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//===--- SemaExceptionSpec.cpp - C++ Exception Specifications ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides Sema routines for C++ exception specification testing.
//
//===----------------------------------------------------------------------===//
#include "Sema.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/SourceManager.h"
#include "llvm/ADT/SmallPtrSet.h"
namespace clang {
static const FunctionProtoType *GetUnderlyingFunction(QualType T)
{
if (const PointerType *PtrTy = T->getAs<PointerType>())
T = PtrTy->getPointeeType();
else if (const ReferenceType *RefTy = T->getAs<ReferenceType>())
T = RefTy->getPointeeType();
else if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>())
T = MPTy->getPointeeType();
return T->getAs<FunctionProtoType>();
}
/// CheckSpecifiedExceptionType - Check if the given type is valid in an
/// exception specification. Incomplete types, or pointers to incomplete types
/// other than void are not allowed.
bool Sema::CheckSpecifiedExceptionType(QualType T, const SourceRange &Range) {
// This check (and the similar one below) deals with issue 437, that changes
// C++ 9.2p2 this way:
// Within the class member-specification, the class is regarded as complete
// within function bodies, default arguments, exception-specifications, and
// constructor ctor-initializers (including such things in nested classes).
if (T->isRecordType() && T->getAs<RecordType>()->isBeingDefined())
return false;
// C++ 15.4p2: A type denoted in an exception-specification shall not denote
// an incomplete type.
if (RequireCompleteType(Range.getBegin(), T,
PDiag(diag::err_incomplete_in_exception_spec) << /*direct*/0 << Range))
return true;
// C++ 15.4p2: A type denoted in an exception-specification shall not denote
// an incomplete type a pointer or reference to an incomplete type, other
// than (cv) void*.
int kind;
if (const PointerType* IT = T->getAs<PointerType>()) {
T = IT->getPointeeType();
kind = 1;
} else if (const ReferenceType* IT = T->getAs<ReferenceType>()) {
T = IT->getPointeeType();
kind = 2;
} else
return false;
// Again as before
if (T->isRecordType() && T->getAs<RecordType>()->isBeingDefined())
return false;
if (!T->isVoidType() && RequireCompleteType(Range.getBegin(), T,
PDiag(diag::err_incomplete_in_exception_spec) << kind << Range))
return true;
return false;
}
/// CheckDistantExceptionSpec - Check if the given type is a pointer or pointer
/// to member to a function with an exception specification. This means that
/// it is invalid to add another level of indirection.
bool Sema::CheckDistantExceptionSpec(QualType T) {
if (const PointerType *PT = T->getAs<PointerType>())
T = PT->getPointeeType();
else if (const MemberPointerType *PT = T->getAs<MemberPointerType>())
T = PT->getPointeeType();
else
return false;
const FunctionProtoType *FnT = T->getAs<FunctionProtoType>();
if (!FnT)
return false;
return FnT->hasExceptionSpec();
}
bool Sema::CheckEquivalentExceptionSpec(FunctionDecl *Old, FunctionDecl *New) {
bool MissingExceptionSpecification = false;
bool MissingEmptyExceptionSpecification = false;
if (!CheckEquivalentExceptionSpec(PDiag(diag::err_mismatched_exception_spec),
PDiag(diag::note_previous_declaration),
Old->getType()->getAs<FunctionProtoType>(),
Old->getLocation(),
New->getType()->getAs<FunctionProtoType>(),
New->getLocation(),
&MissingExceptionSpecification,
&MissingEmptyExceptionSpecification))
return false;
// The failure was something other than an empty exception
// specification; return an error.
if (!MissingExceptionSpecification && !MissingEmptyExceptionSpecification)
return true;
// The new function declaration is only missing an empty exception
// specification "throw()". If the throw() specification came from a
// function in a system header that has C linkage, just add an empty
// exception specification to the "new" declaration. This is an
// egregious workaround for glibc, which adds throw() specifications
// to many libc functions as an optimization. Unfortunately, that
// optimization isn't permitted by the C++ standard, so we're forced
// to work around it here.
if (MissingEmptyExceptionSpecification &&
isa<FunctionProtoType>(New->getType()) &&
(Old->getLocation().isInvalid() ||
Context.getSourceManager().isInSystemHeader(Old->getLocation())) &&
Old->isExternC()) {
const FunctionProtoType *NewProto
= cast<FunctionProtoType>(New->getType());
QualType NewType = Context.getFunctionType(NewProto->getResultType(),
NewProto->arg_type_begin(),
NewProto->getNumArgs(),
NewProto->isVariadic(),
NewProto->getTypeQuals(),
true, false, 0, 0,
NewProto->getExtInfo());
New->setType(NewType);
return false;
}
if (MissingExceptionSpecification && isa<FunctionProtoType>(New->getType())) {
const FunctionProtoType *NewProto
= cast<FunctionProtoType>(New->getType());
const FunctionProtoType *OldProto
= Old->getType()->getAs<FunctionProtoType>();
// Update the type of the function with the appropriate exception
// specification.
QualType NewType = Context.getFunctionType(NewProto->getResultType(),
NewProto->arg_type_begin(),
NewProto->getNumArgs(),
NewProto->isVariadic(),
NewProto->getTypeQuals(),
OldProto->hasExceptionSpec(),
OldProto->hasAnyExceptionSpec(),
OldProto->getNumExceptions(),
OldProto->exception_begin(),
NewProto->getExtInfo());
New->setType(NewType);
// If exceptions are disabled, suppress the warning about missing
// exception specifications for new and delete operators.
if (!getLangOptions().Exceptions) {
switch (New->getDeclName().getCXXOverloadedOperator()) {
case OO_New:
case OO_Array_New:
case OO_Delete:
case OO_Array_Delete:
if (New->getDeclContext()->isTranslationUnit())
return false;
break;
default:
break;
}
}
// Warn about the lack of exception specification.
llvm::SmallString<128> ExceptionSpecString;
llvm::raw_svector_ostream OS(ExceptionSpecString);
OS << "throw(";
bool OnFirstException = true;
for (FunctionProtoType::exception_iterator E = OldProto->exception_begin(),
EEnd = OldProto->exception_end();
E != EEnd;
++E) {
if (OnFirstException)
OnFirstException = false;
else
OS << ", ";
OS << E->getAsString(Context.PrintingPolicy);
}
OS << ")";
OS.flush();
SourceLocation AfterParenLoc;
if (TypeSourceInfo *TSInfo = New->getTypeSourceInfo()) {
TypeLoc TL = TSInfo->getTypeLoc();
if (const FunctionTypeLoc *FTLoc = dyn_cast<FunctionTypeLoc>(&TL))
AfterParenLoc = PP.getLocForEndOfToken(FTLoc->getRParenLoc());
}
if (AfterParenLoc.isInvalid())
Diag(New->getLocation(), diag::warn_missing_exception_specification)
<< New << OS.str();
else {
// FIXME: This will get more complicated with C++0x
// late-specified return types.
Diag(New->getLocation(), diag::warn_missing_exception_specification)
<< New << OS.str()
<< FixItHint::CreateInsertion(AfterParenLoc, " " + OS.str().str());
}
if (!Old->getLocation().isInvalid())
Diag(Old->getLocation(), diag::note_previous_declaration);
return false;
}
Diag(New->getLocation(), diag::err_mismatched_exception_spec);
Diag(Old->getLocation(), diag::note_previous_declaration);
return true;
}
/// CheckEquivalentExceptionSpec - Check if the two types have equivalent
/// exception specifications. Exception specifications are equivalent if
/// they allow exactly the same set of exception types. It does not matter how
/// that is achieved. See C++ [except.spec]p2.
bool Sema::CheckEquivalentExceptionSpec(
const FunctionProtoType *Old, SourceLocation OldLoc,
const FunctionProtoType *New, SourceLocation NewLoc) {
return CheckEquivalentExceptionSpec(
PDiag(diag::err_mismatched_exception_spec),
PDiag(diag::note_previous_declaration),
Old, OldLoc, New, NewLoc);
}
/// CheckEquivalentExceptionSpec - Check if the two types have equivalent
/// exception specifications. Exception specifications are equivalent if
/// they allow exactly the same set of exception types. It does not matter how
/// that is achieved. See C++ [except.spec]p2.
bool Sema::CheckEquivalentExceptionSpec(const PartialDiagnostic &DiagID,
const PartialDiagnostic & NoteID,
const FunctionProtoType *Old,
SourceLocation OldLoc,
const FunctionProtoType *New,
SourceLocation NewLoc,
bool *MissingExceptionSpecification,
bool *MissingEmptyExceptionSpecification) {
if (MissingExceptionSpecification)
*MissingExceptionSpecification = false;
if (MissingEmptyExceptionSpecification)
*MissingEmptyExceptionSpecification = false;
bool OldAny = !Old->hasExceptionSpec() || Old->hasAnyExceptionSpec();
bool NewAny = !New->hasExceptionSpec() || New->hasAnyExceptionSpec();
if (OldAny && NewAny)
return false;
if (OldAny || NewAny) {
if (MissingExceptionSpecification && Old->hasExceptionSpec() &&
!New->hasExceptionSpec()) {
// The old type has an exception specification of some sort, but
// the new type does not.
*MissingExceptionSpecification = true;
if (MissingEmptyExceptionSpecification &&
!Old->hasAnyExceptionSpec() && Old->getNumExceptions() == 0) {
// The old type has a throw() exception specification and the
// new type has no exception specification, and the caller asked
// to handle this itself.
*MissingEmptyExceptionSpecification = true;
}
return true;
}
Diag(NewLoc, DiagID);
if (NoteID.getDiagID() != 0)
Diag(OldLoc, NoteID);
return true;
}
bool Success = true;
// Both have a definite exception spec. Collect the first set, then compare
// to the second.
llvm::SmallPtrSet<CanQualType, 8> OldTypes, NewTypes;
for (FunctionProtoType::exception_iterator I = Old->exception_begin(),
E = Old->exception_end(); I != E; ++I)
OldTypes.insert(Context.getCanonicalType(*I).getUnqualifiedType());
for (FunctionProtoType::exception_iterator I = New->exception_begin(),
E = New->exception_end(); I != E && Success; ++I) {
CanQualType TypePtr = Context.getCanonicalType(*I).getUnqualifiedType();
if(OldTypes.count(TypePtr))
NewTypes.insert(TypePtr);
else
Success = false;
}
Success = Success && OldTypes.size() == NewTypes.size();
if (Success) {
return false;
}
Diag(NewLoc, DiagID);
if (NoteID.getDiagID() != 0)
Diag(OldLoc, NoteID);
return true;
}
/// CheckExceptionSpecSubset - Check whether the second function type's
/// exception specification is a subset (or equivalent) of the first function
/// type. This is used by override and pointer assignment checks.
bool Sema::CheckExceptionSpecSubset(
const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
const FunctionProtoType *Superset, SourceLocation SuperLoc,
const FunctionProtoType *Subset, SourceLocation SubLoc) {
// FIXME: As usual, we could be more specific in our error messages, but
// that better waits until we've got types with source locations.
if (!SubLoc.isValid())
SubLoc = SuperLoc;
// If superset contains everything, we're done.
if (!Superset->hasExceptionSpec() || Superset->hasAnyExceptionSpec())
return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
// It does not. If the subset contains everything, we've failed.
if (!Subset->hasExceptionSpec() || Subset->hasAnyExceptionSpec()) {
Diag(SubLoc, DiagID);
if (NoteID.getDiagID() != 0)
Diag(SuperLoc, NoteID);
return true;
}
// Neither contains everything. Do a proper comparison.
for (FunctionProtoType::exception_iterator SubI = Subset->exception_begin(),
SubE = Subset->exception_end(); SubI != SubE; ++SubI) {
// Take one type from the subset.
QualType CanonicalSubT = Context.getCanonicalType(*SubI);
// Unwrap pointers and references so that we can do checks within a class
// hierarchy. Don't unwrap member pointers; they don't have hierarchy
// conversions on the pointee.
bool SubIsPointer = false;
if (const ReferenceType *RefTy = CanonicalSubT->getAs<ReferenceType>())
CanonicalSubT = RefTy->getPointeeType();
if (const PointerType *PtrTy = CanonicalSubT->getAs<PointerType>()) {
CanonicalSubT = PtrTy->getPointeeType();
SubIsPointer = true;
}
bool SubIsClass = CanonicalSubT->isRecordType();
CanonicalSubT = CanonicalSubT.getLocalUnqualifiedType();
CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
/*DetectVirtual=*/false);
bool Contained = false;
// Make sure it's in the superset.
for (FunctionProtoType::exception_iterator SuperI =
Superset->exception_begin(), SuperE = Superset->exception_end();
SuperI != SuperE; ++SuperI) {
QualType CanonicalSuperT = Context.getCanonicalType(*SuperI);
// SubT must be SuperT or derived from it, or pointer or reference to
// such types.
if (const ReferenceType *RefTy = CanonicalSuperT->getAs<ReferenceType>())
CanonicalSuperT = RefTy->getPointeeType();
if (SubIsPointer) {
if (const PointerType *PtrTy = CanonicalSuperT->getAs<PointerType>())
CanonicalSuperT = PtrTy->getPointeeType();
else {
continue;
}
}
CanonicalSuperT = CanonicalSuperT.getLocalUnqualifiedType();
// If the types are the same, move on to the next type in the subset.
if (CanonicalSubT == CanonicalSuperT) {
Contained = true;
break;
}
// Otherwise we need to check the inheritance.
if (!SubIsClass || !CanonicalSuperT->isRecordType())
continue;
Paths.clear();
if (!IsDerivedFrom(CanonicalSubT, CanonicalSuperT, Paths))
continue;
if (Paths.isAmbiguous(CanonicalSuperT))
continue;
// Do this check from a context without privileges.
switch (CheckBaseClassAccess(SourceLocation(),
CanonicalSuperT, CanonicalSubT,
Paths.front(),
/*Diagnostic*/ 0,
/*ForceCheck*/ true,
/*ForceUnprivileged*/ true)) {
case AR_accessible: break;
case AR_inaccessible: continue;
case AR_dependent:
llvm_unreachable("access check dependent for unprivileged context");
break;
case AR_delayed:
llvm_unreachable("access check delayed in non-declaration");
break;
}
Contained = true;
break;
}
if (!Contained) {
Diag(SubLoc, DiagID);
if (NoteID.getDiagID() != 0)
Diag(SuperLoc, NoteID);
return true;
}
}
// We've run half the gauntlet.
return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
}
static bool CheckSpecForTypesEquivalent(Sema &S,
const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
QualType Target, SourceLocation TargetLoc,
QualType Source, SourceLocation SourceLoc)
{
const FunctionProtoType *TFunc = GetUnderlyingFunction(Target);
if (!TFunc)
return false;
const FunctionProtoType *SFunc = GetUnderlyingFunction(Source);
if (!SFunc)
return false;
return S.CheckEquivalentExceptionSpec(DiagID, NoteID, TFunc, TargetLoc,
SFunc, SourceLoc);
}
/// CheckParamExceptionSpec - Check if the parameter and return types of the
/// two functions have equivalent exception specs. This is part of the
/// assignment and override compatibility check. We do not check the parameters
/// of parameter function pointers recursively, as no sane programmer would
/// even be able to write such a function type.
bool Sema::CheckParamExceptionSpec(const PartialDiagnostic & NoteID,
const FunctionProtoType *Target, SourceLocation TargetLoc,
const FunctionProtoType *Source, SourceLocation SourceLoc)
{
if (CheckSpecForTypesEquivalent(*this,
PDiag(diag::err_deep_exception_specs_differ) << 0,
PDiag(),
Target->getResultType(), TargetLoc,
Source->getResultType(), SourceLoc))
return true;
// We shouldn't even be testing this unless the arguments are otherwise
// compatible.
assert(Target->getNumArgs() == Source->getNumArgs() &&
"Functions have different argument counts.");
for (unsigned i = 0, E = Target->getNumArgs(); i != E; ++i) {
if (CheckSpecForTypesEquivalent(*this,
PDiag(diag::err_deep_exception_specs_differ) << 1,
PDiag(),
Target->getArgType(i), TargetLoc,
Source->getArgType(i), SourceLoc))
return true;
}
return false;
}
bool Sema::CheckExceptionSpecCompatibility(Expr *From, QualType ToType)
{
// First we check for applicability.
// Target type must be a function, function pointer or function reference.
const FunctionProtoType *ToFunc = GetUnderlyingFunction(ToType);
if (!ToFunc)
return false;
// SourceType must be a function or function pointer.
const FunctionProtoType *FromFunc = GetUnderlyingFunction(From->getType());
if (!FromFunc)
return false;
// Now we've got the correct types on both sides, check their compatibility.
// This means that the source of the conversion can only throw a subset of
// the exceptions of the target, and any exception specs on arguments or
// return types must be equivalent.
return CheckExceptionSpecSubset(PDiag(diag::err_incompatible_exception_specs),
PDiag(), ToFunc,
From->getSourceRange().getBegin(),
FromFunc, SourceLocation());
}
bool Sema::CheckOverridingFunctionExceptionSpec(const CXXMethodDecl *New,
const CXXMethodDecl *Old) {
return CheckExceptionSpecSubset(PDiag(diag::err_override_exception_spec),
PDiag(diag::note_overridden_virtual_function),
Old->getType()->getAs<FunctionProtoType>(),
Old->getLocation(),
New->getType()->getAs<FunctionProtoType>(),
New->getLocation());
}
} // end namespace clang