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SemaInit.cpp
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//===--- SemaInit.cpp - Semantic Analysis for Initializers ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for initializers.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Sema/Designator.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/SemaInternal.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
//===----------------------------------------------------------------------===//
// Sema Initialization Checking
//===----------------------------------------------------------------------===//
/// \brief Check whether T is compatible with a wide character type (wchar_t,
/// char16_t or char32_t).
static bool IsWideCharCompatible(QualType T, ASTContext &Context) {
if (Context.typesAreCompatible(Context.getWideCharType(), T))
return true;
if (Context.getLangOpts().CPlusPlus || Context.getLangOpts().C11) {
return Context.typesAreCompatible(Context.Char16Ty, T) ||
Context.typesAreCompatible(Context.Char32Ty, T);
}
return false;
}
enum StringInitFailureKind {
SIF_None,
SIF_NarrowStringIntoWideChar,
SIF_WideStringIntoChar,
SIF_IncompatWideStringIntoWideChar,
SIF_Other
};
/// \brief Check whether the array of type AT can be initialized by the Init
/// expression by means of string initialization. Returns SIF_None if so,
/// otherwise returns a StringInitFailureKind that describes why the
/// initialization would not work.
static StringInitFailureKind IsStringInit(Expr *Init, const ArrayType *AT,
ASTContext &Context) {
if (!isa<ConstantArrayType>(AT) && !isa<IncompleteArrayType>(AT))
return SIF_Other;
// See if this is a string literal or @encode.
Init = Init->IgnoreParens();
// Handle @encode, which is a narrow string.
if (isa<ObjCEncodeExpr>(Init) && AT->getElementType()->isCharType())
return SIF_None;
// Otherwise we can only handle string literals.
StringLiteral *SL = dyn_cast<StringLiteral>(Init);
if (!SL)
return SIF_Other;
const QualType ElemTy =
Context.getCanonicalType(AT->getElementType()).getUnqualifiedType();
switch (SL->getKind()) {
case StringLiteral::Ascii:
case StringLiteral::UTF8:
// char array can be initialized with a narrow string.
// Only allow char x[] = "foo"; not char x[] = L"foo";
if (ElemTy->isCharType())
return SIF_None;
if (IsWideCharCompatible(ElemTy, Context))
return SIF_NarrowStringIntoWideChar;
return SIF_Other;
// C99 6.7.8p15 (with correction from DR343), or C11 6.7.9p15:
// "An array with element type compatible with a qualified or unqualified
// version of wchar_t, char16_t, or char32_t may be initialized by a wide
// string literal with the corresponding encoding prefix (L, u, or U,
// respectively), optionally enclosed in braces.
case StringLiteral::UTF16:
if (Context.typesAreCompatible(Context.Char16Ty, ElemTy))
return SIF_None;
if (ElemTy->isCharType())
return SIF_WideStringIntoChar;
if (IsWideCharCompatible(ElemTy, Context))
return SIF_IncompatWideStringIntoWideChar;
return SIF_Other;
case StringLiteral::UTF32:
if (Context.typesAreCompatible(Context.Char32Ty, ElemTy))
return SIF_None;
if (ElemTy->isCharType())
return SIF_WideStringIntoChar;
if (IsWideCharCompatible(ElemTy, Context))
return SIF_IncompatWideStringIntoWideChar;
return SIF_Other;
case StringLiteral::Wide:
if (Context.typesAreCompatible(Context.getWideCharType(), ElemTy))
return SIF_None;
if (ElemTy->isCharType())
return SIF_WideStringIntoChar;
if (IsWideCharCompatible(ElemTy, Context))
return SIF_IncompatWideStringIntoWideChar;
return SIF_Other;
}
llvm_unreachable("missed a StringLiteral kind?");
}
static StringInitFailureKind IsStringInit(Expr *init, QualType declType,
ASTContext &Context) {
const ArrayType *arrayType = Context.getAsArrayType(declType);
if (!arrayType)
return SIF_Other;
return IsStringInit(init, arrayType, Context);
}
/// Update the type of a string literal, including any surrounding parentheses,
/// to match the type of the object which it is initializing.
static void updateStringLiteralType(Expr *E, QualType Ty) {
while (true) {
E->setType(Ty);
if (isa<StringLiteral>(E) || isa<ObjCEncodeExpr>(E))
break;
else if (ParenExpr *PE = dyn_cast<ParenExpr>(E))
E = PE->getSubExpr();
else if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E))
E = UO->getSubExpr();
else if (GenericSelectionExpr *GSE = dyn_cast<GenericSelectionExpr>(E))
E = GSE->getResultExpr();
else
llvm_unreachable("unexpected expr in string literal init");
}
}
static void CheckStringInit(Expr *Str, QualType &DeclT, const ArrayType *AT,
Sema &S) {
// Get the length of the string as parsed.
auto *ConstantArrayTy =
cast<ConstantArrayType>(Str->getType()->getAsArrayTypeUnsafe());
uint64_t StrLength = ConstantArrayTy->getSize().getZExtValue();
if (const IncompleteArrayType *IAT = dyn_cast<IncompleteArrayType>(AT)) {
// C99 6.7.8p14. We have an array of character type with unknown size
// being initialized to a string literal.
llvm::APInt ConstVal(32, StrLength);
// Return a new array type (C99 6.7.8p22).
DeclT = S.Context.getConstantArrayType(IAT->getElementType(),
ConstVal,
ArrayType::Normal, 0);
updateStringLiteralType(Str, DeclT);
return;
}
const ConstantArrayType *CAT = cast<ConstantArrayType>(AT);
// We have an array of character type with known size. However,
// the size may be smaller or larger than the string we are initializing.
// FIXME: Avoid truncation for 64-bit length strings.
if (S.getLangOpts().CPlusPlus) {
if (StringLiteral *SL = dyn_cast<StringLiteral>(Str->IgnoreParens())) {
// For Pascal strings it's OK to strip off the terminating null character,
// so the example below is valid:
//
// unsigned char a[2] = "\pa";
if (SL->isPascal())
StrLength--;
}
// [dcl.init.string]p2
if (StrLength > CAT->getSize().getZExtValue())
S.Diag(Str->getLocStart(),
diag::err_initializer_string_for_char_array_too_long)
<< Str->getSourceRange();
} else {
// C99 6.7.8p14.
if (StrLength-1 > CAT->getSize().getZExtValue())
S.Diag(Str->getLocStart(),
diag::ext_initializer_string_for_char_array_too_long)
<< Str->getSourceRange();
}
// Set the type to the actual size that we are initializing. If we have
// something like:
// char x[1] = "foo";
// then this will set the string literal's type to char[1].
updateStringLiteralType(Str, DeclT);
}
//===----------------------------------------------------------------------===//
// Semantic checking for initializer lists.
//===----------------------------------------------------------------------===//
namespace {
/// @brief Semantic checking for initializer lists.
///
/// The InitListChecker class contains a set of routines that each
/// handle the initialization of a certain kind of entity, e.g.,
/// arrays, vectors, struct/union types, scalars, etc. The
/// InitListChecker itself performs a recursive walk of the subobject
/// structure of the type to be initialized, while stepping through
/// the initializer list one element at a time. The IList and Index
/// parameters to each of the Check* routines contain the active
/// (syntactic) initializer list and the index into that initializer
/// list that represents the current initializer. Each routine is
/// responsible for moving that Index forward as it consumes elements.
///
/// Each Check* routine also has a StructuredList/StructuredIndex
/// arguments, which contains the current "structured" (semantic)
/// initializer list and the index into that initializer list where we
/// are copying initializers as we map them over to the semantic
/// list. Once we have completed our recursive walk of the subobject
/// structure, we will have constructed a full semantic initializer
/// list.
///
/// C99 designators cause changes in the initializer list traversal,
/// because they make the initialization "jump" into a specific
/// subobject and then continue the initialization from that
/// point. CheckDesignatedInitializer() recursively steps into the
/// designated subobject and manages backing out the recursion to
/// initialize the subobjects after the one designated.
class InitListChecker {
Sema &SemaRef;
bool hadError;
bool VerifyOnly; // no diagnostics, no structure building
bool TreatUnavailableAsInvalid; // Used only in VerifyOnly mode.
llvm::DenseMap<InitListExpr *, InitListExpr *> SyntacticToSemantic;
InitListExpr *FullyStructuredList;
void CheckImplicitInitList(const InitializedEntity &Entity,
InitListExpr *ParentIList, QualType T,
unsigned &Index, InitListExpr *StructuredList,
unsigned &StructuredIndex);
void CheckExplicitInitList(const InitializedEntity &Entity,
InitListExpr *IList, QualType &T,
InitListExpr *StructuredList,
bool TopLevelObject = false);
void CheckListElementTypes(const InitializedEntity &Entity,
InitListExpr *IList, QualType &DeclType,
bool SubobjectIsDesignatorContext,
unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex,
bool TopLevelObject = false);
void CheckSubElementType(const InitializedEntity &Entity,
InitListExpr *IList, QualType ElemType,
unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex);
void CheckComplexType(const InitializedEntity &Entity,
InitListExpr *IList, QualType DeclType,
unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex);
void CheckScalarType(const InitializedEntity &Entity,
InitListExpr *IList, QualType DeclType,
unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex);
void CheckReferenceType(const InitializedEntity &Entity,
InitListExpr *IList, QualType DeclType,
unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex);
void CheckVectorType(const InitializedEntity &Entity,
InitListExpr *IList, QualType DeclType, unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex);
void CheckStructUnionTypes(const InitializedEntity &Entity,
InitListExpr *IList, QualType DeclType,
CXXRecordDecl::base_class_range Bases,
RecordDecl::field_iterator Field,
bool SubobjectIsDesignatorContext, unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex,
bool TopLevelObject = false);
void CheckArrayType(const InitializedEntity &Entity,
InitListExpr *IList, QualType &DeclType,
llvm::APSInt elementIndex,
bool SubobjectIsDesignatorContext, unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex);
bool CheckDesignatedInitializer(const InitializedEntity &Entity,
InitListExpr *IList, DesignatedInitExpr *DIE,
unsigned DesigIdx,
QualType &CurrentObjectType,
RecordDecl::field_iterator *NextField,
llvm::APSInt *NextElementIndex,
unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex,
bool FinishSubobjectInit,
bool TopLevelObject);
InitListExpr *getStructuredSubobjectInit(InitListExpr *IList, unsigned Index,
QualType CurrentObjectType,
InitListExpr *StructuredList,
unsigned StructuredIndex,
SourceRange InitRange,
bool IsFullyOverwritten = false);
void UpdateStructuredListElement(InitListExpr *StructuredList,
unsigned &StructuredIndex,
Expr *expr);
int numArrayElements(QualType DeclType);
int numStructUnionElements(QualType DeclType);
static ExprResult PerformEmptyInit(Sema &SemaRef,
SourceLocation Loc,
const InitializedEntity &Entity,
bool VerifyOnly,
bool TreatUnavailableAsInvalid);
// Explanation on the "FillWithNoInit" mode:
//
// Assume we have the following definitions (Case#1):
// struct P { char x[6][6]; } xp = { .x[1] = "bar" };
// struct PP { struct P lp; } l = { .lp = xp, .lp.x[1][2] = 'f' };
//
// l.lp.x[1][0..1] should not be filled with implicit initializers because the
// "base" initializer "xp" will provide values for them; l.lp.x[1] will be "baf".
//
// But if we have (Case#2):
// struct PP l = { .lp = xp, .lp.x[1] = { [2] = 'f' } };
//
// l.lp.x[1][0..1] are implicitly initialized and do not use values from the
// "base" initializer; l.lp.x[1] will be "\0\0f\0\0\0".
//
// To distinguish Case#1 from Case#2, and also to avoid leaving many "holes"
// in the InitListExpr, the "holes" in Case#1 are filled not with empty
// initializers but with special "NoInitExpr" place holders, which tells the
// CodeGen not to generate any initializers for these parts.
void FillInEmptyInitForBase(unsigned Init, const CXXBaseSpecifier &Base,
const InitializedEntity &ParentEntity,
InitListExpr *ILE, bool &RequiresSecondPass,
bool FillWithNoInit);
void FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
const InitializedEntity &ParentEntity,
InitListExpr *ILE, bool &RequiresSecondPass,
bool FillWithNoInit = false);
void FillInEmptyInitializations(const InitializedEntity &Entity,
InitListExpr *ILE, bool &RequiresSecondPass,
bool FillWithNoInit = false);
bool CheckFlexibleArrayInit(const InitializedEntity &Entity,
Expr *InitExpr, FieldDecl *Field,
bool TopLevelObject);
void CheckEmptyInitializable(const InitializedEntity &Entity,
SourceLocation Loc);
public:
InitListChecker(Sema &S, const InitializedEntity &Entity,
InitListExpr *IL, QualType &T, bool VerifyOnly,
bool TreatUnavailableAsInvalid);
bool HadError() { return hadError; }
// @brief Retrieves the fully-structured initializer list used for
// semantic analysis and code generation.
InitListExpr *getFullyStructuredList() const { return FullyStructuredList; }
};
} // end anonymous namespace
ExprResult InitListChecker::PerformEmptyInit(Sema &SemaRef,
SourceLocation Loc,
const InitializedEntity &Entity,
bool VerifyOnly,
bool TreatUnavailableAsInvalid) {
InitializationKind Kind = InitializationKind::CreateValue(Loc, Loc, Loc,
true);
MultiExprArg SubInit;
Expr *InitExpr;
InitListExpr DummyInitList(SemaRef.Context, Loc, None, Loc);
// C++ [dcl.init.aggr]p7:
// If there are fewer initializer-clauses in the list than there are
// members in the aggregate, then each member not explicitly initialized
// ...
bool EmptyInitList = SemaRef.getLangOpts().CPlusPlus11 &&
Entity.getType()->getBaseElementTypeUnsafe()->isRecordType();
if (EmptyInitList) {
// C++1y / DR1070:
// shall be initialized [...] from an empty initializer list.
//
// We apply the resolution of this DR to C++11 but not C++98, since C++98
// does not have useful semantics for initialization from an init list.
// We treat this as copy-initialization, because aggregate initialization
// always performs copy-initialization on its elements.
//
// Only do this if we're initializing a class type, to avoid filling in
// the initializer list where possible.
InitExpr = VerifyOnly ? &DummyInitList : new (SemaRef.Context)
InitListExpr(SemaRef.Context, Loc, None, Loc);
InitExpr->setType(SemaRef.Context.VoidTy);
SubInit = InitExpr;
Kind = InitializationKind::CreateCopy(Loc, Loc);
} else {
// C++03:
// shall be value-initialized.
}
InitializationSequence InitSeq(SemaRef, Entity, Kind, SubInit);
// libstdc++4.6 marks the vector default constructor as explicit in
// _GLIBCXX_DEBUG mode, so recover using the C++03 logic in that case.
// stlport does so too. Look for std::__debug for libstdc++, and for
// std:: for stlport. This is effectively a compiler-side implementation of
// LWG2193.
if (!InitSeq && EmptyInitList && InitSeq.getFailureKind() ==
InitializationSequence::FK_ExplicitConstructor) {
OverloadCandidateSet::iterator Best;
OverloadingResult O =
InitSeq.getFailedCandidateSet()
.BestViableFunction(SemaRef, Kind.getLocation(), Best);
(void)O;
assert(O == OR_Success && "Inconsistent overload resolution");
CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
CXXRecordDecl *R = CtorDecl->getParent();
if (CtorDecl->getMinRequiredArguments() == 0 &&
CtorDecl->isExplicit() && R->getDeclName() &&
SemaRef.SourceMgr.isInSystemHeader(CtorDecl->getLocation())) {
bool IsInStd = false;
for (NamespaceDecl *ND = dyn_cast<NamespaceDecl>(R->getDeclContext());
ND && !IsInStd; ND = dyn_cast<NamespaceDecl>(ND->getParent())) {
if (SemaRef.getStdNamespace()->InEnclosingNamespaceSetOf(ND))
IsInStd = true;
}
if (IsInStd && llvm::StringSwitch<bool>(R->getName())
.Cases("basic_string", "deque", "forward_list", true)
.Cases("list", "map", "multimap", "multiset", true)
.Cases("priority_queue", "queue", "set", "stack", true)
.Cases("unordered_map", "unordered_set", "vector", true)
.Default(false)) {
InitSeq.InitializeFrom(
SemaRef, Entity,
InitializationKind::CreateValue(Loc, Loc, Loc, true),
MultiExprArg(), /*TopLevelOfInitList=*/false,
TreatUnavailableAsInvalid);
// Emit a warning for this. System header warnings aren't shown
// by default, but people working on system headers should see it.
if (!VerifyOnly) {
SemaRef.Diag(CtorDecl->getLocation(),
diag::warn_invalid_initializer_from_system_header);
if (Entity.getKind() == InitializedEntity::EK_Member)
SemaRef.Diag(Entity.getDecl()->getLocation(),
diag::note_used_in_initialization_here);
else if (Entity.getKind() == InitializedEntity::EK_ArrayElement)
SemaRef.Diag(Loc, diag::note_used_in_initialization_here);
}
}
}
}
if (!InitSeq) {
if (!VerifyOnly) {
InitSeq.Diagnose(SemaRef, Entity, Kind, SubInit);
if (Entity.getKind() == InitializedEntity::EK_Member)
SemaRef.Diag(Entity.getDecl()->getLocation(),
diag::note_in_omitted_aggregate_initializer)
<< /*field*/1 << Entity.getDecl();
else if (Entity.getKind() == InitializedEntity::EK_ArrayElement) {
bool IsTrailingArrayNewMember =
Entity.getParent() &&
Entity.getParent()->isVariableLengthArrayNew();
SemaRef.Diag(Loc, diag::note_in_omitted_aggregate_initializer)
<< (IsTrailingArrayNewMember ? 2 : /*array element*/0)
<< Entity.getElementIndex();
}
}
return ExprError();
}
return VerifyOnly ? ExprResult(static_cast<Expr *>(nullptr))
: InitSeq.Perform(SemaRef, Entity, Kind, SubInit);
}
void InitListChecker::CheckEmptyInitializable(const InitializedEntity &Entity,
SourceLocation Loc) {
assert(VerifyOnly &&
"CheckEmptyInitializable is only inteded for verification mode.");
if (PerformEmptyInit(SemaRef, Loc, Entity, /*VerifyOnly*/true,
TreatUnavailableAsInvalid).isInvalid())
hadError = true;
}
void InitListChecker::FillInEmptyInitForBase(
unsigned Init, const CXXBaseSpecifier &Base,
const InitializedEntity &ParentEntity, InitListExpr *ILE,
bool &RequiresSecondPass, bool FillWithNoInit) {
assert(Init < ILE->getNumInits() && "should have been expanded");
InitializedEntity BaseEntity = InitializedEntity::InitializeBase(
SemaRef.Context, &Base, false, &ParentEntity);
if (!ILE->getInit(Init)) {
ExprResult BaseInit =
FillWithNoInit ? new (SemaRef.Context) NoInitExpr(Base.getType())
: PerformEmptyInit(SemaRef, ILE->getLocEnd(), BaseEntity,
/*VerifyOnly*/ false,
TreatUnavailableAsInvalid);
if (BaseInit.isInvalid()) {
hadError = true;
return;
}
ILE->setInit(Init, BaseInit.getAs<Expr>());
} else if (InitListExpr *InnerILE =
dyn_cast<InitListExpr>(ILE->getInit(Init))) {
FillInEmptyInitializations(BaseEntity, InnerILE,
RequiresSecondPass, FillWithNoInit);
} else if (DesignatedInitUpdateExpr *InnerDIUE =
dyn_cast<DesignatedInitUpdateExpr>(ILE->getInit(Init))) {
FillInEmptyInitializations(BaseEntity, InnerDIUE->getUpdater(),
RequiresSecondPass, /*FillWithNoInit =*/true);
}
}
void InitListChecker::FillInEmptyInitForField(unsigned Init, FieldDecl *Field,
const InitializedEntity &ParentEntity,
InitListExpr *ILE,
bool &RequiresSecondPass,
bool FillWithNoInit) {
SourceLocation Loc = ILE->getLocEnd();
unsigned NumInits = ILE->getNumInits();
InitializedEntity MemberEntity
= InitializedEntity::InitializeMember(Field, &ParentEntity);
if (const RecordType *RType = ILE->getType()->getAs<RecordType>())
if (!RType->getDecl()->isUnion())
assert(Init < NumInits && "This ILE should have been expanded");
if (Init >= NumInits || !ILE->getInit(Init)) {
if (FillWithNoInit) {
Expr *Filler = new (SemaRef.Context) NoInitExpr(Field->getType());
if (Init < NumInits)
ILE->setInit(Init, Filler);
else
ILE->updateInit(SemaRef.Context, Init, Filler);
return;
}
// C++1y [dcl.init.aggr]p7:
// If there are fewer initializer-clauses in the list than there are
// members in the aggregate, then each member not explicitly initialized
// shall be initialized from its brace-or-equal-initializer [...]
if (Field->hasInClassInitializer()) {
ExprResult DIE = SemaRef.BuildCXXDefaultInitExpr(Loc, Field);
if (DIE.isInvalid()) {
hadError = true;
return;
}
if (Init < NumInits)
ILE->setInit(Init, DIE.get());
else {
ILE->updateInit(SemaRef.Context, Init, DIE.get());
RequiresSecondPass = true;
}
return;
}
if (Field->getType()->isReferenceType()) {
// C++ [dcl.init.aggr]p9:
// If an incomplete or empty initializer-list leaves a
// member of reference type uninitialized, the program is
// ill-formed.
SemaRef.Diag(Loc, diag::err_init_reference_member_uninitialized)
<< Field->getType()
<< ILE->getSyntacticForm()->getSourceRange();
SemaRef.Diag(Field->getLocation(),
diag::note_uninit_reference_member);
hadError = true;
return;
}
ExprResult MemberInit = PerformEmptyInit(SemaRef, Loc, MemberEntity,
/*VerifyOnly*/false,
TreatUnavailableAsInvalid);
if (MemberInit.isInvalid()) {
hadError = true;
return;
}
if (hadError) {
// Do nothing
} else if (Init < NumInits) {
ILE->setInit(Init, MemberInit.getAs<Expr>());
} else if (!isa<ImplicitValueInitExpr>(MemberInit.get())) {
// Empty initialization requires a constructor call, so
// extend the initializer list to include the constructor
// call and make a note that we'll need to take another pass
// through the initializer list.
ILE->updateInit(SemaRef.Context, Init, MemberInit.getAs<Expr>());
RequiresSecondPass = true;
}
} else if (InitListExpr *InnerILE
= dyn_cast<InitListExpr>(ILE->getInit(Init)))
FillInEmptyInitializations(MemberEntity, InnerILE,
RequiresSecondPass, FillWithNoInit);
else if (DesignatedInitUpdateExpr *InnerDIUE
= dyn_cast<DesignatedInitUpdateExpr>(ILE->getInit(Init)))
FillInEmptyInitializations(MemberEntity, InnerDIUE->getUpdater(),
RequiresSecondPass, /*FillWithNoInit =*/ true);
}
/// Recursively replaces NULL values within the given initializer list
/// with expressions that perform value-initialization of the
/// appropriate type.
void
InitListChecker::FillInEmptyInitializations(const InitializedEntity &Entity,
InitListExpr *ILE,
bool &RequiresSecondPass,
bool FillWithNoInit) {
assert((ILE->getType() != SemaRef.Context.VoidTy) &&
"Should not have void type");
// A transparent ILE is not performing aggregate initialization and should
// not be filled in.
if (ILE->isTransparent())
return;
if (const RecordType *RType = ILE->getType()->getAs<RecordType>()) {
const RecordDecl *RDecl = RType->getDecl();
if (RDecl->isUnion() && ILE->getInitializedFieldInUnion())
FillInEmptyInitForField(0, ILE->getInitializedFieldInUnion(),
Entity, ILE, RequiresSecondPass, FillWithNoInit);
else if (RDecl->isUnion() && isa<CXXRecordDecl>(RDecl) &&
cast<CXXRecordDecl>(RDecl)->hasInClassInitializer()) {
for (auto *Field : RDecl->fields()) {
if (Field->hasInClassInitializer()) {
FillInEmptyInitForField(0, Field, Entity, ILE, RequiresSecondPass,
FillWithNoInit);
break;
}
}
} else {
// The fields beyond ILE->getNumInits() are default initialized, so in
// order to leave them uninitialized, the ILE is expanded and the extra
// fields are then filled with NoInitExpr.
unsigned NumElems = numStructUnionElements(ILE->getType());
if (RDecl->hasFlexibleArrayMember())
++NumElems;
if (ILE->getNumInits() < NumElems)
ILE->resizeInits(SemaRef.Context, NumElems);
unsigned Init = 0;
if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RDecl)) {
for (auto &Base : CXXRD->bases()) {
if (hadError)
return;
FillInEmptyInitForBase(Init, Base, Entity, ILE, RequiresSecondPass,
FillWithNoInit);
++Init;
}
}
for (auto *Field : RDecl->fields()) {
if (Field->isUnnamedBitfield())
continue;
if (hadError)
return;
FillInEmptyInitForField(Init, Field, Entity, ILE, RequiresSecondPass,
FillWithNoInit);
if (hadError)
return;
++Init;
// Only look at the first initialization of a union.
if (RDecl->isUnion())
break;
}
}
return;
}
QualType ElementType;
InitializedEntity ElementEntity = Entity;
unsigned NumInits = ILE->getNumInits();
unsigned NumElements = NumInits;
if (const ArrayType *AType = SemaRef.Context.getAsArrayType(ILE->getType())) {
ElementType = AType->getElementType();
if (const auto *CAType = dyn_cast<ConstantArrayType>(AType))
NumElements = CAType->getSize().getZExtValue();
// For an array new with an unknown bound, ask for one additional element
// in order to populate the array filler.
if (Entity.isVariableLengthArrayNew())
++NumElements;
ElementEntity = InitializedEntity::InitializeElement(SemaRef.Context,
0, Entity);
} else if (const VectorType *VType = ILE->getType()->getAs<VectorType>()) {
ElementType = VType->getElementType();
NumElements = VType->getNumElements();
ElementEntity = InitializedEntity::InitializeElement(SemaRef.Context,
0, Entity);
} else
ElementType = ILE->getType();
for (unsigned Init = 0; Init != NumElements; ++Init) {
if (hadError)
return;
if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement ||
ElementEntity.getKind() == InitializedEntity::EK_VectorElement)
ElementEntity.setElementIndex(Init);
Expr *InitExpr = (Init < NumInits ? ILE->getInit(Init) : nullptr);
if (!InitExpr && Init < NumInits && ILE->hasArrayFiller())
ILE->setInit(Init, ILE->getArrayFiller());
else if (!InitExpr && !ILE->hasArrayFiller()) {
Expr *Filler = nullptr;
if (FillWithNoInit)
Filler = new (SemaRef.Context) NoInitExpr(ElementType);
else {
ExprResult ElementInit = PerformEmptyInit(SemaRef, ILE->getLocEnd(),
ElementEntity,
/*VerifyOnly*/false,
TreatUnavailableAsInvalid);
if (ElementInit.isInvalid()) {
hadError = true;
return;
}
Filler = ElementInit.getAs<Expr>();
}
if (hadError) {
// Do nothing
} else if (Init < NumInits) {
// For arrays, just set the expression used for value-initialization
// of the "holes" in the array.
if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement)
ILE->setArrayFiller(Filler);
else
ILE->setInit(Init, Filler);
} else {
// For arrays, just set the expression used for value-initialization
// of the rest of elements and exit.
if (ElementEntity.getKind() == InitializedEntity::EK_ArrayElement) {
ILE->setArrayFiller(Filler);
return;
}
if (!isa<ImplicitValueInitExpr>(Filler) && !isa<NoInitExpr>(Filler)) {
// Empty initialization requires a constructor call, so
// extend the initializer list to include the constructor
// call and make a note that we'll need to take another pass
// through the initializer list.
ILE->updateInit(SemaRef.Context, Init, Filler);
RequiresSecondPass = true;
}
}
} else if (InitListExpr *InnerILE
= dyn_cast_or_null<InitListExpr>(InitExpr))
FillInEmptyInitializations(ElementEntity, InnerILE, RequiresSecondPass,
FillWithNoInit);
else if (DesignatedInitUpdateExpr *InnerDIUE
= dyn_cast_or_null<DesignatedInitUpdateExpr>(InitExpr))
FillInEmptyInitializations(ElementEntity, InnerDIUE->getUpdater(),
RequiresSecondPass, /*FillWithNoInit =*/ true);
}
}
InitListChecker::InitListChecker(Sema &S, const InitializedEntity &Entity,
InitListExpr *IL, QualType &T,
bool VerifyOnly,
bool TreatUnavailableAsInvalid)
: SemaRef(S), VerifyOnly(VerifyOnly),
TreatUnavailableAsInvalid(TreatUnavailableAsInvalid) {
// FIXME: Check that IL isn't already the semantic form of some other
// InitListExpr. If it is, we'd create a broken AST.
hadError = false;
FullyStructuredList =
getStructuredSubobjectInit(IL, 0, T, nullptr, 0, IL->getSourceRange());
CheckExplicitInitList(Entity, IL, T, FullyStructuredList,
/*TopLevelObject=*/true);
if (!hadError && !VerifyOnly) {
bool RequiresSecondPass = false;
FillInEmptyInitializations(Entity, FullyStructuredList, RequiresSecondPass);
if (RequiresSecondPass && !hadError)
FillInEmptyInitializations(Entity, FullyStructuredList,
RequiresSecondPass);
}
}
int InitListChecker::numArrayElements(QualType DeclType) {
// FIXME: use a proper constant
int maxElements = 0x7FFFFFFF;
if (const ConstantArrayType *CAT =
SemaRef.Context.getAsConstantArrayType(DeclType)) {
maxElements = static_cast<int>(CAT->getSize().getZExtValue());
}
return maxElements;
}
int InitListChecker::numStructUnionElements(QualType DeclType) {
RecordDecl *structDecl = DeclType->getAs<RecordType>()->getDecl();
int InitializableMembers = 0;
if (auto *CXXRD = dyn_cast<CXXRecordDecl>(structDecl))
InitializableMembers += CXXRD->getNumBases();
for (const auto *Field : structDecl->fields())
if (!Field->isUnnamedBitfield())
++InitializableMembers;
if (structDecl->isUnion())
return std::min(InitializableMembers, 1);
return InitializableMembers - structDecl->hasFlexibleArrayMember();
}
/// Determine whether Entity is an entity for which it is idiomatic to elide
/// the braces in aggregate initialization.
static bool isIdiomaticBraceElisionEntity(const InitializedEntity &Entity) {
// Recursive initialization of the one and only field within an aggregate
// class is considered idiomatic. This case arises in particular for
// initialization of std::array, where the C++ standard suggests the idiom of
//
// std::array<T, N> arr = {1, 2, 3};
//
// (where std::array is an aggregate struct containing a single array field.
// FIXME: Should aggregate initialization of a struct with a single
// base class and no members also suppress the warning?
if (Entity.getKind() != InitializedEntity::EK_Member || !Entity.getParent())
return false;
auto *ParentRD =
Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD))
if (CXXRD->getNumBases())
return false;
auto FieldIt = ParentRD->field_begin();
assert(FieldIt != ParentRD->field_end() &&
"no fields but have initializer for member?");
return ++FieldIt == ParentRD->field_end();
}
/// Check whether the range of the initializer \p ParentIList from element
/// \p Index onwards can be used to initialize an object of type \p T. Update
/// \p Index to indicate how many elements of the list were consumed.
///
/// This also fills in \p StructuredList, from element \p StructuredIndex
/// onwards, with the fully-braced, desugared form of the initialization.
void InitListChecker::CheckImplicitInitList(const InitializedEntity &Entity,
InitListExpr *ParentIList,
QualType T, unsigned &Index,
InitListExpr *StructuredList,
unsigned &StructuredIndex) {
int maxElements = 0;
if (T->isArrayType())
maxElements = numArrayElements(T);
else if (T->isRecordType())
maxElements = numStructUnionElements(T);
else if (T->isVectorType())
maxElements = T->getAs<VectorType>()->getNumElements();
else
llvm_unreachable("CheckImplicitInitList(): Illegal type");
if (maxElements == 0) {
if (!VerifyOnly)
SemaRef.Diag(ParentIList->getInit(Index)->getLocStart(),
diag::err_implicit_empty_initializer);
++Index;
hadError = true;
return;
}
// Build a structured initializer list corresponding to this subobject.
InitListExpr *StructuredSubobjectInitList
= getStructuredSubobjectInit(ParentIList, Index, T, StructuredList,
StructuredIndex,
SourceRange(ParentIList->getInit(Index)->getLocStart(),
ParentIList->getSourceRange().getEnd()));
unsigned StructuredSubobjectInitIndex = 0;
// Check the element types and build the structural subobject.
unsigned StartIndex = Index;
CheckListElementTypes(Entity, ParentIList, T,
/*SubobjectIsDesignatorContext=*/false, Index,
StructuredSubobjectInitList,
StructuredSubobjectInitIndex);
if (!VerifyOnly) {
StructuredSubobjectInitList->setType(T);
unsigned EndIndex = (Index == StartIndex? StartIndex : Index - 1);
// Update the structured sub-object initializer so that it's ending
// range corresponds with the end of the last initializer it used.
if (EndIndex < ParentIList->getNumInits() &&
ParentIList->getInit(EndIndex)) {
SourceLocation EndLoc
= ParentIList->getInit(EndIndex)->getSourceRange().getEnd();
StructuredSubobjectInitList->setRBraceLoc(EndLoc);
}
// Complain about missing braces.
if ((T->isArrayType() || T->isRecordType()) &&
!ParentIList->isIdiomaticZeroInitializer(SemaRef.getLangOpts()) &&
!isIdiomaticBraceElisionEntity(Entity)) {
SemaRef.Diag(StructuredSubobjectInitList->getLocStart(),
diag::warn_missing_braces)
<< StructuredSubobjectInitList->getSourceRange()
<< FixItHint::CreateInsertion(
StructuredSubobjectInitList->getLocStart(), "{")
<< FixItHint::CreateInsertion(
SemaRef.getLocForEndOfToken(
StructuredSubobjectInitList->getLocEnd()),
"}");
}
}
}
/// Warn that \p Entity was of scalar type and was initialized by a
/// single-element braced initializer list.
static void warnBracedScalarInit(Sema &S, const InitializedEntity &Entity,
SourceRange Braces) {
// Don't warn during template instantiation. If the initialization was
// non-dependent, we warned during the initial parse; otherwise, the
// type might not be scalar in some uses of the template.
if (S.inTemplateInstantiation())
return;
unsigned DiagID = 0;
switch (Entity.getKind()) {
case InitializedEntity::EK_VectorElement:
case InitializedEntity::EK_ComplexElement:
case InitializedEntity::EK_ArrayElement:
case InitializedEntity::EK_Parameter:
case InitializedEntity::EK_Parameter_CF_Audited:
case InitializedEntity::EK_Result:
// Extra braces here are suspicious.
DiagID = diag::warn_braces_around_scalar_init;
break;
case InitializedEntity::EK_Member:
// Warn on aggregate initialization but not on ctor init list or
// default member initializer.
if (Entity.getParent())
DiagID = diag::warn_braces_around_scalar_init;
break;
case InitializedEntity::EK_Variable:
case InitializedEntity::EK_LambdaCapture:
// No warning, might be direct-list-initialization.
// FIXME: Should we warn for copy-list-initialization in these cases?
break;
case InitializedEntity::EK_New:
case InitializedEntity::EK_Temporary:
case InitializedEntity::EK_CompoundLiteralInit:
// No warning, braces are part of the syntax of the underlying construct.
break;
case InitializedEntity::EK_RelatedResult:
// No warning, we already warned when initializing the result.
break;
case InitializedEntity::EK_Exception:
case InitializedEntity::EK_Base:
case InitializedEntity::EK_Delegating:
case InitializedEntity::EK_BlockElement:
case InitializedEntity::EK_LambdaToBlockConversionBlockElement:
case InitializedEntity::EK_Binding:
llvm_unreachable("unexpected braced scalar init");
}
if (DiagID) {
S.Diag(Braces.getBegin(), DiagID)
<< Braces
<< FixItHint::CreateRemoval(Braces.getBegin())
<< FixItHint::CreateRemoval(Braces.getEnd());
}
}
/// Check whether the initializer \p IList (that was written with explicit
/// braces) can be used to initialize an object of type \p T.
///
/// This also fills in \p StructuredList with the fully-braced, desugared
/// form of the initialization.