Author: rsmith
Date: Sun Aug 27 17:28:14 2017
New Revision: 311867
URL: http://llvm.org/viewvc/llvm-project?rev=311867&view=rev
Log:
[c++2a] P0683R1: Permit default member initializers for bit-fields.
This would be trivial, except that our in-memory and serialized representations
for FieldDecls assumed that this can't happen.
Added:
cfe/trunk/test/PCH/cxx2a-bitfield-init.cpp
cfe/trunk/test/Parser/cxx2a-bitfield-init.cpp
Modified:
cfe/trunk/include/clang/AST/Decl.h
cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
cfe/trunk/lib/AST/Decl.cpp
cfe/trunk/lib/Parse/ParseDeclCXX.cpp
cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
cfe/trunk/lib/Serialization/ASTWriterDecl.cpp
cfe/trunk/test/SemaCXX/member-init.cpp
cfe/trunk/www/cxx_status.html
Modified: cfe/trunk/include/clang/AST/Decl.h
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Decl.h?rev=311867&r1=311866&r2=311867&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Decl.h (original)
+++ cfe/trunk/include/clang/AST/Decl.h Sun Aug 27 17:28:14 2017
@@ -2364,9 +2364,9 @@ public:
/// FieldDecl - An instance of this class is created by Sema::ActOnField to
/// represent a member of a struct/union/class.
class FieldDecl : public DeclaratorDecl, public Mergeable<FieldDecl> {
- // FIXME: This can be packed into the bitfields in Decl.
+ unsigned BitField : 1;
unsigned Mutable : 1;
- mutable unsigned CachedFieldIndex : 31;
+ mutable unsigned CachedFieldIndex : 30;
/// The kinds of value we can store in InitializerOrBitWidth.
///
@@ -2376,7 +2376,7 @@ class FieldDecl : public DeclaratorDecl,
/// If the pointer is null, there's nothing special. Otherwise,
/// this is a bitfield and the pointer is the Expr* storing the
/// bit-width.
- ISK_BitWidthOrNothing = (unsigned) ICIS_NoInit,
+ ISK_NoInit = (unsigned) ICIS_NoInit,
/// The pointer is an (optional due to delayed parsing) Expr*
/// holding the copy-initializer.
@@ -2391,27 +2391,34 @@ class FieldDecl : public DeclaratorDecl,
ISK_CapturedVLAType,
};
- /// \brief Storage for either the bit-width, the in-class
- /// initializer, or the captured variable length array bound.
- ///
- /// We can safely combine these because in-class initializers are
- /// not permitted for bit-fields, and both are exclusive with VLA
- /// captures.
+ /// If this is a bitfield with a default member initializer, this
+ /// structure is used to represent the two expressions.
+ struct InitAndBitWidth {
+ Expr *Init;
+ Expr *BitWidth;
+ };
+
+ /// \brief Storage for either the bit-width, the in-class initializer, or
+ /// both (via InitAndBitWidth), or the captured variable length array bound.
///
/// If the storage kind is ISK_InClassCopyInit or
/// ISK_InClassListInit, but the initializer is null, then this
- /// field has an in-class initializer which has not yet been parsed
+ /// field has an in-class initializer that has not yet been parsed
/// and attached.
+ // FIXME: Tail-allocate this to reduce the size of FieldDecl in the
+ // overwhelmingly common case that we have none of these things.
llvm::PointerIntPair<void *, 2, InitStorageKind> InitStorage;
+
protected:
FieldDecl(Kind DK, DeclContext *DC, SourceLocation StartLoc,
SourceLocation IdLoc, IdentifierInfo *Id,
QualType T, TypeSourceInfo *TInfo, Expr *BW, bool Mutable,
InClassInitStyle InitStyle)
: DeclaratorDecl(DK, DC, IdLoc, Id, T, TInfo, StartLoc),
- Mutable(Mutable), CachedFieldIndex(0),
- InitStorage(BW, (InitStorageKind) InitStyle) {
- assert((!BW || InitStyle == ICIS_NoInit) && "got initializer for
bitfield");
+ BitField(false), Mutable(Mutable), CachedFieldIndex(0),
+ InitStorage(nullptr, (InitStorageKind) InitStyle) {
+ if (BW)
+ setBitWidth(BW);
}
public:
@@ -2431,10 +2438,7 @@ public:
bool isMutable() const { return Mutable; }
/// \brief Determines whether this field is a bitfield.
- bool isBitField() const {
- return InitStorage.getInt() == ISK_BitWidthOrNothing &&
- InitStorage.getPointer() != nullptr;
- }
+ bool isBitField() const { return BitField; }
/// @brief Determines whether this is an unnamed bitfield.
bool isUnnamedBitfield() const { return isBitField() && !getDeclName(); }
@@ -2446,66 +2450,76 @@ public:
bool isAnonymousStructOrUnion() const;
Expr *getBitWidth() const {
- return isBitField()
- ? static_cast<Expr *>(InitStorage.getPointer())
- : nullptr;
+ if (!BitField)
+ return nullptr;
+ void *Ptr = InitStorage.getPointer();
+ if (getInClassInitStyle())
+ return static_cast<InitAndBitWidth*>(Ptr)->BitWidth;
+ return static_cast<Expr*>(Ptr);
}
unsigned getBitWidthValue(const ASTContext &Ctx) const;
/// setBitWidth - Set the bit-field width for this member.
// Note: used by some clients (i.e., do not remove it).
void setBitWidth(Expr *Width) {
- assert(InitStorage.getInt() == ISK_BitWidthOrNothing &&
- InitStorage.getPointer() == nullptr &&
- "bit width, initializer or captured type already set");
- InitStorage.setPointerAndInt(Width, ISK_BitWidthOrNothing);
+ assert(!hasCapturedVLAType() && !BitField &&
+ "bit width or captured type already set");
+ assert(Width && "no bit width specified");
+ InitStorage.setPointer(
+ InitStorage.getInt()
+ ? new (getASTContext())
+ InitAndBitWidth{getInClassInitializer(), Width}
+ : static_cast<void*>(Width));
+ BitField = true;
}
/// removeBitWidth - Remove the bit-field width from this member.
// Note: used by some clients (i.e., do not remove it).
void removeBitWidth() {
assert(isBitField() && "no bitfield width to remove");
- InitStorage.setPointerAndInt(nullptr, ISK_BitWidthOrNothing);
+ InitStorage.setPointer(getInClassInitializer());
+ BitField = false;
}
- /// getInClassInitStyle - Get the kind of (C++11) in-class initializer which
- /// this field has.
+ /// Get the kind of (C++11) default member initializer that this field has.
InClassInitStyle getInClassInitStyle() const {
InitStorageKind storageKind = InitStorage.getInt();
return (storageKind == ISK_CapturedVLAType
? ICIS_NoInit : (InClassInitStyle) storageKind);
}
- /// hasInClassInitializer - Determine whether this member has a C++11
in-class
- /// initializer.
+ /// Determine whether this member has a C++11 default member initializer.
bool hasInClassInitializer() const {
return getInClassInitStyle() != ICIS_NoInit;
}
- /// getInClassInitializer - Get the C++11 in-class initializer for this
- /// member, or null if one has not been set. If a valid declaration has an
- /// in-class initializer, but this returns null, then we have not parsed and
- /// attached it yet.
+ /// Get the C++11 default member initializer for this member, or null if one
+ /// has not been set. If a valid declaration has a default member
initializer,
+ /// but this returns null, then we have not parsed and attached it yet.
Expr *getInClassInitializer() const {
- return hasInClassInitializer()
- ? static_cast<Expr *>(InitStorage.getPointer())
- : nullptr;
+ if (!hasInClassInitializer())
+ return nullptr;
+ void *Ptr = InitStorage.getPointer();
+ if (BitField)
+ return static_cast<InitAndBitWidth*>(Ptr)->Init;
+ return static_cast<Expr*>(Ptr);
}
/// setInClassInitializer - Set the C++11 in-class initializer for this
/// member.
void setInClassInitializer(Expr *Init) {
- assert(hasInClassInitializer() &&
- InitStorage.getPointer() == nullptr &&
- "bit width, initializer or captured type already set");
- InitStorage.setPointer(Init);
+ assert(hasInClassInitializer() && !getInClassInitializer());
+ if (BitField)
+ static_cast<InitAndBitWidth*>(InitStorage.getPointer())->Init = Init;
+ else
+ InitStorage.setPointer(Init);
}
/// removeInClassInitializer - Remove the C++11 in-class initializer from
this
/// member.
void removeInClassInitializer() {
assert(hasInClassInitializer() && "no initializer to remove");
- InitStorage.setPointerAndInt(nullptr, ISK_BitWidthOrNothing);
+ InitStorage.setPointerAndInt(getBitWidth(), ISK_NoInit);
}
/// \brief Determine whether this member captures the variable length array
Modified: cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td?rev=311867&r1=311866&r2=311867&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td Sun Aug 27 17:28:14
2017
@@ -730,8 +730,12 @@ def ext_nonstatic_member_init : ExtWarn<
def warn_cxx98_compat_nonstatic_member_init : Warning<
"in-class initialization of non-static data members is incompatible with
C++98">,
InGroup<CXX98Compat>, DefaultIgnore;
-def err_bitfield_member_init: Error<
- "bit-field member cannot have an in-class initializer">;
+def ext_bitfield_member_init: ExtWarn<
+ "default member initializer for bit-field is a C++2a extension">,
+ InGroup<CXX2a>;
+def warn_cxx17_compat_bitfield_member_init: Warning<
+ "default member initializer for bit-field is incompatible with "
+ "C++ standards before C++2a">, InGroup<CXXPre2aCompat>, DefaultIgnore;
def err_incomplete_array_member_init: Error<
"array bound cannot be deduced from an in-class initializer">;
Modified: cfe/trunk/lib/AST/Decl.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Decl.cpp?rev=311867&r1=311866&r2=311867&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Decl.cpp (original)
+++ cfe/trunk/lib/AST/Decl.cpp Sun Aug 27 17:28:14 2017
@@ -3553,8 +3553,7 @@ bool FieldDecl::isAnonymousStructOrUnion
unsigned FieldDecl::getBitWidthValue(const ASTContext &Ctx) const {
assert(isBitField() && "not a bitfield");
- auto *BitWidth = static_cast<Expr *>(InitStorage.getPointer());
- return BitWidth->EvaluateKnownConstInt(Ctx).getZExtValue();
+ return getBitWidth()->EvaluateKnownConstInt(Ctx).getZExtValue();
}
unsigned FieldDecl::getFieldIndex() const {
@@ -3577,25 +3576,18 @@ unsigned FieldDecl::getFieldIndex() cons
}
SourceRange FieldDecl::getSourceRange() const {
- switch (InitStorage.getInt()) {
- // All three of these cases store an optional Expr*.
- case ISK_BitWidthOrNothing:
- case ISK_InClassCopyInit:
- case ISK_InClassListInit:
- if (const auto *E = static_cast<const Expr *>(InitStorage.getPointer()))
- return SourceRange(getInnerLocStart(), E->getLocEnd());
- // FALLTHROUGH
-
- case ISK_CapturedVLAType:
- return DeclaratorDecl::getSourceRange();
- }
- llvm_unreachable("bad init storage kind");
+ const Expr *FinalExpr = getInClassInitializer();
+ if (!FinalExpr)
+ FinalExpr = getBitWidth();
+ if (FinalExpr)
+ return SourceRange(getInnerLocStart(), FinalExpr->getLocEnd());
+ return DeclaratorDecl::getSourceRange();
}
void FieldDecl::setCapturedVLAType(const VariableArrayType *VLAType) {
assert((getParent()->isLambda() || getParent()->isCapturedRecord()) &&
"capturing type in non-lambda or captured record.");
- assert(InitStorage.getInt() == ISK_BitWidthOrNothing &&
+ assert(InitStorage.getInt() == ISK_NoInit &&
InitStorage.getPointer() == nullptr &&
"bit width, initializer or captured type already set");
InitStorage.setPointerAndInt(const_cast<VariableArrayType *>(VLAType),
Modified: cfe/trunk/lib/Parse/ParseDeclCXX.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseDeclCXX.cpp?rev=311867&r1=311866&r2=311867&view=diff
==============================================================================
--- cfe/trunk/lib/Parse/ParseDeclCXX.cpp (original)
+++ cfe/trunk/lib/Parse/ParseDeclCXX.cpp Sun Aug 27 17:28:14 2017
@@ -2720,10 +2720,7 @@ Parser::ParseCXXClassMemberDeclaration(A
InClassInitStyle HasInClassInit = ICIS_NoInit;
bool HasStaticInitializer = false;
if (Tok.isOneOf(tok::equal, tok::l_brace) && PureSpecLoc.isInvalid()) {
- if (BitfieldSize.get()) {
- Diag(Tok, diag::err_bitfield_member_init);
- SkipUntil(tok::comma, StopAtSemi | StopBeforeMatch);
- } else if (DeclaratorInfo.isDeclarationOfFunction()) {
+ if (DeclaratorInfo.isDeclarationOfFunction()) {
// It's a pure-specifier.
if (!TryConsumePureSpecifier(/*AllowFunctionDefinition*/ false))
// Parse it as an expression so that Sema can diagnose it.
@@ -2734,6 +2731,10 @@ Parser::ParseCXXClassMemberDeclaration(A
DeclSpec::SCS_typedef &&
!DS.isFriendSpecified()) {
// It's a default member initializer.
+ if (BitfieldSize.get())
+ Diag(Tok, getLangOpts().CPlusPlus2a
+ ? diag::warn_cxx17_compat_bitfield_member_init
+ : diag::ext_bitfield_member_init);
HasInClassInit = Tok.is(tok::equal) ? ICIS_CopyInit : ICIS_ListInit;
} else {
HasStaticInitializer = true;
Modified: cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTReaderDecl.cpp?rev=311867&r1=311866&r2=311867&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTReaderDecl.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTReaderDecl.cpp Sun Aug 27 17:28:14 2017
@@ -1219,16 +1219,17 @@ void ASTDeclReader::VisitObjCPropertyImp
void ASTDeclReader::VisitFieldDecl(FieldDecl *FD) {
VisitDeclaratorDecl(FD);
FD->Mutable = Record.readInt();
- if (int BitWidthOrInitializer = Record.readInt()) {
- FD->InitStorage.setInt(
- static_cast<FieldDecl::InitStorageKind>(BitWidthOrInitializer - 1));
- if (FD->InitStorage.getInt() == FieldDecl::ISK_CapturedVLAType) {
- // Read captured variable length array.
- FD->InitStorage.setPointer(Record.readType().getAsOpaquePtr());
- } else {
- FD->InitStorage.setPointer(Record.readExpr());
- }
+
+ if (auto ISK = static_cast<FieldDecl::InitStorageKind>(Record.readInt())) {
+ FD->InitStorage.setInt(ISK);
+ FD->InitStorage.setPointer(ISK == FieldDecl::ISK_CapturedVLAType
+ ? Record.readType().getAsOpaquePtr()
+ : Record.readExpr());
}
+
+ if (auto *BW = Record.readExpr())
+ FD->setBitWidth(BW);
+
if (!FD->getDeclName()) {
if (FieldDecl *Tmpl = ReadDeclAs<FieldDecl>())
Reader.getContext().setInstantiatedFromUnnamedFieldDecl(FD, Tmpl);
Modified: cfe/trunk/lib/Serialization/ASTWriterDecl.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTWriterDecl.cpp?rev=311867&r1=311866&r2=311867&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTWriterDecl.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTWriterDecl.cpp Sun Aug 27 17:28:14 2017
@@ -849,17 +849,16 @@ void ASTDeclWriter::VisitObjCPropertyImp
void ASTDeclWriter::VisitFieldDecl(FieldDecl *D) {
VisitDeclaratorDecl(D);
Record.push_back(D->isMutable());
- if (D->InitStorage.getInt() == FieldDecl::ISK_BitWidthOrNothing &&
- D->InitStorage.getPointer() == nullptr) {
- Record.push_back(0);
- } else if (D->InitStorage.getInt() == FieldDecl::ISK_CapturedVLAType) {
- Record.push_back(D->InitStorage.getInt() + 1);
- Record.AddTypeRef(
- QualType(static_cast<Type *>(D->InitStorage.getPointer()), 0));
- } else {
- Record.push_back(D->InitStorage.getInt() + 1);
- Record.AddStmt(static_cast<Expr *>(D->InitStorage.getPointer()));
- }
+
+ FieldDecl::InitStorageKind ISK = D->InitStorage.getInt();
+ Record.push_back(ISK);
+ if (ISK == FieldDecl::ISK_CapturedVLAType)
+ Record.AddTypeRef(QualType(D->getCapturedVLAType(), 0));
+ else if (ISK)
+ Record.AddStmt(D->getInClassInitializer());
+
+ Record.AddStmt(D->getBitWidth());
+
if (!D->getDeclName())
Record.AddDeclRef(Context.getInstantiatedFromUnnamedFieldDecl(D));
@@ -873,6 +872,7 @@ void ASTDeclWriter::VisitFieldDecl(Field
!D->isModulePrivate() &&
!D->getBitWidth() &&
!D->hasInClassInitializer() &&
+ !D->hasCapturedVLAType() &&
!D->hasExtInfo() &&
!ObjCIvarDecl::classofKind(D->getKind()) &&
!ObjCAtDefsFieldDecl::classofKind(D->getKind()) &&
@@ -1741,7 +1741,7 @@ void ASTWriter::WriteDeclAbbrevs() {
Abv->Add(BitCodeAbbrevOp(0)); // hasExtInfo
// FieldDecl
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
- Abv->Add(BitCodeAbbrevOp(0)); //getBitWidth
+ Abv->Add(BitCodeAbbrevOp(0)); // InitStyle
// Type Source Info
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
@@ -1774,7 +1774,7 @@ void ASTWriter::WriteDeclAbbrevs() {
Abv->Add(BitCodeAbbrevOp(0)); // hasExtInfo
// FieldDecl
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
- Abv->Add(BitCodeAbbrevOp(0)); //getBitWidth
+ Abv->Add(BitCodeAbbrevOp(0)); // InitStyle
// ObjC Ivar
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getAccessControl
Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getSynthesize
Added: cfe/trunk/test/PCH/cxx2a-bitfield-init.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/cxx2a-bitfield-init.cpp?rev=311867&view=auto
==============================================================================
--- cfe/trunk/test/PCH/cxx2a-bitfield-init.cpp (added)
+++ cfe/trunk/test/PCH/cxx2a-bitfield-init.cpp Sun Aug 27 17:28:14 2017
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -std=c++2a -include %s -verify %s
+// RUN: %clang_cc1 -std=c++2a -emit-pch %s -o %t
+// RUN: %clang_cc1 -std=c++2a -include-pch %t -verify %s -DPCH
+
+#ifndef HEADER
+#define HEADER
+
+struct S {
+ unsigned int n : 5 = 49; // expected-warning {{changes value}}
+};
+
+int a;
+template<bool B> struct T {
+ int m : B ? 8 : a = 42;
+};
+
+#else
+
+// expected-error@-5 {{constant expression}} expected-note@-5 {{cannot modify}}
+
+static_assert(S().n == 17);
+static_assert(T<true>().m == 0);
+int q = T<false>().m; // expected-note {{instantiation of}}
+
+#endif
Added: cfe/trunk/test/Parser/cxx2a-bitfield-init.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/cxx2a-bitfield-init.cpp?rev=311867&view=auto
==============================================================================
--- cfe/trunk/test/Parser/cxx2a-bitfield-init.cpp (added)
+++ cfe/trunk/test/Parser/cxx2a-bitfield-init.cpp Sun Aug 27 17:28:14 2017
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -std=c++2a -verify %s
+
+namespace std_example {
+ int a;
+ const int b = 0; // expected-note {{here}}
+ struct S {
+ int x1 : 8 = 42;
+ int x2 : 8 { 42 };
+ int y1 : true ? 8 : a = 42;
+ int y3 : (true ? 8 : b) = 42;
+ int z : 1 || new int { 1 };
+ };
+ static_assert(S{}.x1 == 42);
+ static_assert(S{}.x2 == 42);
+ static_assert(S{}.y1 == 0);
+ static_assert(S{}.y3 == 42);
+ static_assert(S{}.z == 0);
+
+ struct T {
+ int y2 : true ? 8 : b = 42; // expected-error {{cannot assign to variable
'b'}}
+ };
+}
Modified: cfe/trunk/test/SemaCXX/member-init.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/member-init.cpp?rev=311867&r1=311866&r2=311867&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/member-init.cpp (original)
+++ cfe/trunk/test/SemaCXX/member-init.cpp Sun Aug 27 17:28:14 2017
@@ -1,7 +1,7 @@
// RUN: %clang_cc1 -fsyntax-only -fcxx-exceptions -verify -std=c++11 -Wall %s
struct Bitfield {
- int n : 3 = 7; // expected-error {{bit-field member cannot have an in-class
initializer}}
+ int n : 3 = 7; // expected-warning {{C++2a extension}} expected-warning
{{changes value from 7 to -1}}
};
int a;
Modified: cfe/trunk/www/cxx_status.html
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/www/cxx_status.html?rev=311867&r1=311866&r2=311867&view=diff
==============================================================================
--- cfe/trunk/www/cxx_status.html (original)
+++ cfe/trunk/www/cxx_status.html Sun Aug 27 17:28:14 2017
@@ -797,7 +797,7 @@ as the draft C++2a standard evolves.
<tr>
<td>Default member initializers for bit-fields</td>
<td><a href="http://wg21.link/p0683r1";>P0683R1</a></td>
- <td class="none" align="center">No</td>
+ <td class="svn" align="center">SVN</td>
</tr>
<tr>
<td><tt>const&</tt>-qualified pointers to members</td>
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