[cfe-commits] r67870 - in /cfe/trunk: lib/Sema/SemaDeclCXX.cpp lib/Sema/SemaOverload.cpp lib/Sema/SemaOverload.h test/SemaCXX/rval-references.cpp
Sebastian Redl
sebastian.redl at getdesigned.at
Fri Mar 27 14:36:42 PDT 2009
Author: cornedbee
Date: Fri Mar 27 16:36:42 2009
New Revision: 67870
URL: http://llvm.org/viewvc/llvm-project?rev=67870&view=rev
Log:
Better overload resolution for rvalue references.
Modified:
cfe/trunk/lib/Sema/SemaDeclCXX.cpp
cfe/trunk/lib/Sema/SemaOverload.cpp
cfe/trunk/lib/Sema/SemaOverload.h
cfe/trunk/test/SemaCXX/rval-references.cpp
Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=67870&r1=67869&r2=67870&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Fri Mar 27 16:36:42 2009
@@ -1970,6 +1970,18 @@
// -- If the initializer expression
+ // Rvalue references cannot bind to lvalues (N2812).
+ // There is absolutely no situation where they can. In particular, note that
+ // this is ill-formed, even if B has a user-defined conversion to A&&:
+ // B b;
+ // A&& r = b;
+ if (isRValRef && InitLvalue == Expr::LV_Valid) {
+ if (!ICS)
+ Diag(Init->getSourceRange().getBegin(), diag::err_lvalue_to_rvalue_ref)
+ << Init->getSourceRange();
+ return true;
+ }
+
bool BindsDirectly = false;
// -- is an lvalue (but is not a bit-field), and âcv1 T1â is
// reference-compatible with âcv2 T2,â or
@@ -1980,14 +1992,6 @@
RefRelationship >= Ref_Compatible_With_Added_Qualification) {
BindsDirectly = true;
- // Rvalue references cannot bind to lvalues (N2812).
- if (isRValRef) {
- if (!ICS)
- Diag(Init->getSourceRange().getBegin(), diag::err_lvalue_to_rvalue_ref)
- << Init->getSourceRange();
- return true;
- }
-
if (ICS) {
// C++ [over.ics.ref]p1:
// When a parameter of reference type binds directly (8.5.3)
@@ -2004,6 +2008,7 @@
ICS->Standard.ToTypePtr = T1.getAsOpaquePtr();
ICS->Standard.ReferenceBinding = true;
ICS->Standard.DirectBinding = true;
+ ICS->Standard.RRefBinding = false;
// Nothing more to do: the inaccessibility/ambiguity check for
// derived-to-base conversions is suppressed when we're
@@ -2111,7 +2116,8 @@
}
// -- Otherwise, the reference shall be to a non-volatile const
- // type (i.e., cv1 shall be const), or shall be an rvalue reference.
+ // type (i.e., cv1 shall be const), or the reference shall be an
+ // rvalue reference and the initializer expression shall be an rvalue.
if (!isRValRef && T1.getCVRQualifiers() != QualType::Const) {
if (!ICS)
Diag(Init->getSourceRange().getBegin(),
@@ -2140,7 +2146,7 @@
// shall be callable whether or not the copy is actually
// done.
//
- // Note that C++0x [dcl.ref.init]p5 takes away this implementation
+ // Note that C++0x [dcl.init.ref]p5 takes away this implementation
// freedom, so we will always take the first option and never build
// a temporary in this case. FIXME: We will, however, have to check
// for the presence of a copy constructor in C++98/03 mode.
@@ -2154,7 +2160,8 @@
ICS->Standard.FromTypePtr = T2.getAsOpaquePtr();
ICS->Standard.ToTypePtr = T1.getAsOpaquePtr();
ICS->Standard.ReferenceBinding = true;
- ICS->Standard.DirectBinding = false;
+ ICS->Standard.DirectBinding = false;
+ ICS->Standard.RRefBinding = isRValRef;
} else {
// FIXME: Binding to a subobject of the rvalue is going to require
// more AST annotation than this.
@@ -2199,18 +2206,27 @@
// Actually try to convert the initializer to T1.
if (ICS) {
- /// C++ [over.ics.ref]p2:
- ///
- /// When a parameter of reference type is not bound directly to
- /// an argument expression, the conversion sequence is the one
- /// required to convert the argument expression to the
- /// underlying type of the reference according to
- /// 13.3.3.1. Conceptually, this conversion sequence corresponds
- /// to copy-initializing a temporary of the underlying type with
- /// the argument expression. Any difference in top-level
- /// cv-qualification is subsumed by the initialization itself
- /// and does not constitute a conversion.
+ // C++ [over.ics.ref]p2:
+ //
+ // When a parameter of reference type is not bound directly to
+ // an argument expression, the conversion sequence is the one
+ // required to convert the argument expression to the
+ // underlying type of the reference according to
+ // 13.3.3.1. Conceptually, this conversion sequence corresponds
+ // to copy-initializing a temporary of the underlying type with
+ // the argument expression. Any difference in top-level
+ // cv-qualification is subsumed by the initialization itself
+ // and does not constitute a conversion.
*ICS = TryImplicitConversion(Init, T1, SuppressUserConversions);
+ // Of course, that's still a reference binding.
+ if (ICS->ConversionKind == ImplicitConversionSequence::StandardConversion) {
+ ICS->Standard.ReferenceBinding = true;
+ ICS->Standard.RRefBinding = isRValRef;
+ } else if(ICS->ConversionKind ==
+ ImplicitConversionSequence::UserDefinedConversion) {
+ ICS->UserDefined.After.ReferenceBinding = true;
+ ICS->UserDefined.After.RRefBinding = isRValRef;
+ }
return ICS->ConversionKind == ImplicitConversionSequence::BadConversion;
} else {
return PerformImplicitConversion(Init, T1, "initializing");
Modified: cfe/trunk/lib/Sema/SemaOverload.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaOverload.cpp?rev=67870&r1=67869&r2=67870&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaOverload.cpp (original)
+++ cfe/trunk/lib/Sema/SemaOverload.cpp Fri Mar 27 16:36:42 2009
@@ -1584,18 +1584,17 @@
return QualCK;
if (SCS1.ReferenceBinding && SCS2.ReferenceBinding) {
- QualType T1 = QualType::getFromOpaquePtr(SCS1.ToTypePtr);
- QualType T2 = QualType::getFromOpaquePtr(SCS2.ToTypePtr);
// C++0x [over.ics.rank]p3b4:
// -- S1 and S2 are reference bindings (8.5.3) and neither refers to an
// implicit object parameter of a non-static member function declared
// without a ref-qualifier, and S1 binds an rvalue reference to an
// rvalue and S2 binds an lvalue reference.
- // FIXME: We have far too little information for this check. We don't know
- // if the bound object is an rvalue. We don't know if the binding type is
- // an rvalue or lvalue reference. We don't know if we're dealing with the
- // implicit object parameter, or if the member function in this case has
- // a ref qualifier.
+ // FIXME: We don't know if we're dealing with the implicit object parameter,
+ // or if the member function in this case has a ref qualifier.
+ // (Of course, we don't have ref qualifiers yet.)
+ if (SCS1.RRefBinding != SCS2.RRefBinding)
+ return SCS1.RRefBinding ? ImplicitConversionSequence::Better
+ : ImplicitConversionSequence::Worse;
// C++ [over.ics.rank]p3b4:
// -- S1 and S2 are reference bindings (8.5.3), and the types to
@@ -1603,6 +1602,8 @@
// top-level cv-qualifiers, and the type to which the reference
// initialized by S2 refers is more cv-qualified than the type
// to which the reference initialized by S1 refers.
+ QualType T1 = QualType::getFromOpaquePtr(SCS1.ToTypePtr);
+ QualType T2 = QualType::getFromOpaquePtr(SCS2.ToTypePtr);
T1 = Context.getCanonicalType(T1);
T2 = Context.getCanonicalType(T2);
if (T1.getUnqualifiedType() == T2.getUnqualifiedType()) {
Modified: cfe/trunk/lib/Sema/SemaOverload.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaOverload.h?rev=67870&r1=67869&r2=67870&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaOverload.h (original)
+++ cfe/trunk/lib/Sema/SemaOverload.h Fri Mar 27 16:36:42 2009
@@ -114,6 +114,10 @@
/// direct binding (C++ [dcl.init.ref]).
bool DirectBinding : 1;
+ /// RRefBinding - True when this is a reference binding of an rvalue
+ /// reference to an rvalue (C++0x [over.ics.rank]p3b4).
+ bool RRefBinding : 1;
+
/// FromType - The type that this conversion is converting
/// from. This is an opaque pointer that can be translated into a
/// QualType.
Modified: cfe/trunk/test/SemaCXX/rval-references.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/rval-references.cpp?rev=67870&r1=67869&r2=67870&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/rval-references.cpp (original)
+++ cfe/trunk/test/SemaCXX/rval-references.cpp Fri Mar 27 16:36:42 2009
@@ -37,14 +37,15 @@
not_int ni2 = over(ret_irr());
int i4 = over2(i1);
- // not_int ni3 = over2(0); FIXME: this should be well-formed.
+ not_int ni3 = over2(0);
ilr_c1 vilr1 = i1;
ilr_c2 vilr2 = i1;
conv_to_not_int_rvalue cnir;
- not_int &&ni4 = cnir;
+ not_int &&ni4 = cnir; // expected-error {{rvalue reference cannot bind to lvalue}}
not_int &ni5 = cnir; // expected-error{{non-const lvalue reference to type 'struct not_int' cannot be initialized with a value of type 'struct conv_to_not_int_rvalue'}}
+ not_int &&ni6 = conv_to_not_int_rvalue();
try {
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