PR12012: Fix a regression in r150419 where we would try (and fail) to

zero-initialize class types with virtual bases when constant-evaluating an
initializer.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150770 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/ExprConstant.cpp

@@ -3387,6 +3387,11 @@ bool RecordExprEvaluator::ZeroInitialization(const Expr *E) {
     return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE);
   }
 
+  if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) {
+    Info.Diag(E->getExprLoc(), diag::note_constexpr_virtual_base) << RD;
+    return false;
+  }
+
   return HandleClassZeroInitialization(Info, E, RD, This, Result);
 }
 

test/CodeGenCXX/const-init-cxx11.cpp

@@ -279,3 +279,17 @@ namespace CrossFuncLabelDiff {
   // CHECK: sub nsw i64 ptrtoint (i8* blockaddress(@_ZN18CrossFuncLabelDiff4testEv, {{.*}}) to i64),
   // CHECK: store i64 {{.*}}, i64* @_ZZN18CrossFuncLabelDiff4testEvE1b, align 8
 }
+
+// PR12012
+namespace VirtualBase {
+  struct B {};
+  struct D : virtual B {};
+  D d;
+  // CHECK: call {{.*}}@_ZN11VirtualBase1DC1Ev
+
+  template<typename T> struct X : T {
+    constexpr X() : T() {}
+  };
+  X<D> x;
+  // CHECK: call {{.*}}@_ZN11VirtualBase1XINS_1DEEC1Ev
+}

test/SemaCXX/constexpr-value-init.cpp

@@ -29,3 +29,9 @@ constexpr D d1; // expected-error {{requires a user-provided default constructor
 constexpr D d2 = D(); // ok with DR1452
 static_assert(D().c == 0, "");
 static_assert(D().d == 0, "");
+
+struct V : virtual C {};
+template<typename T> struct Z : T {
+  constexpr Z() : V() {}
+};
+constexpr int n = Z<V>().c; // expected-error {{constant expression}} expected-note {{virtual base class}}