1 //===--- SemaExceptionSpec.cpp - C++ Exception Specifications ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file provides Sema routines for C++ exception specification testing.
12 //===----------------------------------------------------------------------===//
14 #include "clang/Sema/SemaInternal.h"
15 #include "clang/AST/ASTMutationListener.h"
16 #include "clang/AST/CXXInheritance.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/ExprCXX.h"
19 #include "clang/AST/TypeLoc.h"
20 #include "clang/Basic/Diagnostic.h"
21 #include "clang/Basic/SourceManager.h"
22 #include "llvm/ADT/SmallPtrSet.h"
23 #include "llvm/ADT/SmallString.h"
27 static const FunctionProtoType *GetUnderlyingFunction(QualType T)
29 if (const PointerType *PtrTy = T->getAs<PointerType>())
30 T = PtrTy->getPointeeType();
31 else if (const ReferenceType *RefTy = T->getAs<ReferenceType>())
32 T = RefTy->getPointeeType();
33 else if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>())
34 T = MPTy->getPointeeType();
35 return T->getAs<FunctionProtoType>();
38 /// HACK: libstdc++ has a bug where it shadows std::swap with a member
39 /// swap function then tries to call std::swap unqualified from the exception
40 /// specification of that function. This function detects whether we're in
41 /// such a case and turns off delay-parsing of exception specifications.
42 bool Sema::isLibstdcxxEagerExceptionSpecHack(const Declarator &D) {
43 auto *RD = dyn_cast<CXXRecordDecl>(CurContext);
45 // All the problem cases are member functions named "swap" within class
46 // templates declared directly within namespace std.
47 if (!RD || RD->getEnclosingNamespaceContext() != getStdNamespace() ||
48 !RD->getIdentifier() || !RD->getDescribedClassTemplate() ||
49 !D.getIdentifier() || !D.getIdentifier()->isStr("swap"))
52 // Only apply this hack within a system header.
53 if (!Context.getSourceManager().isInSystemHeader(D.getLocStart()))
56 return llvm::StringSwitch<bool>(RD->getIdentifier()->getName())
59 .Case("priority_queue", true)
65 /// CheckSpecifiedExceptionType - Check if the given type is valid in an
66 /// exception specification. Incomplete types, or pointers to incomplete types
67 /// other than void are not allowed.
69 /// \param[in,out] T The exception type. This will be decayed to a pointer type
70 /// when the input is an array or a function type.
71 bool Sema::CheckSpecifiedExceptionType(QualType &T, const SourceRange &Range) {
72 // C++11 [except.spec]p2:
73 // A type cv T, "array of T", or "function returning T" denoted
74 // in an exception-specification is adjusted to type T, "pointer to T", or
75 // "pointer to function returning T", respectively.
77 // We also apply this rule in C++98.
79 T = Context.getArrayDecayedType(T);
80 else if (T->isFunctionType())
81 T = Context.getPointerType(T);
84 QualType PointeeT = T;
85 if (const PointerType *PT = T->getAs<PointerType>()) {
86 PointeeT = PT->getPointeeType();
89 // cv void* is explicitly permitted, despite being a pointer to an
91 if (PointeeT->isVoidType())
93 } else if (const ReferenceType *RT = T->getAs<ReferenceType>()) {
94 PointeeT = RT->getPointeeType();
97 if (RT->isRValueReferenceType()) {
98 // C++11 [except.spec]p2:
99 // A type denoted in an exception-specification shall not denote [...]
100 // an rvalue reference type.
101 Diag(Range.getBegin(), diag::err_rref_in_exception_spec)
107 // C++11 [except.spec]p2:
108 // A type denoted in an exception-specification shall not denote an
109 // incomplete type other than a class currently being defined [...].
110 // A type denoted in an exception-specification shall not denote a
111 // pointer or reference to an incomplete type, other than (cv) void* or a
112 // pointer or reference to a class currently being defined.
113 if (!(PointeeT->isRecordType() &&
114 PointeeT->getAs<RecordType>()->isBeingDefined()) &&
115 RequireCompleteType(Range.getBegin(), PointeeT,
116 diag::err_incomplete_in_exception_spec, Kind, Range))
122 /// CheckDistantExceptionSpec - Check if the given type is a pointer or pointer
123 /// to member to a function with an exception specification. This means that
124 /// it is invalid to add another level of indirection.
125 bool Sema::CheckDistantExceptionSpec(QualType T) {
126 if (const PointerType *PT = T->getAs<PointerType>())
127 T = PT->getPointeeType();
128 else if (const MemberPointerType *PT = T->getAs<MemberPointerType>())
129 T = PT->getPointeeType();
133 const FunctionProtoType *FnT = T->getAs<FunctionProtoType>();
137 return FnT->hasExceptionSpec();
140 const FunctionProtoType *
141 Sema::ResolveExceptionSpec(SourceLocation Loc, const FunctionProtoType *FPT) {
142 if (FPT->getExceptionSpecType() == EST_Unparsed) {
143 Diag(Loc, diag::err_exception_spec_not_parsed);
147 if (!isUnresolvedExceptionSpec(FPT->getExceptionSpecType()))
150 FunctionDecl *SourceDecl = FPT->getExceptionSpecDecl();
151 const FunctionProtoType *SourceFPT =
152 SourceDecl->getType()->castAs<FunctionProtoType>();
154 // If the exception specification has already been resolved, just return it.
155 if (!isUnresolvedExceptionSpec(SourceFPT->getExceptionSpecType()))
158 // Compute or instantiate the exception specification now.
159 if (SourceFPT->getExceptionSpecType() == EST_Unevaluated)
160 EvaluateImplicitExceptionSpec(Loc, cast<CXXMethodDecl>(SourceDecl));
162 InstantiateExceptionSpec(Loc, SourceDecl);
164 return SourceDecl->getType()->castAs<FunctionProtoType>();
168 Sema::UpdateExceptionSpec(FunctionDecl *FD,
169 const FunctionProtoType::ExceptionSpecInfo &ESI) {
170 for (auto *Redecl : FD->redecls())
171 Context.adjustExceptionSpec(cast<FunctionDecl>(Redecl), ESI);
173 // If we've fully resolved the exception specification, notify listeners.
174 if (!isUnresolvedExceptionSpec(ESI.Type))
175 if (auto *Listener = getASTMutationListener())
176 Listener->ResolvedExceptionSpec(FD);
179 /// Determine whether a function has an implicitly-generated exception
181 static bool hasImplicitExceptionSpec(FunctionDecl *Decl) {
182 if (!isa<CXXDestructorDecl>(Decl) &&
183 Decl->getDeclName().getCXXOverloadedOperator() != OO_Delete &&
184 Decl->getDeclName().getCXXOverloadedOperator() != OO_Array_Delete)
187 // For a function that the user didn't declare:
188 // - if this is a destructor, its exception specification is implicit.
189 // - if this is 'operator delete' or 'operator delete[]', the exception
190 // specification is as-if an explicit exception specification was given
191 // (per [basic.stc.dynamic]p2).
192 if (!Decl->getTypeSourceInfo())
193 return isa<CXXDestructorDecl>(Decl);
195 const FunctionProtoType *Ty =
196 Decl->getTypeSourceInfo()->getType()->getAs<FunctionProtoType>();
197 return !Ty->hasExceptionSpec();
200 bool Sema::CheckEquivalentExceptionSpec(FunctionDecl *Old, FunctionDecl *New) {
201 OverloadedOperatorKind OO = New->getDeclName().getCXXOverloadedOperator();
202 bool IsOperatorNew = OO == OO_New || OO == OO_Array_New;
203 bool MissingExceptionSpecification = false;
204 bool MissingEmptyExceptionSpecification = false;
206 unsigned DiagID = diag::err_mismatched_exception_spec;
207 bool ReturnValueOnError = true;
208 if (getLangOpts().MicrosoftExt) {
209 DiagID = diag::ext_mismatched_exception_spec;
210 ReturnValueOnError = false;
213 // Check the types as written: they must match before any exception
214 // specification adjustment is applied.
215 if (!CheckEquivalentExceptionSpec(
216 PDiag(DiagID), PDiag(diag::note_previous_declaration),
217 Old->getType()->getAs<FunctionProtoType>(), Old->getLocation(),
218 New->getType()->getAs<FunctionProtoType>(), New->getLocation(),
219 &MissingExceptionSpecification, &MissingEmptyExceptionSpecification,
220 /*AllowNoexceptAllMatchWithNoSpec=*/true, IsOperatorNew)) {
221 // C++11 [except.spec]p4 [DR1492]:
222 // If a declaration of a function has an implicit
223 // exception-specification, other declarations of the function shall
224 // not specify an exception-specification.
225 if (getLangOpts().CPlusPlus11 &&
226 hasImplicitExceptionSpec(Old) != hasImplicitExceptionSpec(New)) {
227 Diag(New->getLocation(), diag::ext_implicit_exception_spec_mismatch)
228 << hasImplicitExceptionSpec(Old);
229 if (!Old->getLocation().isInvalid())
230 Diag(Old->getLocation(), diag::note_previous_declaration);
235 // The failure was something other than an missing exception
236 // specification; return an error, except in MS mode where this is a warning.
237 if (!MissingExceptionSpecification)
238 return ReturnValueOnError;
240 const FunctionProtoType *NewProto =
241 New->getType()->castAs<FunctionProtoType>();
243 // The new function declaration is only missing an empty exception
244 // specification "throw()". If the throw() specification came from a
245 // function in a system header that has C linkage, just add an empty
246 // exception specification to the "new" declaration. This is an
247 // egregious workaround for glibc, which adds throw() specifications
248 // to many libc functions as an optimization. Unfortunately, that
249 // optimization isn't permitted by the C++ standard, so we're forced
250 // to work around it here.
251 if (MissingEmptyExceptionSpecification && NewProto &&
252 (Old->getLocation().isInvalid() ||
253 Context.getSourceManager().isInSystemHeader(Old->getLocation())) &&
255 New->setType(Context.getFunctionType(
256 NewProto->getReturnType(), NewProto->getParamTypes(),
257 NewProto->getExtProtoInfo().withExceptionSpec(EST_DynamicNone)));
261 const FunctionProtoType *OldProto =
262 Old->getType()->castAs<FunctionProtoType>();
264 FunctionProtoType::ExceptionSpecInfo ESI = OldProto->getExceptionSpecType();
265 if (ESI.Type == EST_Dynamic) {
266 ESI.Exceptions = OldProto->exceptions();
267 } else if (ESI.Type == EST_ComputedNoexcept) {
268 // FIXME: We can't just take the expression from the old prototype. It
269 // likely contains references to the old prototype's parameters.
272 // Update the type of the function with the appropriate exception
274 New->setType(Context.getFunctionType(
275 NewProto->getReturnType(), NewProto->getParamTypes(),
276 NewProto->getExtProtoInfo().withExceptionSpec(ESI)));
278 // Warn about the lack of exception specification.
279 SmallString<128> ExceptionSpecString;
280 llvm::raw_svector_ostream OS(ExceptionSpecString);
281 switch (OldProto->getExceptionSpecType()) {
282 case EST_DynamicNone:
288 bool OnFirstException = true;
289 for (const auto &E : OldProto->exceptions()) {
290 if (OnFirstException)
291 OnFirstException = false;
295 OS << E.getAsString(getPrintingPolicy());
301 case EST_BasicNoexcept:
305 case EST_ComputedNoexcept:
307 assert(OldProto->getNoexceptExpr() != nullptr && "Expected non-null Expr");
308 OldProto->getNoexceptExpr()->printPretty(OS, nullptr, getPrintingPolicy());
313 llvm_unreachable("This spec type is compatible with none.");
317 SourceLocation FixItLoc;
318 if (TypeSourceInfo *TSInfo = New->getTypeSourceInfo()) {
319 TypeLoc TL = TSInfo->getTypeLoc().IgnoreParens();
320 if (FunctionTypeLoc FTLoc = TL.getAs<FunctionTypeLoc>())
321 FixItLoc = getLocForEndOfToken(FTLoc.getLocalRangeEnd());
324 if (FixItLoc.isInvalid())
325 Diag(New->getLocation(), diag::warn_missing_exception_specification)
328 // FIXME: This will get more complicated with C++0x
329 // late-specified return types.
330 Diag(New->getLocation(), diag::warn_missing_exception_specification)
332 << FixItHint::CreateInsertion(FixItLoc, " " + OS.str().str());
335 if (!Old->getLocation().isInvalid())
336 Diag(Old->getLocation(), diag::note_previous_declaration);
341 /// CheckEquivalentExceptionSpec - Check if the two types have equivalent
342 /// exception specifications. Exception specifications are equivalent if
343 /// they allow exactly the same set of exception types. It does not matter how
344 /// that is achieved. See C++ [except.spec]p2.
345 bool Sema::CheckEquivalentExceptionSpec(
346 const FunctionProtoType *Old, SourceLocation OldLoc,
347 const FunctionProtoType *New, SourceLocation NewLoc) {
348 unsigned DiagID = diag::err_mismatched_exception_spec;
349 if (getLangOpts().MicrosoftExt)
350 DiagID = diag::ext_mismatched_exception_spec;
351 bool Result = CheckEquivalentExceptionSpec(PDiag(DiagID),
352 PDiag(diag::note_previous_declaration), Old, OldLoc, New, NewLoc);
354 // In Microsoft mode, mismatching exception specifications just cause a warning.
355 if (getLangOpts().MicrosoftExt)
360 /// CheckEquivalentExceptionSpec - Check if the two types have compatible
361 /// exception specifications. See C++ [except.spec]p3.
363 /// \return \c false if the exception specifications match, \c true if there is
364 /// a problem. If \c true is returned, either a diagnostic has already been
365 /// produced or \c *MissingExceptionSpecification is set to \c true.
366 bool Sema::CheckEquivalentExceptionSpec(const PartialDiagnostic &DiagID,
367 const PartialDiagnostic & NoteID,
368 const FunctionProtoType *Old,
369 SourceLocation OldLoc,
370 const FunctionProtoType *New,
371 SourceLocation NewLoc,
372 bool *MissingExceptionSpecification,
373 bool*MissingEmptyExceptionSpecification,
374 bool AllowNoexceptAllMatchWithNoSpec,
375 bool IsOperatorNew) {
376 // Just completely ignore this under -fno-exceptions.
377 if (!getLangOpts().CXXExceptions)
380 if (MissingExceptionSpecification)
381 *MissingExceptionSpecification = false;
383 if (MissingEmptyExceptionSpecification)
384 *MissingEmptyExceptionSpecification = false;
386 Old = ResolveExceptionSpec(NewLoc, Old);
389 New = ResolveExceptionSpec(NewLoc, New);
393 // C++0x [except.spec]p3: Two exception-specifications are compatible if:
394 // - both are non-throwing, regardless of their form,
395 // - both have the form noexcept(constant-expression) and the constant-
396 // expressions are equivalent,
397 // - both are dynamic-exception-specifications that have the same set of
400 // C++0x [except.spec]p12: An exception-specifcation is non-throwing if it is
401 // of the form throw(), noexcept, or noexcept(constant-expression) where the
402 // constant-expression yields true.
404 // C++0x [except.spec]p4: If any declaration of a function has an exception-
405 // specifier that is not a noexcept-specification allowing all exceptions,
406 // all declarations [...] of that function shall have a compatible
407 // exception-specification.
409 // That last point basically means that noexcept(false) matches no spec.
410 // It's considered when AllowNoexceptAllMatchWithNoSpec is true.
412 ExceptionSpecificationType OldEST = Old->getExceptionSpecType();
413 ExceptionSpecificationType NewEST = New->getExceptionSpecType();
415 assert(!isUnresolvedExceptionSpec(OldEST) &&
416 !isUnresolvedExceptionSpec(NewEST) &&
417 "Shouldn't see unknown exception specifications here");
419 // Shortcut the case where both have no spec.
420 if (OldEST == EST_None && NewEST == EST_None)
423 FunctionProtoType::NoexceptResult OldNR = Old->getNoexceptSpec(Context);
424 FunctionProtoType::NoexceptResult NewNR = New->getNoexceptSpec(Context);
425 if (OldNR == FunctionProtoType::NR_BadNoexcept ||
426 NewNR == FunctionProtoType::NR_BadNoexcept)
429 // Dependent noexcept specifiers are compatible with each other, but nothing
431 // One noexcept is compatible with another if the argument is the same
432 if (OldNR == NewNR &&
433 OldNR != FunctionProtoType::NR_NoNoexcept &&
434 NewNR != FunctionProtoType::NR_NoNoexcept)
436 if (OldNR != NewNR &&
437 OldNR != FunctionProtoType::NR_NoNoexcept &&
438 NewNR != FunctionProtoType::NR_NoNoexcept) {
439 Diag(NewLoc, DiagID);
440 if (NoteID.getDiagID() != 0)
441 Diag(OldLoc, NoteID);
445 // The MS extension throw(...) is compatible with itself.
446 if (OldEST == EST_MSAny && NewEST == EST_MSAny)
449 // It's also compatible with no spec.
450 if ((OldEST == EST_None && NewEST == EST_MSAny) ||
451 (OldEST == EST_MSAny && NewEST == EST_None))
454 // It's also compatible with noexcept(false).
455 if (OldEST == EST_MSAny && NewNR == FunctionProtoType::NR_Throw)
457 if (NewEST == EST_MSAny && OldNR == FunctionProtoType::NR_Throw)
460 // As described above, noexcept(false) matches no spec only for functions.
461 if (AllowNoexceptAllMatchWithNoSpec) {
462 if (OldEST == EST_None && NewNR == FunctionProtoType::NR_Throw)
464 if (NewEST == EST_None && OldNR == FunctionProtoType::NR_Throw)
468 // Any non-throwing specifications are compatible.
469 bool OldNonThrowing = OldNR == FunctionProtoType::NR_Nothrow ||
470 OldEST == EST_DynamicNone;
471 bool NewNonThrowing = NewNR == FunctionProtoType::NR_Nothrow ||
472 NewEST == EST_DynamicNone;
473 if (OldNonThrowing && NewNonThrowing)
476 // As a special compatibility feature, under C++0x we accept no spec and
477 // throw(std::bad_alloc) as equivalent for operator new and operator new[].
478 // This is because the implicit declaration changed, but old code would break.
479 if (getLangOpts().CPlusPlus11 && IsOperatorNew) {
480 const FunctionProtoType *WithExceptions = nullptr;
481 if (OldEST == EST_None && NewEST == EST_Dynamic)
482 WithExceptions = New;
483 else if (OldEST == EST_Dynamic && NewEST == EST_None)
484 WithExceptions = Old;
485 if (WithExceptions && WithExceptions->getNumExceptions() == 1) {
486 // One has no spec, the other throw(something). If that something is
487 // std::bad_alloc, all conditions are met.
488 QualType Exception = *WithExceptions->exception_begin();
489 if (CXXRecordDecl *ExRecord = Exception->getAsCXXRecordDecl()) {
490 IdentifierInfo* Name = ExRecord->getIdentifier();
491 if (Name && Name->getName() == "bad_alloc") {
492 // It's called bad_alloc, but is it in std?
493 if (ExRecord->isInStdNamespace()) {
501 // At this point, the only remaining valid case is two matching dynamic
502 // specifications. We return here unless both specifications are dynamic.
503 if (OldEST != EST_Dynamic || NewEST != EST_Dynamic) {
504 if (MissingExceptionSpecification && Old->hasExceptionSpec() &&
505 !New->hasExceptionSpec()) {
506 // The old type has an exception specification of some sort, but
507 // the new type does not.
508 *MissingExceptionSpecification = true;
510 if (MissingEmptyExceptionSpecification && OldNonThrowing) {
511 // The old type has a throw() or noexcept(true) exception specification
512 // and the new type has no exception specification, and the caller asked
513 // to handle this itself.
514 *MissingEmptyExceptionSpecification = true;
520 Diag(NewLoc, DiagID);
521 if (NoteID.getDiagID() != 0)
522 Diag(OldLoc, NoteID);
526 assert(OldEST == EST_Dynamic && NewEST == EST_Dynamic &&
527 "Exception compatibility logic error: non-dynamic spec slipped through.");
530 // Both have a dynamic exception spec. Collect the first set, then compare
532 llvm::SmallPtrSet<CanQualType, 8> OldTypes, NewTypes;
533 for (const auto &I : Old->exceptions())
534 OldTypes.insert(Context.getCanonicalType(I).getUnqualifiedType());
536 for (const auto &I : New->exceptions()) {
537 CanQualType TypePtr = Context.getCanonicalType(I).getUnqualifiedType();
538 if(OldTypes.count(TypePtr))
539 NewTypes.insert(TypePtr);
544 Success = Success && OldTypes.size() == NewTypes.size();
549 Diag(NewLoc, DiagID);
550 if (NoteID.getDiagID() != 0)
551 Diag(OldLoc, NoteID);
555 /// CheckExceptionSpecSubset - Check whether the second function type's
556 /// exception specification is a subset (or equivalent) of the first function
557 /// type. This is used by override and pointer assignment checks.
558 bool Sema::CheckExceptionSpecSubset(
559 const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
560 const FunctionProtoType *Superset, SourceLocation SuperLoc,
561 const FunctionProtoType *Subset, SourceLocation SubLoc) {
563 // Just auto-succeed under -fno-exceptions.
564 if (!getLangOpts().CXXExceptions)
567 // FIXME: As usual, we could be more specific in our error messages, but
568 // that better waits until we've got types with source locations.
570 if (!SubLoc.isValid())
573 // Resolve the exception specifications, if needed.
574 Superset = ResolveExceptionSpec(SuperLoc, Superset);
577 Subset = ResolveExceptionSpec(SubLoc, Subset);
581 ExceptionSpecificationType SuperEST = Superset->getExceptionSpecType();
583 // If superset contains everything, we're done.
584 if (SuperEST == EST_None || SuperEST == EST_MSAny)
585 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
587 // If there are dependent noexcept specs, assume everything is fine. Unlike
588 // with the equivalency check, this is safe in this case, because we don't
589 // want to merge declarations. Checks after instantiation will catch any
590 // omissions we make here.
591 // We also shortcut checking if a noexcept expression was bad.
593 FunctionProtoType::NoexceptResult SuperNR =Superset->getNoexceptSpec(Context);
594 if (SuperNR == FunctionProtoType::NR_BadNoexcept ||
595 SuperNR == FunctionProtoType::NR_Dependent)
598 // Another case of the superset containing everything.
599 if (SuperNR == FunctionProtoType::NR_Throw)
600 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
602 ExceptionSpecificationType SubEST = Subset->getExceptionSpecType();
604 assert(!isUnresolvedExceptionSpec(SuperEST) &&
605 !isUnresolvedExceptionSpec(SubEST) &&
606 "Shouldn't see unknown exception specifications here");
608 // It does not. If the subset contains everything, we've failed.
609 if (SubEST == EST_None || SubEST == EST_MSAny) {
610 Diag(SubLoc, DiagID);
611 if (NoteID.getDiagID() != 0)
612 Diag(SuperLoc, NoteID);
616 FunctionProtoType::NoexceptResult SubNR = Subset->getNoexceptSpec(Context);
617 if (SubNR == FunctionProtoType::NR_BadNoexcept ||
618 SubNR == FunctionProtoType::NR_Dependent)
621 // Another case of the subset containing everything.
622 if (SubNR == FunctionProtoType::NR_Throw) {
623 Diag(SubLoc, DiagID);
624 if (NoteID.getDiagID() != 0)
625 Diag(SuperLoc, NoteID);
629 // If the subset contains nothing, we're done.
630 if (SubEST == EST_DynamicNone || SubNR == FunctionProtoType::NR_Nothrow)
631 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
633 // Otherwise, if the superset contains nothing, we've failed.
634 if (SuperEST == EST_DynamicNone || SuperNR == FunctionProtoType::NR_Nothrow) {
635 Diag(SubLoc, DiagID);
636 if (NoteID.getDiagID() != 0)
637 Diag(SuperLoc, NoteID);
641 assert(SuperEST == EST_Dynamic && SubEST == EST_Dynamic &&
642 "Exception spec subset: non-dynamic case slipped through.");
644 // Neither contains everything or nothing. Do a proper comparison.
645 for (const auto &SubI : Subset->exceptions()) {
646 // Take one type from the subset.
647 QualType CanonicalSubT = Context.getCanonicalType(SubI);
648 // Unwrap pointers and references so that we can do checks within a class
649 // hierarchy. Don't unwrap member pointers; they don't have hierarchy
650 // conversions on the pointee.
651 bool SubIsPointer = false;
652 if (const ReferenceType *RefTy = CanonicalSubT->getAs<ReferenceType>())
653 CanonicalSubT = RefTy->getPointeeType();
654 if (const PointerType *PtrTy = CanonicalSubT->getAs<PointerType>()) {
655 CanonicalSubT = PtrTy->getPointeeType();
658 bool SubIsClass = CanonicalSubT->isRecordType();
659 CanonicalSubT = CanonicalSubT.getLocalUnqualifiedType();
661 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
662 /*DetectVirtual=*/false);
664 bool Contained = false;
665 // Make sure it's in the superset.
666 for (const auto &SuperI : Superset->exceptions()) {
667 QualType CanonicalSuperT = Context.getCanonicalType(SuperI);
668 // SubT must be SuperT or derived from it, or pointer or reference to
670 if (const ReferenceType *RefTy = CanonicalSuperT->getAs<ReferenceType>())
671 CanonicalSuperT = RefTy->getPointeeType();
673 if (const PointerType *PtrTy = CanonicalSuperT->getAs<PointerType>())
674 CanonicalSuperT = PtrTy->getPointeeType();
679 CanonicalSuperT = CanonicalSuperT.getLocalUnqualifiedType();
680 // If the types are the same, move on to the next type in the subset.
681 if (CanonicalSubT == CanonicalSuperT) {
686 // Otherwise we need to check the inheritance.
687 if (!SubIsClass || !CanonicalSuperT->isRecordType())
691 if (!IsDerivedFrom(CanonicalSubT, CanonicalSuperT, Paths))
694 if (Paths.isAmbiguous(Context.getCanonicalType(CanonicalSuperT)))
697 // Do this check from a context without privileges.
698 switch (CheckBaseClassAccess(SourceLocation(),
699 CanonicalSuperT, CanonicalSubT,
703 /*ForceUnprivileged*/ true)) {
704 case AR_accessible: break;
705 case AR_inaccessible: continue;
707 llvm_unreachable("access check dependent for unprivileged context");
709 llvm_unreachable("access check delayed in non-declaration");
716 Diag(SubLoc, DiagID);
717 if (NoteID.getDiagID() != 0)
718 Diag(SuperLoc, NoteID);
722 // We've run half the gauntlet.
723 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
726 static bool CheckSpecForTypesEquivalent(Sema &S,
727 const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
728 QualType Target, SourceLocation TargetLoc,
729 QualType Source, SourceLocation SourceLoc)
731 const FunctionProtoType *TFunc = GetUnderlyingFunction(Target);
734 const FunctionProtoType *SFunc = GetUnderlyingFunction(Source);
738 return S.CheckEquivalentExceptionSpec(DiagID, NoteID, TFunc, TargetLoc,
742 /// CheckParamExceptionSpec - Check if the parameter and return types of the
743 /// two functions have equivalent exception specs. This is part of the
744 /// assignment and override compatibility check. We do not check the parameters
745 /// of parameter function pointers recursively, as no sane programmer would
746 /// even be able to write such a function type.
747 bool Sema::CheckParamExceptionSpec(const PartialDiagnostic &NoteID,
748 const FunctionProtoType *Target,
749 SourceLocation TargetLoc,
750 const FunctionProtoType *Source,
751 SourceLocation SourceLoc) {
752 if (CheckSpecForTypesEquivalent(
753 *this, PDiag(diag::err_deep_exception_specs_differ) << 0, PDiag(),
754 Target->getReturnType(), TargetLoc, Source->getReturnType(),
758 // We shouldn't even be testing this unless the arguments are otherwise
760 assert(Target->getNumParams() == Source->getNumParams() &&
761 "Functions have different argument counts.");
762 for (unsigned i = 0, E = Target->getNumParams(); i != E; ++i) {
763 if (CheckSpecForTypesEquivalent(
764 *this, PDiag(diag::err_deep_exception_specs_differ) << 1, PDiag(),
765 Target->getParamType(i), TargetLoc, Source->getParamType(i),
772 bool Sema::CheckExceptionSpecCompatibility(Expr *From, QualType ToType) {
773 // First we check for applicability.
774 // Target type must be a function, function pointer or function reference.
775 const FunctionProtoType *ToFunc = GetUnderlyingFunction(ToType);
776 if (!ToFunc || ToFunc->hasDependentExceptionSpec())
779 // SourceType must be a function or function pointer.
780 const FunctionProtoType *FromFunc = GetUnderlyingFunction(From->getType());
781 if (!FromFunc || FromFunc->hasDependentExceptionSpec())
784 // Now we've got the correct types on both sides, check their compatibility.
785 // This means that the source of the conversion can only throw a subset of
786 // the exceptions of the target, and any exception specs on arguments or
787 // return types must be equivalent.
789 // FIXME: If there is a nested dependent exception specification, we should
790 // not be checking it here. This is fine:
791 // template<typename T> void f() {
792 // void (*p)(void (*) throw(T));
793 // void (*q)(void (*) throw(int)) = p;
795 // ... because it might be instantiated with T=int.
796 return CheckExceptionSpecSubset(PDiag(diag::err_incompatible_exception_specs),
798 From->getSourceRange().getBegin(),
799 FromFunc, SourceLocation());
802 bool Sema::CheckOverridingFunctionExceptionSpec(const CXXMethodDecl *New,
803 const CXXMethodDecl *Old) {
804 // If the new exception specification hasn't been parsed yet, skip the check.
805 // We'll get called again once it's been parsed.
806 if (New->getType()->castAs<FunctionProtoType>()->getExceptionSpecType() ==
809 if (getLangOpts().CPlusPlus11 && isa<CXXDestructorDecl>(New)) {
810 // Don't check uninstantiated template destructors at all. We can only
811 // synthesize correct specs after the template is instantiated.
812 if (New->getParent()->isDependentType())
814 if (New->getParent()->isBeingDefined()) {
815 // The destructor might be updated once the definition is finished. So
816 // remember it and check later.
817 DelayedExceptionSpecChecks.push_back(std::make_pair(New, Old));
821 // If the old exception specification hasn't been parsed yet, remember that
822 // we need to perform this check when we get to the end of the outermost
823 // lexically-surrounding class.
824 if (Old->getType()->castAs<FunctionProtoType>()->getExceptionSpecType() ==
826 DelayedExceptionSpecChecks.push_back(std::make_pair(New, Old));
829 unsigned DiagID = diag::err_override_exception_spec;
830 if (getLangOpts().MicrosoftExt)
831 DiagID = diag::ext_override_exception_spec;
832 return CheckExceptionSpecSubset(PDiag(DiagID),
833 PDiag(diag::note_overridden_virtual_function),
834 Old->getType()->getAs<FunctionProtoType>(),
836 New->getType()->getAs<FunctionProtoType>(),
840 static CanThrowResult canSubExprsThrow(Sema &S, const Expr *CE) {
841 Expr *E = const_cast<Expr*>(CE);
842 CanThrowResult R = CT_Cannot;
843 for (Expr::child_range I = E->children(); I && R != CT_Can; ++I)
844 R = mergeCanThrow(R, S.canThrow(cast<Expr>(*I)));
848 static CanThrowResult canCalleeThrow(Sema &S, const Expr *E, const Decl *D) {
849 assert(D && "Expected decl");
851 // See if we can get a function type from the decl somehow.
852 const ValueDecl *VD = dyn_cast<ValueDecl>(D);
853 if (!VD) // If we have no clue what we're calling, assume the worst.
856 // As an extension, we assume that __attribute__((nothrow)) functions don't
858 if (isa<FunctionDecl>(D) && D->hasAttr<NoThrowAttr>())
861 QualType T = VD->getType();
862 const FunctionProtoType *FT;
863 if ((FT = T->getAs<FunctionProtoType>())) {
864 } else if (const PointerType *PT = T->getAs<PointerType>())
865 FT = PT->getPointeeType()->getAs<FunctionProtoType>();
866 else if (const ReferenceType *RT = T->getAs<ReferenceType>())
867 FT = RT->getPointeeType()->getAs<FunctionProtoType>();
868 else if (const MemberPointerType *MT = T->getAs<MemberPointerType>())
869 FT = MT->getPointeeType()->getAs<FunctionProtoType>();
870 else if (const BlockPointerType *BT = T->getAs<BlockPointerType>())
871 FT = BT->getPointeeType()->getAs<FunctionProtoType>();
876 FT = S.ResolveExceptionSpec(E->getLocStart(), FT);
880 return FT->isNothrow(S.Context) ? CT_Cannot : CT_Can;
883 static CanThrowResult canDynamicCastThrow(const CXXDynamicCastExpr *DC) {
884 if (DC->isTypeDependent())
887 if (!DC->getTypeAsWritten()->isReferenceType())
890 if (DC->getSubExpr()->isTypeDependent())
893 return DC->getCastKind() == clang::CK_Dynamic? CT_Can : CT_Cannot;
896 static CanThrowResult canTypeidThrow(Sema &S, const CXXTypeidExpr *DC) {
897 if (DC->isTypeOperand())
900 Expr *Op = DC->getExprOperand();
901 if (Op->isTypeDependent())
904 const RecordType *RT = Op->getType()->getAs<RecordType>();
908 if (!cast<CXXRecordDecl>(RT->getDecl())->isPolymorphic())
911 if (Op->Classify(S.Context).isPRValue())
917 CanThrowResult Sema::canThrow(const Expr *E) {
918 // C++ [expr.unary.noexcept]p3:
919 // [Can throw] if in a potentially-evaluated context the expression would
921 switch (E->getStmtClass()) {
922 case Expr::CXXThrowExprClass:
923 // - a potentially evaluated throw-expression
926 case Expr::CXXDynamicCastExprClass: {
927 // - a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
928 // where T is a reference type, that requires a run-time check
929 CanThrowResult CT = canDynamicCastThrow(cast<CXXDynamicCastExpr>(E));
932 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
935 case Expr::CXXTypeidExprClass:
936 // - a potentially evaluated typeid expression applied to a glvalue
937 // expression whose type is a polymorphic class type
938 return canTypeidThrow(*this, cast<CXXTypeidExpr>(E));
940 // - a potentially evaluated call to a function, member function, function
941 // pointer, or member function pointer that does not have a non-throwing
942 // exception-specification
943 case Expr::CallExprClass:
944 case Expr::CXXMemberCallExprClass:
945 case Expr::CXXOperatorCallExprClass:
946 case Expr::UserDefinedLiteralClass: {
947 const CallExpr *CE = cast<CallExpr>(E);
949 if (E->isTypeDependent())
951 else if (isa<CXXPseudoDestructorExpr>(CE->getCallee()->IgnoreParens()))
953 else if (CE->getCalleeDecl())
954 CT = canCalleeThrow(*this, E, CE->getCalleeDecl());
959 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
962 case Expr::CXXConstructExprClass:
963 case Expr::CXXTemporaryObjectExprClass: {
964 CanThrowResult CT = canCalleeThrow(*this, E,
965 cast<CXXConstructExpr>(E)->getConstructor());
968 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
971 case Expr::LambdaExprClass: {
972 const LambdaExpr *Lambda = cast<LambdaExpr>(E);
973 CanThrowResult CT = CT_Cannot;
974 for (LambdaExpr::capture_init_iterator Cap = Lambda->capture_init_begin(),
975 CapEnd = Lambda->capture_init_end();
976 Cap != CapEnd; ++Cap)
977 CT = mergeCanThrow(CT, canThrow(*Cap));
981 case Expr::CXXNewExprClass: {
983 if (E->isTypeDependent())
986 CT = canCalleeThrow(*this, E, cast<CXXNewExpr>(E)->getOperatorNew());
989 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
992 case Expr::CXXDeleteExprClass: {
994 QualType DTy = cast<CXXDeleteExpr>(E)->getDestroyedType();
995 if (DTy.isNull() || DTy->isDependentType()) {
998 CT = canCalleeThrow(*this, E,
999 cast<CXXDeleteExpr>(E)->getOperatorDelete());
1000 if (const RecordType *RT = DTy->getAs<RecordType>()) {
1001 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1002 const CXXDestructorDecl *DD = RD->getDestructor();
1004 CT = mergeCanThrow(CT, canCalleeThrow(*this, E, DD));
1009 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1012 case Expr::CXXBindTemporaryExprClass: {
1013 // The bound temporary has to be destroyed again, which might throw.
1014 CanThrowResult CT = canCalleeThrow(*this, E,
1015 cast<CXXBindTemporaryExpr>(E)->getTemporary()->getDestructor());
1018 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1021 // ObjC message sends are like function calls, but never have exception
1023 case Expr::ObjCMessageExprClass:
1024 case Expr::ObjCPropertyRefExprClass:
1025 case Expr::ObjCSubscriptRefExprClass:
1028 // All the ObjC literals that are implemented as calls are
1029 // potentially throwing unless we decide to close off that
1031 case Expr::ObjCArrayLiteralClass:
1032 case Expr::ObjCDictionaryLiteralClass:
1033 case Expr::ObjCBoxedExprClass:
1036 // Many other things have subexpressions, so we have to test those.
1038 case Expr::ConditionalOperatorClass:
1039 case Expr::CompoundLiteralExprClass:
1040 case Expr::CXXConstCastExprClass:
1041 case Expr::CXXReinterpretCastExprClass:
1042 case Expr::CXXStdInitializerListExprClass:
1043 case Expr::DesignatedInitExprClass:
1044 case Expr::ExprWithCleanupsClass:
1045 case Expr::ExtVectorElementExprClass:
1046 case Expr::InitListExprClass:
1047 case Expr::MemberExprClass:
1048 case Expr::ObjCIsaExprClass:
1049 case Expr::ObjCIvarRefExprClass:
1050 case Expr::ParenExprClass:
1051 case Expr::ParenListExprClass:
1052 case Expr::ShuffleVectorExprClass:
1053 case Expr::ConvertVectorExprClass:
1054 case Expr::VAArgExprClass:
1055 return canSubExprsThrow(*this, E);
1057 // Some might be dependent for other reasons.
1058 case Expr::ArraySubscriptExprClass:
1059 case Expr::BinaryOperatorClass:
1060 case Expr::CompoundAssignOperatorClass:
1061 case Expr::CStyleCastExprClass:
1062 case Expr::CXXStaticCastExprClass:
1063 case Expr::CXXFunctionalCastExprClass:
1064 case Expr::ImplicitCastExprClass:
1065 case Expr::MaterializeTemporaryExprClass:
1066 case Expr::UnaryOperatorClass: {
1067 CanThrowResult CT = E->isTypeDependent() ? CT_Dependent : CT_Cannot;
1068 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1071 // FIXME: We should handle StmtExpr, but that opens a MASSIVE can of worms.
1072 case Expr::StmtExprClass:
1075 case Expr::CXXDefaultArgExprClass:
1076 return canThrow(cast<CXXDefaultArgExpr>(E)->getExpr());
1078 case Expr::CXXDefaultInitExprClass:
1079 return canThrow(cast<CXXDefaultInitExpr>(E)->getExpr());
1081 case Expr::ChooseExprClass:
1082 if (E->isTypeDependent() || E->isValueDependent())
1083 return CT_Dependent;
1084 return canThrow(cast<ChooseExpr>(E)->getChosenSubExpr());
1086 case Expr::GenericSelectionExprClass:
1087 if (cast<GenericSelectionExpr>(E)->isResultDependent())
1088 return CT_Dependent;
1089 return canThrow(cast<GenericSelectionExpr>(E)->getResultExpr());
1091 // Some expressions are always dependent.
1092 case Expr::CXXDependentScopeMemberExprClass:
1093 case Expr::CXXUnresolvedConstructExprClass:
1094 case Expr::DependentScopeDeclRefExprClass:
1095 case Expr::CXXFoldExprClass:
1096 return CT_Dependent;
1098 case Expr::AsTypeExprClass:
1099 case Expr::BinaryConditionalOperatorClass:
1100 case Expr::BlockExprClass:
1101 case Expr::CUDAKernelCallExprClass:
1102 case Expr::DeclRefExprClass:
1103 case Expr::ObjCBridgedCastExprClass:
1104 case Expr::ObjCIndirectCopyRestoreExprClass:
1105 case Expr::ObjCProtocolExprClass:
1106 case Expr::ObjCSelectorExprClass:
1107 case Expr::OffsetOfExprClass:
1108 case Expr::PackExpansionExprClass:
1109 case Expr::PseudoObjectExprClass:
1110 case Expr::SubstNonTypeTemplateParmExprClass:
1111 case Expr::SubstNonTypeTemplateParmPackExprClass:
1112 case Expr::FunctionParmPackExprClass:
1113 case Expr::UnaryExprOrTypeTraitExprClass:
1114 case Expr::UnresolvedLookupExprClass:
1115 case Expr::UnresolvedMemberExprClass:
1116 case Expr::TypoExprClass:
1117 // FIXME: Can any of the above throw? If so, when?
1120 case Expr::AddrLabelExprClass:
1121 case Expr::ArrayTypeTraitExprClass:
1122 case Expr::AtomicExprClass:
1123 case Expr::TypeTraitExprClass:
1124 case Expr::CXXBoolLiteralExprClass:
1125 case Expr::CXXNoexceptExprClass:
1126 case Expr::CXXNullPtrLiteralExprClass:
1127 case Expr::CXXPseudoDestructorExprClass:
1128 case Expr::CXXScalarValueInitExprClass:
1129 case Expr::CXXThisExprClass:
1130 case Expr::CXXUuidofExprClass:
1131 case Expr::CharacterLiteralClass:
1132 case Expr::ExpressionTraitExprClass:
1133 case Expr::FloatingLiteralClass:
1134 case Expr::GNUNullExprClass:
1135 case Expr::ImaginaryLiteralClass:
1136 case Expr::ImplicitValueInitExprClass:
1137 case Expr::IntegerLiteralClass:
1138 case Expr::ObjCEncodeExprClass:
1139 case Expr::ObjCStringLiteralClass:
1140 case Expr::ObjCBoolLiteralExprClass:
1141 case Expr::OpaqueValueExprClass:
1142 case Expr::PredefinedExprClass:
1143 case Expr::SizeOfPackExprClass:
1144 case Expr::StringLiteralClass:
1145 // These expressions can never throw.
1148 case Expr::MSPropertyRefExprClass:
1149 llvm_unreachable("Invalid class for expression");
1151 #define STMT(CLASS, PARENT) case Expr::CLASS##Class:
1152 #define STMT_RANGE(Base, First, Last)
1153 #define LAST_STMT_RANGE(BASE, FIRST, LAST)
1154 #define EXPR(CLASS, PARENT)
1155 #define ABSTRACT_STMT(STMT)
1156 #include "clang/AST/StmtNodes.inc"
1157 case Expr::NoStmtClass:
1158 llvm_unreachable("Invalid class for expression");
1160 llvm_unreachable("Bogus StmtClass");
1163 } // end namespace clang