[Sema][ObjC] Allow declaring ObjC pointer members with non-trivial

ownership qualifications in C++ unions under ARC.

An ObjC pointer member with non-trivial ownership qualifications causes
all of the defaulted special functions of the enclosing union to be
defined as deleted, except when the member has an in-class initializer,
the default constructor isn't defined as deleted.

rdar://problem/34213306

Differential Revision: https://reviews.llvm.org/D57438

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@352949 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 159 insertions, 2 deletions

diff --git a/test/SemaObjCXX/arc-0x.mm b/test/SemaObjCXX/arc-0x.mm
index d0f3284a18..052c99ac13 100644
--- a/test/SemaObjCXX/arc-0x.mm
+++ b/test/SemaObjCXX/arc-0x.mm
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -fobjc-arc -verify -fblocks -fobjc-exceptions %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -fobjc-arc -fobjc-runtime-has-weak -fobjc-weak -verify -fblocks -fobjc-exceptions %s
 
 // "Move" semantics, trivial version.
 void move_it(__strong id &&from) {
@@ -111,3 +111,160 @@ namespace test_err_arc_array_param_no_ownership {
     func(^(A *a[]){}); // expected-error{{must explicitly describe intended ownership of an object array parameter}}
   }
 }
+
+namespace test_union {
+  // Implicitly-declared special functions of a union are deleted by default if
+  // ARC is enabled and the union has an ObjC pointer field.
+  union U0 {
+    id f0; // expected-note 6 {{'U0' is implicitly deleted because variant field 'f0' is an ObjC pointer}}
+  };
+
+  union U1 {
+    __weak id f0; // expected-note 12 {{'U1' is implicitly deleted because variant field 'f0' is an ObjC pointer}}
+    U1() = default; // expected-warning {{explicitly defaulted default constructor is implicitly deleted}} expected-note {{explicitly defaulted function was implicitly deleted here}}
+    ~U1() = default; // expected-warning {{explicitly defaulted destructor is implicitly deleted}} expected-note {{explicitly defaulted function was implicitly deleted here}}
+    U1(const U1 &) = default; // expected-warning {{explicitly defaulted copy constructor is implicitly deleted}} expected-note 2 {{explicitly defaulted function was implicitly deleted here}}
+    U1(U1 &&) = default; // expected-warning {{explicitly defaulted move constructor is implicitly deleted}}
+    U1 & operator=(const U1 &) = default; // expected-warning {{explicitly defaulted copy assignment operator is implicitly deleted}} expected-note 2 {{explicitly defaulted function was implicitly deleted here}}
+    U1 & operator=(U1 &&) = default; // expected-warning {{explicitly defaulted move assignment operator is implicitly deleted}}
+  };
+
+  id getStrong();
+
+  // If the ObjC pointer field of a union has a default member initializer, the
+  // implicitly-declared default constructor of the union is not deleted by
+  // default.
+  union U2 {
+    id f0 = getStrong(); // expected-note 4 {{'U2' is implicitly deleted because variant field 'f0' is an ObjC pointer}}
+    ~U2();
+  };
+
+  // It's fine if the user has explicitly defined the special functions.
+  union U3 {
+    id f0;
+    U3();
+    ~U3();
+    U3(const U3 &);
+    U3(U3 &&);
+    U3 & operator=(const U3 &);
+    U3 & operator=(U3 &&);
+  };
+
+  // ObjC pointer fields in anonymous union fields delete the defaulted special
+  // functions of the containing class.
+  struct S0 {
+    union {
+      id f0; // expected-note 6 {{'' is implicitly deleted because variant field 'f0' is an ObjC pointer}}
+      char f1;
+    };
+  };
+
+  struct S1 {
+    union {
+      union { // expected-note 2 {{'S1' is implicitly deleted because variant field '' has a non-trivial}} expected-note 4 {{'S1' is implicitly deleted because field '' has a deleted}}
+        id f0; // expected-note 2 {{'' is implicitly deleted because variant field 'f0' is an ObjC pointer}}
+        char f1;
+      };
+      int f2;
+    };
+  };
+
+  struct S2 {
+    union {
+      // FIXME: the note should say 'f0' is causing the special functions to be deleted.
+      struct { // expected-note 6 {{'S2' is implicitly deleted because variant field '' has a non-trivial}}
+        id f0;
+        int f1;
+      };
+      int f2;
+    };
+    int f3;
+  };
+
+  U0 *x0;
+  U1 *x1;
+  U2 *x2;
+  U3 *x3;
+  S0 *x4;
+  S1 *x5;
+  S2 *x6;
+
+  static union { // expected-error {{call to implicitly-deleted default constructor of}}
+    id g0; // expected-note {{default constructor of '' is implicitly deleted because variant field 'g0' is an ObjC pointer}}
+  };
+
+  static union { // expected-error {{call to implicitly-deleted default constructor of}}
+    union { // expected-note {{default constructor of '' is implicitly deleted because field '' has a deleted default constructor}}
+      union { // expected-note {{default constructor of '' is implicitly deleted because field '' has a deleted default constructor}}
+        __weak id g1; // expected-note {{default constructor of '' is implicitly deleted because variant field 'g1' is an ObjC pointer}}
+        int g2;
+      };
+      int g3;
+    };
+    int g4;
+  };
+
+  void testDefaultConstructor() {
+    U0 t0; // expected-error {{call to implicitly-deleted default constructor}}
+    U1 t1; // expected-error {{call to implicitly-deleted default constructor}}
+    U2 t2;
+    U3 t3;
+    S0 t4; // expected-error {{call to implicitly-deleted default constructor}}
+    S1 t5; // expected-error {{call to implicitly-deleted default constructor}}
+    S2 t6; // expected-error {{call to implicitly-deleted default constructor}}
+  }
+
+  void testDestructor(U0 *u0, U1 *u1, U2 *u2, U3 *u3, S0 *s0, S1 *s1, S2 *s2) {
+    delete u0; // expected-error {{attempt to use a deleted function}}
+    delete u1; // expected-error {{attempt to use a deleted function}}
+    delete u2;
+    delete u3;
+    delete s0; // expected-error {{attempt to use a deleted function}}
+    delete s1; // expected-error {{attempt to use a deleted function}}
+    delete s2; // expected-error {{attempt to use a deleted function}}
+  }
+
+  void testCopyConstructor(U0 *u0, U1 *u1, U2 *u2, U3 *u3, S0 *s0, S1 *s1, S2 *s2) {
+    U0 t0(*u0); // expected-error {{call to implicitly-deleted copy constructor}}
+    U1 t1(*u1); // expected-error {{call to implicitly-deleted copy constructor}}
+    U2 t2(*u2); // expected-error {{call to implicitly-deleted copy constructor}}
+    U3 t3(*u3);
+    S0 t4(*s0); // expected-error {{call to implicitly-deleted copy constructor}}
+    S1 t5(*s1); // expected-error {{call to implicitly-deleted copy constructor}}
+    S2 t6(*s2); // expected-error {{call to implicitly-deleted copy constructor}}
+  }
+
+  void testCopyAssignment(U0 *u0, U1 *u1, U2 *u2, U3 *u3, S0 *s0, S1 *s1, S2 *s2) {
+    *x0 = *u0; // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x1 = *u1; // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x2 = *u2; // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x3 = *u3;
+    *x4 = *s0; // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x5 = *s1; // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x6 = *s2; // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+  }
+
+  // The diagnostics below refer to the deleted copy constructors and assignment
+  // operators since defaulted move constructors and assignment operators that are
+  // defined as deleted are ignored by overload resolution.
+
+  void testMoveConstructor(U0 *u0, U1 *u1, U2 *u2, U3 *u3, S0 *s0, S1 *s1, S2 *s2) {
+    U0 t0(static_cast<U0 &&>(*u0)); // expected-error {{call to implicitly-deleted copy constructor}}
+    U1 t1(static_cast<U1 &&>(*u1)); // expected-error {{call to implicitly-deleted copy constructor}}
+    U2 t2(static_cast<U2 &&>(*u2)); // expected-error {{call to implicitly-deleted copy constructor}}
+    U3 t3(static_cast<U3 &&>(*u3));
+    S0 t4(static_cast<S0 &&>(*s0)); // expected-error {{call to implicitly-deleted copy constructor}}
+    S1 t5(static_cast<S1 &&>(*s1)); // expected-error {{call to implicitly-deleted copy constructor}}
+    S2 t6(static_cast<S2 &&>(*s2)); // expected-error {{call to implicitly-deleted copy constructor}}
+  }
+
+  void testMoveAssignment(U0 *u0, U1 *u1, U2 *u2, U3 *u3, S0 *s0, S1 *s1, S2 *s2) {
+    *x0 = static_cast<U0 &&>(*u0); // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x1 = static_cast<U1 &&>(*u1); // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x2 = static_cast<U2 &&>(*u2); // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x3 = static_cast<U3 &&>(*u3);
+    *x4 = static_cast<S0 &&>(*s0); // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x5 = static_cast<S1 &&>(*s1); // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+    *x6 = static_cast<S2 &&>(*s2); // expected-error {{cannot be assigned because its copy assignment operator is implicitly deleted}}
+  }
+}
diff --git a/test/SemaObjCXX/objc-weak.mm b/test/SemaObjCXX/objc-weak.mm
index 93c6af1aa3..2671dc104c 100644
--- a/test/SemaObjCXX/objc-weak.mm
+++ b/test/SemaObjCXX/objc-weak.mm
@@ -13,7 +13,7 @@ struct S {
 };
 
 union U {
-  __weak id a; // expected-error {{ARC forbids Objective-C objects in union}}
+  __weak id a;
   S b;         // expected-error {{union member 'b' has a non-trivial copy constructor}}
 };