Revert r184401 which reverted r183462.

The problem with r183462 was that we assumed that a diagnostic id of
zero would be silent.

This small correction to CheckDerivedToBaseConversion changes it's
behavior to omit the diagnostic when given a diagnostic id of zero.

This fix passes the test case added in r184402.

llvm-svn: 184631

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1022,8 +1022,8 @@ def err_access_dtor_base :
     Error<"base class %0 has %select{private|protected}1 destructor">,
     AccessControl;
 def err_access_dtor_vbase :
-    Error<"inherited virtual base class %0 has "
-    "%select{private|protected}1 destructor">,
+    Error<"inherited virtual base class %1 has "
+    "%select{private|protected}2 destructor">,
     AccessControl;
 def err_access_dtor_temp :
     Error<"temporary of type %0 has %select{private|protected}1 destructor">,

clang/lib/Sema/SemaDeclCXX.cpp

@@ -1311,7 +1311,7 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
   assert(BaseDecl && "Record type has no declaration");
   BaseDecl = BaseDecl->getDefinition();
   assert(BaseDecl && "Base type is not incomplete, but has no definition");
-  CXXRecordDecl * CXXBaseDecl = cast<CXXRecordDecl>(BaseDecl);
+  CXXRecordDecl *CXXBaseDecl = cast<CXXRecordDecl>(BaseDecl);
   assert(CXXBaseDecl && "Base type is not a C++ type");
 
   // C++ [class]p3:
@@ -1590,26 +1590,28 @@ Sema::CheckDerivedToBaseConversion(QualType Derived, QualType Base,
     return false;
   }
   
-  // We know that the derived-to-base conversion is ambiguous, and
-  // we're going to produce a diagnostic. Perform the derived-to-base
-  // search just one more time to compute all of the possible paths so
-  // that we can print them out. This is more expensive than any of
-  // the previous derived-to-base checks we've done, but at this point
-  // performance isn't as much of an issue.
-  Paths.clear();
-  Paths.setRecordingPaths(true);
-  bool StillOkay = IsDerivedFrom(Derived, Base, Paths);
-  assert(StillOkay && "Can only be used with a derived-to-base conversion");
-  (void)StillOkay;
+  if (AmbigiousBaseConvID) {
+    // We know that the derived-to-base conversion is ambiguous, and
+    // we're going to produce a diagnostic. Perform the derived-to-base
+    // search just one more time to compute all of the possible paths so
+    // that we can print them out. This is more expensive than any of
+    // the previous derived-to-base checks we've done, but at this point
+    // performance isn't as much of an issue.
+    Paths.clear();
+    Paths.setRecordingPaths(true);
+    bool StillOkay = IsDerivedFrom(Derived, Base, Paths);
+    assert(StillOkay && "Can only be used with a derived-to-base conversion");
+    (void)StillOkay;
 
-  // Build up a textual representation of the ambiguous paths, e.g.,
-  // D -> B -> A, that will be used to illustrate the ambiguous
-  // conversions in the diagnostic. We only print one of the paths
-  // to each base class subobject.
-  std::string PathDisplayStr = getAmbiguousPathsDisplayString(Paths);
+    // Build up a textual representation of the ambiguous paths, e.g.,
+    // D -> B -> A, that will be used to illustrate the ambiguous
+    // conversions in the diagnostic. We only print one of the paths
+    // to each base class subobject.
+    std::string PathDisplayStr = getAmbiguousPathsDisplayString(Paths);
 
-  Diag(Loc, AmbigiousBaseConvID)
-  << Derived << Base << PathDisplayStr << Range << Name;
+    Diag(Loc, AmbigiousBaseConvID)
+    << Derived << Base << PathDisplayStr << Range << Name;
+  }
   return true;
 }
 
@@ -3790,10 +3792,17 @@ Sema::MarkBaseAndMemberDestructorsReferenced(SourceLocation Location,
 
     CXXDestructorDecl *Dtor = LookupDestructor(BaseClassDecl);
     assert(Dtor && "No dtor found for BaseClassDecl!");
-    CheckDestructorAccess(ClassDecl->getLocation(), Dtor,
-                          PDiag(diag::err_access_dtor_vbase)
-                            << VBase->getType(),
-                          Context.getTypeDeclType(ClassDecl));
+    if (CheckDestructorAccess(
+            ClassDecl->getLocation(), Dtor,
+            PDiag(diag::err_access_dtor_vbase)
+                << Context.getTypeDeclType(ClassDecl) << VBase->getType(),
+            Context.getTypeDeclType(ClassDecl)) ==
+        AR_accessible) {
+      CheckDerivedToBaseConversion(
+          Context.getTypeDeclType(ClassDecl), VBase->getType(),
+          diag::err_access_dtor_vbase, 0, ClassDecl->getLocation(),
+          SourceRange(), DeclarationName(), 0);
+    }
 
     MarkFunctionReferenced(Location, const_cast<CXXDestructorDecl*>(Dtor));
     DiagnoseUseOfDecl(Dtor, Location);

clang/test/CXX/drs/dr0xx.cpp

@@ -59,10 +59,13 @@ namespace dr5 { // dr5: yes
   const C c = e;
 }
 
-namespace dr7 { // dr7: no
+namespace dr7 { // dr7: yes
   class A { public: ~A(); };
-  class B : virtual private A {};
-  class C : public B {} c; // FIXME: should be rejected, ~A is inaccessible
+  class B : virtual private A {}; // expected-note 2 {{declared private here}}
+  class C : public B {} c; // expected-error 2 {{inherited virtual base class 'dr7::A' has private destructor}} \
+                           // expected-note {{implicit default constructor for 'dr7::C' first required here}} \
+                           // expected-note {{implicit destructor for 'dr7::C' first required here}}
+  class VeryDerivedC : public B, virtual public A {} vdc;
 
   class X { ~X(); }; // expected-note {{here}}
   class Y : X { ~Y() {} }; // expected-error {{private destructor}}