Generate constructor for value-initialization cases, even if the

implementation technique doesn't call the constructor at that point.
DR302. Fixes pr5296.

llvm-svn: 85249

clang/lib/Sema/SemaExprCXX.cpp

@@ -288,7 +288,20 @@ Sema::ActOnCXXTypeConstructExpr(SourceRange TypeRange, TypeTy *TypeRep,
       << FullRange);
 
   assert(NumExprs == 0 && "Expected 0 expressions");
-
+  
+  if (const RecordType *Record = Ty->getAs<RecordType>()) {
+    if (!Record->getDecl()->isUnion()) {
+    // As clarified in C++ DR302, generate constructor for 
+    // value-initialization cases, even if the implementation technique 
+    // doesn't call the constructor at that point.
+      ASTOwningVector<&ActionBase::DeleteExpr> ConstructorArgs(*this);
+      (void)PerformInitializationByConstructor(Ty, MultiExprArg(*this, 0, 0), 
+                                               TypeRange.getBegin(), 
+                                               TypeRange, DeclarationName(),
+                                               IK_Default, ConstructorArgs);
+    }
+  }
+                                           
   // C++ [expr.type.conv]p2:
   // The expression T(), where T is a simple-type-specifier for a non-array
   // complete object type or the (possibly cv-qualified) void type, creates an
@@ -489,7 +502,21 @@ Sema::BuildCXXNew(SourceLocation StartLoc, bool UseGlobal,
         return ExprError(Diag(StartLoc, diag::err_new_uninitialized_const)
                            << TypeRange);
     } else if (NumConsArgs == 0) {
-      // Object is value-initialized. Do nothing.
+      // Object is value-initialized. 
+      if (const RecordType *Record = AllocType->getAs<RecordType>()) {
+        if (!Record->getDecl()->isUnion()) {
+        // As clarified in C++ DR302, generate constructor for 
+        // value-initialization cases, even if the implementation technique 
+        // doesn't call the constructor at that point.
+          ASTOwningVector<&ActionBase::DeleteExpr> ConstructorArgs(*this);
+          (void)PerformInitializationByConstructor(AllocType, 
+                                                   MultiExprArg(*this, 0, 0), 
+                                                   TypeRange.getBegin(), 
+                                                   TypeRange, DeclarationName(),
+                                                   IK_Default, 
+                                                   ConstructorArgs);
+        }
+      }
     } else if (NumConsArgs == 1) {
       // Object is direct-initialized.
       // FIXME: What DeclarationName do we pass in here?

clang/test/SemaCXX/value-initialization.cpp

@@ -0,0 +1,23 @@
+// RUN: clang-cc -fsyntax-only -verify %s -std=c++0x
+
+struct A {
+      ~A();
+      const int i;	// expected-note {{declared at}}
+};
+
+struct B {
+      // B is a non-POD with no user-written constructor.
+      // It has a nontrivial generated constructor.
+      const int i[12];	// expected-note {{declared at}}
+      A a;
+};
+
+int main () {
+      // Value-initializing a "B" doesn't call the default constructor for
+      // "B"; it value-initializes the members of B.  Therefore it shouldn't
+      // cause an error on generation of the default constructor for the
+      // following:
+      new B();	// expected-error {{cannot define the implicit default constructor for 'struct B', because const member 'i'}}
+      (void)B();
+      (void)A(); // expected-error {{cannot define the implicit default constructor for 'struct A', because const member 'i'}}
+}