Revert "[Sema] Diagnose default-initialization, destruction, and copying of"

This reverts commit r365985.

Prior to r365985, clang used to mark C union fields that have
non-trivial ObjC ownership qualifiers as unavailable if the union was
declared in a system header. r365985 stopped doing so, which caused the
swift compiler to crash when it tried to import a non-trivial union.

I have a patch that fixes the crash (https://reviews.llvm.org/D65256),
but I'm temporarily reverting the original patch until we can decide on
whether it's taking the right approach.

llvm-svn: 367076

1 files changed, 1 insertions, 32 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 8f5a892b9a2..52fa932eee8 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6076,7 +6076,7 @@ Sema::BuildCompoundLiteralExpr(SourceLocation LParenLoc, TypeSourceInfo *TInfo,
         ILE->setInit(i, ConstantExpr::Create(Context, Init));
       }
 
-  auto *E = new (Context) CompoundLiteralExpr(LParenLoc, TInfo, literalType,
+  Expr *E = new (Context) CompoundLiteralExpr(LParenLoc, TInfo, literalType,
                                               VK, LiteralExpr, isFileScope);
   if (isFileScope) {
     if (!LiteralExpr->isTypeDependent() &&
@@ -6094,19 +6094,6 @@ Sema::BuildCompoundLiteralExpr(SourceLocation LParenLoc, TypeSourceInfo *TInfo,
     return ExprError();
   }
 
-  // Compound literals that have automatic storage duration are destroyed at
-  // the end of the scope. Emit diagnostics if it is or contains a C union type
-  // that is non-trivial to destruct.
-  if (!isFileScope)
-    if (E->getType().hasNonTrivialToPrimitiveDestructCUnion())
-      checkNonTrivialCUnion(E->getType(), E->getExprLoc(),
-                            NTCUC_CompoundLiteral, NTCUK_Destruct);
-
-  if (E->getType().hasNonTrivialToPrimitiveDefaultInitializeCUnion() ||
-      E->getType().hasNonTrivialToPrimitiveCopyCUnion())
-    checkNonTrivialCUnionInInitializer(E->getInitializer(),
-                                       E->getInitializer()->getExprLoc());
-
   return MaybeBindToTemporary(E);
 }
 
@@ -12556,10 +12543,6 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
           if (auto *VD = dyn_cast<VarDecl>(DRE->getDecl()))
             if (VD->hasLocalStorage() && getCurScope()->isDeclScope(VD))
               BE->getBlockDecl()->setCanAvoidCopyToHeap();
-
-      if (LHS.get()->getType().hasNonTrivialToPrimitiveCopyCUnion())
-        checkNonTrivialCUnion(LHS.get()->getType(), LHS.get()->getExprLoc(),
-                              NTCUC_Assignment, NTCUK_Copy);
     }
     RecordModifiableNonNullParam(*this, LHS.get());
     break;
@@ -13972,11 +13955,6 @@ ExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
       !BD->isDependentContext())
     computeNRVO(Body, BSI);
 
-  if (RetTy.hasNonTrivialToPrimitiveDestructCUnion() ||
-      RetTy.hasNonTrivialToPrimitiveCopyCUnion())
-    checkNonTrivialCUnion(RetTy, BD->getCaretLocation(), NTCUC_FunctionReturn,
-                          NTCUK_Destruct|NTCUK_Copy);
-
   PopDeclContext();
 
   // Pop the block scope now but keep it alive to the end of this function.
@@ -16228,15 +16206,6 @@ static ExprResult rebuildPotentialResultsAsNonOdrUsed(Sema &S, Expr *E,
 }
 
 ExprResult Sema::CheckLValueToRValueConversionOperand(Expr *E) {
-  // Check whether the operand is or contains an object of non-trivial C union
-  // type.
-  if (E->getType().isVolatileQualified() &&
-      (E->getType().hasNonTrivialToPrimitiveDestructCUnion() ||
-       E->getType().hasNonTrivialToPrimitiveCopyCUnion()))
-    checkNonTrivialCUnion(E->getType(), E->getExprLoc(),
-                          Sema::NTCUC_LValueToRValueVolatile,
-                          NTCUK_Destruct|NTCUK_Copy);
-
   // C++2a [basic.def.odr]p4:
   //   [...] an expression of non-volatile-qualified non-class type to which
   //   the lvalue-to-rvalue conversion is applied [...]