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, 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().isValid())
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();
275 if (ESI.Type == EST_ComputedNoexcept) {
276 // For computed noexcept, we can't just take the expression from the old
277 // prototype. It likely contains references to the old prototype's
279 New->setInvalidDecl();
281 // Update the type of the function with the appropriate exception
283 New->setType(Context.getFunctionType(
284 NewProto->getReturnType(), NewProto->getParamTypes(),
285 NewProto->getExtProtoInfo().withExceptionSpec(ESI)));
288 if (getLangOpts().MicrosoftExt && ESI.Type != EST_ComputedNoexcept) {
289 // Allow missing exception specifications in redeclarations as an extension.
290 DiagID = diag::ext_ms_missing_exception_specification;
291 ReturnValueOnError = false;
292 } else if (New->isReplaceableGlobalAllocationFunction() &&
293 ESI.Type != EST_ComputedNoexcept) {
294 // Allow missing exception specifications in redeclarations as an extension,
295 // when declaring a replaceable global allocation function.
296 DiagID = diag::ext_missing_exception_specification;
297 ReturnValueOnError = false;
299 DiagID = diag::err_missing_exception_specification;
300 ReturnValueOnError = true;
303 // Warn about the lack of exception specification.
304 SmallString<128> ExceptionSpecString;
305 llvm::raw_svector_ostream OS(ExceptionSpecString);
306 switch (OldProto->getExceptionSpecType()) {
307 case EST_DynamicNone:
313 bool OnFirstException = true;
314 for (const auto &E : OldProto->exceptions()) {
315 if (OnFirstException)
316 OnFirstException = false;
320 OS << E.getAsString(getPrintingPolicy());
326 case EST_BasicNoexcept:
330 case EST_ComputedNoexcept:
332 assert(OldProto->getNoexceptExpr() != nullptr && "Expected non-null Expr");
333 OldProto->getNoexceptExpr()->printPretty(OS, nullptr, getPrintingPolicy());
338 llvm_unreachable("This spec type is compatible with none.");
341 SourceLocation FixItLoc;
342 if (TypeSourceInfo *TSInfo = New->getTypeSourceInfo()) {
343 TypeLoc TL = TSInfo->getTypeLoc().IgnoreParens();
344 // FIXME: Preserve enough information so that we can produce a correct fixit
345 // location when there is a trailing return type.
346 if (auto FTLoc = TL.getAs<FunctionProtoTypeLoc>())
347 if (!FTLoc.getTypePtr()->hasTrailingReturn())
348 FixItLoc = getLocForEndOfToken(FTLoc.getLocalRangeEnd());
351 if (FixItLoc.isInvalid())
352 Diag(New->getLocation(), DiagID)
355 Diag(New->getLocation(), DiagID)
357 << FixItHint::CreateInsertion(FixItLoc, " " + OS.str().str());
360 if (Old->getLocation().isValid())
361 Diag(Old->getLocation(), diag::note_previous_declaration);
363 return ReturnValueOnError;
366 /// CheckEquivalentExceptionSpec - Check if the two types have equivalent
367 /// exception specifications. Exception specifications are equivalent if
368 /// they allow exactly the same set of exception types. It does not matter how
369 /// that is achieved. See C++ [except.spec]p2.
370 bool Sema::CheckEquivalentExceptionSpec(
371 const FunctionProtoType *Old, SourceLocation OldLoc,
372 const FunctionProtoType *New, SourceLocation NewLoc) {
373 unsigned DiagID = diag::err_mismatched_exception_spec;
374 if (getLangOpts().MicrosoftExt)
375 DiagID = diag::ext_mismatched_exception_spec;
376 bool Result = CheckEquivalentExceptionSpec(PDiag(DiagID),
377 PDiag(diag::note_previous_declaration), Old, OldLoc, New, NewLoc);
379 // In Microsoft mode, mismatching exception specifications just cause a warning.
380 if (getLangOpts().MicrosoftExt)
385 /// CheckEquivalentExceptionSpec - Check if the two types have compatible
386 /// exception specifications. See C++ [except.spec]p3.
388 /// \return \c false if the exception specifications match, \c true if there is
389 /// a problem. If \c true is returned, either a diagnostic has already been
390 /// produced or \c *MissingExceptionSpecification is set to \c true.
391 bool Sema::CheckEquivalentExceptionSpec(const PartialDiagnostic &DiagID,
392 const PartialDiagnostic & NoteID,
393 const FunctionProtoType *Old,
394 SourceLocation OldLoc,
395 const FunctionProtoType *New,
396 SourceLocation NewLoc,
397 bool *MissingExceptionSpecification,
398 bool*MissingEmptyExceptionSpecification,
399 bool AllowNoexceptAllMatchWithNoSpec,
400 bool IsOperatorNew) {
401 // Just completely ignore this under -fno-exceptions.
402 if (!getLangOpts().CXXExceptions)
405 if (MissingExceptionSpecification)
406 *MissingExceptionSpecification = false;
408 if (MissingEmptyExceptionSpecification)
409 *MissingEmptyExceptionSpecification = false;
411 Old = ResolveExceptionSpec(NewLoc, Old);
414 New = ResolveExceptionSpec(NewLoc, New);
418 // C++0x [except.spec]p3: Two exception-specifications are compatible if:
419 // - both are non-throwing, regardless of their form,
420 // - both have the form noexcept(constant-expression) and the constant-
421 // expressions are equivalent,
422 // - both are dynamic-exception-specifications that have the same set of
425 // C++0x [except.spec]p12: An exception-specification is non-throwing if it is
426 // of the form throw(), noexcept, or noexcept(constant-expression) where the
427 // constant-expression yields true.
429 // C++0x [except.spec]p4: If any declaration of a function has an exception-
430 // specifier that is not a noexcept-specification allowing all exceptions,
431 // all declarations [...] of that function shall have a compatible
432 // exception-specification.
434 // That last point basically means that noexcept(false) matches no spec.
435 // It's considered when AllowNoexceptAllMatchWithNoSpec is true.
437 ExceptionSpecificationType OldEST = Old->getExceptionSpecType();
438 ExceptionSpecificationType NewEST = New->getExceptionSpecType();
440 assert(!isUnresolvedExceptionSpec(OldEST) &&
441 !isUnresolvedExceptionSpec(NewEST) &&
442 "Shouldn't see unknown exception specifications here");
444 // Shortcut the case where both have no spec.
445 if (OldEST == EST_None && NewEST == EST_None)
448 FunctionProtoType::NoexceptResult OldNR = Old->getNoexceptSpec(Context);
449 FunctionProtoType::NoexceptResult NewNR = New->getNoexceptSpec(Context);
450 if (OldNR == FunctionProtoType::NR_BadNoexcept ||
451 NewNR == FunctionProtoType::NR_BadNoexcept)
454 // Dependent noexcept specifiers are compatible with each other, but nothing
456 // One noexcept is compatible with another if the argument is the same
457 if (OldNR == NewNR &&
458 OldNR != FunctionProtoType::NR_NoNoexcept &&
459 NewNR != FunctionProtoType::NR_NoNoexcept)
461 if (OldNR != NewNR &&
462 OldNR != FunctionProtoType::NR_NoNoexcept &&
463 NewNR != FunctionProtoType::NR_NoNoexcept) {
464 Diag(NewLoc, DiagID);
465 if (NoteID.getDiagID() != 0 && OldLoc.isValid())
466 Diag(OldLoc, NoteID);
470 // The MS extension throw(...) is compatible with itself.
471 if (OldEST == EST_MSAny && NewEST == EST_MSAny)
474 // It's also compatible with no spec.
475 if ((OldEST == EST_None && NewEST == EST_MSAny) ||
476 (OldEST == EST_MSAny && NewEST == EST_None))
479 // It's also compatible with noexcept(false).
480 if (OldEST == EST_MSAny && NewNR == FunctionProtoType::NR_Throw)
482 if (NewEST == EST_MSAny && OldNR == FunctionProtoType::NR_Throw)
485 // As described above, noexcept(false) matches no spec only for functions.
486 if (AllowNoexceptAllMatchWithNoSpec) {
487 if (OldEST == EST_None && NewNR == FunctionProtoType::NR_Throw)
489 if (NewEST == EST_None && OldNR == FunctionProtoType::NR_Throw)
493 // Any non-throwing specifications are compatible.
494 bool OldNonThrowing = OldNR == FunctionProtoType::NR_Nothrow ||
495 OldEST == EST_DynamicNone;
496 bool NewNonThrowing = NewNR == FunctionProtoType::NR_Nothrow ||
497 NewEST == EST_DynamicNone;
498 if (OldNonThrowing && NewNonThrowing)
501 // As a special compatibility feature, under C++0x we accept no spec and
502 // throw(std::bad_alloc) as equivalent for operator new and operator new[].
503 // This is because the implicit declaration changed, but old code would break.
504 if (getLangOpts().CPlusPlus11 && IsOperatorNew) {
505 const FunctionProtoType *WithExceptions = nullptr;
506 if (OldEST == EST_None && NewEST == EST_Dynamic)
507 WithExceptions = New;
508 else if (OldEST == EST_Dynamic && NewEST == EST_None)
509 WithExceptions = Old;
510 if (WithExceptions && WithExceptions->getNumExceptions() == 1) {
511 // One has no spec, the other throw(something). If that something is
512 // std::bad_alloc, all conditions are met.
513 QualType Exception = *WithExceptions->exception_begin();
514 if (CXXRecordDecl *ExRecord = Exception->getAsCXXRecordDecl()) {
515 IdentifierInfo* Name = ExRecord->getIdentifier();
516 if (Name && Name->getName() == "bad_alloc") {
517 // It's called bad_alloc, but is it in std?
518 if (ExRecord->isInStdNamespace()) {
526 // At this point, the only remaining valid case is two matching dynamic
527 // specifications. We return here unless both specifications are dynamic.
528 if (OldEST != EST_Dynamic || NewEST != EST_Dynamic) {
529 if (MissingExceptionSpecification && Old->hasExceptionSpec() &&
530 !New->hasExceptionSpec()) {
531 // The old type has an exception specification of some sort, but
532 // the new type does not.
533 *MissingExceptionSpecification = true;
535 if (MissingEmptyExceptionSpecification && OldNonThrowing) {
536 // The old type has a throw() or noexcept(true) exception specification
537 // and the new type has no exception specification, and the caller asked
538 // to handle this itself.
539 *MissingEmptyExceptionSpecification = true;
545 Diag(NewLoc, DiagID);
546 if (NoteID.getDiagID() != 0 && OldLoc.isValid())
547 Diag(OldLoc, NoteID);
551 assert(OldEST == EST_Dynamic && NewEST == EST_Dynamic &&
552 "Exception compatibility logic error: non-dynamic spec slipped through.");
555 // Both have a dynamic exception spec. Collect the first set, then compare
557 llvm::SmallPtrSet<CanQualType, 8> OldTypes, NewTypes;
558 for (const auto &I : Old->exceptions())
559 OldTypes.insert(Context.getCanonicalType(I).getUnqualifiedType());
561 for (const auto &I : New->exceptions()) {
562 CanQualType TypePtr = Context.getCanonicalType(I).getUnqualifiedType();
563 if(OldTypes.count(TypePtr))
564 NewTypes.insert(TypePtr);
569 Success = Success && OldTypes.size() == NewTypes.size();
574 Diag(NewLoc, DiagID);
575 if (NoteID.getDiagID() != 0 && OldLoc.isValid())
576 Diag(OldLoc, NoteID);
580 /// CheckExceptionSpecSubset - Check whether the second function type's
581 /// exception specification is a subset (or equivalent) of the first function
582 /// type. This is used by override and pointer assignment checks.
583 bool Sema::CheckExceptionSpecSubset(
584 const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
585 const FunctionProtoType *Superset, SourceLocation SuperLoc,
586 const FunctionProtoType *Subset, SourceLocation SubLoc) {
588 // Just auto-succeed under -fno-exceptions.
589 if (!getLangOpts().CXXExceptions)
592 // FIXME: As usual, we could be more specific in our error messages, but
593 // that better waits until we've got types with source locations.
595 if (!SubLoc.isValid())
598 // Resolve the exception specifications, if needed.
599 Superset = ResolveExceptionSpec(SuperLoc, Superset);
602 Subset = ResolveExceptionSpec(SubLoc, Subset);
606 ExceptionSpecificationType SuperEST = Superset->getExceptionSpecType();
608 // If superset contains everything, we're done.
609 if (SuperEST == EST_None || SuperEST == EST_MSAny)
610 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
612 // If there are dependent noexcept specs, assume everything is fine. Unlike
613 // with the equivalency check, this is safe in this case, because we don't
614 // want to merge declarations. Checks after instantiation will catch any
615 // omissions we make here.
616 // We also shortcut checking if a noexcept expression was bad.
618 FunctionProtoType::NoexceptResult SuperNR =Superset->getNoexceptSpec(Context);
619 if (SuperNR == FunctionProtoType::NR_BadNoexcept ||
620 SuperNR == FunctionProtoType::NR_Dependent)
623 // Another case of the superset containing everything.
624 if (SuperNR == FunctionProtoType::NR_Throw)
625 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
627 ExceptionSpecificationType SubEST = Subset->getExceptionSpecType();
629 assert(!isUnresolvedExceptionSpec(SuperEST) &&
630 !isUnresolvedExceptionSpec(SubEST) &&
631 "Shouldn't see unknown exception specifications here");
633 // It does not. If the subset contains everything, we've failed.
634 if (SubEST == EST_None || SubEST == EST_MSAny) {
635 Diag(SubLoc, DiagID);
636 if (NoteID.getDiagID() != 0)
637 Diag(SuperLoc, NoteID);
641 FunctionProtoType::NoexceptResult SubNR = Subset->getNoexceptSpec(Context);
642 if (SubNR == FunctionProtoType::NR_BadNoexcept ||
643 SubNR == FunctionProtoType::NR_Dependent)
646 // Another case of the subset containing everything.
647 if (SubNR == FunctionProtoType::NR_Throw) {
648 Diag(SubLoc, DiagID);
649 if (NoteID.getDiagID() != 0)
650 Diag(SuperLoc, NoteID);
654 // If the subset contains nothing, we're done.
655 if (SubEST == EST_DynamicNone || SubNR == FunctionProtoType::NR_Nothrow)
656 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
658 // Otherwise, if the superset contains nothing, we've failed.
659 if (SuperEST == EST_DynamicNone || SuperNR == FunctionProtoType::NR_Nothrow) {
660 Diag(SubLoc, DiagID);
661 if (NoteID.getDiagID() != 0)
662 Diag(SuperLoc, NoteID);
666 assert(SuperEST == EST_Dynamic && SubEST == EST_Dynamic &&
667 "Exception spec subset: non-dynamic case slipped through.");
669 // Neither contains everything or nothing. Do a proper comparison.
670 for (const auto &SubI : Subset->exceptions()) {
671 // Take one type from the subset.
672 QualType CanonicalSubT = Context.getCanonicalType(SubI);
673 // Unwrap pointers and references so that we can do checks within a class
674 // hierarchy. Don't unwrap member pointers; they don't have hierarchy
675 // conversions on the pointee.
676 bool SubIsPointer = false;
677 if (const ReferenceType *RefTy = CanonicalSubT->getAs<ReferenceType>())
678 CanonicalSubT = RefTy->getPointeeType();
679 if (const PointerType *PtrTy = CanonicalSubT->getAs<PointerType>()) {
680 CanonicalSubT = PtrTy->getPointeeType();
683 bool SubIsClass = CanonicalSubT->isRecordType();
684 CanonicalSubT = CanonicalSubT.getLocalUnqualifiedType();
686 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
687 /*DetectVirtual=*/false);
689 bool Contained = false;
690 // Make sure it's in the superset.
691 for (const auto &SuperI : Superset->exceptions()) {
692 QualType CanonicalSuperT = Context.getCanonicalType(SuperI);
693 // SubT must be SuperT or derived from it, or pointer or reference to
695 if (const ReferenceType *RefTy = CanonicalSuperT->getAs<ReferenceType>())
696 CanonicalSuperT = RefTy->getPointeeType();
698 if (const PointerType *PtrTy = CanonicalSuperT->getAs<PointerType>())
699 CanonicalSuperT = PtrTy->getPointeeType();
704 CanonicalSuperT = CanonicalSuperT.getLocalUnqualifiedType();
705 // If the types are the same, move on to the next type in the subset.
706 if (CanonicalSubT == CanonicalSuperT) {
711 // Otherwise we need to check the inheritance.
712 if (!SubIsClass || !CanonicalSuperT->isRecordType())
716 if (!IsDerivedFrom(SubLoc, CanonicalSubT, CanonicalSuperT, Paths))
719 if (Paths.isAmbiguous(Context.getCanonicalType(CanonicalSuperT)))
722 // Do this check from a context without privileges.
723 switch (CheckBaseClassAccess(SourceLocation(),
724 CanonicalSuperT, CanonicalSubT,
728 /*ForceUnprivileged*/ true)) {
729 case AR_accessible: break;
730 case AR_inaccessible: continue;
732 llvm_unreachable("access check dependent for unprivileged context");
734 llvm_unreachable("access check delayed in non-declaration");
741 Diag(SubLoc, DiagID);
742 if (NoteID.getDiagID() != 0)
743 Diag(SuperLoc, NoteID);
747 // We've run half the gauntlet.
748 return CheckParamExceptionSpec(NoteID, Superset, SuperLoc, Subset, SubLoc);
751 static bool CheckSpecForTypesEquivalent(Sema &S,
752 const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
753 QualType Target, SourceLocation TargetLoc,
754 QualType Source, SourceLocation SourceLoc)
756 const FunctionProtoType *TFunc = GetUnderlyingFunction(Target);
759 const FunctionProtoType *SFunc = GetUnderlyingFunction(Source);
763 return S.CheckEquivalentExceptionSpec(DiagID, NoteID, TFunc, TargetLoc,
767 /// CheckParamExceptionSpec - Check if the parameter and return types of the
768 /// two functions have equivalent exception specs. This is part of the
769 /// assignment and override compatibility check. We do not check the parameters
770 /// of parameter function pointers recursively, as no sane programmer would
771 /// even be able to write such a function type.
772 bool Sema::CheckParamExceptionSpec(const PartialDiagnostic &NoteID,
773 const FunctionProtoType *Target,
774 SourceLocation TargetLoc,
775 const FunctionProtoType *Source,
776 SourceLocation SourceLoc) {
777 if (CheckSpecForTypesEquivalent(
778 *this, PDiag(diag::err_deep_exception_specs_differ) << 0, PDiag(),
779 Target->getReturnType(), TargetLoc, Source->getReturnType(),
783 // We shouldn't even be testing this unless the arguments are otherwise
785 assert(Target->getNumParams() == Source->getNumParams() &&
786 "Functions have different argument counts.");
787 for (unsigned i = 0, E = Target->getNumParams(); i != E; ++i) {
788 if (CheckSpecForTypesEquivalent(
789 *this, PDiag(diag::err_deep_exception_specs_differ) << 1, PDiag(),
790 Target->getParamType(i), TargetLoc, Source->getParamType(i),
797 bool Sema::CheckExceptionSpecCompatibility(Expr *From, QualType ToType) {
798 // First we check for applicability.
799 // Target type must be a function, function pointer or function reference.
800 const FunctionProtoType *ToFunc = GetUnderlyingFunction(ToType);
801 if (!ToFunc || ToFunc->hasDependentExceptionSpec())
804 // SourceType must be a function or function pointer.
805 const FunctionProtoType *FromFunc = GetUnderlyingFunction(From->getType());
806 if (!FromFunc || FromFunc->hasDependentExceptionSpec())
809 // Now we've got the correct types on both sides, check their compatibility.
810 // This means that the source of the conversion can only throw a subset of
811 // the exceptions of the target, and any exception specs on arguments or
812 // return types must be equivalent.
814 // FIXME: If there is a nested dependent exception specification, we should
815 // not be checking it here. This is fine:
816 // template<typename T> void f() {
817 // void (*p)(void (*) throw(T));
818 // void (*q)(void (*) throw(int)) = p;
820 // ... because it might be instantiated with T=int.
821 return CheckExceptionSpecSubset(PDiag(diag::err_incompatible_exception_specs),
823 From->getSourceRange().getBegin(),
824 FromFunc, SourceLocation());
827 bool Sema::CheckOverridingFunctionExceptionSpec(const CXXMethodDecl *New,
828 const CXXMethodDecl *Old) {
829 // If the new exception specification hasn't been parsed yet, skip the check.
830 // We'll get called again once it's been parsed.
831 if (New->getType()->castAs<FunctionProtoType>()->getExceptionSpecType() ==
834 if (getLangOpts().CPlusPlus11 && isa<CXXDestructorDecl>(New)) {
835 // Don't check uninstantiated template destructors at all. We can only
836 // synthesize correct specs after the template is instantiated.
837 if (New->getParent()->isDependentType())
839 if (New->getParent()->isBeingDefined()) {
840 // The destructor might be updated once the definition is finished. So
841 // remember it and check later.
842 DelayedExceptionSpecChecks.push_back(std::make_pair(New, Old));
846 // If the old exception specification hasn't been parsed yet, remember that
847 // we need to perform this check when we get to the end of the outermost
848 // lexically-surrounding class.
849 if (Old->getType()->castAs<FunctionProtoType>()->getExceptionSpecType() ==
851 DelayedExceptionSpecChecks.push_back(std::make_pair(New, Old));
854 unsigned DiagID = diag::err_override_exception_spec;
855 if (getLangOpts().MicrosoftExt)
856 DiagID = diag::ext_override_exception_spec;
857 return CheckExceptionSpecSubset(PDiag(DiagID),
858 PDiag(diag::note_overridden_virtual_function),
859 Old->getType()->getAs<FunctionProtoType>(),
861 New->getType()->getAs<FunctionProtoType>(),
865 static CanThrowResult canSubExprsThrow(Sema &S, const Expr *E) {
866 CanThrowResult R = CT_Cannot;
867 for (const Stmt *SubStmt : E->children()) {
868 R = mergeCanThrow(R, S.canThrow(cast<Expr>(SubStmt)));
875 static CanThrowResult canCalleeThrow(Sema &S, const Expr *E, const Decl *D) {
876 assert(D && "Expected decl");
878 // See if we can get a function type from the decl somehow.
879 const ValueDecl *VD = dyn_cast<ValueDecl>(D);
880 if (!VD) // If we have no clue what we're calling, assume the worst.
883 // As an extension, we assume that __attribute__((nothrow)) functions don't
885 if (isa<FunctionDecl>(D) && D->hasAttr<NoThrowAttr>())
888 QualType T = VD->getType();
889 const FunctionProtoType *FT;
890 if ((FT = T->getAs<FunctionProtoType>())) {
891 } else if (const PointerType *PT = T->getAs<PointerType>())
892 FT = PT->getPointeeType()->getAs<FunctionProtoType>();
893 else if (const ReferenceType *RT = T->getAs<ReferenceType>())
894 FT = RT->getPointeeType()->getAs<FunctionProtoType>();
895 else if (const MemberPointerType *MT = T->getAs<MemberPointerType>())
896 FT = MT->getPointeeType()->getAs<FunctionProtoType>();
897 else if (const BlockPointerType *BT = T->getAs<BlockPointerType>())
898 FT = BT->getPointeeType()->getAs<FunctionProtoType>();
903 FT = S.ResolveExceptionSpec(E->getLocStart(), FT);
907 return FT->isNothrow(S.Context) ? CT_Cannot : CT_Can;
910 static CanThrowResult canDynamicCastThrow(const CXXDynamicCastExpr *DC) {
911 if (DC->isTypeDependent())
914 if (!DC->getTypeAsWritten()->isReferenceType())
917 if (DC->getSubExpr()->isTypeDependent())
920 return DC->getCastKind() == clang::CK_Dynamic? CT_Can : CT_Cannot;
923 static CanThrowResult canTypeidThrow(Sema &S, const CXXTypeidExpr *DC) {
924 if (DC->isTypeOperand())
927 Expr *Op = DC->getExprOperand();
928 if (Op->isTypeDependent())
931 const RecordType *RT = Op->getType()->getAs<RecordType>();
935 if (!cast<CXXRecordDecl>(RT->getDecl())->isPolymorphic())
938 if (Op->Classify(S.Context).isPRValue())
944 CanThrowResult Sema::canThrow(const Expr *E) {
945 // C++ [expr.unary.noexcept]p3:
946 // [Can throw] if in a potentially-evaluated context the expression would
948 switch (E->getStmtClass()) {
949 case Expr::CXXThrowExprClass:
950 // - a potentially evaluated throw-expression
953 case Expr::CXXDynamicCastExprClass: {
954 // - a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
955 // where T is a reference type, that requires a run-time check
956 CanThrowResult CT = canDynamicCastThrow(cast<CXXDynamicCastExpr>(E));
959 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
962 case Expr::CXXTypeidExprClass:
963 // - a potentially evaluated typeid expression applied to a glvalue
964 // expression whose type is a polymorphic class type
965 return canTypeidThrow(*this, cast<CXXTypeidExpr>(E));
967 // - a potentially evaluated call to a function, member function, function
968 // pointer, or member function pointer that does not have a non-throwing
969 // exception-specification
970 case Expr::CallExprClass:
971 case Expr::CXXMemberCallExprClass:
972 case Expr::CXXOperatorCallExprClass:
973 case Expr::UserDefinedLiteralClass: {
974 const CallExpr *CE = cast<CallExpr>(E);
976 if (E->isTypeDependent())
978 else if (isa<CXXPseudoDestructorExpr>(CE->getCallee()->IgnoreParens()))
980 else if (CE->getCalleeDecl())
981 CT = canCalleeThrow(*this, E, CE->getCalleeDecl());
986 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
989 case Expr::CXXConstructExprClass:
990 case Expr::CXXTemporaryObjectExprClass: {
991 CanThrowResult CT = canCalleeThrow(*this, E,
992 cast<CXXConstructExpr>(E)->getConstructor());
995 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
998 case Expr::LambdaExprClass: {
999 const LambdaExpr *Lambda = cast<LambdaExpr>(E);
1000 CanThrowResult CT = CT_Cannot;
1001 for (LambdaExpr::const_capture_init_iterator
1002 Cap = Lambda->capture_init_begin(),
1003 CapEnd = Lambda->capture_init_end();
1004 Cap != CapEnd; ++Cap)
1005 CT = mergeCanThrow(CT, canThrow(*Cap));
1009 case Expr::CXXNewExprClass: {
1011 if (E->isTypeDependent())
1014 CT = canCalleeThrow(*this, E, cast<CXXNewExpr>(E)->getOperatorNew());
1017 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1020 case Expr::CXXDeleteExprClass: {
1022 QualType DTy = cast<CXXDeleteExpr>(E)->getDestroyedType();
1023 if (DTy.isNull() || DTy->isDependentType()) {
1026 CT = canCalleeThrow(*this, E,
1027 cast<CXXDeleteExpr>(E)->getOperatorDelete());
1028 if (const RecordType *RT = DTy->getAs<RecordType>()) {
1029 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1030 const CXXDestructorDecl *DD = RD->getDestructor();
1032 CT = mergeCanThrow(CT, canCalleeThrow(*this, E, DD));
1037 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1040 case Expr::CXXBindTemporaryExprClass: {
1041 // The bound temporary has to be destroyed again, which might throw.
1042 CanThrowResult CT = canCalleeThrow(*this, E,
1043 cast<CXXBindTemporaryExpr>(E)->getTemporary()->getDestructor());
1046 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1049 // ObjC message sends are like function calls, but never have exception
1051 case Expr::ObjCMessageExprClass:
1052 case Expr::ObjCPropertyRefExprClass:
1053 case Expr::ObjCSubscriptRefExprClass:
1056 // All the ObjC literals that are implemented as calls are
1057 // potentially throwing unless we decide to close off that
1059 case Expr::ObjCArrayLiteralClass:
1060 case Expr::ObjCDictionaryLiteralClass:
1061 case Expr::ObjCBoxedExprClass:
1064 // Many other things have subexpressions, so we have to test those.
1066 case Expr::CoawaitExprClass:
1067 case Expr::ConditionalOperatorClass:
1068 case Expr::CompoundLiteralExprClass:
1069 case Expr::CoyieldExprClass:
1070 case Expr::CXXConstCastExprClass:
1071 case Expr::CXXReinterpretCastExprClass:
1072 case Expr::CXXStdInitializerListExprClass:
1073 case Expr::DesignatedInitExprClass:
1074 case Expr::DesignatedInitUpdateExprClass:
1075 case Expr::ExprWithCleanupsClass:
1076 case Expr::ExtVectorElementExprClass:
1077 case Expr::InitListExprClass:
1078 case Expr::MemberExprClass:
1079 case Expr::ObjCIsaExprClass:
1080 case Expr::ObjCIvarRefExprClass:
1081 case Expr::ParenExprClass:
1082 case Expr::ParenListExprClass:
1083 case Expr::ShuffleVectorExprClass:
1084 case Expr::ConvertVectorExprClass:
1085 case Expr::VAArgExprClass:
1086 return canSubExprsThrow(*this, E);
1088 // Some might be dependent for other reasons.
1089 case Expr::ArraySubscriptExprClass:
1090 case Expr::OMPArraySectionExprClass:
1091 case Expr::BinaryOperatorClass:
1092 case Expr::CompoundAssignOperatorClass:
1093 case Expr::CStyleCastExprClass:
1094 case Expr::CXXStaticCastExprClass:
1095 case Expr::CXXFunctionalCastExprClass:
1096 case Expr::ImplicitCastExprClass:
1097 case Expr::MaterializeTemporaryExprClass:
1098 case Expr::UnaryOperatorClass: {
1099 CanThrowResult CT = E->isTypeDependent() ? CT_Dependent : CT_Cannot;
1100 return mergeCanThrow(CT, canSubExprsThrow(*this, E));
1103 // FIXME: We should handle StmtExpr, but that opens a MASSIVE can of worms.
1104 case Expr::StmtExprClass:
1107 case Expr::CXXDefaultArgExprClass:
1108 return canThrow(cast<CXXDefaultArgExpr>(E)->getExpr());
1110 case Expr::CXXDefaultInitExprClass:
1111 return canThrow(cast<CXXDefaultInitExpr>(E)->getExpr());
1113 case Expr::ChooseExprClass:
1114 if (E->isTypeDependent() || E->isValueDependent())
1115 return CT_Dependent;
1116 return canThrow(cast<ChooseExpr>(E)->getChosenSubExpr());
1118 case Expr::GenericSelectionExprClass:
1119 if (cast<GenericSelectionExpr>(E)->isResultDependent())
1120 return CT_Dependent;
1121 return canThrow(cast<GenericSelectionExpr>(E)->getResultExpr());
1123 // Some expressions are always dependent.
1124 case Expr::CXXDependentScopeMemberExprClass:
1125 case Expr::CXXUnresolvedConstructExprClass:
1126 case Expr::DependentScopeDeclRefExprClass:
1127 case Expr::CXXFoldExprClass:
1128 return CT_Dependent;
1130 case Expr::AsTypeExprClass:
1131 case Expr::BinaryConditionalOperatorClass:
1132 case Expr::BlockExprClass:
1133 case Expr::CUDAKernelCallExprClass:
1134 case Expr::DeclRefExprClass:
1135 case Expr::ObjCBridgedCastExprClass:
1136 case Expr::ObjCIndirectCopyRestoreExprClass:
1137 case Expr::ObjCProtocolExprClass:
1138 case Expr::ObjCSelectorExprClass:
1139 case Expr::OffsetOfExprClass:
1140 case Expr::PackExpansionExprClass:
1141 case Expr::PseudoObjectExprClass:
1142 case Expr::SubstNonTypeTemplateParmExprClass:
1143 case Expr::SubstNonTypeTemplateParmPackExprClass:
1144 case Expr::FunctionParmPackExprClass:
1145 case Expr::UnaryExprOrTypeTraitExprClass:
1146 case Expr::UnresolvedLookupExprClass:
1147 case Expr::UnresolvedMemberExprClass:
1148 case Expr::TypoExprClass:
1149 // FIXME: Can any of the above throw? If so, when?
1152 case Expr::AddrLabelExprClass:
1153 case Expr::ArrayTypeTraitExprClass:
1154 case Expr::AtomicExprClass:
1155 case Expr::TypeTraitExprClass:
1156 case Expr::CXXBoolLiteralExprClass:
1157 case Expr::CXXNoexceptExprClass:
1158 case Expr::CXXNullPtrLiteralExprClass:
1159 case Expr::CXXPseudoDestructorExprClass:
1160 case Expr::CXXScalarValueInitExprClass:
1161 case Expr::CXXThisExprClass:
1162 case Expr::CXXUuidofExprClass:
1163 case Expr::CharacterLiteralClass:
1164 case Expr::ExpressionTraitExprClass:
1165 case Expr::FloatingLiteralClass:
1166 case Expr::GNUNullExprClass:
1167 case Expr::ImaginaryLiteralClass:
1168 case Expr::ImplicitValueInitExprClass:
1169 case Expr::IntegerLiteralClass:
1170 case Expr::NoInitExprClass:
1171 case Expr::ObjCEncodeExprClass:
1172 case Expr::ObjCStringLiteralClass:
1173 case Expr::ObjCBoolLiteralExprClass:
1174 case Expr::OpaqueValueExprClass:
1175 case Expr::PredefinedExprClass:
1176 case Expr::SizeOfPackExprClass:
1177 case Expr::StringLiteralClass:
1178 // These expressions can never throw.
1181 case Expr::MSPropertyRefExprClass:
1182 case Expr::MSPropertySubscriptExprClass:
1183 llvm_unreachable("Invalid class for expression");
1185 #define STMT(CLASS, PARENT) case Expr::CLASS##Class:
1186 #define STMT_RANGE(Base, First, Last)
1187 #define LAST_STMT_RANGE(BASE, FIRST, LAST)
1188 #define EXPR(CLASS, PARENT)
1189 #define ABSTRACT_STMT(STMT)
1190 #include "clang/AST/StmtNodes.inc"
1191 case Expr::NoStmtClass:
1192 llvm_unreachable("Invalid class for expression");
1194 llvm_unreachable("Bogus StmtClass");
1197 } // end namespace clang