Introduce a new expression node, ImplicitValueInitExpr, that

represents an implicit value-initialization of a subobject of a
particular type. This replaces the (ab)use of CXXZeroValueInitExpr
within initializer lists for the "holes" that occur due to the use of
C99 designated initializers.

The new test case is currently XFAIL'd, because CodeGen's
ConstExprEmitter (in lib/CodeGen/CGExprConstant.cpp) needs to be
taught to value-initialize when it sees ImplicitValueInitExprs.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@63317 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 8 deletions

diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 527f965dc3..5d7f705edb 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -17,7 +17,6 @@
 #include "clang/Parse/Designator.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Expr.h"
-#include "clang/AST/ExprCXX.h"
 #include <map>
 using namespace clang;
 
@@ -137,10 +136,9 @@ static void fillInValueInitializations(ASTContext &Context, InitListExpr *ILE) {
       // FIXME: Check for fields with reference type in C++?
       if (!ILE->getInit(Init))
         ILE->setInit(Init, 
-                     new (Context) CXXZeroInitValueExpr(Field->getType(), 
-                                                        SourceLocation(),
-                                                        SourceLocation()));
-      else if (InitListExpr *InnerILE = dyn_cast<InitListExpr>(ILE->getInit(Init)))
+                     new (Context) ImplicitValueInitExpr(Field->getType()));
+      else if (InitListExpr *InnerILE 
+                 = dyn_cast<InitListExpr>(ILE->getInit(Init)))
         fillInValueInitializations(Context, InnerILE);
       ++Init;
     }
@@ -160,9 +158,7 @@ static void fillInValueInitializations(ASTContext &Context, InitListExpr *ILE) {
   for (unsigned Init = 0, NumInits = ILE->getNumInits(); Init != NumInits; 
        ++Init) {
     if (!ILE->getInit(Init))
-      ILE->setInit(Init, new (Context) CXXZeroInitValueExpr(ElementType, 
-                                                            SourceLocation(),
-                                                            SourceLocation()));
+      ILE->setInit(Init, new (Context) ImplicitValueInitExpr(ElementType));
     else if (InitListExpr *InnerILE =dyn_cast<InitListExpr>(ILE->getInit(Init)))
       fillInValueInitializations(Context, InnerILE);
   }
@@ -550,6 +546,22 @@ void InitListChecker::CheckStructUnionTypes(InitListExpr *IList,
     hadError = true;
     return;
   }    
+
+  if (DeclType->isUnionType() && IList->getNumInits() == 0) {
+    // Value-initialize the first named member of the union.
+    RecordDecl *RD = DeclType->getAsRecordType()->getDecl();
+    for (RecordDecl::field_iterator FieldEnd = RD->field_end();
+         Field != FieldEnd; ++Field) {
+      if (Field->getDeclName()) {
+        StructuredList->setInitializedFieldInUnion(*Field);
+        break;
+      }
+    }
+    return;
+  }
+
+
+
   // If structDecl is a forward declaration, this loop won't do
   // anything except look at designated initializers; That's okay,
   // because an error should get printed out elsewhere. It might be