PR23281: Fix implementation of DR1891 to implement the intent: that i…

…s, a

lambda-expression does not have a move-assignment operator.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@287057 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/AST/DeclCXX.h

@@ -993,7 +993,11 @@ class CXXRecordDecl : public RecordDecl {
            !hasUserDeclaredCopyConstructor() &&
            !hasUserDeclaredCopyAssignment() &&
            !hasUserDeclaredMoveConstructor() &&
-           !hasUserDeclaredDestructor();
+           !hasUserDeclaredDestructor() &&
+           // C++1z [expr.prim.lambda]p21: "the closure type has a deleted copy
+           // assignment operator". The intent is that this counts as a user
+           // declared copy assignment, but we do not model it that way.
+           !isLambda();
   }
 
   /// \brief Determine whether we need to eagerly declare a move assignment

test/CXX/drs/dr18xx.cpp

@@ -7,11 +7,11 @@
 // expected-no-diagnostics
 #endif
 
-void dr1891() { // dr1891: 3.6
+void dr1891() { // dr1891: 4.0
 #if __cplusplus >= 201103L
   int n;
-  auto a = []{}; // expected-note 2{{candidate}}
-  auto b = [=]{ return n; }; // expected-note 2{{candidate}}
+  auto a = []{}; // expected-note 2{{candidate}} expected-note 2{{here}}
+  auto b = [=]{ return n; }; // expected-note 2{{candidate}} expected-note 2{{here}}
   typedef decltype(a) A;
   typedef decltype(b) B;
 
@@ -20,5 +20,10 @@ void dr1891() { // dr1891: 3.6
 
   A x; // expected-error {{no matching constructor}}
   B y; // expected-error {{no matching constructor}}
+
+  a = a; // expected-error {{copy assignment operator is implicitly deleted}}
+  a = static_cast<A&&>(a); // expected-error {{copy assignment operator is implicitly deleted}}
+  b = b; // expected-error {{copy assignment operator is implicitly deleted}}
+  b = static_cast<B&&>(b); // expected-error {{copy assignment operator is implicitly deleted}}
 #endif
 }

test/CXX/expr/expr.prim/expr.prim.lambda/p19.cpp

@@ -7,7 +7,7 @@ struct MoveOnly {
 
 template<typename T> T &&move(T&);
 void test_special_member_functions(MoveOnly mo, int i) {
-  auto lambda1 = [i]() { }; // expected-note {{lambda expression begins here}} expected-note 2{{candidate}}
+  auto lambda1 = [i]() { }; // expected-note 2{{lambda expression begins here}} expected-note 2{{candidate}}
 
   // Default constructor
   decltype(lambda1) lambda2; // expected-error{{no matching constructor}}
@@ -16,7 +16,7 @@ void test_special_member_functions(MoveOnly mo, int i) {
   lambda1 = lambda1; // expected-error{{copy assignment operator is implicitly deleted}}
 
   // Move assignment operator
-  lambda1 = move(lambda1);
+  lambda1 = move(lambda1); // expected-error{{copy assignment operator is implicitly deleted}}
 
   // Copy constructor
   decltype(lambda1) lambda3 = lambda1;

test/SemaCXX/lambda-expressions.cpp

@@ -95,6 +95,39 @@ namespace ImplicitCapture {
   }
 }
 
+namespace SpecialMembers {
+  void f() {
+    auto a = []{}; // expected-note 2{{here}} expected-note 2{{candidate}}
+    decltype(a) b; // expected-error {{no matching constructor}}
+    decltype(a) c = a;
+    decltype(a) d = static_cast<decltype(a)&&>(a);
+    a = a; // expected-error {{copy assignment operator is implicitly deleted}}
+    a = static_cast<decltype(a)&&>(a); // expected-error {{copy assignment operator is implicitly deleted}}
+  }
+  struct P {
+    P(const P&) = delete; // expected-note {{deleted here}}
+  };
+  struct Q {
+    ~Q() = delete; // expected-note {{deleted here}}
+  };
+  struct R {
+    R(const R&) = default;
+    R(R&&) = delete;
+    R &operator=(const R&) = delete;
+    R &operator=(R&&) = delete;
+  };
+  void g(P &p, Q &q, R &r) {
+    auto pp = [p]{}; // expected-error {{deleted constructor}}
+    auto qq = [q]{}; // expected-error {{deleted function}} expected-note {{because}}
+
+    auto a = [r]{}; // expected-note 2{{here}}
+    decltype(a) b = a;
+    decltype(a) c = static_cast<decltype(a)&&>(a); // ok, copies R
+    a = a; // expected-error {{copy assignment operator is implicitly deleted}}
+    a = static_cast<decltype(a)&&>(a); // expected-error {{copy assignment operator is implicitly deleted}}
+  }
+}
+
 namespace PR12031 {
   struct X {
     template<typename T>

www/cxx_dr_status.html

@@ -11161,7 +11161,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1891">1891</a></td>
     <td>DRWP</td>
     <td>Move constructor/assignment for closure class</td>
-    <td class="full" align="center">Clang 3.6</td>
+    <td class="svn" align="center">SVN</td>
   </tr>
   <tr id="1892">
     <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1892">1892</a></td>