r310963 - Allow the target field of a CK_ToUnion to be more easily recovered.

[John McCall via cfe-commits]

Author: rjmccall
Date: Tue Aug 15 14:42:47 2017
New Revision: 310963

URL: http://llvm.org/viewvc/llvm-project?rev=310963&view=rev
Log:
Allow the target field of a CK_ToUnion to be more easily recovered.

Modified:
    cfe/trunk/include/clang/AST/Expr.h
    cfe/trunk/lib/AST/Expr.cpp
    cfe/trunk/lib/Sema/SemaCast.cpp

Modified: cfe/trunk/include/clang/AST/Expr.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Expr.h?rev=310963&r1=310962&r2=310963&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Expr.h (original)
+++ cfe/trunk/include/clang/AST/Expr.h Tue Aug 15 14:42:47 2017
@@ -2772,6 +2772,16 @@ public:
   path_const_iterator path_begin() const { return path_buffer(); }
   path_const_iterator path_end() const { return path_buffer() + path_size(); }
 
+  const FieldDecl *getTargetUnionField() const {
+    assert(getCastKind() == CK_ToUnion);
+    return getTargetFieldForToUnionCast(getType(), getSubExpr()->getType());
+  }
+
+  static const FieldDecl *getTargetFieldForToUnionCast(QualType unionType,
+                                                       QualType opType);
+  static const FieldDecl *getTargetFieldForToUnionCast(const RecordDecl *RD,
+                                                       QualType opType);
+
   static bool classof(const Stmt *T) {
     return T->getStmtClass() >= firstCastExprConstant &&
            T->getStmtClass() <= lastCastExprConstant;

Modified: cfe/trunk/lib/AST/Expr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=310963&r1=310962&r2=310963&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Expr.cpp (original)
+++ cfe/trunk/lib/AST/Expr.cpp Tue Aug 15 14:42:47 2017
@@ -1695,6 +1695,26 @@ CXXBaseSpecifier **CastExpr::path_buffer
   }
 }
 
+const FieldDecl *CastExpr::getTargetFieldForToUnionCast(QualType unionType,
+                                                        QualType opType) {
+  auto RD = unionType->castAs<RecordType>()->getDecl();
+  return getTargetFieldForToUnionCast(RD, opType);
+}
+
+const FieldDecl *CastExpr::getTargetFieldForToUnionCast(const RecordDecl *RD,
+                                                        QualType OpType) {
+  auto &Ctx = RD->getASTContext();
+  RecordDecl::field_iterator Field, FieldEnd;
+  for (Field = RD->field_begin(), FieldEnd = RD->field_end();
+       Field != FieldEnd; ++Field) {
+    if (Ctx.hasSameUnqualifiedType(Field->getType(), OpType) &&
+        !Field->isUnnamedBitfield()) {
+      return *Field;
+    }
+  }
+  return nullptr;
+}
+
 ImplicitCastExpr *ImplicitCastExpr::Create(const ASTContext &C, QualType T,
                                            CastKind Kind, Expr *Operand,
                                            const CXXCastPath *BasePath,

Modified: cfe/trunk/lib/Sema/SemaCast.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaCast.cpp?rev=310963&r1=310962&r2=310963&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaCast.cpp (original)
+++ cfe/trunk/lib/Sema/SemaCast.cpp Tue Aug 15 14:42:47 2017
@@ -2458,24 +2458,17 @@ void CastOperation::CheckCStyleCast() {
     // GCC's cast to union extension.
     if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) {
       RecordDecl *RD = DestRecordTy->getDecl();
-      RecordDecl::field_iterator Field, FieldEnd;
-      for (Field = RD->field_begin(), FieldEnd = RD->field_end();
-           Field != FieldEnd; ++Field) {
-        if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) &&
-            !Field->isUnnamedBitfield()) {
-          Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union)
-            << SrcExpr.get()->getSourceRange();
-          break;
-        }
-      }
-      if (Field == FieldEnd) {
+      if (CastExpr::getTargetFieldForToUnionCast(RD, SrcType)) {
+        Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union)
+          << SrcExpr.get()->getSourceRange();
+        Kind = CK_ToUnion;
+        return;
+      } else {
         Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type)
           << SrcType << SrcExpr.get()->getSourceRange();
         SrcExpr = ExprError();
         return;
       }
-      Kind = CK_ToUnion;
-      return;
     }
 
     // OpenCL v2.0 s6.13.10 - Allow casts from '0' to event_t type.