #1
+template<class T> auto f(T) -> void; // #2
+auto g() -> void {
+  f(42); // ok, calls #2, since #1 is not viable.
+}
+template<class T> auto q(T) -> decltype((h<T>()));
+void r() {
+  // Deduction against q succeeds, but results in a temporary which can't be
+  // destroyed.
+  q(42); // expected-error {{attempt to use a deleted function}}
+}
+
+}
+
+class PD {
+  friend struct A;
+  ~PD(); // expected-note 4{{here}}
+public:
+  typedef int n;
+};
+struct DD {
+  ~DD() = delete; // expected-note 2{{here}}
+  typedef int n;
+};
+
+struct A {
+  decltype(PD()) s; // ok
+  decltype(PD())::n n; // ok
+  decltype(DD()) *p = new decltype(DD()); // ok
+};
+
+// Two errors here: one for the decltype, one for the variable.
+decltype(PD(), PD()) pd1; // expected-error 2{{private destructor}}
+decltype(DD(), DD()) dd1; // expected-error 2{{deleted function}}
+
+decltype(((13, ((DD())))))::n dd_parens; // ok
+decltype(((((42)), PD())))::n pd_parens_comma; // ok
+
+// Ensure parens aren't stripped from a decltype node.
+extern decltype(PD()) pd_ref; // ok
+decltype((pd_ref)) pd_ref3 = pd_ref; // ok, PD &
+decltype(pd_ref) pd_ref2 = pd_ref; // expected-error {{private destructor}}
+
+namespace libcxx_example {
+  struct nat {
+    nat() = delete;
+    nat(const nat&) = delete;
+    nat &operator=(const nat&) = delete;
+    ~nat() = delete;
+  };
+  struct any {
+    any(...);
+  };
+
+  template<typename T, typename U> struct is_same { static const bool value = false; };
+  template<typename T> struct is_same<T, T> { static const bool value = true; };
+
+  template<typename T> T declval();
+
+  void swap(int &a, int &b);
+  nat swap(any, any);
+
+  template<typename T> struct swappable {
+    typedef decltype(swap(declval<T&>(), declval<T&>())) type;
+    static const bool value = !is_same<type, nat>::value;
+    constexpr operator bool() { return value; }
+  };
+
+  static_assert(swappable<int>(), "");
+  static_assert(!swappable<const int>(), "");
+}
+
+namespace RequireCompleteType {
+  template<int N, bool OK> struct S {
+    static_assert(OK, "boom!"); // expected-error 2{{boom!}}
+  };
+
+  template<typename T> T make();
+  template<int N, bool OK> S<N, OK> make();
+  void consume(...);
+
+  decltype(make<0, false>()) *p1; // ok
+  decltype((make<1, false>())) *p2; // ok
+
+  // A complete type is required here in order to detect an overloaded 'operator,'.
+  decltype(123, make<2, false>()) *p3; // expected-note {{here}}
+
+  decltype(consume(make<3, false>())) *p4; // expected-note {{here}}
+
+  decltype(make<decltype(make<4, false>())>()) *p5; // ok
+}
+
+namespace Overload {
+  DD operator+(PD &a, PD &b);
+  decltype(PD()) *pd_ptr;
+  decltype(*pd_ptr + *pd_ptr) *dd_ptr; // ok
+
+  decltype(0, *pd_ptr) pd_ref2 = pd_ref; // ok
+  DD operator,(int a, PD b);
+  decltype(0, *pd_ptr) *dd_ptr2; // expected-error {{private destructor}}
+}