PR23833, DR2140: an lvalue-to-rvalue conversion on a glvalue of type
nullptr_t does not access memory.
We now reuse CK_NullToPointer to represent a conversion from a glvalue
of type nullptr_t to a prvalue of nullptr_t where necessary.
This reinstates r363337, reverted in r363352.
llvm-svn: 363429
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 77d4441..72e1119 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -1885,6 +1885,11 @@
ExprValueKind VK) {
unsigned PathSize = (BasePath ? BasePath->size() : 0);
void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+ // Per C++ [conv.lval]p3, lvalue-to-rvalue conversions on class and
+ // std::nullptr_t have special semantics not captured by CK_LValueToRValue.
+ assert((Kind != CK_LValueToRValue ||
+ !(T->isNullPtrType() || T->getAsCXXRecordDecl())) &&
+ "invalid type for lvalue-to-rvalue conversion");
ImplicitCastExpr *E =
new (Buffer) ImplicitCastExpr(T, Kind, Operand, PathSize, VK);
if (PathSize)
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index a76058c..3b1c5bf 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -1352,7 +1352,8 @@
// (int*)0 - Null pointer expressions.
if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
return ICE->getCastKind() == CK_NullToPointer &&
- CGF.getTypes().isPointerZeroInitializable(E->getType());
+ CGF.getTypes().isPointerZeroInitializable(E->getType()) &&
+ !E->HasSideEffects(CGF.getContext());
// '\0'
if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
return CL->getValue() == 0;
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 267402d..c416753 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -2148,14 +2148,14 @@
case CK_NullToPointer:
if (MustVisitNullValue(E))
- (void) Visit(E);
+ CGF.EmitIgnoredExpr(E);
return CGF.CGM.getNullPointer(cast<llvm::PointerType>(ConvertType(DestTy)),
DestTy);
case CK_NullToMemberPointer: {
if (MustVisitNullValue(E))
- (void) Visit(E);
+ CGF.EmitIgnoredExpr(E);
const MemberPointerType *MPT = CE->getType()->getAs<MemberPointerType>();
return CGF.CGM.getCXXABI().EmitNullMemberPointer(MPT);
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 7b3590a..9b1e362 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -635,8 +635,10 @@
if (E->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
Cleanup.setExprNeedsCleanups(true);
- Res = ImplicitCastExpr::Create(Context, T, CK_LValueToRValue, E, nullptr,
- VK_RValue);
+ // C++ [conv.lval]p3:
+ // If T is cv std::nullptr_t, the result is a null pointer constant.
+ CastKind CK = T->isNullPtrType() ? CK_NullToPointer : CK_LValueToRValue;
+ Res = ImplicitCastExpr::Create(Context, T, CK, E, nullptr, VK_RValue);
// C11 6.3.2.1p2:
// ... if the lvalue has atomic type, the value has the non-atomic version
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 1a1d934..1301de4 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -7779,9 +7779,13 @@
case SK_LValueToRValue: {
assert(CurInit.get()->isGLValue() && "cannot load from a prvalue");
- CurInit = ImplicitCastExpr::Create(S.Context, Step->Type,
- CK_LValueToRValue, CurInit.get(),
- /*BasePath=*/nullptr, VK_RValue);
+ // C++ [conv.lval]p3:
+ // If T is cv std::nullptr_t, the result is a null pointer constant.
+ CastKind CK =
+ Step->Type->isNullPtrType() ? CK_NullToPointer : CK_LValueToRValue;
+ CurInit =
+ ImplicitCastExpr::Create(S.Context, Step->Type, CK, CurInit.get(),
+ /*BasePath=*/nullptr, VK_RValue);
break;
}
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
index df78b49..cc62cf1 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
@@ -378,7 +378,6 @@
case CK_BitCast:
case CK_AddressSpaceConversion:
case CK_BooleanToSignedIntegral:
- case CK_NullToPointer:
case CK_IntegralToPointer:
case CK_PointerToIntegral: {
SVal V = state->getSVal(Ex, LCtx);
@@ -503,6 +502,12 @@
Bldr.generateNode(CastE, Pred, state);
continue;
}
+ case CK_NullToPointer: {
+ SVal V = svalBuilder.makeNull();
+ state = state->BindExpr(CastE, LCtx, V);
+ Bldr.generateNode(CastE, Pred, state);
+ continue;
+ }
case CK_NullToMemberPointer: {
SVal V = svalBuilder.getMemberPointer(nullptr);
state = state->BindExpr(CastE, LCtx, V);