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llvm / llvm-project / 1e8286467036d8ef1a972de723f805a4981b2692 / . / clang / lib / Sema / SemaDeclCXX.cpp
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//===------ SemaDeclCXX.cpp - Semantic Analysis for C++ Declarations ------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for C++ declarations.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/ASTMutationListener.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/ComparisonCategories.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/TypeLoc.h"
#include "clang/AST/TypeOrdering.h"
#include "clang/Basic/AttributeCommonInfo.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/Specifiers.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/LiteralSupport.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/CXXFieldCollector.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/ParsedTemplate.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/Template.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include <map>
#include <set>
using namespace clang;
//===----------------------------------------------------------------------===//
// CheckDefaultArgumentVisitor
//===----------------------------------------------------------------------===//
namespace {
/// CheckDefaultArgumentVisitor - C++ [dcl.fct.default] Traverses
/// the default argument of a parameter to determine whether it
/// contains any ill-formed subexpressions. For example, this will
/// diagnose the use of local variables or parameters within the
/// default argument expression.
class CheckDefaultArgumentVisitor
: public ConstStmtVisitor<CheckDefaultArgumentVisitor, bool> {
Sema &S;
const Expr *DefaultArg;
public:
CheckDefaultArgumentVisitor(Sema &S, const Expr *DefaultArg)
: S(S), DefaultArg(DefaultArg) {}
bool VisitExpr(const Expr *Node);
bool VisitDeclRefExpr(const DeclRefExpr *DRE);
bool VisitCXXThisExpr(const CXXThisExpr *ThisE);
bool VisitLambdaExpr(const LambdaExpr *Lambda);
bool VisitPseudoObjectExpr(const PseudoObjectExpr *POE);
};
/// VisitExpr - Visit all of the children of this expression.
bool CheckDefaultArgumentVisitor::VisitExpr(const Expr *Node) {
bool IsInvalid = false;
for (const Stmt *SubStmt : Node->children())
IsInvalid |= Visit(SubStmt);
return IsInvalid;
}
/// VisitDeclRefExpr - Visit a reference to a declaration, to
/// determine whether this declaration can be used in the default
/// argument expression.
bool CheckDefaultArgumentVisitor::VisitDeclRefExpr(const DeclRefExpr *DRE) {
const NamedDecl *Decl = DRE->getDecl();
if (const auto *Param = dyn_cast<ParmVarDecl>(Decl)) {
// C++ [dcl.fct.default]p9:
// [...] parameters of a function shall not be used in default
// argument expressions, even if they are not evaluated. [...]
//
// C++17 [dcl.fct.default]p9 (by CWG 2082):
// [...] A parameter shall not appear as a potentially-evaluated
// expression in a default argument. [...]
//
if (DRE->isNonOdrUse() != NOUR_Unevaluated)
return S.Diag(DRE->getBeginLoc(),
diag::err_param_default_argument_references_param)
<< Param->getDeclName() << DefaultArg->getSourceRange();
} else if (const auto *VDecl = dyn_cast<VarDecl>(Decl)) {
// C++ [dcl.fct.default]p7:
// Local variables shall not be used in default argument
// expressions.
//
// C++17 [dcl.fct.default]p7 (by CWG 2082):
// A local variable shall not appear as a potentially-evaluated
// expression in a default argument.
//
// C++20 [dcl.fct.default]p7 (DR as part of P0588R1, see also CWG 2346):
// Note: A local variable cannot be odr-used (6.3) in a default argument.
//
if (VDecl->isLocalVarDecl() && !DRE->isNonOdrUse())
return S.Diag(DRE->getBeginLoc(),
diag::err_param_default_argument_references_local)
<< VDecl->getDeclName() << DefaultArg->getSourceRange();
}
return false;
}
/// VisitCXXThisExpr - Visit a C++ "this" expression.
bool CheckDefaultArgumentVisitor::VisitCXXThisExpr(const CXXThisExpr *ThisE) {
// C++ [dcl.fct.default]p8:
// The keyword this shall not be used in a default argument of a
// member function.
return S.Diag(ThisE->getBeginLoc(),
diag::err_param_default_argument_references_this)
<< ThisE->getSourceRange();
}
bool CheckDefaultArgumentVisitor::VisitPseudoObjectExpr(
const PseudoObjectExpr *POE) {
bool Invalid = false;
for (const Expr *E : POE->semantics()) {
// Look through bindings.
if (const auto *OVE = dyn_cast<OpaqueValueExpr>(E)) {
E = OVE->getSourceExpr();
assert(E && "pseudo-object binding without source expression?");
}
Invalid |= Visit(E);
}
return Invalid;
}
bool CheckDefaultArgumentVisitor::VisitLambdaExpr(const LambdaExpr *Lambda) {
// C++11 [expr.lambda.prim]p13:
// A lambda-expression appearing in a default argument shall not
// implicitly or explicitly capture any entity.
if (Lambda->capture_begin() == Lambda->capture_end())
return false;
return S.Diag(Lambda->getBeginLoc(), diag::err_lambda_capture_default_arg);
}
} // namespace
void
Sema::ImplicitExceptionSpecification::CalledDecl(SourceLocation CallLoc,
const CXXMethodDecl *Method) {
// If we have an MSAny spec already, don't bother.
if (!Method || ComputedEST == EST_MSAny)
return;
const FunctionProtoType *Proto
= Method->getType()->getAs<FunctionProtoType>();
Proto = Self->ResolveExceptionSpec(CallLoc, Proto);
if (!Proto)
return;
ExceptionSpecificationType EST = Proto->getExceptionSpecType();
// If we have a throw-all spec at this point, ignore the function.
if (ComputedEST == EST_None)
return;
if (EST == EST_None && Method->hasAttr<NoThrowAttr>())
EST = EST_BasicNoexcept;
switch (EST) {
case EST_Unparsed:
case EST_Uninstantiated:
case EST_Unevaluated:
llvm_unreachable("should not see unresolved exception specs here");
// If this function can throw any exceptions, make a note of that.
case EST_MSAny:
case EST_None:
// FIXME: Whichever we see last of MSAny and None determines our result.
// We should make a consistent, order-independent choice here.
ClearExceptions();
ComputedEST = EST;
return;
case EST_NoexceptFalse:
ClearExceptions();
ComputedEST = EST_None;
return;
// FIXME: If the call to this decl is using any of its default arguments, we
// need to search them for potentially-throwing calls.
// If this function has a basic noexcept, it doesn't affect the outcome.
case EST_BasicNoexcept:
case EST_NoexceptTrue:
case EST_NoThrow:
return;
// If we're still at noexcept(true) and there's a throw() callee,
// change to that specification.
case EST_DynamicNone:
if (ComputedEST == EST_BasicNoexcept)
ComputedEST = EST_DynamicNone;
return;
case EST_DependentNoexcept:
llvm_unreachable(
"should not generate implicit declarations for dependent cases");
case EST_Dynamic:
break;
}
assert(EST == EST_Dynamic && "EST case not considered earlier.");
assert(ComputedEST != EST_None &&
"Shouldn't collect exceptions when throw-all is guaranteed.");
ComputedEST = EST_Dynamic;
// Record the exceptions in this function's exception specification.
for (const auto &E : Proto->exceptions())
if (ExceptionsSeen.insert(Self->Context.getCanonicalType(E)).second)
Exceptions.push_back(E);
}
void Sema::ImplicitExceptionSpecification::CalledStmt(Stmt *S) {
if (!S || ComputedEST == EST_MSAny)
return;
// FIXME:
//
// C++0x [except.spec]p14:
// [An] implicit exception-specification specifies the type-id T if and
// only if T is allowed by the exception-specification of a function directly
// invoked by f's implicit definition; f shall allow all exceptions if any
// function it directly invokes allows all exceptions, and f shall allow no
// exceptions if every function it directly invokes allows no exceptions.
//
// Note in particular that if an implicit exception-specification is generated
// for a function containing a throw-expression, that specification can still
// be noexcept(true).
//
// Note also that 'directly invoked' is not defined in the standard, and there
// is no indication that we should only consider potentially-evaluated calls.
//
// Ultimately we should implement the intent of the standard: the exception
// specification should be the set of exceptions which can be thrown by the
// implicit definition. For now, we assume that any non-nothrow expression can
// throw any exception.
if (Self->canThrow(S))
ComputedEST = EST_None;
}
ExprResult Sema::ConvertParamDefaultArgument(ParmVarDecl *Param, Expr *Arg,
SourceLocation EqualLoc) {
if (RequireCompleteType(Param->getLocation(), Param->getType(),
diag::err_typecheck_decl_incomplete_type))
return true;
// C++ [dcl.fct.default]p5
// A default argument expression is implicitly converted (clause
// 4) to the parameter type. The default argument expression has
// the same semantic constraints as the initializer expression in
// a declaration of a variable of the parameter type, using the
// copy-initialization semantics (8.5).
InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
Param);
InitializationKind Kind = InitializationKind::CreateCopy(Param->getLocation(),
EqualLoc);
InitializationSequence InitSeq(*this, Entity, Kind, Arg);
ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Arg);
if (Result.isInvalid())
return true;
Arg = Result.getAs<Expr>();
CheckCompletedExpr(Arg, EqualLoc);
Arg = MaybeCreateExprWithCleanups(Arg);
return Arg;
}
void Sema::SetParamDefaultArgument(ParmVarDecl *Param, Expr *Arg,
SourceLocation EqualLoc) {
// Add the default argument to the parameter
Param->setDefaultArg(Arg);
// We have already instantiated this parameter; provide each of the
// instantiations with the uninstantiated default argument.
UnparsedDefaultArgInstantiationsMap::iterator InstPos
= UnparsedDefaultArgInstantiations.find(Param);
if (InstPos != UnparsedDefaultArgInstantiations.end()) {
for (unsigned I = 0, N = InstPos->second.size(); I != N; ++I)
InstPos->second[I]->setUninstantiatedDefaultArg(Arg);
// We're done tracking this parameter's instantiations.
UnparsedDefaultArgInstantiations.erase(InstPos);
}
}
/// ActOnParamDefaultArgument - Check whether the default argument
/// provided for a function parameter is well-formed. If so, attach it
/// to the parameter declaration.
void
Sema::ActOnParamDefaultArgument(Decl *param, SourceLocation EqualLoc,
Expr *DefaultArg) {
if (!param || !DefaultArg)
return;
ParmVarDecl *Param = cast<ParmVarDecl>(param);
UnparsedDefaultArgLocs.erase(Param);
auto Fail = [&] {
Param->setInvalidDecl();
Param->setDefaultArg(new (Context) OpaqueValueExpr(
EqualLoc, Param->getType().getNonReferenceType(), VK_PRValue));
};
// Default arguments are only permitted in C++
if (!getLangOpts().CPlusPlus) {
Diag(EqualLoc, diag::err_param_default_argument)
<< DefaultArg->getSourceRange();
return Fail();
}
// Check for unexpanded parameter packs.
if (DiagnoseUnexpandedParameterPack(DefaultArg, UPPC_DefaultArgument)) {
return Fail();
}
// C++11 [dcl.fct.default]p3
// A default argument expression [...] shall not be specified for a
// parameter pack.
if (Param->isParameterPack()) {
Diag(EqualLoc, diag::err_param_default_argument_on_parameter_pack)
<< DefaultArg->getSourceRange();
// Recover by discarding the default argument.
Param->setDefaultArg(nullptr);
return;
}
ExprResult Result = ConvertParamDefaultArgument(Param, DefaultArg, EqualLoc);
if (Result.isInvalid())
return Fail();
DefaultArg = Result.getAs<Expr>();
// Check that the default argument is well-formed
CheckDefaultArgumentVisitor DefaultArgChecker(*this, DefaultArg);
if (DefaultArgChecker.Visit(DefaultArg))
return Fail();
SetParamDefaultArgument(Param, DefaultArg, EqualLoc);
}
/// ActOnParamUnparsedDefaultArgument - We've seen a default
/// argument for a function parameter, but we can't parse it yet
/// because we're inside a class definition. Note that this default
/// argument will be parsed later.
void Sema::ActOnParamUnparsedDefaultArgument(Decl *param,
SourceLocation EqualLoc,
SourceLocation ArgLoc) {
if (!param)
return;
ParmVarDecl *Param = cast<ParmVarDecl>(param);
Param->setUnparsedDefaultArg();
UnparsedDefaultArgLocs[Param] = ArgLoc;
}
/// ActOnParamDefaultArgumentError - Parsing or semantic analysis of
/// the default argument for the parameter param failed.
void Sema::ActOnParamDefaultArgumentError(Decl *param,
SourceLocation EqualLoc) {
if (!param)
return;
ParmVarDecl *Param = cast<ParmVarDecl>(param);
Param->setInvalidDecl();
UnparsedDefaultArgLocs.erase(Param);
Param->setDefaultArg(new (Context) OpaqueValueExpr(
EqualLoc, Param->getType().getNonReferenceType(), VK_PRValue));
}
/// CheckExtraCXXDefaultArguments - Check for any extra default
/// arguments in the declarator, which is not a function declaration
/// or definition and therefore is not permitted to have default
/// arguments. This routine should be invoked for every declarator
/// that is not a function declaration or definition.
void Sema::CheckExtraCXXDefaultArguments(Declarator &D) {
// C++ [dcl.fct.default]p3
// A default argument expression shall be specified only in the
// parameter-declaration-clause of a function declaration or in a
// template-parameter (14.1). It shall not be specified for a
// parameter pack. If it is specified in a
// parameter-declaration-clause, it shall not occur within a
// declarator or abstract-declarator of a parameter-declaration.
bool MightBeFunction = D.isFunctionDeclarationContext();
for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
DeclaratorChunk &chunk = D.getTypeObject(i);
if (chunk.Kind == DeclaratorChunk::Function) {
if (MightBeFunction) {
// This is a function declaration. It can have default arguments, but
// keep looking in case its return type is a function type with default
// arguments.
MightBeFunction = false;
continue;
}
for (unsigned argIdx = 0, e = chunk.Fun.NumParams; argIdx != e;
++argIdx) {
ParmVarDecl *Param = cast<ParmVarDecl>(chunk.Fun.Params[argIdx].Param);
if (Param->hasUnparsedDefaultArg()) {
std::unique_ptr<CachedTokens> Toks =
std::move(chunk.Fun.Params[argIdx].DefaultArgTokens);
SourceRange SR;
if (Toks->size() > 1)
SR = SourceRange((*Toks)[1].getLocation(),
Toks->back().getLocation());
else
SR = UnparsedDefaultArgLocs[Param];
Diag(Param->getLocation(), diag::err_param_default_argument_nonfunc)
<< SR;
} else if (Param->getDefaultArg()) {
Diag(Param->getLocation(), diag::err_param_default_argument_nonfunc)
<< Param->getDefaultArg()->getSourceRange();
Param->setDefaultArg(nullptr);
}
}
} else if (chunk.Kind != DeclaratorChunk::Paren) {
MightBeFunction = false;
}
}
}
static bool functionDeclHasDefaultArgument(const FunctionDecl *FD) {
return llvm::any_of(FD->parameters(), [](ParmVarDecl *P) {
return P->hasDefaultArg() && !P->hasInheritedDefaultArg();
});
}
/// MergeCXXFunctionDecl - Merge two declarations of the same C++
/// function, once we already know that they have the same
/// type. Subroutine of MergeFunctionDecl. Returns true if there was an
/// error, false otherwise.
bool Sema::MergeCXXFunctionDecl(FunctionDecl *New, FunctionDecl *Old,
Scope *S) {
bool Invalid = false;
// The declaration context corresponding to the scope is the semantic
// parent, unless this is a local function declaration, in which case
// it is that surrounding function.
DeclContext *ScopeDC = New->isLocalExternDecl()
? New->getLexicalDeclContext()
: New->getDeclContext();
// Find the previous declaration for the purpose of default arguments.
FunctionDecl *PrevForDefaultArgs = Old;
for (/**/; PrevForDefaultArgs;
// Don't bother looking back past the latest decl if this is a local
// extern declaration; nothing else could work.
PrevForDefaultArgs = New->isLocalExternDecl()
? nullptr
: PrevForDefaultArgs->getPreviousDecl()) {
// Ignore hidden declarations.
if (!LookupResult::isVisible(*this, PrevForDefaultArgs))
continue;
if (S && !isDeclInScope(PrevForDefaultArgs, ScopeDC, S) &&
!New->isCXXClassMember()) {
// Ignore default arguments of old decl if they are not in
// the same scope and this is not an out-of-line definition of
// a member function.
continue;
}
if (PrevForDefaultArgs->isLocalExternDecl() != New->isLocalExternDecl()) {
// If only one of these is a local function declaration, then they are
// declared in different scopes, even though isDeclInScope may think
// they're in the same scope. (If both are local, the scope check is
// sufficient, and if neither is local, then they are in the same scope.)
continue;
}
// We found the right previous declaration.
break;
}
// C++ [dcl.fct.default]p4:
// For non-template functions, default arguments can be added in
// later declarations of a function in the same
// scope. Declarations in different scopes have completely
// distinct sets of default arguments. That is, declarations in
// inner scopes do not acquire default arguments from
// declarations in outer scopes, and vice versa. In a given
// function declaration, all parameters subsequent to a
// parameter with a default argument shall have default
// arguments supplied in this or previous declarations. A
// default argument shall not be redefined by a later
// declaration (not even to the same value).
//
// C++ [dcl.fct.default]p6:
// Except for member functions of class templates, the default arguments
// in a member function definition that appears outside of the class
// definition are added to the set of default arguments provided by the
// member function declaration in the class definition.
for (unsigned p = 0, NumParams = PrevForDefaultArgs
? PrevForDefaultArgs->getNumParams()
: 0;
p < NumParams; ++p) {
ParmVarDecl *OldParam = PrevForDefaultArgs->getParamDecl(p);
ParmVarDecl *NewParam = New->getParamDecl(p);
bool OldParamHasDfl = OldParam ? OldParam->hasDefaultArg() : false;
bool NewParamHasDfl = NewParam->hasDefaultArg();
if (OldParamHasDfl && NewParamHasDfl) {
unsigned DiagDefaultParamID =
diag::err_param_default_argument_redefinition;
// MSVC accepts that default parameters be redefined for member functions
// of template class. The new default parameter's value is ignored.
Invalid = true;
if (getLangOpts().MicrosoftExt) {
CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(New);
if (MD && MD->getParent()->getDescribedClassTemplate()) {
// Merge the old default argument into the new parameter.
NewParam->setHasInheritedDefaultArg();
if (OldParam->hasUninstantiatedDefaultArg())
NewParam->setUninstantiatedDefaultArg(
OldParam->getUninstantiatedDefaultArg());
else
NewParam->setDefaultArg(OldParam->getInit());
DiagDefaultParamID = diag::ext_param_default_argument_redefinition;
Invalid = false;
}
}
// FIXME: If we knew where the '=' was, we could easily provide a fix-it
// hint here. Alternatively, we could walk the type-source information
// for NewParam to find the last source location in the type... but it
// isn't worth the effort right now. This is the kind of test case that
// is hard to get right:
// int f(int);
// void g(int (*fp)(int) = f);
// void g(int (*fp)(int) = &f);
Diag(NewParam->getLocation(), DiagDefaultParamID)
<< NewParam->getDefaultArgRange();
// Look for the function declaration where the default argument was
// actually written, which may be a declaration prior to Old.
for (auto Older = PrevForDefaultArgs;
OldParam->hasInheritedDefaultArg(); /**/) {
Older = Older->getPreviousDecl();
OldParam = Older->getParamDecl(p);
}
Diag(OldParam->getLocation(), diag::note_previous_definition)
<< OldParam->getDefaultArgRange();
} else if (OldParamHasDfl) {
// Merge the old default argument into the new parameter unless the new
// function is a friend declaration in a template class. In the latter
// case the default arguments will be inherited when the friend
// declaration will be instantiated.
if (New->getFriendObjectKind() == Decl::FOK_None ||
!New->getLexicalDeclContext()->isDependentContext()) {
// It's important to use getInit() here; getDefaultArg()
// strips off any top-level ExprWithCleanups.
NewParam->setHasInheritedDefaultArg();
if (OldParam->hasUnparsedDefaultArg())
NewParam->setUnparsedDefaultArg();
else if (OldParam->hasUninstantiatedDefaultArg())
NewParam->setUninstantiatedDefaultArg(
OldParam->getUninstantiatedDefaultArg());
else
NewParam->setDefaultArg(OldParam->getInit());
}
} else if (NewParamHasDfl) {
if (New->getDescribedFunctionTemplate()) {
// Paragraph 4, quoted above, only applies to non-template functions.
Diag(NewParam->getLocation(),
diag::err_param_default_argument_template_redecl)
<< NewParam->getDefaultArgRange();
Diag(PrevForDefaultArgs->getLocation(),
diag::note_template_prev_declaration)
<< false;
} else if (New->getTemplateSpecializationKind()
!= TSK_ImplicitInstantiation &&
New->getTemplateSpecializationKind() != TSK_Undeclared) {
// C++ [temp.expr.spec]p21:
// Default function arguments shall not be specified in a declaration
// or a definition for one of the following explicit specializations:
// - the explicit specialization of a function template;
// - the explicit specialization of a member function template;
// - the explicit specialization of a member function of a class
// template where the class template specialization to which the
// member function specialization belongs is implicitly
// instantiated.
Diag(NewParam->getLocation(), diag::err_template_spec_default_arg)
<< (New->getTemplateSpecializationKind() ==TSK_ExplicitSpecialization)
<< New->getDeclName()
<< NewParam->getDefaultArgRange();
} else if (New->getDeclContext()->isDependentContext()) {
// C++ [dcl.fct.default]p6 (DR217):
// Default arguments for a member function of a class template shall
// be specified on the initial declaration of the member function
// within the class template.
//
// Reading the tea leaves a bit in DR217 and its reference to DR205
// leads me to the conclusion that one cannot add default function
// arguments for an out-of-line definition of a member function of a
// dependent type.
int WhichKind = 2;
if (CXXRecordDecl *Record
= dyn_cast<CXXRecordDecl>(New->getDeclContext())) {
if (Record->getDescribedClassTemplate())
WhichKind = 0;
else if (isa<ClassTemplatePartialSpecializationDecl>(Record))
WhichKind = 1;
else
WhichKind = 2;
}
Diag(NewParam->getLocation(),
diag::err_param_default_argument_member_template_redecl)
<< WhichKind
<< NewParam->getDefaultArgRange();
}
}
}
// DR1344: If a default argument is added outside a class definition and that
// default argument makes the function a special member function, the program
// is ill-formed. This can only happen for constructors.
if (isa<CXXConstructorDecl>(New) &&
New->getMinRequiredArguments() < Old->getMinRequiredArguments()) {
CXXSpecialMember NewSM = getSpecialMember(cast<CXXMethodDecl>(New)),
OldSM = getSpecialMember(cast<CXXMethodDecl>(Old));
if (NewSM != OldSM) {
ParmVarDecl *NewParam = New->getParamDecl(New->getMinRequiredArguments());
assert(NewParam->hasDefaultArg());
Diag(NewParam->getLocation(), diag::err_default_arg_makes_ctor_special)
<< NewParam->getDefaultArgRange() << NewSM;
Diag(Old->getLocation(), diag::note_previous_declaration);
}
}
const FunctionDecl *Def;
// C++11 [dcl.constexpr]p1: If any declaration of a function or function
// template has a constexpr specifier then all its declarations shall
// contain the constexpr specifier.
if (New->getConstexprKind() != Old->getConstexprKind()) {
Diag(New->getLocation(), diag::err_constexpr_redecl_mismatch)
<< New << static_cast<int>(New->getConstexprKind())
<< static_cast<int>(Old->getConstexprKind());
Diag(Old->getLocation(), diag::note_previous_declaration);
Invalid = true;
} else if (!Old->getMostRecentDecl()->isInlined() && New->isInlined() &&
Old->isDefined(Def) &&
// If a friend function is inlined but does not have 'inline'
// specifier, it is a definition. Do not report attribute conflict
// in this case, redefinition will be diagnosed later.
(New->isInlineSpecified() ||
New->getFriendObjectKind() == Decl::FOK_None)) {
// C++11 [dcl.fcn.spec]p4:
// If the definition of a function appears in a translation unit before its
// first declaration as inline, the program is ill-formed.
Diag(New->getLocation(), diag::err_inline_decl_follows_def) << New;
Diag(Def->getLocation(), diag::note_previous_definition);
Invalid = true;
}
// C++17 [temp.deduct.guide]p3:
// Two deduction guide declarations in the same translation unit
// for the same class template shall not have equivalent
// parameter-declaration-clauses.
if (isa<CXXDeductionGuideDecl>(New) &&
!New->isFunctionTemplateSpecialization() && isVisible(Old)) {
Diag(New->getLocation(), diag::err_deduction_guide_redeclared);
Diag(Old->getLocation(), diag::note_previous_declaration);
}
// C++11 [dcl.fct.default]p4: If a friend declaration specifies a default
// argument expression, that declaration shall be a definition and shall be
// the only declaration of the function or function template in the
// translation unit.
if (Old->getFriendObjectKind() == Decl::FOK_Undeclared &&
functionDeclHasDefaultArgument(Old)) {
Diag(New->getLocation(), diag::err_friend_decl_with_def_arg_redeclared);
Diag(Old->getLocation(), diag::note_previous_declaration);
Invalid = true;
}
// C++11 [temp.friend]p4 (DR329):
// When a function is defined in a friend function declaration in a class
// template, the function is instantiated when the function is odr-used.
// The same restrictions on multiple declarations and definitions that
// apply to non-template function declarations and definitions also apply
// to these implicit definitions.
const FunctionDecl *OldDefinition = nullptr;
if (New->isThisDeclarationInstantiatedFromAFriendDefinition() &&
Old->isDefined(OldDefinition, true))
CheckForFunctionRedefinition(New, OldDefinition);
return Invalid;
}
NamedDecl *
Sema::ActOnDecompositionDeclarator(Scope *S, Declarator &D,
MultiTemplateParamsArg TemplateParamLists) {
assert(D.isDecompositionDeclarator());
const DecompositionDeclarator &Decomp = D.getDecompositionDeclarator();
// The syntax only allows a decomposition declarator as a simple-declaration,
// a for-range-declaration, or a condition in Clang, but we parse it in more
// cases than that.
if (!D.mayHaveDecompositionDeclarator()) {
Diag(Decomp.getLSquareLoc(), diag::err_decomp_decl_context)
<< Decomp.getSourceRange();
return nullptr;
}
if (!TemplateParamLists.empty()) {
// FIXME: There's no rule against this, but there are also no rules that
// would actually make it usable, so we reject it for now.
Diag(TemplateParamLists.front()->getTemplateLoc(),
diag::err_decomp_decl_template);
return nullptr;
}
Diag(Decomp.getLSquareLoc(),
!getLangOpts().CPlusPlus17
? diag::ext_decomp_decl
: D.getContext() == DeclaratorContext::Condition
? diag::ext_decomp_decl_cond
: diag::warn_cxx14_compat_decomp_decl)
<< Decomp.getSourceRange();
// The semantic context is always just the current context.
DeclContext *const DC = CurContext;
// C++17 [dcl.dcl]/8:
// The decl-specifier-seq shall contain only the type-specifier auto
// and cv-qualifiers.
// C++2a [dcl.dcl]/8:
// If decl-specifier-seq contains any decl-specifier other than static,
// thread_local, auto, or cv-qualifiers, the program is ill-formed.
auto &DS = D.getDeclSpec();
{
SmallVector<StringRef, 8> BadSpecifiers;
SmallVector<SourceLocation, 8> BadSpecifierLocs;
SmallVector<StringRef, 8> CPlusPlus20Specifiers;
SmallVector<SourceLocation, 8> CPlusPlus20SpecifierLocs;
if (auto SCS = DS.getStorageClassSpec()) {
if (SCS == DeclSpec::SCS_static) {
CPlusPlus20Specifiers.push_back(DeclSpec::getSpecifierName(SCS));
CPlusPlus20SpecifierLocs.push_back(DS.getStorageClassSpecLoc());
} else {
BadSpecifiers.push_back(DeclSpec::getSpecifierName(SCS));
BadSpecifierLocs.push_back(DS.getStorageClassSpecLoc());
}
}
if (auto TSCS = DS.getThreadStorageClassSpec()) {
CPlusPlus20Specifiers.push_back(DeclSpec::getSpecifierName(TSCS));
CPlusPlus20SpecifierLocs.push_back(DS.getThreadStorageClassSpecLoc());
}
if (DS.hasConstexprSpecifier()) {
BadSpecifiers.push_back(
DeclSpec::getSpecifierName(DS.getConstexprSpecifier()));
BadSpecifierLocs.push_back(DS.getConstexprSpecLoc());
}
if (DS.isInlineSpecified()) {
BadSpecifiers.push_back("inline");
BadSpecifierLocs.push_back(DS.getInlineSpecLoc());
}
if (!BadSpecifiers.empty()) {
auto &&Err = Diag(BadSpecifierLocs.front(), diag::err_decomp_decl_spec);
Err << (int)BadSpecifiers.size()
<< llvm::join(BadSpecifiers.begin(), BadSpecifiers.end(), " ");
// Don't add FixItHints to remove the specifiers; we do still respect
// them when building the underlying variable.
for (auto Loc : BadSpecifierLocs)
Err << SourceRange(Loc, Loc);
} else if (!CPlusPlus20Specifiers.empty()) {
auto &&Warn = Diag(CPlusPlus20SpecifierLocs.front(),
getLangOpts().CPlusPlus20
? diag::warn_cxx17_compat_decomp_decl_spec
: diag::ext_decomp_decl_spec);
Warn << (int)CPlusPlus20Specifiers.size()
<< llvm::join(CPlusPlus20Specifiers.begin(),
CPlusPlus20Specifiers.end(), " ");
for (auto Loc : CPlusPlus20SpecifierLocs)
Warn << SourceRange(Loc, Loc);
}
// We can't recover from it being declared as a typedef.
if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef)
return nullptr;
}
// C++2a [dcl.struct.bind]p1:
// A cv that includes volatile is deprecated
if ((DS.getTypeQualifiers() & DeclSpec::TQ_volatile) &&
getLangOpts().CPlusPlus20)
Diag(DS.getVolatileSpecLoc(),
diag::warn_deprecated_volatile_structured_binding);
TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
QualType R = TInfo->getType();
if (DiagnoseUnexpandedParameterPack(D.getIdentifierLoc(), TInfo,
UPPC_DeclarationType))
D.setInvalidType();
// The syntax only allows a single ref-qualifier prior to the decomposition
// declarator. No other declarator chunks are permitted. Also check the type
// specifier here.
if (DS.getTypeSpecType() != DeclSpec::TST_auto ||
D.hasGroupingParens() || D.getNumTypeObjects() > 1 ||
(D.getNumTypeObjects() == 1 &&
D.getTypeObject(0).Kind != DeclaratorChunk::Reference)) {
Diag(Decomp.getLSquareLoc(),
(D.hasGroupingParens() ||
(D.getNumTypeObjects() &&
D.getTypeObject(0).Kind == DeclaratorChunk::Paren))
? diag::err_decomp_decl_parens
: diag::err_decomp_decl_type)
<< R;
// In most cases, there's no actual problem with an explicitly-specified
// type, but a function type won't work here, and ActOnVariableDeclarator
// shouldn't be called for such a type.
if (R->isFunctionType())
D.setInvalidType();
}
// Build the BindingDecls.
SmallVector<BindingDecl*, 8> Bindings;
// Build the BindingDecls.
for (auto &B : D.getDecompositionDeclarator().bindings()) {
// Check for name conflicts.
DeclarationNameInfo NameInfo(B.Name, B.NameLoc);
LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
ForVisibleRedeclaration);
LookupName(Previous, S,
/*CreateBuiltins*/DC->getRedeclContext()->isTranslationUnit());
// It's not permitted to shadow a template parameter name.
if (Previous.isSingleResult() &&
Previous.getFoundDecl()->isTemplateParameter()) {
DiagnoseTemplateParameterShadow(D.getIdentifierLoc(),
Previous.getFoundDecl());
Previous.clear();
}
auto *BD = BindingDecl::Create(Context, DC, B.NameLoc, B.Name);
// Find the shadowed declaration before filtering for scope.
NamedDecl *ShadowedDecl = D.getCXXScopeSpec().isEmpty()
? getShadowedDeclaration(BD, Previous)
: nullptr;
bool ConsiderLinkage = DC->isFunctionOrMethod() &&
DS.getStorageClassSpec() == DeclSpec::SCS_extern;
FilterLookupForScope(Previous, DC, S, ConsiderLinkage,
/*AllowInlineNamespace*/false);
if (!Previous.empty()) {
auto *Old = Previous.getRepresentativeDecl();
Diag(B.NameLoc, diag::err_redefinition) << B.Name;
Diag(Old->getLocation(), diag::note_previous_definition);
} else if (ShadowedDecl && !D.isRedeclaration()) {
CheckShadow(BD, ShadowedDecl, Previous);
}
PushOnScopeChains(BD, S, true);
Bindings.push_back(BD);
ParsingInitForAutoVars.insert(BD);
}
// There are no prior lookup results for the variable itself, because it
// is unnamed.
DeclarationNameInfo NameInfo((IdentifierInfo *)nullptr,
Decomp.getLSquareLoc());
LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
ForVisibleRedeclaration);
// Build the variable that holds the non-decomposed object.
bool AddToScope = true;
NamedDecl *New =
ActOnVariableDeclarator(S, D, DC, TInfo, Previous,
MultiTemplateParamsArg(), AddToScope, Bindings);
if (AddToScope) {
S->AddDecl(New);
CurContext->addHiddenDecl(New);
}
if (isInOpenMPDeclareTargetContext())
checkDeclIsAllowedInOpenMPTarget(nullptr, New);
return New;
}
static bool checkSimpleDecomposition(
Sema &S, ArrayRef<BindingDecl *> Bindings, ValueDecl *Src,
QualType DecompType, const llvm::APSInt &NumElems, QualType ElemType,
llvm::function_ref<ExprResult(SourceLocation, Expr *, unsigned)> GetInit) {
if ((int64_t)Bindings.size() != NumElems) {
S.Diag(Src->getLocation(), diag::err_decomp_decl_wrong_number_bindings)
<< DecompType << (unsigned)Bindings.size()
<< (unsigned)NumElems.getLimitedValue(UINT_MAX)
<< toString(NumElems, 10) << (NumElems < Bindings.size());
return true;
}
unsigned I = 0;
for (auto *B : Bindings) {
SourceLocation Loc = B->getLocation();
ExprResult E = S.BuildDeclRefExpr(Src, DecompType, VK_LValue, Loc);
if (E.isInvalid())
return true;
E = GetInit(Loc, E.get(), I++);
if (E.isInvalid())
return true;
B->setBinding(ElemType, E.get());
}
return false;
}
static bool checkArrayLikeDecomposition(Sema &S,
ArrayRef<BindingDecl *> Bindings,
ValueDecl *Src, QualType DecompType,
const llvm::APSInt &NumElems,
QualType ElemType) {
return checkSimpleDecomposition(
S, Bindings, Src, DecompType, NumElems, ElemType,
[&](SourceLocation Loc, Expr *Base, unsigned I) -> ExprResult {
ExprResult E = S.ActOnIntegerConstant(Loc, I);
if (E.isInvalid())
return ExprError();
return S.CreateBuiltinArraySubscriptExpr(Base, Loc, E.get(), Loc);
});
}
static bool checkArrayDecomposition(Sema &S, ArrayRef<BindingDecl*> Bindings,
ValueDecl *Src, QualType DecompType,
const ConstantArrayType *CAT) {
return checkArrayLikeDecomposition(S, Bindings, Src, DecompType,
llvm::APSInt(CAT->getSize()),
CAT->getElementType());
}
static bool checkVectorDecomposition(Sema &S, ArrayRef<BindingDecl*> Bindings,
ValueDecl *Src, QualType DecompType,
const VectorType *VT) {
return checkArrayLikeDecomposition(
S, Bindings, Src, DecompType, llvm::APSInt::get(VT->getNumElements()),
S.Context.getQualifiedType(VT->getElementType(),
DecompType.getQualifiers()));
}
static bool checkComplexDecomposition(Sema &S,
ArrayRef<BindingDecl *> Bindings,
ValueDecl *Src, QualType DecompType,
const ComplexType *CT) {
return checkSimpleDecomposition(
S, Bindings, Src, DecompType, llvm::APSInt::get(2),
S.Context.getQualifiedType(CT->getElementType(),
DecompType.getQualifiers()),
[&](SourceLocation Loc, Expr *Base, unsigned I) -> ExprResult {
return S.CreateBuiltinUnaryOp(Loc, I ? UO_Imag : UO_Real, Base);
});
}
static std::string printTemplateArgs(const PrintingPolicy &PrintingPolicy,
TemplateArgumentListInfo &Args,
const TemplateParameterList *Params) {
SmallString<128> SS;
llvm::raw_svector_ostream OS(SS);
bool First = true;
unsigned I = 0;
for (auto &Arg : Args.arguments()) {
if (!First)
OS << ", ";
Arg.getArgument().print(PrintingPolicy, OS,
TemplateParameterList::shouldIncludeTypeForArgument(
PrintingPolicy, Params, I));
First = false;
I++;
}
return std::string(OS.str());
}
static bool lookupStdTypeTraitMember(Sema &S, LookupResult &TraitMemberLookup,
SourceLocation Loc, StringRef Trait,
TemplateArgumentListInfo &Args,
unsigned DiagID) {
auto DiagnoseMissing = [&] {
if (DiagID)
S.Diag(Loc, DiagID) << printTemplateArgs(S.Context.getPrintingPolicy(),
Args, /*Params*/ nullptr);
return true;
};
// FIXME: Factor out duplication with lookupPromiseType in SemaCoroutine.
NamespaceDecl *Std = S.getStdNamespace();
if (!Std)
return DiagnoseMissing();
// Look up the trait itself, within namespace std. We can diagnose various
// problems with this lookup even if we've been asked to not diagnose a
// missing specialization, because this can only fail if the user has been
// declaring their own names in namespace std or we don't support the
// standard library implementation in use.
LookupResult Result(S, &S.PP.getIdentifierTable().get(Trait),
Loc, Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Result, Std))
return DiagnoseMissing();
if (Result.isAmbiguous())
return true;
ClassTemplateDecl *TraitTD = Result.getAsSingle<ClassTemplateDecl>();
if (!TraitTD) {
Result.suppressDiagnostics();
NamedDecl *Found = *Result.begin();
S.Diag(Loc, diag::err_std_type_trait_not_class_template) << Trait;
S.Diag(Found->getLocation(), diag::note_declared_at);
return true;
}
// Build the template-id.
QualType TraitTy = S.CheckTemplateIdType(TemplateName(TraitTD), Loc, Args);
if (TraitTy.isNull())
return true;
if (!S.isCompleteType(Loc, TraitTy)) {
if (DiagID)
S.RequireCompleteType(
Loc, TraitTy, DiagID,
printTemplateArgs(S.Context.getPrintingPolicy(), Args,
TraitTD->getTemplateParameters()));
return true;
}
CXXRecordDecl *RD = TraitTy->getAsCXXRecordDecl();
assert(RD && "specialization of class template is not a class?");
// Look up the member of the trait type.
S.LookupQualifiedName(TraitMemberLookup, RD);
return TraitMemberLookup.isAmbiguous();
}
static TemplateArgumentLoc
getTrivialIntegralTemplateArgument(Sema &S, SourceLocation Loc, QualType T,
uint64_t I) {
TemplateArgument Arg(S.Context, S.Context.MakeIntValue(I, T), T);
return S.getTrivialTemplateArgumentLoc(Arg, T, Loc);
}
static TemplateArgumentLoc
getTrivialTypeTemplateArgument(Sema &S, SourceLocation Loc, QualType T) {
return S.getTrivialTemplateArgumentLoc(TemplateArgument(T), QualType(), Loc);
}
namespace { enum class IsTupleLike { TupleLike, NotTupleLike, Error }; }
static IsTupleLike isTupleLike(Sema &S, SourceLocation Loc, QualType T,
llvm::APSInt &Size) {
EnterExpressionEvaluationContext ContextRAII(
S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
DeclarationName Value = S.PP.getIdentifierInfo("value");
LookupResult R(S, Value, Loc, Sema::LookupOrdinaryName);
// Form template argument list for tuple_size<T>.
TemplateArgumentListInfo Args(Loc, Loc);
Args.addArgument(getTrivialTypeTemplateArgument(S, Loc, T));
// If there's no tuple_size specialization or the lookup of 'value' is empty,
// it's not tuple-like.
if (lookupStdTypeTraitMember(S, R, Loc, "tuple_size", Args, /*DiagID*/ 0) ||
R.empty())
return IsTupleLike::NotTupleLike;
// If we get this far, we've committed to the tuple interpretation, but
// we can still fail if there actually isn't a usable ::value.
struct ICEDiagnoser : Sema::VerifyICEDiagnoser {
LookupResult &R;
TemplateArgumentListInfo &Args;
ICEDiagnoser(LookupResult &R, TemplateArgumentListInfo &Args)
: R(R), Args(Args) {}
Sema::SemaDiagnosticBuilder diagnoseNotICE(Sema &S,
SourceLocation Loc) override {
return S.Diag(Loc, diag::err_decomp_decl_std_tuple_size_not_constant)
<< printTemplateArgs(S.Context.getPrintingPolicy(), Args,
/*Params*/ nullptr);
}
} Diagnoser(R, Args);
ExprResult E =
S.BuildDeclarationNameExpr(CXXScopeSpec(), R, /*NeedsADL*/false);
if (E.isInvalid())
return IsTupleLike::Error;
E = S.VerifyIntegerConstantExpression(E.get(), &Size, Diagnoser);
if (E.isInvalid())
return IsTupleLike::Error;
return IsTupleLike::TupleLike;
}
/// \return std::tuple_element<I, T>::type.
static QualType getTupleLikeElementType(Sema &S, SourceLocation Loc,
unsigned I, QualType T) {
// Form template argument list for tuple_element<I, T>.
TemplateArgumentListInfo Args(Loc, Loc);
Args.addArgument(
getTrivialIntegralTemplateArgument(S, Loc, S.Context.getSizeType(), I));
Args.addArgument(getTrivialTypeTemplateArgument(S, Loc, T));
DeclarationName TypeDN = S.PP.getIdentifierInfo("type");
LookupResult R(S, TypeDN, Loc, Sema::LookupOrdinaryName);
if (lookupStdTypeTraitMember(
S, R, Loc, "tuple_element", Args,
diag::err_decomp_decl_std_tuple_element_not_specialized))
return QualType();
auto *TD = R.getAsSingle<TypeDecl>();
if (!TD) {
R.suppressDiagnostics();
S.Diag(Loc, diag::err_decomp_decl_std_tuple_element_not_specialized)
<< printTemplateArgs(S.Context.getPrintingPolicy(), Args,
/*Params*/ nullptr);
if (!R.empty())
S.Diag(R.getRepresentativeDecl()->getLocation(), diag::note_declared_at);
return QualType();
}
return S.Context.getTypeDeclType(TD);
}
namespace {
struct InitializingBinding {
Sema &S;
InitializingBinding(Sema &S, BindingDecl *BD) : S(S) {
Sema::CodeSynthesisContext Ctx;
Ctx.Kind = Sema::CodeSynthesisContext::InitializingStructuredBinding;
Ctx.PointOfInstantiation = BD->getLocation();
Ctx.Entity = BD;
S.pushCodeSynthesisContext(Ctx);
}
~InitializingBinding() {
S.popCodeSynthesisContext();
}
};
}
static bool checkTupleLikeDecomposition(Sema &S,
ArrayRef<BindingDecl *> Bindings,
VarDecl *Src, QualType DecompType,
const llvm::APSInt &TupleSize) {
if ((int64_t)Bindings.size() != TupleSize) {
S.Diag(Src->getLocation(), diag::err_decomp_decl_wrong_number_bindings)
<< DecompType << (unsigned)Bindings.size()
<< (unsigned)TupleSize.getLimitedValue(UINT_MAX)
<< toString(TupleSize, 10) << (TupleSize < Bindings.size());
return true;
}
if (Bindings.empty())
return false;
DeclarationName GetDN = S.PP.getIdentifierInfo("get");
// [dcl.decomp]p3:
// The unqualified-id get is looked up in the scope of E by class member
// access lookup ...
LookupResult MemberGet(S, GetDN, Src->getLocation(), Sema::LookupMemberName);
bool UseMemberGet = false;
if (S.isCompleteType(Src->getLocation(), DecompType)) {
if (auto *RD = DecompType->getAsCXXRecordDecl())
S.LookupQualifiedName(MemberGet, RD);
if (MemberGet.isAmbiguous())
return true;
// ... and if that finds at least one declaration that is a function
// template whose first template parameter is a non-type parameter ...
for (NamedDecl *D : MemberGet) {
if (FunctionTemplateDecl *FTD =
dyn_cast<FunctionTemplateDecl>(D->getUnderlyingDecl())) {
TemplateParameterList *TPL = FTD->getTemplateParameters();
if (TPL->size() != 0 &&
isa<NonTypeTemplateParmDecl>(TPL->getParam(0))) {
// ... the initializer is e.get<i>().
UseMemberGet = true;
break;
}
}
}
}
unsigned I = 0;
for (auto *B : Bindings) {
InitializingBinding InitContext(S, B);
SourceLocation Loc = B->getLocation();
ExprResult E = S.BuildDeclRefExpr(Src, DecompType, VK_LValue, Loc);
if (E.isInvalid())
return true;
// e is an lvalue if the type of the entity is an lvalue reference and
// an xvalue otherwise
if (!Src->getType()->isLValueReferenceType())
E = ImplicitCastExpr::Create(S.Context, E.get()->getType(), CK_NoOp,
E.get(), nullptr, VK_XValue,
FPOptionsOverride());
TemplateArgumentListInfo Args(Loc, Loc);
Args.addArgument(
getTrivialIntegralTemplateArgument(S, Loc, S.Context.getSizeType(), I));
if (UseMemberGet) {
// if [lookup of member get] finds at least one declaration, the
// initializer is e.get<i-1>().
E = S.BuildMemberReferenceExpr(E.get(), DecompType, Loc, false,
CXXScopeSpec(), SourceLocation(), nullptr,
MemberGet, &Args, nullptr);
if (E.isInvalid())
return true;
E = S.BuildCallExpr(nullptr, E.get(), Loc, None, Loc);
} else {
// Otherwise, the initializer is get<i-1>(e), where get is looked up
// in the associated namespaces.
Expr *Get = UnresolvedLookupExpr::Create(
S.Context, nullptr, NestedNameSpecifierLoc(), SourceLocation(),
DeclarationNameInfo(GetDN, Loc), /*RequiresADL*/true, &Args,
UnresolvedSetIterator(), UnresolvedSetIterator());
Expr *Arg = E.get();
E = S.BuildCallExpr(nullptr, Get, Loc, Arg, Loc);
}
if (E.isInvalid())
return true;
Expr *Init = E.get();
// Given the type T designated by std::tuple_element<i - 1, E>::type,
QualType T = getTupleLikeElementType(S, Loc, I, DecompType);
if (T.isNull())
return true;
// each vi is a variable of type "reference to T" initialized with the
// initializer, where the reference is an lvalue reference if the
// initializer is an lvalue and an rvalue reference otherwise
QualType RefType =
S.BuildReferenceType(T, E.get()->isLValue(), Loc, B->getDeclName());
if (RefType.isNull())
return true;
auto *RefVD = VarDecl::Create(
S.Context, Src->getDeclContext(), Loc, Loc,
B->getDeclName().getAsIdentifierInfo(), RefType,
S.Context.getTrivialTypeSourceInfo(T, Loc), Src->getStorageClass());
RefVD->setLexicalDeclContext(Src->getLexicalDeclContext());
RefVD->setTSCSpec(Src->getTSCSpec());
RefVD->setImplicit();
if (Src->isInlineSpecified())
RefVD->setInlineSpecified();
RefVD->getLexicalDeclContext()->addHiddenDecl(RefVD);
InitializedEntity Entity = InitializedEntity::InitializeBinding(RefVD);
InitializationKind Kind = InitializationKind::CreateCopy(Loc, Loc);
InitializationSequence Seq(S, Entity, Kind, Init);
E = Seq.Perform(S, Entity, Kind, Init);
if (E.isInvalid())
return true;
E = S.ActOnFinishFullExpr(E.get(), Loc, /*DiscardedValue*/ false);
if (E.isInvalid())
return true;
RefVD->setInit(E.get());
S.CheckCompleteVariableDeclaration(RefVD);
E = S.BuildDeclarationNameExpr(CXXScopeSpec(),
DeclarationNameInfo(B->getDeclName(), Loc),
RefVD);
if (E.isInvalid())
return true;
B->setBinding(T, E.get());
I++;
}
return false;
}
/// Find the base class to decompose in a built-in decomposition of a class type.
/// This base class search is, unfortunately, not quite like any other that we
/// perform anywhere else in C++.
static DeclAccessPair findDecomposableBaseClass(Sema &S, SourceLocation Loc,
const CXXRecordDecl *RD,
CXXCastPath &BasePath) {
auto BaseHasFields = [](const CXXBaseSpecifier *Specifier,
CXXBasePath &Path) {
return Specifier->getType()->getAsCXXRecordDecl()->hasDirectFields();
};
const CXXRecordDecl *ClassWithFields = nullptr;
AccessSpecifier AS = AS_public;
if (RD->hasDirectFields())
// [dcl.decomp]p4:
// Otherwise, all of E's non-static data members shall be public direct
// members of E ...
ClassWithFields = RD;
else {
// ... or of ...
CXXBasePaths Paths;
Paths.setOrigin(const_cast<CXXRecordDecl*>(RD));
if (!RD->lookupInBases(BaseHasFields, Paths)) {
// If no classes have fields, just decompose RD itself. (This will work
// if and only if zero bindings were provided.)
return DeclAccessPair::make(const_cast<CXXRecordDecl*>(RD), AS_public);
}
CXXBasePath *BestPath = nullptr;
for (auto &P : Paths) {
if (!BestPath)
BestPath = &P;
else if (!S.Context.hasSameType(P.back().Base->getType(),
BestPath->back().Base->getType())) {
// ... the same ...
S.Diag(Loc, diag::err_decomp_decl_multiple_bases_with_members)
<< false << RD << BestPath->back().Base->getType()
<< P.back().Base->getType();
return DeclAccessPair();
} else if (P.Access < BestPath->Access) {
BestPath = &P;
}
}
// ... unambiguous ...
QualType BaseType = BestPath->back().Base->getType();
if (Paths.isAmbiguous(S.Context.getCanonicalType(BaseType))) {
S.Diag(Loc, diag::err_decomp_decl_ambiguous_base)
<< RD << BaseType << S.getAmbiguousPathsDisplayString(Paths);
return DeclAccessPair();
}
// ... [accessible, implied by other rules] base class of E.
S.CheckBaseClassAccess(Loc, BaseType, S.Context.getRecordType(RD),
*BestPath, diag::err_decomp_decl_inaccessible_base);
AS = BestPath->Access;
ClassWithFields = BaseType->getAsCXXRecordDecl();
S.BuildBasePathArray(Paths, BasePath);
}
// The above search did not check whether the selected class itself has base
// classes with fields, so check that now.
CXXBasePaths Paths;
if (ClassWithFields->lookupInBases(BaseHasFields, Paths)) {
S.Diag(Loc, diag::err_decomp_decl_multiple_bases_with_members)
<< (ClassWithFields == RD) << RD << ClassWithFields
<< Paths.front().back().Base->getType();
return DeclAccessPair();
}
return DeclAccessPair::make(const_cast<CXXRecordDecl*>(ClassWithFields), AS);
}
static bool checkMemberDecomposition(Sema &S, ArrayRef<BindingDecl*> Bindings,
ValueDecl *Src, QualType DecompType,
const CXXRecordDecl *OrigRD) {
if (S.RequireCompleteType(Src->getLocation(), DecompType,
diag::err_incomplete_type))
return true;
CXXCastPath BasePath;
DeclAccessPair BasePair =
findDecomposableBaseClass(S, Src->getLocation(), OrigRD, BasePath);
const CXXRecordDecl *RD = cast_or_null<CXXRecordDecl>(BasePair.getDecl());
if (!RD)
return true;
QualType BaseType = S.Context.getQualifiedType(S.Context.getRecordType(RD),
DecompType.getQualifiers());
auto DiagnoseBadNumberOfBindings = [&]() -> bool {
unsigned NumFields = llvm::count_if(
RD->fields(), [](FieldDecl *FD) { return !FD->isUnnamedBitfield(); });
assert(Bindings.size() != NumFields);
S.Diag(Src->getLocation(), diag::err_decomp_decl_wrong_number_bindings)
<< DecompType << (unsigned)Bindings.size() << NumFields << NumFields
<< (NumFields < Bindings.size());
return true;
};
// all of E's non-static data members shall be [...] well-formed
// when named as e.name in the context of the structured binding,
// E shall not have an anonymous union member, ...
unsigned I = 0;
for (auto *FD : RD->fields()) {
if (FD->isUnnamedBitfield())
continue;
// All the non-static data members are required to be nameable, so they
// must all have names.
if (!FD->getDeclName()) {
if (RD->isLambda()) {
S.Diag(Src->getLocation(), diag::err_decomp_decl_lambda);
S.Diag(RD->getLocation(), diag::note_lambda_decl);
return true;
}
if (FD->isAnonymousStructOrUnion()) {
S.Diag(Src->getLocation(), diag::err_decomp_decl_anon_union_member)
<< DecompType << FD->getType()->isUnionType();
S.Diag(FD->getLocation(), diag::note_declared_at);
return true;
}
// FIXME: Are there any other ways we could have an anonymous member?
}
// We have a real field to bind.
if (I >= Bindings.size())
return DiagnoseBadNumberOfBindings();
auto *B = Bindings[I++];
SourceLocation Loc = B->getLocation();
// The field must be accessible in the context of the structured binding.
// We already checked that the base class is accessible.
// FIXME: Add 'const' to AccessedEntity's classes so we can remove the
// const_cast here.
S.CheckStructuredBindingMemberAccess(
Loc, const_cast<CXXRecordDecl *>(OrigRD),
DeclAccessPair::make(FD, CXXRecordDecl::MergeAccess(
BasePair.getAccess(), FD->getAccess())));
// Initialize the binding to Src.FD.
ExprResult E = S.BuildDeclRefExpr(Src, DecompType, VK_LValue, Loc);
if (E.isInvalid())
return true;
E = S.ImpCastExprToType(E.get(), BaseType, CK_UncheckedDerivedToBase,
VK_LValue, &BasePath);
if (E.isInvalid())
return true;
E = S.BuildFieldReferenceExpr(E.get(), /*IsArrow*/ false, Loc,
CXXScopeSpec(), FD,
DeclAccessPair::make(FD, FD->getAccess()),
DeclarationNameInfo(FD->getDeclName(), Loc));
if (E.isInvalid())
return true;
// If the type of the member is T, the referenced type is cv T, where cv is
// the cv-qualification of the decomposition expression.
//
// FIXME: We resolve a defect here: if the field is mutable, we do not add
// 'const' to the type of the field.
Qualifiers Q = DecompType.getQualifiers();
if (FD->isMutable())
Q.removeConst();
B->setBinding(S.BuildQualifiedType(FD->getType(), Loc, Q), E.get());
}
if (I != Bindings.size())
return DiagnoseBadNumberOfBindings();
return false;
}
void Sema::CheckCompleteDecompositionDeclaration(DecompositionDecl *DD) {
QualType DecompType = DD->getType();
// If the type of the decomposition is dependent, then so is the type of
// each binding.
if (DecompType->isDependentType()) {
for (auto *B : DD->bindings())
B->setType(Context.DependentTy);
return;
}
DecompType = DecompType.getNonReferenceType();
ArrayRef<BindingDecl*> Bindings = DD->bindings();
// C++1z [dcl.decomp]/2:
// If E is an array type [...]
// As an extension, we also support decomposition of built-in complex and
// vector types.
if (auto *CAT = Context.getAsConstantArrayType(DecompType)) {
if (checkArrayDecomposition(*this, Bindings, DD, DecompType, CAT))
DD->setInvalidDecl();
return;
}
if (auto *VT = DecompType->getAs<VectorType>()) {
if (checkVectorDecomposition(*this, Bindings, DD, DecompType, VT))
DD->setInvalidDecl();
return;
}
if (auto *CT = DecompType->getAs<ComplexType>()) {
if (checkComplexDecomposition(*this, Bindings, DD, DecompType, CT))
DD->setInvalidDecl();
return;
}
// C++1z [dcl.decomp]/3:
// if the expression std::tuple_size<E>::value is a well-formed integral
// constant expression, [...]
llvm::APSInt TupleSize(32);
switch (isTupleLike(*this, DD->getLocation(), DecompType, TupleSize)) {
case IsTupleLike::Error:
DD->setInvalidDecl();
return;
case IsTupleLike::TupleLike:
if (checkTupleLikeDecomposition(*this, Bindings, DD, DecompType, TupleSize))
DD->setInvalidDecl();
return;
case IsTupleLike::NotTupleLike:
break;
}
// C++1z [dcl.dcl]/8:
// [E shall be of array or non-union class type]
CXXRecordDecl *RD = DecompType->getAsCXXRecordDecl();
if (!RD || RD->isUnion()) {
Diag(DD->getLocation(), diag::err_decomp_decl_unbindable_type)
<< DD << !RD << DecompType;
DD->setInvalidDecl();
return;
}
// C++1z [dcl.decomp]/4:
// all of E's non-static data members shall be [...] direct members of
// E or of the same unambiguous public base class of E, ...
if (checkMemberDecomposition(*this, Bindings, DD, DecompType, RD))
DD->setInvalidDecl();
}
/// Merge the exception specifications of two variable declarations.
///
/// This is called when there's a redeclaration of a VarDecl. The function
/// checks if the redeclaration might have an exception specification and
/// validates compatibility and merges the specs if necessary.
void Sema::MergeVarDeclExceptionSpecs(VarDecl *New, VarDecl *Old) {
// Shortcut if exceptions are disabled.
if (!getLangOpts().CXXExceptions)
return;
assert(Context.hasSameType(New->getType(), Old->getType()) &&
"Should only be called if types are otherwise the same.");
QualType NewType = New->getType();
QualType OldType = Old->getType();
// We're only interested in pointers and references to functions, as well
// as pointers to member functions.
if (const ReferenceType *R = NewType->getAs<ReferenceType>()) {
NewType = R->getPointeeType();
OldType = OldType->castAs<ReferenceType>()->getPointeeType();
} else if (const PointerType *P = NewType->getAs<PointerType>()) {
NewType = P->getPointeeType();
OldType = OldType->castAs<PointerType>()->getPointeeType();
} else if (const MemberPointerType *M = NewType->getAs<MemberPointerType>()) {
NewType = M->getPointeeType();
OldType = OldType->castAs<MemberPointerType>()->getPointeeType();
}
if (!NewType->isFunctionProtoType())
return;
// There's lots of special cases for functions. For function pointers, system
// libraries are hopefully not as broken so that we don't need these
// workarounds.
if (CheckEquivalentExceptionSpec(
OldType->getAs<FunctionProtoType>(), Old->getLocation(),
NewType->getAs<FunctionProtoType>(), New->getLocation())) {
New->setInvalidDecl();
}
}
/// CheckCXXDefaultArguments - Verify that the default arguments for a
/// function declaration are well-formed according to C++
/// [dcl.fct.default].
void Sema::CheckCXXDefaultArguments(FunctionDecl *FD) {
unsigned NumParams = FD->getNumParams();
unsigned ParamIdx = 0;
// This checking doesn't make sense for explicit specializations; their
// default arguments are determined by the declaration we're specializing,
// not by FD.
if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
return;
if (auto *FTD = FD->getDescribedFunctionTemplate())
if (FTD->isMemberSpecialization())
return;
// Find first parameter with a default argument
for (; ParamIdx < NumParams; ++ParamIdx) {
ParmVarDecl *Param = FD->getParamDecl(ParamIdx);
if (Param->hasDefaultArg())
break;
}
// C++20 [dcl.fct.default]p4:
// In a given function declaration, each parameter subsequent to a parameter
// with a default argument shall have a default argument supplied in this or
// a previous declaration, unless the parameter was expanded from a
// parameter pack, or shall be a function parameter pack.
for (; ParamIdx < NumParams; ++ParamIdx) {
ParmVarDecl *Param = FD->getParamDecl(ParamIdx);
if (!Param->hasDefaultArg() && !Param->isParameterPack() &&
!(CurrentInstantiationScope &&
CurrentInstantiationScope->isLocalPackExpansion(Param))) {
if (Param->isInvalidDecl())
/* We already complained about this parameter. */;
else if (Param->getIdentifier())
Diag(Param->getLocation(),
diag::err_param_default_argument_missing_name)
<< Param->getIdentifier();
else
Diag(Param->getLocation(),
diag::err_param_default_argument_missing);
}
}
}
/// Check that the given type is a literal type. Issue a diagnostic if not,
/// if Kind is Diagnose.
/// \return \c true if a problem has been found (and optionally diagnosed).
template <typename... Ts>
static bool CheckLiteralType(Sema &SemaRef, Sema::CheckConstexprKind Kind,
SourceLocation Loc, QualType T, unsigned DiagID,
Ts &&...DiagArgs) {
if (T->isDependentType())
return false;
switch (Kind) {
case Sema::CheckConstexprKind::Diagnose:
return SemaRef.RequireLiteralType(Loc, T, DiagID,
std::forward<Ts>(DiagArgs)...);
case Sema::CheckConstexprKind::CheckValid:
return !T->isLiteralType(SemaRef.Context);
}
llvm_unreachable("unknown CheckConstexprKind");
}
/// Determine whether a destructor cannot be constexpr due to
static bool CheckConstexprDestructorSubobjects(Sema &SemaRef,
const CXXDestructorDecl *DD,
Sema::CheckConstexprKind Kind) {
auto Check = [&](SourceLocation Loc, QualType T, const FieldDecl *FD) {
const CXXRecordDecl *RD =
T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
if (!RD || RD->hasConstexprDestructor())
return true;
if (Kind == Sema::CheckConstexprKind::Diagnose) {
SemaRef.Diag(DD->getLocation(), diag::err_constexpr_dtor_subobject)
<< static_cast<int>(DD->getConstexprKind()) << !FD
<< (FD ? FD->getDeclName() : DeclarationName()) << T;
SemaRef.Diag(Loc, diag::note_constexpr_dtor_subobject)
<< !FD << (FD ? FD->getDeclName() : DeclarationName()) << T;
}
return false;
};
const CXXRecordDecl *RD = DD->getParent();
for (const CXXBaseSpecifier &B : RD->bases())
if (!Check(B.getBaseTypeLoc(), B.getType(), nullptr))
return false;
for (const FieldDecl *FD : RD->fields())
if (!Check(FD->getLocation(), FD->getType(), FD))
return false;
return true;
}
/// Check whether a function's parameter types are all literal types. If so,
/// return true. If not, produce a suitable diagnostic and return false.
static bool CheckConstexprParameterTypes(Sema &SemaRef,
const FunctionDecl *FD,
Sema::CheckConstexprKind Kind) {
unsigned ArgIndex = 0;
const auto *FT = FD->getType()->castAs<FunctionProtoType>();
for (FunctionProtoType::param_type_iterator i = FT->param_type_begin(),
e = FT->param_type_end();
i != e; ++i, ++ArgIndex) {
const ParmVarDecl *PD = FD->getParamDecl(ArgIndex);
SourceLocation ParamLoc = PD->getLocation();
if (CheckLiteralType(SemaRef, Kind, ParamLoc, *i,
diag::err_constexpr_non_literal_param, ArgIndex + 1,
PD->getSourceRange(), isa<CXXConstructorDecl>(FD),
FD->isConsteval()))
return false;
}
return true;
}
/// Check whether a function's return type is a literal type. If so, return
/// true. If not, produce a suitable diagnostic and return false.
static bool CheckConstexprReturnType(Sema &SemaRef, const FunctionDecl *FD,
Sema::CheckConstexprKind Kind) {
if (CheckLiteralType(SemaRef, Kind, FD->getLocation(), FD->getReturnType(),
diag::err_constexpr_non_literal_return,
FD->isConsteval()))
return false;
return true;
}
/// Get diagnostic %select index for tag kind for
/// record diagnostic message.
/// WARNING: Indexes apply to particular diagnostics only!
///
/// \returns diagnostic %select index.
static unsigned getRecordDiagFromTagKind(TagTypeKind Tag) {
switch (Tag) {
case TTK_Struct: return 0;
case TTK_Interface: return 1;
case TTK_Class: return 2;
default: llvm_unreachable("Invalid tag kind for record diagnostic!");
}
}
static bool CheckConstexprFunctionBody(Sema &SemaRef, const FunctionDecl *Dcl,
Stmt *Body,
Sema::CheckConstexprKind Kind);
// Check whether a function declaration satisfies the requirements of a
// constexpr function definition or a constexpr constructor definition. If so,
// return true. If not, produce appropriate diagnostics (unless asked not to by
// Kind) and return false.
//
// This implements C++11 [dcl.constexpr]p3,4, as amended by DR1360.
bool Sema::CheckConstexprFunctionDefinition(const FunctionDecl *NewFD,
CheckConstexprKind Kind) {
const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(NewFD);
if (MD && MD->isInstance()) {
// C++11 [dcl.constexpr]p4:
// The definition of a constexpr constructor shall satisfy the following
// constraints:
// - the class shall not have any virtual base classes;
//
// FIXME: This only applies to constructors and destructors, not arbitrary
// member functions.
const CXXRecordDecl *RD = MD->getParent();
if (RD->getNumVBases()) {
if (Kind == CheckConstexprKind::CheckValid)
return false;
Diag(NewFD->getLocation(), diag::err_constexpr_virtual_base)
<< isa<CXXConstructorDecl>(NewFD)
<< getRecordDiagFromTagKind(RD->getTagKind()) << RD->getNumVBases();
for (const auto &I : RD->vbases())
Diag(I.getBeginLoc(), diag::note_constexpr_virtual_base_here)
<< I.getSourceRange();
return false;
}
}
if (!isa<CXXConstructorDecl>(NewFD)) {
// C++11 [dcl.constexpr]p3:
// The definition of a constexpr function shall satisfy the following
// constraints:
// - it shall not be virtual; (removed in C++20)
const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(NewFD);
if (Method && Method->isVirtual()) {
if (getLangOpts().CPlusPlus20) {
if (Kind == CheckConstexprKind::Diagnose)
Diag(Method->getLocation(), diag::warn_cxx17_compat_constexpr_virtual);
} else {
if (Kind == CheckConstexprKind::CheckValid)
return false;
Method = Method->getCanonicalDecl();
Diag(Method->getLocation(), diag::err_constexpr_virtual);
// If it's not obvious why this function is virtual, find an overridden
// function which uses the 'virtual' keyword.
const CXXMethodDecl *WrittenVirtual = Method;
while (!WrittenVirtual->isVirtualAsWritten())
WrittenVirtual = *WrittenVirtual->begin_overridden_methods();
if (WrittenVirtual != Method)
Diag(WrittenVirtual->getLocation(),
diag::note_overridden_virtual_function);
return false;
}
}
// - its return type shall be a literal type;
if (!CheckConstexprReturnType(*this, NewFD, Kind))
return false;
}
if (auto *Dtor = dyn_cast<CXXDestructorDecl>(NewFD)) {
// A destructor can be constexpr only if the defaulted destructor could be;
// we don't need to check the members and bases if we already know they all
// have constexpr destructors.
if (!Dtor->getParent()->defaultedDestructorIsConstexpr()) {
if (Kind == CheckConstexprKind::CheckValid)
return false;
if (!CheckConstexprDestructorSubobjects(*this, Dtor, Kind))
return false;
}
}
// - each of its parameter types shall be a literal type;
if (!CheckConstexprParameterTypes(*this, NewFD, Kind))
return false;
Stmt *Body = NewFD->getBody();
assert(Body &&
"CheckConstexprFunctionDefinition called on function with no body");
return CheckConstexprFunctionBody(*this, NewFD, Body, Kind);
}
/// Check the given declaration statement is legal within a constexpr function
/// body. C++11 [dcl.constexpr]p3,p4, and C++1y [dcl.constexpr]p3.
///
/// \return true if the body is OK (maybe only as an extension), false if we
/// have diagnosed a problem.
static bool CheckConstexprDeclStmt(Sema &SemaRef, const FunctionDecl *Dcl,
DeclStmt *DS, SourceLocation &Cxx1yLoc,
Sema::CheckConstexprKind Kind) {
// C++11 [dcl.constexpr]p3 and p4:
// The definition of a constexpr function(p3) or constructor(p4) [...] shall
// contain only
for (const auto *DclIt : DS->decls()) {
switch (DclIt->getKind()) {
case Decl::StaticAssert:
case Decl::Using:
case Decl::UsingShadow:
case Decl::UsingDirective:
case Decl::UnresolvedUsingTypename:
case Decl::UnresolvedUsingValue:
case Decl::UsingEnum:
// - static_assert-declarations
// - using-declarations,
// - using-directives,
// - using-enum-declaration
continue;
case Decl::Typedef:
case Decl::TypeAlias: {
// - typedef declarations and alias-declarations that do not define
// classes or enumerations,
const auto *TN = cast<TypedefNameDecl>(DclIt);
if (TN->getUnderlyingType()->isVariablyModifiedType()) {
// Don't allow variably-modified types in constexpr functions.
if (Kind == Sema::CheckConstexprKind::Diagnose) {
TypeLoc TL = TN->getTypeSourceInfo()->getTypeLoc();
SemaRef.Diag(TL.getBeginLoc(), diag::err_constexpr_vla)
<< TL.getSourceRange() << TL.getType()
<< isa<CXXConstructorDecl>(Dcl);
}
return false;
}
continue;
}
case Decl::Enum:
case Decl::CXXRecord:
// C++1y allows types to be defined, not just declared.
if (cast<TagDecl>(DclIt)->isThisDeclarationADefinition()) {
if (Kind == Sema::CheckConstexprKind::Diagnose) {
SemaRef.Diag(DS->getBeginLoc(),
SemaRef.getLangOpts().CPlusPlus14
? diag::warn_cxx11_compat_constexpr_type_definition
: diag::ext_constexpr_type_definition)
<< isa<CXXConstructorDecl>(Dcl);
} else if (!SemaRef.getLangOpts().CPlusPlus14) {
return false;
}
}
continue;
case Decl::EnumConstant:
case Decl::IndirectField:
case Decl::ParmVar:
// These can only appear with other declarations which are banned in
// C++11 and permitted in C++1y, so ignore them.
continue;
case Decl::Var:
case Decl::Decomposition: {
// C++1y [dcl.constexpr]p3 allows anything except:
// a definition of a variable of non-literal type or of static or
// thread storage duration or [before C++2a] for which no
// initialization is performed.
const auto *VD = cast<VarDecl>(DclIt);
if (VD->isThisDeclarationADefinition()) {
if (VD->isStaticLocal()) {
if (Kind == Sema::CheckConstexprKind::Diagnose) {
SemaRef.Diag(VD->getLocation(),
diag::err_constexpr_local_var_static)
<< isa<CXXConstructorDecl>(Dcl)
<< (VD->getTLSKind() == VarDecl::TLS_Dynamic);
}
return false;
}
if (CheckLiteralType(SemaRef, Kind, VD->getLocation(), VD->getType(),
diag::err_constexpr_local_var_non_literal_type,
isa<CXXConstructorDecl>(Dcl)))
return false;
if (!VD->getType()->isDependentType() &&
!VD->hasInit() && !VD->isCXXForRangeDecl()) {
if (Kind == Sema::CheckConstexprKind::Diagnose) {
SemaRef.Diag(
VD->getLocation(),
SemaRef.getLangOpts().CPlusPlus20
? diag::warn_cxx17_compat_constexpr_local_var_no_init
: diag::ext_constexpr_local_var_no_init)
<< isa<CXXConstructorDecl>(Dcl);
} else if (!SemaRef.getLangOpts().CPlusPlus20) {
return false;
}
continue;
}
}
if (Kind == Sema::CheckConstexprKind::Diagnose) {
SemaRef.Diag(VD->getLocation(),
SemaRef.getLangOpts().CPlusPlus14
? diag::warn_cxx11_compat_constexpr_local_var
: diag::ext_constexpr_local_var)
<< isa<CXXConstructorDecl>(Dcl);
} else if (!SemaRef.getLangOpts().CPlusPlus14) {
return false;
}
continue;
}
case Decl::NamespaceAlias:
case Decl::Function:
// These are disallowed in C++11 and permitted in C++1y. Allow them
// everywhere as an extension.
if (!Cxx1yLoc.isValid())
Cxx1yLoc = DS->getBeginLoc();
continue;
default:
if (Kind == Sema::CheckConstexprKind::Diagnose) {
SemaRef.Diag(DS->getBeginLoc(), diag::err_constexpr_body_invalid_stmt)
<< isa<CXXConstructorDecl>(Dcl) << Dcl->isConsteval();
}
return false;
}
}
return true;
}
/// Check that the given field is initialized within a constexpr constructor.
///
/// \param Dcl The constexpr constructor being checked.
/// \param Field The field being checked. This may be a member of an anonymous
/// struct or union nested within the class being checked.
/// \param Inits All declarations, including anonymous struct/union members and
/// indirect members, for which any initialization was provided.
/// \param Diagnosed Whether we've emitted the error message yet. Used to attach
/// multiple notes for different members to the same error.
/// \param Kind Whether we're diagnosing a constructor as written or determining
/// whether the formal requirements are satisfied.
/// \return \c false if we're checking for validity and the constructor does
/// not satisfy the requirements on a constexpr constructor.
static bool CheckConstexprCtorInitializer(Sema &SemaRef,
const FunctionDecl *Dcl,
FieldDecl *Field,
llvm::SmallSet<Decl*, 16> &Inits,
bool &Diagnosed,
Sema::CheckConstexprKind Kind) {
// In C++20 onwards, there's nothing to check for validity.
if (Kind == Sema::CheckConstexprKind::CheckValid &&
SemaRef.getLangOpts().CPlusPlus20)
return true;
if (Field->isInvalidDecl())
return true;
if (Field->isUnnamedBitfield())
return true;
// Anonymous unions with no variant members and empty anonymous structs do not
// need to be explicitly initialized. FIXME: Anonymous structs that contain no
// indirect fields don't need initializing.
if (Field->isAnonymousStructOrUnion() &&
(Field->getType()->isUnionType()
? !Field->getType()->getAsCXXRecordDecl()->hasVariantMembers()
: Field->getType()->getAsCXXRecordDecl()->isEmpty()))
return true;
if (!Inits.count(Field)) {
if (Kind == Sema::CheckConstexprKind::Diagnose) {
if (!Diagnosed) {
SemaRef.Diag(Dcl->getLocation(),
SemaRef.getLangOpts().CPlusPlus20
? diag::warn_cxx17_compat_constexpr_ctor_missing_init
: diag::ext_constexpr_ctor_missing_init);
Diagnosed = true;
}
SemaRef.Diag(Field->getLocation(),
diag::note_constexpr_ctor_missing_init);
} else if (!SemaRef.getLangOpts().CPlusPlus20) {
return false;
}
} else if (Field->isAnonymousStructOrUnion()) {
const RecordDecl *RD = Field->getType()->castAs<RecordType>()->getDecl();
for (auto *I : RD->fields())
// If an anonymous union contains an anonymous struct of which any member
// is initialized, all members must be initialized.
if (!RD->isUnion() || Inits.count(I))
if (!CheckConstexprCtorInitializer(SemaRef, Dcl, I, Inits, Diagnosed,
Kind))
return false;
}
return true;
}
/// Check the provided statement is allowed in a constexpr function
/// definition.
static bool
CheckConstexprFunctionStmt(Sema &SemaRef, const FunctionDecl *Dcl, Stmt *S,
SmallVectorImpl<SourceLocation> &ReturnStmts,
SourceLocation &Cxx1yLoc, SourceLocation &Cxx2aLoc,
Sema::CheckConstexprKind Kind) {
// - its function-body shall be [...] a compound-statement that contains only
switch (S->getStmtClass()) {
case Stmt::NullStmtClass:
// - null statements,
return true;
case Stmt::DeclStmtClass:
// - static_assert-declarations
// - using-declarations,
// - using-directives,
// - typedef declarations and alias-declarations that do not define
// classes or enumerations,
if (!CheckConstexprDeclStmt(SemaRef, Dcl, cast<DeclStmt>(S), Cxx1yLoc, Kind))
return false;
return true;
case Stmt::ReturnStmtClass:
// - and exactly one return statement;
if (isa<CXXConstructorDecl>(Dcl)) {
// C++1y allows return statements in constexpr constructors.
if (!Cxx1yLoc.isValid())
Cxx1yLoc = S->getBeginLoc();
return true;
}
ReturnStmts.push_back(S->getBeginLoc());
return true;
case Stmt::AttributedStmtClass:
// Attributes on a statement don't affect its formal kind and hence don't
// affect its validity in a constexpr function.
return CheckConstexprFunctionStmt(SemaRef, Dcl,
cast<AttributedStmt>(S)->getSubStmt(),
ReturnStmts, Cxx1yLoc, Cxx2aLoc, Kind);
case Stmt::CompoundStmtClass: {
// C++1y allows compound-statements.
if (!Cxx1yLoc.isValid())
Cxx1yLoc = S->getBeginLoc();
CompoundStmt *CompStmt = cast<CompoundStmt>(S);
for (auto *BodyIt : CompStmt->body()) {
if (!CheckConstexprFunctionStmt(SemaRef, Dcl, BodyIt, ReturnStmts,
Cxx1yLoc, Cxx2aLoc, Kind))
return false;
}
return true;
}
case Stmt::IfStmtClass: {
// C++1y allows if-statements.
if (!Cxx1yLoc.isValid())
Cxx1yLoc = S->getBeginLoc();
IfStmt *If = cast<IfStmt>(S);
if (!CheckConstexprFunctionStmt(SemaRef, Dcl, If->getThen(), ReturnStmts,
Cxx1yLoc, Cxx2aLoc, Kind))
return false;
if (If->getElse() &&
!CheckConstexprFunctionStmt(SemaRef, Dcl, If->getElse(), ReturnStmts,
Cxx1yLoc, Cxx2aLoc, Kind))
return false;
return true;
}
case Stmt::WhileStmtClass:
case Stmt::DoStmtClass:
case Stmt::ForStmtClass:
case Stmt::CXXForRangeStmtClass:
case Stmt::ContinueStmtClass:
// C++1y allows all of these. We don't allow them as extensions in C++11,
// because they don't make sense without variable mutation.
if (!SemaRef.getLangOpts().CPlusPlus14)
break;
if (!Cxx1yLoc.isValid())
Cxx1yLoc = S->getBeginLoc();
for (Stmt *SubStmt : S->children())
if (SubStmt &&
!CheckConstexprFunctionStmt(SemaRef, Dcl, SubStmt, ReturnStmts,
Cxx1yLoc, Cxx2aLoc, Kind))
return false;
return true;
case Stmt::SwitchStmtClass:
case Stmt::CaseStmtClass:
case Stmt::DefaultStmtClass:
case Stmt::BreakStmtClass:
// C++1y allows switch-statements, and since they don't need variable
// mutation, we can reasonably allow them in C++11 as an extension.
if (!Cxx1yLoc.isValid())
Cxx1yLoc = S->getBeginLoc();
for (Stmt *SubStmt : S->children())
if (SubStmt &&
!CheckConstexprFunctionStmt(SemaRef, Dcl, SubStmt, ReturnStmts,
Cxx1yLoc, Cxx2aLoc, Kind))
return false;
return true;
case Stmt::GCCAsmStmtClass:
case Stmt::MSAsmStmtClass:
// C++2a allows inline assembly statements.
case Stmt::CXXTryStmtClass:
if (Cxx2aLoc.isInvalid())
Cxx2aLoc = S->getBeginLoc();
for (Stmt *SubStmt : S->children()) {
if (SubStmt &&
!CheckConstexprFunctionStmt(SemaRef, Dcl, SubStmt, ReturnStmts,
Cxx1yLoc, Cxx2aLoc, Kind))
return false;
}
return true;
case Stmt::CXXCatchStmtClass:
// Do not bother checking the language mode (already covered by the
// try block check).
if (!CheckConstexprFunctionStmt(SemaRef, Dcl,
cast<CXXCatchStmt>(S)->getHandlerBlock(),
ReturnStmts, Cxx1yLoc, Cxx2aLoc, Kind))
return false;
return true;
default:
if (!isa<Expr>(S))
break;
// C++1y allows expression-statements.
if (!Cxx1yLoc.isValid())
Cxx1yLoc = S->getBeginLoc();
return true;
}
if (Kind == Sema::CheckConstexprKind::Diagnose) {
SemaRef.Diag(S->getBeginLoc(), diag::err_constexpr_body_invalid_stmt)
<< isa<CXXConstructorDecl>(Dcl) << Dcl->isConsteval();
}
return false;
}
/// Check the body for the given constexpr function declaration only contains
/// the permitted types of statement. C++11 [dcl.constexpr]p3,p4.
///
/// \return true if the body is OK, false if we have found or diagnosed a
/// problem.
static bool CheckConstexprFunctionBody(Sema &SemaRef, const FunctionDecl *Dcl,
Stmt *Body,
Sema::CheckConstexprKind Kind) {
SmallVector<SourceLocation, 4> ReturnStmts;
if (isa<CXXTryStmt>(Body)) {
// C++11 [dcl.constexpr]p3:
// The definition of a constexpr function shall satisfy the following
// constraints: [...]
// - its function-body shall be = delete, = default, or a
// compound-statement
//
// C++11 [dcl.constexpr]p4:
// In the definition of a constexpr constructor, [...]
// - its function-body shall not be a function-try-block;
//
// This restriction is lifted in C++2a, as long as inner statements also
// apply the general constexpr rules.
switch (Kind) {
case Sema::CheckConstexprKind::CheckValid:
if (!SemaRef.getLangOpts().CPlusPlus20)
return false;
break;
case Sema::CheckConstexprKind::Diagnose:
SemaRef.Diag(Body->getBeginLoc(),
!SemaRef.getLangOpts().CPlusPlus20
? diag::ext_constexpr_function_try_block_cxx20
: diag::warn_cxx17_compat_constexpr_function_try_block)
<< isa<CXXConstructorDecl>(Dcl);
break;
}
}
// - its function-body shall be [...] a compound-statement that contains only
// [... list of cases ...]
//
// Note that walking the children here is enough to properly check for
// CompoundStmt and CXXTryStmt body.
SourceLocation Cxx1yLoc, Cxx2aLoc;
for (Stmt *SubStmt : Body->children()) {
if (SubStmt &&
!CheckConstexprFunctionStmt(SemaRef, Dcl, SubStmt, ReturnStmts,
Cxx1yLoc, Cxx2aLoc, Kind))
return false;
}
if (Kind == Sema::CheckConstexprKind::CheckValid) {
// If this is only valid as an extension, report that we don't satisfy the
// constraints of the current language.
if ((Cxx2aLoc.isValid() && !SemaRef.getLangOpts().CPlusPlus20) ||
(Cxx1yLoc.isValid() && !SemaRef.getLangOpts().CPlusPlus17))
return false;
} else if (Cxx2aLoc.isValid()) {
SemaRef.Diag(Cxx2aLoc,
SemaRef.getLangOpts().CPlusPlus20
? diag::warn_cxx17_compat_constexpr_body_invalid_stmt
: diag::ext_constexpr_body_invalid_stmt_cxx20)
<< isa<CXXConstructorDecl>(Dcl);
} else if (Cxx1yLoc.isValid()) {
SemaRef.Diag(Cxx1yLoc,
SemaRef.getLangOpts().CPlusPlus14
? diag::warn_cxx11_compat_constexpr_body_invalid_stmt
: diag::ext_constexpr_body_invalid_stmt)
<< isa<CXXConstructorDecl>(Dcl);
}
if (const CXXConstructorDecl *Constructor
= dyn_cast<CXXConstructorDecl>(Dcl)) {
const CXXRecordDecl *RD = Constructor->getParent();
// DR1359:
// - every non-variant non-static data member and base class sub-object
// shall be initialized;
// DR1460:
// - if the class is a union having variant members, exactly one of them
// shall be initialized;
if (RD->isUnion()) {
if (Constructor->getNumCtorInitializers() == 0 &&
RD->hasVariantMembers()) {
if (Kind == Sema::CheckConstexprKind::Diagnose) {
SemaRef.Diag(
Dcl->getLocation(),
SemaRef.getLangOpts().CPlusPlus20
? diag::warn_cxx17_compat_constexpr_union_ctor_no_init
: diag::ext_constexpr_union_ctor_no_init);
} else if (!SemaRef.getLangOpts().CPlusPlus20) {
return false;
}
}
} else if (!Constructor->isDependentContext() &&
!Constructor->isDelegatingConstructor()) {
assert(RD->getNumVBases() == 0 && "constexpr ctor with virtual bases");
// Skip detailed checking if we have enough initializers, and we would
// allow at most one initializer per member.
bool AnyAnonStructUnionMembers = false;
unsigned Fields = 0;
for (CXXRecordDecl::field_iterator I = RD->field_begin(),
E = RD->field_end(); I != E; ++I, ++Fields) {
if (I->isAnonymousStructOrUnion()) {
AnyAnonStructUnionMembers = true;
break;
}
}
// DR1460:
// - if the class is a union-like class, but is not a union, for each of
// its anonymous union members having variant members, exactly one of
// them shall be initialized;
if (AnyAnonStructUnionMembers ||
Constructor->getNumCtorInitializers() != RD->getNumBases() + Fields) {
// Check initialization of non-static data members. Base classes are
// always initialized so do not need to be checked. Dependent bases
// might not have initializers in the member initializer list.
llvm::SmallSet<Decl*, 16> Inits;
for (const auto *I: Constructor->inits()) {
if (FieldDecl *FD = I->getMember())
Inits.insert(FD);
else if (IndirectFieldDecl *ID = I->getIndirectMember())
Inits.insert(ID->chain_begin(), ID->chain_end());
}
bool Diagnosed = false;
for (auto *I : RD->fields())
if (!CheckConstexprCtorInitializer(SemaRef, Dcl, I, Inits, Diagnosed,
Kind))
return false;
}
}
} else {
if (ReturnStmts.empty()) {
// C++1y doesn't require constexpr functions to contain a 'return'
// statement. We still do, unless the return type might be void, because
// otherwise if there's no return statement, the function cannot
// be used in a core constant expression.
bool OK = SemaRef.getLangOpts().CPlusPlus14 &&
(Dcl->getReturnType()->isVoidType() ||
Dcl->getReturnType()->isDependentType());
switch (Kind) {
case Sema::CheckConstexprKind::Diagnose:
SemaRef.Diag(Dcl->getLocation(),
OK ? diag::warn_cxx11_compat_constexpr_body_no_return
: diag::err_constexpr_body_no_return)
<< Dcl->isConsteval();
if (!OK)
return false;
break;
case Sema::CheckConstexprKind::CheckValid:
// The formal requirements don't include this rule in C++14, even
// though the "must be able to produce a constant expression" rules
// still imply it in some cases.
if (!SemaRef.getLangOpts().CPlusPlus14)
return false;
break;
}
} else if (ReturnStmts.size() > 1) {
switch (Kind) {
case Sema::CheckConstexprKind::Diagnose:
SemaRef.Diag(
ReturnStmts.back(),
SemaRef.getLangOpts().CPlusPlus14
? diag::warn_cxx11_compat_constexpr_body_multiple_return
: diag::ext_constexpr_body_multiple_return);
for (unsigned I = 0; I < ReturnStmts.size() - 1; ++I)
SemaRef.Diag(ReturnStmts[I],
diag::note_constexpr_body_previous_return);
break;
case Sema::CheckConstexprKind::CheckValid:
if (!SemaRef.getLangOpts().CPlusPlus14)
return false;
break;
}
}
}
// C++11 [dcl.constexpr]p5:
// if no function argument values exist such that the function invocation
// substitution would produce a constant expression, the program is
// ill-formed; no diagnostic required.
// C++11 [dcl.constexpr]p3:
// - every constructor call and implicit conversion used in initializing the
// return value shall be one of those allowed in a constant expression.
// C++11 [dcl.constexpr]p4:
// - every constructor involved in initializing non-static data members and
// base class sub-objects shall be a constexpr constructor.
//
// Note that this rule is distinct from the "requirements for a constexpr
// function", so is not checked in CheckValid mode.
SmallVector<PartialDiagnosticAt, 8> Diags;
if (Kind == Sema::CheckConstexprKind::Diagnose &&
!Expr::isPotentialConstantExpr(Dcl, Diags)) {
SemaRef.Diag(Dcl->getLocation(),
diag::ext_constexpr_function_never_constant_expr)
<< isa<CXXConstructorDecl>(Dcl) << Dcl->isConsteval();
for (size_t I = 0, N = Diags.size(); I != N; ++I)
SemaRef.Diag(Diags[I].first, Diags[I].second);
// Don't return false here: we allow this for compatibility in
// system headers.
}
return true;
}
/// Get the class that is directly named by the current context. This is the
/// class for which an unqualified-id in this scope could name a constructor
/// or destructor.
///
/// If the scope specifier denotes a class, this will be that class.
/// If the scope specifier is empty, this will be the class whose
/// member-specification we are currently within. Otherwise, there
/// is no such class.
CXXRecordDecl *Sema::getCurrentClass(Scope *, const CXXScopeSpec *SS) {
assert(getLangOpts().CPlusPlus && "No class names in C!");
if (SS && SS->isInvalid())
return nullptr;
if (SS && SS->isNotEmpty()) {
DeclContext *DC = computeDeclContext(*SS, true);
return dyn_cast_or_null<CXXRecordDecl>(DC);
}
return dyn_cast_or_null<CXXRecordDecl>(CurContext);
}
/// isCurrentClassName - Determine whether the identifier II is the
/// name of the class type currently being defined. In the case of
/// nested classes, this will only return true if II is the name of
/// the innermost class.
bool Sema::isCurrentClassName(const IdentifierInfo &II, Scope *S,
const CXXScopeSpec *SS) {
CXXRecordDecl *CurDecl = getCurrentClass(S, SS);
return CurDecl && &II == CurDecl->getIdentifier();
}
/// Determine whether the identifier II is a typo for the name of
/// the class type currently being defined. If so, update it to the identifier
/// that should have been used.
bool Sema::isCurrentClassNameTypo(IdentifierInfo *&II, const CXXScopeSpec *SS) {
assert(getLangOpts().CPlusPlus && "No class names in C!");
if (!getLangOpts().SpellChecking)
return false;
CXXRecordDecl *CurDecl;
if (SS && SS->isSet() && !SS->isInvalid()) {
DeclContext *DC = computeDeclContext(*SS, true);
CurDecl = dyn_cast_or_null<CXXRecordDecl>(DC);
} else
CurDecl = dyn_cast_or_null<CXXRecordDecl>(CurContext);
if (CurDecl && CurDecl->getIdentifier() && II != CurDecl->getIdentifier() &&
3 * II->getName().edit_distance(CurDecl->getIdentifier()->getName())
< II->getLength()) {
II = CurDecl->getIdentifier();
return true;
}
return false;
}
/// Determine whether the given class is a base class of the given
/// class, including looking at dependent bases.
static bool findCircularInheritance(const CXXRecordDecl *Class,
const CXXRecordDecl *Current) {
SmallVector<const CXXRecordDecl*, 8> Queue;
Class = Class->getCanonicalDecl();
while (true) {
for (const auto &I : Current->bases()) {
CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
if (!Base)
continue;
Base = Base->getDefinition();
if (!Base)
continue;
if (Base->getCanonicalDecl() == Class)
return true;
Queue.push_back(Base);
}
if (Queue.empty())
return false;
Current = Queue.pop_back_val();
}
return false;
}
/// Check the validity of a C++ base class specifier.
///
/// \returns a new CXXBaseSpecifier if well-formed, emits diagnostics
/// and returns NULL otherwise.
CXXBaseSpecifier *
Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
SourceRange SpecifierRange,
bool Virtual, AccessSpecifier Access,
TypeSourceInfo *TInfo,
SourceLocation EllipsisLoc) {
QualType BaseType = TInfo->getType();
if (BaseType->containsErrors()) {
// Already emitted a diagnostic when parsing the error type.
return nullptr;
}
// C++ [class.union]p1:
// A union shall not have base classes.
if (Class->isUnion()) {
Diag(Class->getLocation(), diag::err_base_clause_on_union)
<< SpecifierRange;
return nullptr;
}
if (EllipsisLoc.isValid() &&
!TInfo->getType()->containsUnexpandedParameterPack()) {
Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
<< TInfo->getTypeLoc().getSourceRange();
EllipsisLoc = SourceLocation();
}
SourceLocation BaseLoc = TInfo->getTypeLoc().getBeginLoc();
if (BaseType->isDependentType()) {
// Make sure that we don't have circular inheritance among our dependent
// bases. For non-dependent bases, the check for completeness below handles
// this.
if (CXXRecordDecl *BaseDecl = BaseType->getAsCXXRecordDecl()) {
if (BaseDecl->getCanonicalDecl() == Class->getCanonicalDecl() ||
((BaseDecl = BaseDecl->getDefinition()) &&
findCircularInheritance(Class, BaseDecl))) {
Diag(BaseLoc, diag::err_circular_inheritance)
<< BaseType << Context.getTypeDeclType(Class);
if (BaseDecl->getCanonicalDecl() != Class->getCanonicalDecl())
Diag(BaseDecl->getLocation(), diag::note_previous_decl)
<< BaseType;
return nullptr;
}
}
// Make sure that we don't make an ill-formed AST where the type of the
// Class is non-dependent and its attached base class specifier is an
// dependent type, which violates invariants in many clang code paths (e.g.
// constexpr evaluator). If this case happens (in errory-recovery mode), we
// explicitly mark the Class decl invalid. The diagnostic was already
// emitted.
if (!Class->getTypeForDecl()->isDependentType())
Class->setInvalidDecl();
return new (Context) CXXBaseSpecifier(SpecifierRange, Virtual,
Class->getTagKind() == TTK_Class,
Access, TInfo, EllipsisLoc);
}
// Base specifiers must be record types.
if (!BaseType->isRecordType()) {
Diag(BaseLoc, diag::err_base_must_be_class) << SpecifierRange;
return nullptr;
}
// C++ [class.union]p1:
// A union shall not be used as a base class.
if (BaseType->isUnionType()) {
Diag(BaseLoc, diag::err_union_as_base_class) << SpecifierRange;
return nullptr;
}
// For the MS ABI, propagate DLL attributes to base class templates.
if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
if (Attr *ClassAttr = getDLLAttr(Class)) {
if (auto *BaseTemplate = dyn_cast_or_null<ClassTemplateSpecializationDecl>(
BaseType->getAsCXXRecordDecl())) {
propagateDLLAttrToBaseClassTemplate(Class, ClassAttr, BaseTemplate,
BaseLoc);
}
}
}
// C++ [class.derived]p2:
// The class-name in a base-specifier shall not be an incompletely
// defined class.
if (RequireCompleteType(BaseLoc, BaseType,
diag::err_incomplete_base_class, SpecifierRange)) {
Class->setInvalidDecl();
return nullptr;
}
// If the base class is polymorphic or isn't empty, the new one is/isn't, too.
RecordDecl *BaseDecl = BaseType->castAs<RecordType>()->getDecl();
assert(BaseDecl && "Record type has no declaration");
BaseDecl = BaseDecl->getDefinition();
assert(BaseDecl && "Base type is not incomplete, but has no definition");
CXXRecordDecl *CXXBaseDecl = cast<CXXRecordDecl>(BaseDecl);
assert(CXXBaseDecl && "Base type is not a C++ type");
// Microsoft docs say:
// "If a base-class has a code_seg attribute, derived classes must have the
// same attribute."
const auto *BaseCSA = CXXBaseDecl->getAttr<CodeSegAttr>();
const auto *DerivedCSA = Class->getAttr<CodeSegAttr>();
if ((DerivedCSA || BaseCSA) &&
(!BaseCSA || !DerivedCSA || BaseCSA->getName() != DerivedCSA->getName())) {
Diag(Class->getLocation(), diag::err_mismatched_code_seg_base);
Diag(CXXBaseDecl->getLocation(), diag::note_base_class_specified_here)
<< CXXBaseDecl;
return nullptr;
}
// A class which contains a flexible array member is not suitable for use as a
// base class:
// - If the layout determines that a base comes before another base,
// the flexible array member would index into the subsequent base.
// - If the layout determines that base comes before the derived class,
// the flexible array member would index into the derived class.
if (CXXBaseDecl->hasFlexibleArrayMember()) {
Diag(BaseLoc, diag::err_base_class_has_flexible_array_member)
<< CXXBaseDecl->getDeclName();
return nullptr;
}
// C++ [class]p3:
// If a class is marked final and it appears as a base-type-specifier in
// base-clause, the program is ill-formed.
if (FinalAttr *FA = CXXBaseDecl->getAttr<FinalAttr>()) {
Diag(BaseLoc, diag::err_class_marked_final_used_as_base)
<< CXXBaseDecl->getDeclName()
<< FA->isSpelledAsSealed();
Diag(CXXBaseDecl->getLocation(), diag::note_entity_declared_at)
<< CXXBaseDecl->getDeclName() << FA->getRange();
return nullptr;
}
if (BaseDecl->isInvalidDecl())
Class->setInvalidDecl();
// Create the base specifier.
return new (Context) CXXBaseSpecifier(SpecifierRange, Virtual,
Class->getTagKind() == TTK_Class,
Access, TInfo, EllipsisLoc);
}
/// ActOnBaseSpecifier - Parsed a base specifier. A base specifier is
/// one entry in the base class list of a class specifier, for
/// example:
/// class foo : public bar, virtual private baz {
/// 'public bar' and 'virtual private baz' are each base-specifiers.
BaseResult
Sema::ActOnBaseSpecifier(Decl *classdecl, SourceRange SpecifierRange,
ParsedAttributes &Attributes,
bool Virtual, AccessSpecifier Access,
ParsedType basetype, SourceLocation BaseLoc,
SourceLocation EllipsisLoc) {
if (!classdecl)
return true;
AdjustDeclIfTemplate(classdecl);
CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(classdecl);
if (!Class)
return true;
// We haven't yet attached the base specifiers.
Class->setIsParsingBaseSpecifiers();
// We do not support any C++11 attributes on base-specifiers yet.
// Diagnose any attributes we see.
for (const ParsedAttr &AL : Attributes) {
if (AL.isInvalid() || AL.getKind() == ParsedAttr::IgnoredAttribute)
continue;
Diag(AL.getLoc(), AL.getKind() == ParsedAttr::UnknownAttribute
? (unsigned)diag::warn_unknown_attribute_ignored
: (unsigned)diag::err_base_specifier_attribute)
<< AL << AL.getRange();
}
TypeSourceInfo *TInfo = nullptr;
GetTypeFromParser(basetype, &TInfo);
if (EllipsisLoc.isInvalid() &&
DiagnoseUnexpandedParameterPack(SpecifierRange.getBegin(), TInfo,
UPPC_BaseType))
return true;
if (CXXBaseSpecifier *BaseSpec = CheckBaseSpecifier(Class, SpecifierRange,
Virtual, Access, TInfo,
EllipsisLoc))
return BaseSpec;
else
Class->setInvalidDecl();
return true;
}
/// Use small set to collect indirect bases. As this is only used
/// locally, there's no need to abstract the small size parameter.
typedef llvm::SmallPtrSet<QualType, 4> IndirectBaseSet;
/// Recursively add the bases of Type. Don't add Type itself.
static void
NoteIndirectBases(ASTContext &Context, IndirectBaseSet &Set,
const QualType &Type)
{
// Even though the incoming type is a base, it might not be
// a class -- it could be a template parm, for instance.
if (auto Rec = Type->getAs<RecordType>()) {
auto Decl = Rec->getAsCXXRecordDecl();
// Iterate over its bases.
for (const auto &BaseSpec : Decl->bases()) {
QualType Base = Context.getCanonicalType(BaseSpec.getType())
.getUnqualifiedType();
if (Set.insert(Base).second)
// If we've not already seen it, recurse.
NoteIndirectBases(Context, Set, Base);
}
}
}
/// Performs the actual work of attaching the given base class
/// specifiers to a C++ class.
bool Sema::AttachBaseSpecifiers(CXXRecordDecl *Class,
MutableArrayRef<CXXBaseSpecifier *> Bases) {
if (Bases.empty())
return false;
// Used to keep track of which base types we have already seen, so
// that we can properly diagnose redundant direct base types. Note
// that the key is always the unqualified canonical type of the base
// class.
std::map<QualType, CXXBaseSpecifier*, QualTypeOrdering> KnownBaseTypes;
// Used to track indirect bases so we can see if a direct base is
// ambiguous.
IndirectBaseSet IndirectBaseTypes;
// Copy non-redundant base specifiers into permanent storage.
unsigned NumGoodBases = 0;
bool Invalid = false;
for (unsigned idx = 0; idx < Bases.size(); ++idx) {
QualType NewBaseType
= Context.getCanonicalType(Bases[idx]->getType());
NewBaseType = NewBaseType.getLocalUnqualifiedType();
CXXBaseSpecifier *&KnownBase = KnownBaseTypes[NewBaseType];
if (KnownBase) {
// C++ [class.mi]p3:
// A class shall not be specified as a direct base class of a
// derived class more than once.
Diag(Bases[idx]->getBeginLoc(), diag::err_duplicate_base_class)
<< KnownBase->getType() << Bases[idx]->getSourceRange();
// Delete the duplicate base class specifier; we're going to
// overwrite its pointer later.
Context.Deallocate(Bases[idx]);
Invalid = true;
} else {
// Okay, add this new base class.
KnownBase = Bases[idx];
Bases[NumGoodBases++] = Bases[idx];
if (NewBaseType->isDependentType())
continue;
// Note this base's direct & indirect bases, if there could be ambiguity.
if (Bases.size() > 1)
NoteIndirectBases(Context, IndirectBaseTypes, NewBaseType);
if