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PR15884: In the 'taking the address of a temporary' extension, materialize the 

temporary to an lvalue before taking its address. This removes a weird special
case from the AST representation, and allows the constant expression evaluator
to deal with it without (broken) hacks.

llvm-svn: 180866
This commit is contained in:
Richard Smith 2013-05-01 19:00:39 +00:00
parent dc16628c93
commit 9f8400eca4
3 changed files with 19 additions and 8 deletions
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14
clang/lib/AST/ExprConstant.cpp
View File

@ -3215,14 +3215,12 @@ public:
} // end anonymous namespace
/// Evaluate an expression as an lvalue. This can be legitimately called on
/// expressions which are not glvalues, in a few cases:
/// * function designators in C,
/// * "extern void" objects,
/// * temporaries, if building with -Wno-address-of-temporary.
static bool EvaluateLValue(const Expr* E, LValue& Result, EvalInfo &Info) {
assert((E->isGLValue() || E->getType()->isFunctionType() ||
E->getType()->isVoidType() || isa<CXXTemporaryObjectExpr>(E)) &&
"can't evaluate expression as an lvalue");
/// expressions which are not glvalues, in two cases:
/// * function designators in C, and
/// * "extern void" objects
static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info) {
assert(E->isGLValue() || E->getType()->isFunctionType() ||
E->getType()->isVoidType());
return LValueExprEvaluator(Info, Result).Visit(E);
}

3
clang/lib/Sema/SemaExpr.cpp
View File

@ -8306,6 +8306,9 @@ static QualType CheckAddressOfOperand(Sema &S, ExprResult &OrigOp,
<< op->getType() << op->getSourceRange();
if (sfinae)
return QualType();
// Materialize the temporary as an lvalue so that we can take its address.
OrigOp = op = new (S.Context)
MaterializeTemporaryExpr(op->getType(), OrigOp.take(), true);
} else if (isa<ObjCSelectorExpr>(op)) {
return S.Context.getPointerType(op->getType());
} else if (lval == Expr::LV_MemberFunction) {

10
clang/test/SemaCXX/constant-expression-cxx11.cpp
View File

@ -1480,3 +1480,13 @@ namespace ArrayEltInit {
static_assert(b[0].p != &b[9].p, "");
static_assert(b[9].p != &b[0].p, "");
}
namespace PR15884 {
struct S {};
constexpr S f() { return {}; }
constexpr S *p = &f();
// expected-error@-1 {{taking the address of a temporary}}
// expected-error@-2 {{constexpr variable 'p' must be initialized by a constant expression}}
// expected-note@-3 {{pointer to temporary is not a constant expression}}
// expected-note@-4 {{temporary created here}}
}