*sigh* I can't say this is the wrong thing to do—in fact, it's the kind of restriction I usually like—but for the record this breaks OS X's (ancient) libstdc++ implementation of <tr1/unordered_map> when compiling under -std=c++11. I don't think that's such an important configuration, though.
*goes off to unstick internal buildbot* Jordan On Jun 12, 2013, at 19:46 , Richard Smith <[email protected]> wrote: > Author: rsmith > Date: Wed Jun 12 21:46:14 2013 > New Revision: 183883 > > URL: http://llvm.org/viewvc/llvm-project?rev=183883&view=rev > Log: > Implement core issue 903: only integer literals with value 0 and prvalues of > type std::nullptr_t are null pointer constants from C++11 onwards. > > Modified: > cfe/trunk/lib/AST/Expr.cpp > cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp > cfe/trunk/test/SemaCXX/lambda-expressions.cpp > > Modified: cfe/trunk/lib/AST/Expr.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=183883&r1=183882&r2=183883&view=diff > ============================================================================== > --- cfe/trunk/lib/AST/Expr.cpp (original) > +++ cfe/trunk/lib/AST/Expr.cpp Wed Jun 12 21:46:14 2013 > @@ -3024,7 +3024,7 @@ bool Expr::hasNonTrivialCall(ASTContext > Expr::NullPointerConstantKind > Expr::isNullPointerConstant(ASTContext &Ctx, > NullPointerConstantValueDependence NPC) const { > - if (isValueDependent()) { > + if (isValueDependent() && !Ctx.getLangOpts().CPlusPlus11) { > switch (NPC) { > case NPC_NeverValueDependent: > llvm_unreachable("Unexpected value dependent expression!"); > @@ -3085,7 +3085,8 @@ Expr::isNullPointerConstant(ASTContext & > return NPCK_CXX11_nullptr; > > if (const RecordType *UT = getType()->getAsUnionType()) > - if (UT && UT->getDecl()->hasAttr<TransparentUnionAttr>()) > + if (!Ctx.getLangOpts().CPlusPlus11 && > + UT && UT->getDecl()->hasAttr<TransparentUnionAttr>()) > if (const CompoundLiteralExpr *CLE = > dyn_cast<CompoundLiteralExpr>(this)){ > const Expr *InitExpr = CLE->getInitializer(); > if (const InitListExpr *ILE = dyn_cast<InitListExpr>(InitExpr)) > @@ -3096,14 +3097,14 @@ Expr::isNullPointerConstant(ASTContext & > (Ctx.getLangOpts().CPlusPlus && getType()->isEnumeralType())) > return NPCK_NotNull; > > - // If we have an integer constant expression, we need to *evaluate* it and > - // test for the value 0. Don't use the C++11 constant expression semantics > - // for this, for now; once the dust settles on core issue 903, we might > only > - // allow a literal 0 here in C++11 mode. > if (Ctx.getLangOpts().CPlusPlus11) { > - if (!isCXX98IntegralConstantExpr(Ctx)) > - return NPCK_NotNull; > + // C++11 [conv.ptr]p1: A null pointer constant is an integer literal with > + // value zero or a prvalue of type std::nullptr_t. > + const IntegerLiteral *Lit = dyn_cast<IntegerLiteral>(this); > + return (Lit && !Lit->getValue()) ? NPCK_ZeroLiteral : NPCK_NotNull; > } else { > + // If we have an integer constant expression, we need to *evaluate* it > and > + // test for the value 0. > if (!isIntegerConstantExpr(Ctx)) > return NPCK_NotNull; > } > > Modified: cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp?rev=183883&r1=183882&r2=183883&view=diff > ============================================================================== > --- cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp (original) > +++ cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp Wed Jun 12 21:46:14 > 2013 > @@ -769,15 +769,22 @@ static_assert(&ok2 == pok2, ""); > static_assert((Base2*)(Derived*)(Base*)pb1 == pok2, ""); > static_assert((Derived*)(Base*)pb1 == (Derived*)pok2, ""); > > -constexpr Base *nullB = 42 - 6 * 7; // expected-warning {{expression which > evaluates to zero treated as a null pointer constant of type 'Class::Base > *const'}} > +// Core issue 903: we do not perform constant evaluation when checking for a > +// null pointer in C++11. Just check for an integer literal with value 0. > +constexpr Base *nullB = 42 - 6 * 7; // expected-error {{cannot initialize a > variable of type 'Class::Base *const' with an rvalue of type 'int'}} > +constexpr Base *nullB1 = 0; > static_assert((Bottom*)nullB == 0, ""); > static_assert((Derived*)nullB == 0, ""); > static_assert((void*)(Bottom*)nullB == (void*)(Derived*)nullB, ""); > -Base * nullB2 = '\0'; // expected-warning {{expression which evaluates to > zero treated as a null pointer constant of type 'Class::Base *'}} > -Base * nullB3 = (0); > -// We suppress the warning in unevaluated contexts to workaround some gtest > -// behavior. Once this becomes an error this isn't a problem anymore. > -static_assert(nullB == (1 - 1), ""); > +Base *nullB2 = '\0'; // expected-error {{cannot initialize a variable of > type 'Class::Base *' with an rvalue of type 'char'}} > +Base *nullB3 = (0); > +Base *nullB4 = false; // expected-error {{cannot initialize a variable of > type 'Class::Base *' with an rvalue of type 'bool'}} > +Base *nullB5 = ((0ULL)); > +Base *nullB6 = 0.; // expected-error {{cannot initialize a variable of type > 'Class::Base *' with an rvalue of type 'double'}} > +enum Null { kNull }; > +Base *nullB7 = kNull; // expected-error {{cannot initialize a variable of > type 'Class::Base *' with an rvalue of type 'Class::Null'}} > +static_assert(nullB1 == (1 - 1), ""); // expected-error {{comparison between > pointer and integer}} > + > > > namespace ConversionOperators { > > Modified: cfe/trunk/test/SemaCXX/lambda-expressions.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/lambda-expressions.cpp?rev=183883&r1=183882&r2=183883&view=diff > ============================================================================== > --- cfe/trunk/test/SemaCXX/lambda-expressions.cpp (original) > +++ cfe/trunk/test/SemaCXX/lambda-expressions.cpp Wed Jun 12 21:46:14 2013 > @@ -109,27 +109,30 @@ namespace PR12031 { > } > } > > -namespace NullPtr { > +namespace Array { > int &f(int *p); > char &f(...); > void g() { > - int n = 0; > + int n = -1; > [=] { > - char &k = f(n); // not a null pointer constant > + int arr[n]; // VLA > } (); > > - const int m = 0; > - [=] { > - int &k = f(m); // expected-warning{{expression which evaluates to zero > treated as a null pointer constant of type 'int *'}} > + const int m = -1; > + [] { > + int arr[m]; // expected-error{{negative size}} > + } (); > + > + [&] { > + int arr[m]; // expected-error{{negative size}} > } (); > > - [=] () -> bool { > - int &k = f(m); // expected-warning{{expression which evaluates to zero > treated as a null pointer constant of type 'int *'}} > - return &m == 0; > + [=] { > + int arr[m]; // expected-error{{negative size}} > } (); > > [m] { > - int &k = f(m); // expected-warning{{expression which evaluates to zero > treated as a null pointer constant of type 'int *'}} > + int arr[m]; // expected-error{{negative size}} > } (); > } > } > > > _______________________________________________ > cfe-commits mailing list > [email protected] > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
