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DR1213: Ignore implicit conversions when determining if an operand of an 

array subscript expression is an array prvalue.

Also apply DR1213 to vector prvalues for consistency.

llvm-svn: 335779
This commit is contained in:
Richard Smith 2018-06-27 20:29:32 +00:00
parent 1ef49be8b6
commit becac9eb56
2 changed files with 28 additions and 5 deletions
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18
clang/lib/Sema/SemaExpr.cpp
View File

@ -4385,10 +4385,13 @@ Sema::CreateBuiltinArraySubscriptExpr(Expr *Base, SourceLocation LLoc,
// Per C++ core issue 1213, the result is an xvalue if either operand is
// a non-lvalue array, and an lvalue otherwise.
if (getLangOpts().CPlusPlus11 &&
((LHSExp->getType()->isArrayType() && !LHSExp->isLValue()) ||
(RHSExp->getType()->isArrayType() && !RHSExp->isLValue())))
VK = VK_XValue;
if (getLangOpts().CPlusPlus11) {
for (auto *Op : {LHSExp, RHSExp}) {
Op = Op->IgnoreImplicit();
if (Op->getType()->isArrayType() && !Op->isLValue())
VK = VK_XValue;
}
}
// Perform default conversions.
if (!LHSExp->getType()->getAs<VectorType>()) {
@ -4449,6 +4452,13 @@ Sema::CreateBuiltinArraySubscriptExpr(Expr *Base, SourceLocation LLoc,
} else if (const VectorType *VTy = LHSTy->getAs<VectorType>()) {
BaseExpr = LHSExp; // vectors: V[123]
IndexExpr = RHSExp;
// We apply C++ DR1213 to vector subscripting too.
if (getLangOpts().CPlusPlus11 && LHSExp->getValueKind() == VK_RValue) {
ExprResult Materialized = TemporaryMaterializationConversion(LHSExp);
if (Materialized.isInvalid())
return ExprError();
LHSExp = Materialized.get();
}
VK = LHSExp->getValueKind();
if (VK != VK_RValue)
OK = OK_VectorComponent;

15
clang/test/CXX/drs/dr12xx.cpp
View File

@ -3,7 +3,7 @@
// RUN: %clang_cc1 -std=c++14 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
// RUN: %clang_cc1 -std=c++1z %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
namespace dr1213 { // dr1213: 4
namespace dr1213 { // dr1213: 7
#if __cplusplus >= 201103L
using T = int[3];
int &&r = T{}[1];
@ -11,6 +11,19 @@ namespace dr1213 { // dr1213: 4
using T = decltype((T{}));
using U = decltype((T{}[2]));
using U = int &&;
// Same thing but in a case where we consider overloaded operator[].
struct ConvertsToInt {
operator int();
};
struct X { int array[1]; };
using U = decltype(X().array[ConvertsToInt()]);
// We apply the same rule to vector subscripting.
typedef int V4Int __attribute__((__vector_size__(sizeof(int) * 4)));
typedef int EV4Int __attribute__((__ext_vector_type__(4)));
using U = decltype(V4Int()[0]);
using U = decltype(EV4Int()[0]);
#endif
}