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 const FunctionProtoType *Proto =
165 SourceDecl->getType()->castAs<FunctionProtoType>();
166 if (Proto->getExceptionSpecType() == clang::EST_Unparsed) {
167 Diag(Loc, diag::err_exception_spec_not_parsed);
174 Sema::UpdateExceptionSpec(FunctionDecl *FD,
175 const FunctionProtoType::ExceptionSpecInfo &ESI) {
176 // If we've fully resolved the exception specification, notify listeners.
177 if (!isUnresolvedExceptionSpec(ESI.Type))
178 if (auto *Listener = getASTMutationListener())
179 Listener->ResolvedExceptionSpec(FD);
181 for (auto *Redecl : FD->redecls())
182 Context.adjustExceptionSpec(cast<FunctionDecl>(Redecl), ESI);
185 /// Determine whether a function has an implicitly-generated exception
187 static bool hasImplicitExceptionSpec(FunctionDecl *Decl) {
188 if (!isa<CXXDestructorDecl>(Decl) &&
189 Decl->getDeclName().getCXXOverloadedOperator() != OO_Delete &&
190 Decl->getDeclName().getCXXOverloadedOperator() != OO_Array_Delete)
193 // For a function that the user didn't declare:
194 // - if this is a destructor, its exception specification is implicit.
195 // - if this is 'operator delete' or 'operator delete[]', the exception
196 // specification is as-if an explicit exception specification was given
197 // (per [basic.stc.dynamic]p2).
198 if (!Decl->getTypeSourceInfo())
199 return isa<CXXDestructorDecl>(Decl);
201 const FunctionProtoType *Ty =
202 Decl->getTypeSourceInfo()->getType()->getAs<FunctionProtoType>();
203 return !Ty->hasExceptionSpec();
206 bool Sema::CheckEquivalentExceptionSpec(FunctionDecl *Old, FunctionDecl *New) {
207 OverloadedOperatorKind OO = New->getDeclName().getCXXOverloadedOperator();
208 bool IsOperatorNew = OO == OO_New || OO == OO_Array_New;
209 bool MissingExceptionSpecification = false;
210 bool MissingEmptyExceptionSpecification = false;
212 unsigned DiagID = diag::err_mismatched_exception_spec;
213 bool ReturnValueOnError = true;
214 if (getLangOpts().MicrosoftExt) {
215 DiagID = diag::ext_mismatched_exception_spec;
216 ReturnValueOnError = false;
219 // Check the types as written: they must match before any exception
220 // specification adjustment is applied.
221 if (!CheckEquivalentExceptionSpec(
222 PDiag(DiagID), PDiag(diag::note_previous_declaration),
223 Old->getType()->getAs<FunctionProtoType>(), Old->getLocation(),
224 New->getType()->getAs<FunctionProtoType>(), New->getLocation(),
225 &MissingExceptionSpecification, &MissingEmptyExceptionSpecification,
226 /*AllowNoexceptAllMatchWithNoSpec=*/true, IsOperatorNew)) {
227 // C++11 [except.spec]p4 [DR1492]:
228 // If a declaration of a function has an implicit
229 // exception-specification, other declarations of the function shall
230 // not specify an exception-specification.
231 if (getLangOpts().CPlusPlus11 &&
232 hasImplicitExceptionSpec(Old) != hasImplicitExceptionSpec(New)) {
233 Diag(New->getLocation(), diag::ext_implicit_exception_spec_mismatch)
234 << hasImplicitExceptionSpec(Old);
235 if (!Old->getLocation().isInvalid())
236 Diag(Old->getLocation(), diag::note_previous_declaration);
241 // The failure was something other than an missing exception
242 // specification; return an error, except in MS mode where this is a warning.
243 if (!MissingExceptionSpecification)
244 return ReturnValueOnError;
246 const FunctionProtoType *NewProto =
247 New->getType()->castAs<FunctionProtoType>();
249 // The new function declaration is only missing an empty exception
250 // specification "throw()". If the throw() specification came from a
251 // function in a system header that has C linkage, just add an empty
252 // exception specification to the "new" declaration. This is an
253 // egregious workaround for glibc, which adds throw() specifications
254 // to many libc functions as an optimization. Unfortunately, that
255 // optimization isn't permitted by the C++ standard, so we're forced
256 // to work around it here.
257 if (MissingEmptyExceptionSpecification && NewProto &&
258 (Old->getLocation().isInvalid() ||
259 Context.getSourceManager().isInSystemHeader(Old->getLocation())) &&
261 New->setType(Context.getFunctionType(
262 NewProto->getReturnType(), NewProto->getParamTypes(),
263 NewProto->getExtProtoInfo().withExceptionSpec(EST_DynamicNone)));
267 const FunctionProtoType *OldProto =
268 Old->getType()->castAs<FunctionProtoType>();
270 FunctionProtoType::ExceptionSpecInfo ESI = OldProto->getExceptionSpecType();
271 if (ESI.Type == EST_Dynamic) {
272 ESI.Exceptions = OldProto->exceptions();
273 } else if (ESI.Type == EST_ComputedNoexcept) {
274 // FIXME: We can't just take the expression from the old prototype. It
275 // likely contains references to the old prototype's parameters.
278 // Update the type of the function with the appropriate exception
280 New->setType(Context.getFunctionType(
281 NewProto->getReturnType(), NewProto->getParamTypes(),
282 NewProto->getExtProtoInfo().withExceptionSpec(ESI)));
284 // Warn about the lack of exception specification.
285 SmallString<128> ExceptionSpecString;
286 llvm::raw_svector_ostream OS(ExceptionSpecString);
287 switch (OldProto->getExceptionSpecType()) {
288 case EST_DynamicNone:
294 bool OnFirstException = true;
295 for (const auto &E : OldProto->exceptions()) {
296 if (OnFirstException)
297 OnFirstException = false;
301 OS << E.getAsString(getPrintingPolicy());
307 case EST_BasicNoexcept:
311 case EST_ComputedNoexcept:
313 assert(OldProto->getNoexceptExpr() != nullptr && "Expected non-null Expr");
314 OldProto->getNoexceptExpr()->printPretty(OS, nullptr, getPrintingPolicy());
319 llvm_unreachable("This spec type is compatible with none.");
323 SourceLocation FixItLoc;
324 if (TypeSourceInfo *TSInfo = New->getTypeSourceInfo()) {
325 TypeLoc TL = TSInfo->getTypeLoc().IgnoreParens();
326 if (FunctionTypeLoc FTLoc = TL.getAs<FunctionTypeLoc>())
327 FixItLoc = getLocForEndOfToken(FTLoc.getLocalRangeEnd());
330 if (FixItLoc.isInvalid())
331 Diag(New->getLocation(), diag::warn_missing_exception_specification)
334 // FIXME: This will get more complicated with C++0x
335 // late-specified return types.
336 Diag(New->getLocation(), diag::warn_missing_exception_specification)
338 << FixItHint::CreateInsertion(FixItLoc, " " + OS.str().str());
341 if (!Old->getLocation().isInvalid())
342 Diag(Old->getLocation(), diag::note_previous_declaration);
347 /// CheckEquivalentExceptionSpec - Check if the two types have equivalent
348 /// exception specifications. Exception specifications are equivalent if
349 /// they allow exactly the same set of exception types. It does not matter how
350 /// that is achieved. See C++ [except.spec]p2.
351 bool Sema::CheckEquivalentExceptionSpec(
352 const FunctionProtoType *Old, SourceLocation OldLoc,
353 const FunctionProtoType *New, SourceLocation NewLoc) {
354 unsigned DiagID = diag::err_mismatched_exception_spec;
355 if (getLangOpts().MicrosoftExt)
356 DiagID = diag::ext_mismatched_exception_spec;
357 bool Result = CheckEquivalentExceptionSpec(PDiag(DiagID),
358 PDiag(diag::note_previous_declaration), Old, OldLoc, New, NewLoc);
360 // In Microsoft mode, mismatching exception specifications just cause a warning.
361 if (getLangOpts().MicrosoftExt)
366 /// CheckEquivalentExceptionSpec - Check if the two types have compatible
367 /// exception specifications. See C++ [except.spec]p3.
369 /// \return \c false if the exception specifications match, \c true if there is
370 /// a problem. If \c true is returned, either a diagnostic has already been
371 /// produced or \c *MissingExceptionSpecification is set to \c true.
372 bool Sema::CheckEquivalentExceptionSpec(const PartialDiagnostic &DiagID,
373 const PartialDiagnostic & NoteID,
374 const FunctionProtoType *Old,
375 SourceLocation OldLoc,
376 const FunctionProtoType *New,
377 SourceLocation NewLoc,
378 bool *MissingExceptionSpecification,
379 bool*MissingEmptyExceptionSpecification,
380 bool AllowNoexceptAllMatchWithNoSpec,
381 bool IsOperatorNew) {
382 // Just completely ignore this under -fno-exceptions.
383 if (!getLangOpts().CXXExceptions)
386 if (MissingExceptionSpecification)
387 *MissingExceptionSpecification = false;
389 if (MissingEmptyExceptionSpecification)
390 *MissingEmptyExceptionSpecification = false;
392 Old = ResolveExceptionSpec(NewLoc, Old);
395 New = ResolveExceptionSpec(NewLoc, New);
399 // C++0x [except.spec]p3: Two exception-specifications are compatible if:
400 // - both are non-throwing, regardless of their form,
401 // - both have the form noexcept(constant-expression) and the constant-
402 // expressions are equivalent,
403 // - both are dynamic-exception-specifications that have the same set of
406 // C++0x [except.spec]p12: An exception-specification is non-throwing if it is
407 // of the form throw(), noexcept, or noexcept(constant-expression) where the
408 // constant-expression yields true.
410 // C++0x [except.spec]p4: If any declaration of a function has an exception-
411 // specifier that is not a noexcept-specification allowing all exceptions,
412 // all declarations [...] of that function shall have a compatible
413 // exception-specification.
415 // That last point basically means that noexcept(false) matches no spec.
416 // It's considered when AllowNoexceptAllMatchWithNoSpec is true.
418 ExceptionSpecificationType OldEST = Old->getExceptionSpecType();
419 ExceptionSpecificationType NewEST = New->getExceptionSpecType();
421 assert(!isUnresolvedExceptionSpec(OldEST) &&
422 !isUnresolvedExceptionSpec(NewEST) &&
423 "Shouldn't see unknown exception specifications here");
425 // Shortcut the case where both have no spec.
426 if (OldEST == EST_None && NewEST == EST_None)
429 FunctionProtoType::NoexceptResult OldNR = Old->getNoexceptSpec(Context);
430 FunctionProtoType::NoexceptResult NewNR = New->getNoexceptSpec(Context);
431 if (OldNR == FunctionProtoType::NR_BadNoexcept ||
432 NewNR == FunctionProtoType::NR_BadNoexcept)
435 // Dependent noexcept specifiers are compatible with each other, but nothing
437 // One noexcept is compatible with another if the argument is the same
438 if (OldNR == NewNR &&
439 OldNR != FunctionProtoType::NR_NoNoexcept &&
440 NewNR != FunctionProtoType::NR_NoNoexcept)
442 if (OldNR != NewNR &&
443 OldNR != FunctionProtoType::NR_NoNoexcept &&
444 NewNR != FunctionProtoType::NR_NoNoexcept) {
445 Diag(NewLoc, DiagID);
446 if (NoteID.getDiagID() != 0 && OldLoc.isValid())
447 Diag(OldLoc, NoteID);
451 // The MS extension throw(...) is compatible with itself.
452 if (OldEST == EST_MSAny && NewEST == EST_MSAny)
455 // It's also compatible with no spec.
456 if ((OldEST == EST_None && NewEST == EST_MSAny) ||
457 (OldEST == EST_MSAny && NewEST == EST_None))
460 // It's also compatible with noexcept(false).
461 if (OldEST == EST_MSAny && NewNR == FunctionProtoType::NR_Throw)
463 if (NewEST == EST_MSAny && OldNR == FunctionProtoType::NR_Throw)
466 // As described above, noexcept(false) matches no spec only for functions.
467 if (AllowNoexceptAllMatchWithNoSpec) {
468 if (OldEST == EST_None && NewNR == FunctionProtoType::NR_Throw)
470 if (NewEST == EST_None && OldNR == FunctionProtoType::NR_Throw)
474 // Any non-throwing specifications are compatible.
475 bool OldNonThrowing = OldNR == FunctionProtoType::NR_Nothrow ||
476 OldEST == EST_DynamicNone;
477 bool NewNonThrowing = NewNR == FunctionProtoType::NR_Nothrow ||
478 NewEST == EST_DynamicNone;
479 if (OldNonThrowing && NewNonThrowing)
482 // As a special compatibility feature, under C++0x we accept no spec and
483 // throw(std::bad_alloc) as equivalent for operator new and operator new[].
484 // This is because the implicit declaration changed, but old code would break.
485 if (getLangOpts().CPlusPlus11 && IsOperatorNew) {
486 const FunctionProtoType *WithExceptions = nullptr;
487 if (OldEST == EST_None && NewEST == EST_Dynamic)
488 WithExceptions = New;
489 else if (OldEST == EST_Dynamic && NewEST == EST_None)
490 WithExceptions = Old;
491 if (WithExceptions && WithExceptions->getNumExceptions() == 1) {
492 // One has no spec, the other throw(something). If that something is
493 // std::bad_alloc, all conditions are met.
494 QualType Exception = *WithExceptions->exception_begin();
495 if (CXXRecordDecl *ExRecord = Exception->getAsCXXRecordDecl()) {
496 IdentifierInfo* Name = ExRecord->getIdentifier();
497 if (Name && Name->getName() == "bad_alloc") {
498 // It's called bad_alloc, but is it in std?
499 if (ExRecord->isInStdNamespace()) {
507 // At this point, the only remaining valid case is two matching dynamic
508 // specifications. We return here unless both specifications are dynamic.
509 if (OldEST != EST_Dynamic || NewEST != EST_Dynamic) {
510 if (MissingExceptionSpecification && Old->hasExceptionSpec() &&
511 !New->hasExceptionSpec()) {
512 // The old type has an exception specification of some sort, but
513 // the new type does not.
514 *MissingExceptionSpecification = true;
516 if (MissingEmptyExceptionSpecification && OldNonThrowing) {
517 // The old type has a throw() or noexcept(true) exception specification
518 // and the new type has no exception specification, and the caller asked
519 // to handle this itself.
520 *MissingEmptyExceptionSpecification = true;
526 Diag(NewLoc, DiagID);
527 if (NoteID.getDiagID() != 0 && OldLoc.isValid())
528 Diag(OldLoc, NoteID);
532 assert(OldEST == EST_Dynamic && NewEST == EST_Dynamic &&
533 "Exception compatibility logic error: non-dynamic spec slipped through.");
536 // Both have a dynamic exception spec. Collect the first set, then compare
538 llvm::SmallPtrSet<CanQualType, 8> OldTypes, NewTypes;
539 for (const auto &I : Old->exceptions())
540 OldTypes.insert(Context.getCanonicalType(I).getUnqualifiedType());
542 for (const auto &I : New->exceptions()) {
543 CanQualType TypePtr = Context.getCanonicalType(I).getUnqualifiedType();
544 if(OldTypes.count(TypePtr))
545 NewTypes.insert(TypePtr);
550 Success = Success && OldTypes.size() == NewTypes.size();
555 Diag(NewLoc, DiagID);
556 if (NoteID.getDiagID() != 0 && OldLoc.isValid())
557 Diag(OldLoc, NoteID);
561 /// CheckExceptionSpecSubset - Check whether the second function type's
562 /// exception specification is a subset (or equivalent) of the first function
563 /// type. This is used by override and pointer assignment checks.
564 bool Sema::CheckExceptionSpecSubset(
565 const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
566 const FunctionProtoType *Superset, SourceLocation SuperLoc,
567 const FunctionProtoType *Subset, SourceLocation SubLoc) {
569 // Just auto-succeed under -fno-exceptions.
570 if (!getLangOpts().CXXExceptions)
573 // FIXME: As usual, we could be more specific in our error messages, but
574 // that better waits until we've got types with source locations.
576 if (!SubLoc.isValid())
579 // Resolve the exception specifications, if needed.
580 Superset = ResolveExceptionSpec(SuperLoc, Superset);
583 Subset = ResolveExceptionSpec(SubLoc, Subset);
587 ExceptionSpecificationType SuperEST = Superset->getExceptionSpecType();
589 // If superset contains everything, we're done.
590 if (SuperEST == EST_None || SuperEST == EST_MSAny)
591 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
593 // If there are dependent noexcept specs, assume everything is fine. Unlike
594 // with the equivalency check, this is safe in this case, because we don't
595 // want to merge declarations. Checks after instantiation will catch any
596 // omissions we make here.
597 // We also shortcut checking if a noexcept expression was bad.
599 FunctionProtoType::NoexceptResult SuperNR =Superset->getNoexceptSpec(Context);
600 if (SuperNR == FunctionProtoType::NR_BadNoexcept ||
601 SuperNR == FunctionProtoType::NR_Dependent)
604 // Another case of the superset containing everything.
605 if (SuperNR == FunctionProtoType::NR_Throw)
606 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
608 ExceptionSpecificationType SubEST = Subset->getExceptionSpecType();
610 assert(!isUnresolvedExceptionSpec(SuperEST) &&
611 !isUnresolvedExceptionSpec(SubEST) &&
612 "Shouldn't see unknown exception specifications here");
614 // It does not. If the subset contains everything, we've failed.
615 if (SubEST == EST_None || SubEST == EST_MSAny) {
616 Diag(SubLoc, DiagID);
617 if (NoteID.getDiagID() != 0)
618 Diag(SuperLoc, NoteID);
622 FunctionProtoType::NoexceptResult SubNR = Subset->getNoexceptSpec(Context);
623 if (SubNR == FunctionProtoType::NR_BadNoexcept ||
624 SubNR == FunctionProtoType::NR_Dependent)
627 // Another case of the subset containing everything.
628 if (SubNR == FunctionProtoType::NR_Throw) {
629 Diag(SubLoc, DiagID);
630 if (NoteID.getDiagID() != 0)
631 Diag(SuperLoc, NoteID);
635 // If the subset contains nothing, we're done.
636 if (SubEST == EST_DynamicNone || SubNR == FunctionProtoType::NR_Nothrow)
637 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
639 // Otherwise, if the superset contains nothing, we've failed.
640 if (SuperEST == EST_DynamicNone || SuperNR == FunctionProtoType::NR_Nothrow) {
641 Diag(SubLoc, DiagID);
642 if (NoteID.getDiagID() != 0)
643 Diag(SuperLoc, NoteID);
647 assert(SuperEST == EST_Dynamic && SubEST == EST_Dynamic &&
648 "Exception spec subset: non-dynamic case slipped through.");
650 // Neither contains everything or nothing. Do a proper comparison.
651 for (const auto &SubI : Subset->exceptions()) {
652 // Take one type from the subset.
653 QualType CanonicalSubT = Context.getCanonicalType(SubI);
654 // Unwrap pointers and references so that we can do checks within a class
655 // hierarchy. Don't unwrap member pointers; they don't have hierarchy
656 // conversions on the pointee.
657 bool SubIsPointer = false;
658 if (const ReferenceType *RefTy = CanonicalSubT->getAs<ReferenceType>())
659 CanonicalSubT = RefTy->getPointeeType();
660 if (const PointerType *PtrTy = CanonicalSubT->getAs<PointerType>()) {
661 CanonicalSubT = PtrTy->getPointeeType();
664 bool SubIsClass = CanonicalSubT->isRecordType();
665 CanonicalSubT = CanonicalSubT.getLocalUnqualifiedType();
667 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
668 /*DetectVirtual=*/false);
670 bool Contained = false;
671 // Make sure it's in the superset.
672 for (const auto &SuperI : Superset->exceptions()) {
673 QualType CanonicalSuperT = Context.getCanonicalType(SuperI);
674 // SubT must be SuperT or derived from it, or pointer or reference to
676 if (const ReferenceType *RefTy = CanonicalSuperT->getAs<ReferenceType>())
677 CanonicalSuperT = RefTy->getPointeeType();
679 if (const PointerType *PtrTy = CanonicalSuperT->getAs<PointerType>())
680 CanonicalSuperT = PtrTy->getPointeeType();
685 CanonicalSuperT = CanonicalSuperT.getLocalUnqualifiedType();
686 // If the types are the same, move on to the next type in the subset.
687 if (CanonicalSubT == CanonicalSuperT) {
692 // Otherwise we need to check the inheritance.
693 if (!SubIsClass || !CanonicalSuperT->isRecordType())
697 if (!IsDerivedFrom(CanonicalSubT, CanonicalSuperT, Paths))
700 if (Paths.isAmbiguous(Context.getCanonicalType(CanonicalSuperT)))
703 // Do this check from a context without privileges.
704 switch (CheckBaseClassAccess(SourceLocation(),
705 CanonicalSuperT, CanonicalSubT,
709 /*ForceUnprivileged*/ true)) {
710 case AR_accessible: break;
711 case AR_inaccessible: continue;
713 llvm_unreachable("access check dependent for unprivileged context");
715 llvm_unreachable("access check delayed in non-declaration");
722 Diag(SubLoc, DiagID);
723 if (NoteID.getDiagID() != 0)
724 Diag(SuperLoc, NoteID);
728 // We've run half the gauntlet.
729 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
732 static bool CheckSpecForTypesEquivalent(Sema &S,
733 const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
734 QualType Target, SourceLocation TargetLoc,
735 QualType Source, SourceLocation SourceLoc)
737 const FunctionProtoType *TFunc = GetUnderlyingFunction(Target);
740 const FunctionProtoType *SFunc = GetUnderlyingFunction(Source);
744 return S.CheckEquivalentExceptionSpec(DiagID, NoteID, TFunc, TargetLoc,
748 /// CheckParamExceptionSpec - Check if the parameter and return types of the
749 /// two functions have equivalent exception specs. This is part of the
750 /// assignment and override compatibility check. We do not check the parameters
751 /// of parameter function pointers recursively, as no sane programmer would
752 /// even be able to write such a function type.
753 bool Sema::CheckParamExceptionSpec(const PartialDiagnostic &NoteID,
754 const FunctionProtoType *Target,
755 SourceLocation TargetLoc,
756 const FunctionProtoType *Source,
757 SourceLocation SourceLoc) {
758 if (CheckSpecForTypesEquivalent(
759 *this, PDiag(diag::err_deep_exception_specs_differ) << 0, PDiag(),
760 Target->getReturnType(), TargetLoc, Source->getReturnType(),
764 // We shouldn't even be testing this unless the arguments are otherwise
766 assert(Target->getNumParams() == Source->getNumParams() &&
767 "Functions have different argument counts.");
768 for (unsigned i = 0, E = Target->getNumParams(); i != E; ++i) {
769 if (CheckSpecForTypesEquivalent(
770 *this, PDiag(diag::err_deep_exception_specs_differ) << 1, PDiag(),
771 Target->getParamType(i), TargetLoc, Source->getParamType(i),
778 bool Sema::CheckExceptionSpecCompatibility(Expr *From, QualType ToType) {
779 // First we check for applicability.
780 // Target type must be a function, function pointer or function reference.
781 const FunctionProtoType *ToFunc = GetUnderlyingFunction(ToType);
782 if (!ToFunc || ToFunc->hasDependentExceptionSpec())
785 // SourceType must be a function or function pointer.
786 const FunctionProtoType *FromFunc = GetUnderlyingFunction(From->getType());
787 if (!FromFunc || FromFunc->hasDependentExceptionSpec())
790 // Now we've got the correct types on both sides, check their compatibility.
791 // This means that the source of the conversion can only throw a subset of
792 // the exceptions of the target, and any exception specs on arguments or
793 // return types must be equivalent.
795 // FIXME: If there is a nested dependent exception specification, we should
796 // not be checking it here. This is fine:
797 // template<typename T> void f() {
798 // void (*p)(void (*) throw(T));
799 // void (*q)(void (*) throw(int)) = p;
801 // ... because it might be instantiated with T=int.
802 return CheckExceptionSpecSubset(PDiag(diag::err_incompatible_exception_specs),
804 From->getSourceRange().getBegin(),
805 FromFunc, SourceLocation());
808 bool Sema::CheckOverridingFunctionExceptionSpec(const CXXMethodDecl *New,
809 const CXXMethodDecl *Old) {
810 // If the new exception specification hasn't been parsed yet, skip the check.
811 // We'll get called again once it's been parsed.
812 if (New->getType()->castAs<FunctionProtoType>()->getExceptionSpecType() ==
815 if (getLangOpts().CPlusPlus11 && isa<CXXDestructorDecl>(New)) {
816 // Don't check uninstantiated template destructors at all. We can only
817 // synthesize correct specs after the template is instantiated.
818 if (New->getParent()->isDependentType())
820 if (New->getParent()->isBeingDefined()) {
821 // The destructor might be updated once the definition is finished. So
822 // remember it and check later.
823 DelayedExceptionSpecChecks.push_back(std::make_pair(New, Old));
827 // If the old exception specification hasn't been parsed yet, remember that
828 // we need to perform this check when we get to the end of the outermost
829 // lexically-surrounding class.
830 if (Old->getType()->castAs<FunctionProtoType>()->getExceptionSpecType() ==
832 DelayedExceptionSpecChecks.push_back(std::make_pair(New, Old));
835 unsigned DiagID = diag::err_override_exception_spec;
836 if (getLangOpts().MicrosoftExt)
837 DiagID = diag::ext_override_exception_spec;
838 return CheckExceptionSpecSubset(PDiag(DiagID),
839 PDiag(diag::note_overridden_virtual_function),
840 Old->getType()->getAs<FunctionProtoType>(),
842 New->getType()->getAs<FunctionProtoType>(),
846 static CanThrowResult canSubExprsThrow(Sema &S, const Expr *E) {
847 CanThrowResult R = CT_Cannot;
848 for (const Stmt *SubStmt : E->children()) {
849 R = mergeCanThrow(R, S.canThrow(cast<Expr>(SubStmt)));
856 static CanThrowResult canCalleeThrow(Sema &S, const Expr *E, const Decl *D) {
857 assert(D && "Expected decl");
859 // See if we can get a function type from the decl somehow.
860 const ValueDecl *VD = dyn_cast<ValueDecl>(D);
861 if (!VD) // If we have no clue what we're calling, assume the worst.
864 // As an extension, we assume that __attribute__((nothrow)) functions don't
866 if (isa<FunctionDecl>(D) && D->hasAttr<NoThrowAttr>())
869 QualType T = VD->getType();
870 const FunctionProtoType *FT;
871 if ((FT = T->getAs<FunctionProtoType>())) {
872 } else if (const PointerType *PT = T->getAs<PointerType>())
873 FT = PT->getPointeeType()->getAs<FunctionProtoType>();
874 else if (const ReferenceType *RT = T->getAs<ReferenceType>())
875 FT = RT->getPointeeType()->getAs<FunctionProtoType>();
876 else if (const MemberPointerType *MT = T->getAs<MemberPointerType>())
877 FT = MT->getPointeeType()->getAs<FunctionProtoType>();
878 else if (const BlockPointerType *BT = T->getAs<BlockPointerType>())
879 FT = BT->getPointeeType()->getAs<FunctionProtoType>();
884 FT = S.ResolveExceptionSpec(E->getLocStart(), FT);
888 return FT->isNothrow(S.Context) ? CT_Cannot : CT_Can;
891 static CanThrowResult canDynamicCastThrow(const CXXDynamicCastExpr *DC) {
892 if (DC->isTypeDependent())
895 if (!DC->getTypeAsWritten()->isReferenceType())
898 if (DC->getSubExpr()->isTypeDependent())
901 return DC->getCastKind() == clang::CK_Dynamic? CT_Can : CT_Cannot;
904 static CanThrowResult canTypeidThrow(Sema &S, const CXXTypeidExpr *DC) {
905 if (DC->isTypeOperand())
908 Expr *Op = DC->getExprOperand();
909 if (Op->isTypeDependent())
912 const RecordType *RT = Op->getType()->getAs<RecordType>();
916 if (!cast<CXXRecordDecl>(RT->getDecl())->isPolymorphic())
919 if (Op->Classify(S.Context).isPRValue())
925 CanThrowResult Sema::canThrow(const Expr *E) {
926 // C++ [expr.unary.noexcept]p3:
927 // [Can throw] if in a potentially-evaluated context the expression would
929 switch (E->getStmtClass()) {
930 case Expr::CXXThrowExprClass:
931 // - a potentially evaluated throw-expression
934 case Expr::CXXDynamicCastExprClass: {
935 // - a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
936 // where T is a reference type, that requires a run-time check
937 CanThrowResult CT = canDynamicCastThrow(cast<CXXDynamicCastExpr>(E));
940 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
943 case Expr::CXXTypeidExprClass:
944 // - a potentially evaluated typeid expression applied to a glvalue
945 // expression whose type is a polymorphic class type
946 return canTypeidThrow(*this, cast<CXXTypeidExpr>(E));
948 // - a potentially evaluated call to a function, member function, function
949 // pointer, or member function pointer that does not have a non-throwing
950 // exception-specification
951 case Expr::CallExprClass:
952 case Expr::CXXMemberCallExprClass:
953 case Expr::CXXOperatorCallExprClass:
954 case Expr::UserDefinedLiteralClass: {
955 const CallExpr *CE = cast<CallExpr>(E);
957 if (E->isTypeDependent())
959 else if (isa<CXXPseudoDestructorExpr>(CE->getCallee()->IgnoreParens()))
961 else if (CE->getCalleeDecl())
962 CT = canCalleeThrow(*this, E, CE->getCalleeDecl());
967 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
970 case Expr::CXXConstructExprClass:
971 case Expr::CXXTemporaryObjectExprClass: {
972 CanThrowResult CT = canCalleeThrow(*this, E,
973 cast<CXXConstructExpr>(E)->getConstructor());
976 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
979 case Expr::LambdaExprClass: {
980 const LambdaExpr *Lambda = cast<LambdaExpr>(E);
981 CanThrowResult CT = CT_Cannot;
982 for (LambdaExpr::capture_init_iterator Cap = Lambda->capture_init_begin(),
983 CapEnd = Lambda->capture_init_end();
984 Cap != CapEnd; ++Cap)
985 CT = mergeCanThrow(CT, canThrow(*Cap));
989 case Expr::CXXNewExprClass: {
991 if (E->isTypeDependent())
994 CT = canCalleeThrow(*this, E, cast<CXXNewExpr>(E)->getOperatorNew());
997 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1000 case Expr::CXXDeleteExprClass: {
1002 QualType DTy = cast<CXXDeleteExpr>(E)->getDestroyedType();
1003 if (DTy.isNull() || DTy->isDependentType()) {
1006 CT = canCalleeThrow(*this, E,
1007 cast<CXXDeleteExpr>(E)->getOperatorDelete());
1008 if (const RecordType *RT = DTy->getAs<RecordType>()) {
1009 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1010 const CXXDestructorDecl *DD = RD->getDestructor();
1012 CT = mergeCanThrow(CT, canCalleeThrow(*this, E, DD));
1017 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1020 case Expr::CXXBindTemporaryExprClass: {
1021 // The bound temporary has to be destroyed again, which might throw.
1022 CanThrowResult CT = canCalleeThrow(*this, E,
1023 cast<CXXBindTemporaryExpr>(E)->getTemporary()->getDestructor());
1026 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1029 // ObjC message sends are like function calls, but never have exception
1031 case Expr::ObjCMessageExprClass:
1032 case Expr::ObjCPropertyRefExprClass:
1033 case Expr::ObjCSubscriptRefExprClass:
1036 // All the ObjC literals that are implemented as calls are
1037 // potentially throwing unless we decide to close off that
1039 case Expr::ObjCArrayLiteralClass:
1040 case Expr::ObjCDictionaryLiteralClass:
1041 case Expr::ObjCBoxedExprClass:
1044 // Many other things have subexpressions, so we have to test those.
1046 case Expr::ConditionalOperatorClass:
1047 case Expr::CompoundLiteralExprClass:
1048 case Expr::CXXConstCastExprClass:
1049 case Expr::CXXReinterpretCastExprClass:
1050 case Expr::CXXStdInitializerListExprClass:
1051 case Expr::DesignatedInitExprClass:
1052 case Expr::DesignatedInitUpdateExprClass:
1053 case Expr::ExprWithCleanupsClass:
1054 case Expr::ExtVectorElementExprClass:
1055 case Expr::InitListExprClass:
1056 case Expr::MemberExprClass:
1057 case Expr::ObjCIsaExprClass:
1058 case Expr::ObjCIvarRefExprClass:
1059 case Expr::ParenExprClass:
1060 case Expr::ParenListExprClass:
1061 case Expr::ShuffleVectorExprClass:
1062 case Expr::ConvertVectorExprClass:
1063 case Expr::VAArgExprClass:
1064 return canSubExprsThrow(*this, E);
1066 // Some might be dependent for other reasons.
1067 case Expr::ArraySubscriptExprClass:
1068 case Expr::BinaryOperatorClass:
1069 case Expr::CompoundAssignOperatorClass:
1070 case Expr::CStyleCastExprClass:
1071 case Expr::CXXStaticCastExprClass:
1072 case Expr::CXXFunctionalCastExprClass:
1073 case Expr::ImplicitCastExprClass:
1074 case Expr::MaterializeTemporaryExprClass:
1075 case Expr::UnaryOperatorClass: {
1076 CanThrowResult CT = E->isTypeDependent() ? CT_Dependent : CT_Cannot;
1077 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1080 // FIXME: We should handle StmtExpr, but that opens a MASSIVE can of worms.
1081 case Expr::StmtExprClass:
1084 case Expr::CXXDefaultArgExprClass:
1085 return canThrow(cast<CXXDefaultArgExpr>(E)->getExpr());
1087 case Expr::CXXDefaultInitExprClass:
1088 return canThrow(cast<CXXDefaultInitExpr>(E)->getExpr());
1090 case Expr::ChooseExprClass:
1091 if (E->isTypeDependent() || E->isValueDependent())
1092 return CT_Dependent;
1093 return canThrow(cast<ChooseExpr>(E)->getChosenSubExpr());
1095 case Expr::GenericSelectionExprClass:
1096 if (cast<GenericSelectionExpr>(E)->isResultDependent())
1097 return CT_Dependent;
1098 return canThrow(cast<GenericSelectionExpr>(E)->getResultExpr());
1100 // Some expressions are always dependent.
1101 case Expr::CXXDependentScopeMemberExprClass:
1102 case Expr::CXXUnresolvedConstructExprClass:
1103 case Expr::DependentScopeDeclRefExprClass:
1104 case Expr::CXXFoldExprClass:
1105 return CT_Dependent;
1107 case Expr::AsTypeExprClass:
1108 case Expr::BinaryConditionalOperatorClass:
1109 case Expr::BlockExprClass:
1110 case Expr::CUDAKernelCallExprClass:
1111 case Expr::DeclRefExprClass:
1112 case Expr::ObjCBridgedCastExprClass:
1113 case Expr::ObjCIndirectCopyRestoreExprClass:
1114 case Expr::ObjCProtocolExprClass:
1115 case Expr::ObjCSelectorExprClass:
1116 case Expr::OffsetOfExprClass:
1117 case Expr::PackExpansionExprClass:
1118 case Expr::PseudoObjectExprClass:
1119 case Expr::SubstNonTypeTemplateParmExprClass:
1120 case Expr::SubstNonTypeTemplateParmPackExprClass:
1121 case Expr::FunctionParmPackExprClass:
1122 case Expr::UnaryExprOrTypeTraitExprClass:
1123 case Expr::UnresolvedLookupExprClass:
1124 case Expr::UnresolvedMemberExprClass:
1125 case Expr::TypoExprClass:
1126 // FIXME: Can any of the above throw? If so, when?
1129 case Expr::AddrLabelExprClass:
1130 case Expr::ArrayTypeTraitExprClass:
1131 case Expr::AtomicExprClass:
1132 case Expr::TypeTraitExprClass:
1133 case Expr::CXXBoolLiteralExprClass:
1134 case Expr::CXXNoexceptExprClass:
1135 case Expr::CXXNullPtrLiteralExprClass:
1136 case Expr::CXXPseudoDestructorExprClass:
1137 case Expr::CXXScalarValueInitExprClass:
1138 case Expr::CXXThisExprClass:
1139 case Expr::CXXUuidofExprClass:
1140 case Expr::CharacterLiteralClass:
1141 case Expr::ExpressionTraitExprClass:
1142 case Expr::FloatingLiteralClass:
1143 case Expr::GNUNullExprClass:
1144 case Expr::ImaginaryLiteralClass:
1145 case Expr::ImplicitValueInitExprClass:
1146 case Expr::IntegerLiteralClass:
1147 case Expr::NoInitExprClass:
1148 case Expr::ObjCEncodeExprClass:
1149 case Expr::ObjCStringLiteralClass:
1150 case Expr::ObjCBoolLiteralExprClass:
1151 case Expr::OpaqueValueExprClass:
1152 case Expr::PredefinedExprClass:
1153 case Expr::SizeOfPackExprClass:
1154 case Expr::StringLiteralClass:
1155 // These expressions can never throw.
1158 case Expr::MSPropertyRefExprClass:
1159 llvm_unreachable("Invalid class for expression");
1161 #define STMT(CLASS, PARENT) case Expr::CLASS##Class:
1162 #define STMT_RANGE(Base, First, Last)
1163 #define LAST_STMT_RANGE(BASE, FIRST, LAST)
1164 #define EXPR(CLASS, PARENT)
1165 #define ABSTRACT_STMT(STMT)
1166 #include "clang/AST/StmtNodes.inc"
1167 case Expr::NoStmtClass:
1168 llvm_unreachable("Invalid class for expression");
1170 llvm_unreachable("Bogus StmtClass");
1173 } // end namespace clang