Bug Summary

File:clang/lib/Sema/SemaExceptionSpec.cpp
Warning:line 390, column 9
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name SemaExceptionSpec.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/Sema -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/tools/clang/lib/Sema -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/clang/lib/Sema/SemaExceptionSpec.cpp
1//===--- SemaExceptionSpec.cpp - C++ Exception Specifications ---*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file provides Sema routines for C++ exception specification testing.
10//
11//===----------------------------------------------------------------------===//
12
13#include "clang/Sema/SemaInternal.h"
14#include "clang/AST/ASTMutationListener.h"
15#include "clang/AST/CXXInheritance.h"
16#include "clang/AST/Expr.h"
17#include "clang/AST/ExprCXX.h"
18#include "clang/AST/StmtObjC.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"
24
25namespace clang {
26
27static const FunctionProtoType *GetUnderlyingFunction(QualType T)
28{
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>();
36}
37
38/// HACK: 2014-11-14 libstdc++ had a bug where it shadows std::swap with a
39/// member swap function then tries to call std::swap unqualified from the
40/// exception specification of that function. This function detects whether
41/// we're in such a case and turns off delay-parsing of exception
42/// specifications. Libstdc++ 6.1 (released 2016-04-27) appears to have
43/// resolved it as side-effect of commit ddb63209a8d (2015-06-05).
44bool Sema::isLibstdcxxEagerExceptionSpecHack(const Declarator &D) {
45 auto *RD = dyn_cast<CXXRecordDecl>(CurContext);
46
47 // All the problem cases are member functions named "swap" within class
48 // templates declared directly within namespace std or std::__debug or
49 // std::__profile.
50 if (!RD || !RD->getIdentifier() || !RD->getDescribedClassTemplate() ||
51 !D.getIdentifier() || !D.getIdentifier()->isStr("swap"))
52 return false;
53
54 auto *ND = dyn_cast<NamespaceDecl>(RD->getDeclContext());
55 if (!ND)
56 return false;
57
58 bool IsInStd = ND->isStdNamespace();
59 if (!IsInStd) {
60 // This isn't a direct member of namespace std, but it might still be
61 // libstdc++'s std::__debug::array or std::__profile::array.
62 IdentifierInfo *II = ND->getIdentifier();
63 if (!II || !(II->isStr("__debug") || II->isStr("__profile")) ||
64 !ND->isInStdNamespace())
65 return false;
66 }
67
68 // Only apply this hack within a system header.
69 if (!Context.getSourceManager().isInSystemHeader(D.getBeginLoc()))
70 return false;
71
72 return llvm::StringSwitch<bool>(RD->getIdentifier()->getName())
73 .Case("array", true)
74 .Case("pair", IsInStd)
75 .Case("priority_queue", IsInStd)
76 .Case("stack", IsInStd)
77 .Case("queue", IsInStd)
78 .Default(false);
79}
80
81ExprResult Sema::ActOnNoexceptSpec(Expr *NoexceptExpr,
82 ExceptionSpecificationType &EST) {
83
84 if (NoexceptExpr->isTypeDependent() ||
85 NoexceptExpr->containsUnexpandedParameterPack()) {
86 EST = EST_DependentNoexcept;
87 return NoexceptExpr;
88 }
89
90 llvm::APSInt Result;
91 ExprResult Converted = CheckConvertedConstantExpression(
92 NoexceptExpr, Context.BoolTy, Result, CCEK_Noexcept);
93
94 if (Converted.isInvalid()) {
95 EST = EST_NoexceptFalse;
96 // Fill in an expression of 'false' as a fixup.
97 auto *BoolExpr = new (Context)
98 CXXBoolLiteralExpr(false, Context.BoolTy, NoexceptExpr->getBeginLoc());
99 llvm::APSInt Value{1};
100 Value = 0;
101 return ConstantExpr::Create(Context, BoolExpr, APValue{Value});
102 }
103
104 if (Converted.get()->isValueDependent()) {
105 EST = EST_DependentNoexcept;
106 return Converted;
107 }
108
109 if (!Converted.isInvalid())
110 EST = !Result ? EST_NoexceptFalse : EST_NoexceptTrue;
111 return Converted;
112}
113
114/// CheckSpecifiedExceptionType - Check if the given type is valid in an
115/// exception specification. Incomplete types, or pointers to incomplete types
116/// other than void are not allowed.
117///
118/// \param[in,out] T The exception type. This will be decayed to a pointer type
119/// when the input is an array or a function type.
120bool Sema::CheckSpecifiedExceptionType(QualType &T, SourceRange Range) {
121 // C++11 [except.spec]p2:
122 // A type cv T, "array of T", or "function returning T" denoted
123 // in an exception-specification is adjusted to type T, "pointer to T", or
124 // "pointer to function returning T", respectively.
125 //
126 // We also apply this rule in C++98.
127 if (T->isArrayType())
128 T = Context.getArrayDecayedType(T);
129 else if (T->isFunctionType())
130 T = Context.getPointerType(T);
131
132 int Kind = 0;
133 QualType PointeeT = T;
134 if (const PointerType *PT = T->getAs<PointerType>()) {
135 PointeeT = PT->getPointeeType();
136 Kind = 1;
137
138 // cv void* is explicitly permitted, despite being a pointer to an
139 // incomplete type.
140 if (PointeeT->isVoidType())
141 return false;
142 } else if (const ReferenceType *RT = T->getAs<ReferenceType>()) {
143 PointeeT = RT->getPointeeType();
144 Kind = 2;
145
146 if (RT->isRValueReferenceType()) {
147 // C++11 [except.spec]p2:
148 // A type denoted in an exception-specification shall not denote [...]
149 // an rvalue reference type.
150 Diag(Range.getBegin(), diag::err_rref_in_exception_spec)
151 << T << Range;
152 return true;
153 }
154 }
155
156 // C++11 [except.spec]p2:
157 // A type denoted in an exception-specification shall not denote an
158 // incomplete type other than a class currently being defined [...].
159 // A type denoted in an exception-specification shall not denote a
160 // pointer or reference to an incomplete type, other than (cv) void* or a
161 // pointer or reference to a class currently being defined.
162 // In Microsoft mode, downgrade this to a warning.
163 unsigned DiagID = diag::err_incomplete_in_exception_spec;
164 bool ReturnValueOnError = true;
165 if (getLangOpts().MSVCCompat) {
166 DiagID = diag::ext_incomplete_in_exception_spec;
167 ReturnValueOnError = false;
168 }
169 if (!(PointeeT->isRecordType() &&
170 PointeeT->castAs<RecordType>()->isBeingDefined()) &&
171 RequireCompleteType(Range.getBegin(), PointeeT, DiagID, Kind, Range))
172 return ReturnValueOnError;
173
174 // The MSVC compatibility mode doesn't extend to sizeless types,
175 // so diagnose them separately.
176 if (PointeeT->isSizelessType() && Kind != 1) {
177 Diag(Range.getBegin(), diag::err_sizeless_in_exception_spec)
178 << (Kind == 2 ? 1 : 0) << PointeeT << Range;
179 return true;
180 }
181
182 return false;
183}
184
185/// CheckDistantExceptionSpec - Check if the given type is a pointer or pointer
186/// to member to a function with an exception specification. This means that
187/// it is invalid to add another level of indirection.
188bool Sema::CheckDistantExceptionSpec(QualType T) {
189 // C++17 removes this rule in favor of putting exception specifications into
190 // the type system.
191 if (getLangOpts().CPlusPlus17)
192 return false;
193
194 if (const PointerType *PT = T->getAs<PointerType>())
195 T = PT->getPointeeType();
196 else if (const MemberPointerType *PT = T->getAs<MemberPointerType>())
197 T = PT->getPointeeType();
198 else
199 return false;
200
201 const FunctionProtoType *FnT = T->getAs<FunctionProtoType>();
202 if (!FnT)
203 return false;
204
205 return FnT->hasExceptionSpec();
206}
207
208const FunctionProtoType *
209Sema::ResolveExceptionSpec(SourceLocation Loc, const FunctionProtoType *FPT) {
210 if (FPT->getExceptionSpecType() == EST_Unparsed) {
211 Diag(Loc, diag::err_exception_spec_not_parsed);
212 return nullptr;
213 }
214
215 if (!isUnresolvedExceptionSpec(FPT->getExceptionSpecType()))
216 return FPT;
217
218 FunctionDecl *SourceDecl = FPT->getExceptionSpecDecl();
219 const FunctionProtoType *SourceFPT =
220 SourceDecl->getType()->castAs<FunctionProtoType>();
221
222 // If the exception specification has already been resolved, just return it.
223 if (!isUnresolvedExceptionSpec(SourceFPT->getExceptionSpecType()))
224 return SourceFPT;
225
226 // Compute or instantiate the exception specification now.
227 if (SourceFPT->getExceptionSpecType() == EST_Unevaluated)
228 EvaluateImplicitExceptionSpec(Loc, SourceDecl);
229 else
230 InstantiateExceptionSpec(Loc, SourceDecl);
231
232 const FunctionProtoType *Proto =
233 SourceDecl->getType()->castAs<FunctionProtoType>();
234 if (Proto->getExceptionSpecType() == clang::EST_Unparsed) {
235 Diag(Loc, diag::err_exception_spec_not_parsed);
236 Proto = nullptr;
237 }
238 return Proto;
239}
240
241void
242Sema::UpdateExceptionSpec(FunctionDecl *FD,
243 const FunctionProtoType::ExceptionSpecInfo &ESI) {
244 // If we've fully resolved the exception specification, notify listeners.
245 if (!isUnresolvedExceptionSpec(ESI.Type))
246 if (auto *Listener = getASTMutationListener())
247 Listener->ResolvedExceptionSpec(FD);
248
249 for (FunctionDecl *Redecl : FD->redecls())
250 Context.adjustExceptionSpec(Redecl, ESI);
251}
252
253static bool exceptionSpecNotKnownYet(const FunctionDecl *FD) {
254 auto *MD = dyn_cast<CXXMethodDecl>(FD);
4
Assuming 'FD' is not a 'CXXMethodDecl'
9
Assuming 'FD' is not a 'CXXMethodDecl'
255 if (!MD
4.1
'MD' is null
9.1
'MD' is null
)
5
Taking true branch
10
Taking true branch
256 return false;
6
Returning zero, which participates in a condition later
11
Returning zero, which participates in a condition later
257
258 auto EST = MD->getType()->castAs<FunctionProtoType>()->getExceptionSpecType();
259 return EST == EST_Unparsed ||
260 (EST == EST_Unevaluated && MD->getParent()->isBeingDefined());
261}
262
263static bool CheckEquivalentExceptionSpecImpl(
264 Sema &S, const PartialDiagnostic &DiagID, const PartialDiagnostic &NoteID,
265 const FunctionProtoType *Old, SourceLocation OldLoc,
266 const FunctionProtoType *New, SourceLocation NewLoc,
267 bool *MissingExceptionSpecification = nullptr,
268 bool *MissingEmptyExceptionSpecification = nullptr,
269 bool AllowNoexceptAllMatchWithNoSpec = false, bool IsOperatorNew = false);
270
271/// Determine whether a function has an implicitly-generated exception
272/// specification.
273static bool hasImplicitExceptionSpec(FunctionDecl *Decl) {
274 if (!isa<CXXDestructorDecl>(Decl) &&
275 Decl->getDeclName().getCXXOverloadedOperator() != OO_Delete &&
276 Decl->getDeclName().getCXXOverloadedOperator() != OO_Array_Delete)
277 return false;
278
279 // For a function that the user didn't declare:
280 // - if this is a destructor, its exception specification is implicit.
281 // - if this is 'operator delete' or 'operator delete[]', the exception
282 // specification is as-if an explicit exception specification was given
283 // (per [basic.stc.dynamic]p2).
284 if (!Decl->getTypeSourceInfo())
285 return isa<CXXDestructorDecl>(Decl);
286
287 auto *Ty = Decl->getTypeSourceInfo()->getType()->castAs<FunctionProtoType>();
288 return !Ty->hasExceptionSpec();
289}
290
291bool Sema::CheckEquivalentExceptionSpec(FunctionDecl *Old, FunctionDecl *New) {
292 // Just completely ignore this under -fno-exceptions prior to C++17.
293 // In C++17 onwards, the exception specification is part of the type and
294 // we will diagnose mismatches anyway, so it's better to check for them here.
295 if (!getLangOpts().CXXExceptions && !getLangOpts().CPlusPlus17)
1
Assuming field 'CXXExceptions' is not equal to 0
296 return false;
297
298 OverloadedOperatorKind OO = New->getDeclName().getCXXOverloadedOperator();
299 bool IsOperatorNew = OO
1.1
'OO' is not equal to OO_New
== OO_New || OO == OO_Array_New;
300 bool MissingExceptionSpecification = false;
301 bool MissingEmptyExceptionSpecification = false;
302
303 unsigned DiagID = diag::err_mismatched_exception_spec;
304 bool ReturnValueOnError = true;
305 if (getLangOpts().MSVCCompat) {
2
Assuming field 'MSVCCompat' is 0
306 DiagID = diag::ext_mismatched_exception_spec;
307 ReturnValueOnError = false;
308 }
309
310 // If we're befriending a member function of a class that's currently being
311 // defined, we might not be able to work out its exception specification yet.
312 // If not, defer the check until later.
313 if (exceptionSpecNotKnownYet(Old) || exceptionSpecNotKnownYet(New)) {
3
Calling 'exceptionSpecNotKnownYet'
7
Returning from 'exceptionSpecNotKnownYet'
8
Calling 'exceptionSpecNotKnownYet'
12
Returning from 'exceptionSpecNotKnownYet'
13
Taking false branch
314 DelayedEquivalentExceptionSpecChecks.push_back({New, Old});
315 return false;
316 }
317
318 // Check the types as written: they must match before any exception
319 // specification adjustment is applied.
320 if (!CheckEquivalentExceptionSpecImpl(
16
Assuming the condition is false
17
Taking false branch
321 *this, PDiag(DiagID), PDiag(diag::note_previous_declaration),
322 Old->getType()->getAs<FunctionProtoType>(), Old->getLocation(),
14
Assuming the object is not a 'FunctionProtoType'
323 New->getType()->getAs<FunctionProtoType>(), New->getLocation(),
15
Assuming the object is not a 'FunctionProtoType'
324 &MissingExceptionSpecification, &MissingEmptyExceptionSpecification,
325 /*AllowNoexceptAllMatchWithNoSpec=*/true, IsOperatorNew)) {
326 // C++11 [except.spec]p4 [DR1492]:
327 // If a declaration of a function has an implicit
328 // exception-specification, other declarations of the function shall
329 // not specify an exception-specification.
330 if (getLangOpts().CPlusPlus11 && getLangOpts().CXXExceptions &&
331 hasImplicitExceptionSpec(Old) != hasImplicitExceptionSpec(New)) {
332 Diag(New->getLocation(), diag::ext_implicit_exception_spec_mismatch)
333 << hasImplicitExceptionSpec(Old);
334 if (Old->getLocation().isValid())
335 Diag(Old->getLocation(), diag::note_previous_declaration);
336 }
337 return false;
338 }
339
340 // The failure was something other than an missing exception
341 // specification; return an error, except in MS mode where this is a warning.
342 if (!MissingExceptionSpecification)
18
Assuming 'MissingExceptionSpecification' is true
19
Taking false branch
343 return ReturnValueOnError;
344
345 const FunctionProtoType *NewProto =
21
'NewProto' initialized here
346 New->getType()->castAs<FunctionProtoType>();
20
The object is a 'FunctionProtoType'
347
348 // The new function declaration is only missing an empty exception
349 // specification "throw()". If the throw() specification came from a
350 // function in a system header that has C linkage, just add an empty
351 // exception specification to the "new" declaration. Note that C library
352 // implementations are permitted to add these nothrow exception
353 // specifications.
354 //
355 // Likewise if the old function is a builtin.
356 if (MissingEmptyExceptionSpecification && NewProto &&
22
Assuming 'MissingEmptyExceptionSpecification' is true
23
Assuming 'NewProto' is null
24
Assuming pointer value is null
25
Taking false branch
357 (Old->getLocation().isInvalid() ||
358 Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
359 Old->getBuiltinID()) &&
360 Old->isExternC()) {
361 New->setType(Context.getFunctionType(
362 NewProto->getReturnType(), NewProto->getParamTypes(),
363 NewProto->getExtProtoInfo().withExceptionSpec(EST_DynamicNone)));
364 return false;
365 }
366
367 const FunctionProtoType *OldProto =
368 Old->getType()->castAs<FunctionProtoType>();
26
The object is a 'FunctionProtoType'
369
370 FunctionProtoType::ExceptionSpecInfo ESI = OldProto->getExceptionSpecType();
371 if (ESI.Type == EST_Dynamic) {
27
Assuming field 'Type' is not equal to EST_Dynamic
28
Taking false branch
372 // FIXME: What if the exceptions are described in terms of the old
373 // prototype's parameters?
374 ESI.Exceptions = OldProto->exceptions();
375 }
376
377 if (ESI.Type == EST_NoexceptFalse)
29
Assuming field 'Type' is not equal to EST_NoexceptFalse
30
Taking false branch
378 ESI.Type = EST_None;
379 if (ESI.Type == EST_NoexceptTrue)
31
Assuming field 'Type' is not equal to EST_NoexceptTrue
32
Taking false branch
380 ESI.Type = EST_BasicNoexcept;
381
382 // For dependent noexcept, we can't just take the expression from the old
383 // prototype. It likely contains references to the old prototype's parameters.
384 if (ESI.Type == EST_DependentNoexcept) {
33
Assuming field 'Type' is not equal to EST_DependentNoexcept
34
Taking false branch
385 New->setInvalidDecl();
386 } else {
387 // Update the type of the function with the appropriate exception
388 // specification.
389 New->setType(Context.getFunctionType(
390 NewProto->getReturnType(), NewProto->getParamTypes(),
35
Called C++ object pointer is null
391 NewProto->getExtProtoInfo().withExceptionSpec(ESI)));
392 }
393
394 if (getLangOpts().MSVCCompat && ESI.Type != EST_DependentNoexcept) {
395 // Allow missing exception specifications in redeclarations as an extension.
396 DiagID = diag::ext_ms_missing_exception_specification;
397 ReturnValueOnError = false;
398 } else if (New->isReplaceableGlobalAllocationFunction() &&
399 ESI.Type != EST_DependentNoexcept) {
400 // Allow missing exception specifications in redeclarations as an extension,
401 // when declaring a replaceable global allocation function.
402 DiagID = diag::ext_missing_exception_specification;
403 ReturnValueOnError = false;
404 } else if (ESI.Type == EST_NoThrow) {
405 // Allow missing attribute 'nothrow' in redeclarations, since this is a very
406 // common omission.
407 DiagID = diag::ext_missing_exception_specification;
408 ReturnValueOnError = false;
409 } else {
410 DiagID = diag::err_missing_exception_specification;
411 ReturnValueOnError = true;
412 }
413
414 // Warn about the lack of exception specification.
415 SmallString<128> ExceptionSpecString;
416 llvm::raw_svector_ostream OS(ExceptionSpecString);
417 switch (OldProto->getExceptionSpecType()) {
418 case EST_DynamicNone:
419 OS << "throw()";
420 break;
421
422 case EST_Dynamic: {
423 OS << "throw(";
424 bool OnFirstException = true;
425 for (const auto &E : OldProto->exceptions()) {
426 if (OnFirstException)
427 OnFirstException = false;
428 else
429 OS << ", ";
430
431 OS << E.getAsString(getPrintingPolicy());
432 }
433 OS << ")";
434 break;
435 }
436
437 case EST_BasicNoexcept:
438 OS << "noexcept";
439 break;
440
441 case EST_DependentNoexcept:
442 case EST_NoexceptFalse:
443 case EST_NoexceptTrue:
444 OS << "noexcept(";
445 assert(OldProto->getNoexceptExpr() != nullptr && "Expected non-null Expr")(static_cast<void> (0));
446 OldProto->getNoexceptExpr()->printPretty(OS, nullptr, getPrintingPolicy());
447 OS << ")";
448 break;
449 case EST_NoThrow:
450 OS <<"__attribute__((nothrow))";
451 break;
452 case EST_None:
453 case EST_MSAny:
454 case EST_Unevaluated:
455 case EST_Uninstantiated:
456 case EST_Unparsed:
457 llvm_unreachable("This spec type is compatible with none.")__builtin_unreachable();
458 }
459
460 SourceLocation FixItLoc;
461 if (TypeSourceInfo *TSInfo = New->getTypeSourceInfo()) {
462 TypeLoc TL = TSInfo->getTypeLoc().IgnoreParens();
463 // FIXME: Preserve enough information so that we can produce a correct fixit
464 // location when there is a trailing return type.
465 if (auto FTLoc = TL.getAs<FunctionProtoTypeLoc>())
466 if (!FTLoc.getTypePtr()->hasTrailingReturn())
467 FixItLoc = getLocForEndOfToken(FTLoc.getLocalRangeEnd());
468 }
469
470 if (FixItLoc.isInvalid())
471 Diag(New->getLocation(), DiagID)
472 << New << OS.str();
473 else {
474 Diag(New->getLocation(), DiagID)
475 << New << OS.str()
476 << FixItHint::CreateInsertion(FixItLoc, " " + OS.str().str());
477 }
478
479 if (Old->getLocation().isValid())
480 Diag(Old->getLocation(), diag::note_previous_declaration);
481
482 return ReturnValueOnError;
483}
484
485/// CheckEquivalentExceptionSpec - Check if the two types have equivalent
486/// exception specifications. Exception specifications are equivalent if
487/// they allow exactly the same set of exception types. It does not matter how
488/// that is achieved. See C++ [except.spec]p2.
489bool Sema::CheckEquivalentExceptionSpec(
490 const FunctionProtoType *Old, SourceLocation OldLoc,
491 const FunctionProtoType *New, SourceLocation NewLoc) {
492 if (!getLangOpts().CXXExceptions)
493 return false;
494
495 unsigned DiagID = diag::err_mismatched_exception_spec;
496 if (getLangOpts().MSVCCompat)
497 DiagID = diag::ext_mismatched_exception_spec;
498 bool Result = CheckEquivalentExceptionSpecImpl(
499 *this, PDiag(DiagID), PDiag(diag::note_previous_declaration),
500 Old, OldLoc, New, NewLoc);
501
502 // In Microsoft mode, mismatching exception specifications just cause a warning.
503 if (getLangOpts().MSVCCompat)
504 return false;
505 return Result;
506}
507
508/// CheckEquivalentExceptionSpec - Check if the two types have compatible
509/// exception specifications. See C++ [except.spec]p3.
510///
511/// \return \c false if the exception specifications match, \c true if there is
512/// a problem. If \c true is returned, either a diagnostic has already been
513/// produced or \c *MissingExceptionSpecification is set to \c true.
514static bool CheckEquivalentExceptionSpecImpl(
515 Sema &S, const PartialDiagnostic &DiagID, const PartialDiagnostic &NoteID,
516 const FunctionProtoType *Old, SourceLocation OldLoc,
517 const FunctionProtoType *New, SourceLocation NewLoc,
518 bool *MissingExceptionSpecification,
519 bool *MissingEmptyExceptionSpecification,
520 bool AllowNoexceptAllMatchWithNoSpec, bool IsOperatorNew) {
521 if (MissingExceptionSpecification)
522 *MissingExceptionSpecification = false;
523
524 if (MissingEmptyExceptionSpecification)
525 *MissingEmptyExceptionSpecification = false;
526
527 Old = S.ResolveExceptionSpec(NewLoc, Old);
528 if (!Old)
529 return false;
530 New = S.ResolveExceptionSpec(NewLoc, New);
531 if (!New)
532 return false;
533
534 // C++0x [except.spec]p3: Two exception-specifications are compatible if:
535 // - both are non-throwing, regardless of their form,
536 // - both have the form noexcept(constant-expression) and the constant-
537 // expressions are equivalent,
538 // - both are dynamic-exception-specifications that have the same set of
539 // adjusted types.
540 //
541 // C++0x [except.spec]p12: An exception-specification is non-throwing if it is
542 // of the form throw(), noexcept, or noexcept(constant-expression) where the
543 // constant-expression yields true.
544 //
545 // C++0x [except.spec]p4: If any declaration of a function has an exception-
546 // specifier that is not a noexcept-specification allowing all exceptions,
547 // all declarations [...] of that function shall have a compatible
548 // exception-specification.
549 //
550 // That last point basically means that noexcept(false) matches no spec.
551 // It's considered when AllowNoexceptAllMatchWithNoSpec is true.
552
553 ExceptionSpecificationType OldEST = Old->getExceptionSpecType();
554 ExceptionSpecificationType NewEST = New->getExceptionSpecType();
555
556 assert(!isUnresolvedExceptionSpec(OldEST) &&(static_cast<void> (0))
557 !isUnresolvedExceptionSpec(NewEST) &&(static_cast<void> (0))
558 "Shouldn't see unknown exception specifications here")(static_cast<void> (0));
559
560 CanThrowResult OldCanThrow = Old->canThrow();
561 CanThrowResult NewCanThrow = New->canThrow();
562
563 // Any non-throwing specifications are compatible.
564 if (OldCanThrow == CT_Cannot && NewCanThrow == CT_Cannot)
565 return false;
566
567 // Any throws-anything specifications are usually compatible.
568 if (OldCanThrow == CT_Can && OldEST != EST_Dynamic &&
569 NewCanThrow == CT_Can && NewEST != EST_Dynamic) {
570 // The exception is that the absence of an exception specification only
571 // matches noexcept(false) for functions, as described above.
572 if (!AllowNoexceptAllMatchWithNoSpec &&
573 ((OldEST == EST_None && NewEST == EST_NoexceptFalse) ||
574 (OldEST == EST_NoexceptFalse && NewEST == EST_None))) {
575 // This is the disallowed case.
576 } else {
577 return false;
578 }
579 }
580
581 // C++14 [except.spec]p3:
582 // Two exception-specifications are compatible if [...] both have the form
583 // noexcept(constant-expression) and the constant-expressions are equivalent
584 if (OldEST == EST_DependentNoexcept && NewEST == EST_DependentNoexcept) {
585 llvm::FoldingSetNodeID OldFSN, NewFSN;
586 Old->getNoexceptExpr()->Profile(OldFSN, S.Context, true);
587 New->getNoexceptExpr()->Profile(NewFSN, S.Context, true);
588 if (OldFSN == NewFSN)
589 return false;
590 }
591
592 // Dynamic exception specifications with the same set of adjusted types
593 // are compatible.
594 if (OldEST == EST_Dynamic && NewEST == EST_Dynamic) {
595 bool Success = true;
596 // Both have a dynamic exception spec. Collect the first set, then compare
597 // to the second.
598 llvm::SmallPtrSet<CanQualType, 8> OldTypes, NewTypes;
599 for (const auto &I : Old->exceptions())
600 OldTypes.insert(S.Context.getCanonicalType(I).getUnqualifiedType());
601
602 for (const auto &I : New->exceptions()) {
603 CanQualType TypePtr = S.Context.getCanonicalType(I).getUnqualifiedType();
604 if (OldTypes.count(TypePtr))
605 NewTypes.insert(TypePtr);
606 else {
607 Success = false;
608 break;
609 }
610 }
611
612 if (Success && OldTypes.size() == NewTypes.size())
613 return false;
614 }
615
616 // As a special compatibility feature, under C++0x we accept no spec and
617 // throw(std::bad_alloc) as equivalent for operator new and operator new[].
618 // This is because the implicit declaration changed, but old code would break.
619 if (S.getLangOpts().CPlusPlus11 && IsOperatorNew) {
620 const FunctionProtoType *WithExceptions = nullptr;
621 if (OldEST == EST_None && NewEST == EST_Dynamic)
622 WithExceptions = New;
623 else if (OldEST == EST_Dynamic && NewEST == EST_None)
624 WithExceptions = Old;
625 if (WithExceptions && WithExceptions->getNumExceptions() == 1) {
626 // One has no spec, the other throw(something). If that something is
627 // std::bad_alloc, all conditions are met.
628 QualType Exception = *WithExceptions->exception_begin();
629 if (CXXRecordDecl *ExRecord = Exception->getAsCXXRecordDecl()) {
630 IdentifierInfo* Name = ExRecord->getIdentifier();
631 if (Name && Name->getName() == "bad_alloc") {
632 // It's called bad_alloc, but is it in std?
633 if (ExRecord->isInStdNamespace()) {
634 return false;
635 }
636 }
637 }
638 }
639 }
640
641 // If the caller wants to handle the case that the new function is
642 // incompatible due to a missing exception specification, let it.
643 if (MissingExceptionSpecification && OldEST != EST_None &&
644 NewEST == EST_None) {
645 // The old type has an exception specification of some sort, but
646 // the new type does not.
647 *MissingExceptionSpecification = true;
648
649 if (MissingEmptyExceptionSpecification && OldCanThrow == CT_Cannot) {
650 // The old type has a throw() or noexcept(true) exception specification
651 // and the new type has no exception specification, and the caller asked
652 // to handle this itself.
653 *MissingEmptyExceptionSpecification = true;
654 }
655
656 return true;
657 }
658
659 S.Diag(NewLoc, DiagID);
660 if (NoteID.getDiagID() != 0 && OldLoc.isValid())
661 S.Diag(OldLoc, NoteID);
662 return true;
663}
664
665bool Sema::CheckEquivalentExceptionSpec(const PartialDiagnostic &DiagID,
666 const PartialDiagnostic &NoteID,
667 const FunctionProtoType *Old,
668 SourceLocation OldLoc,
669 const FunctionProtoType *New,
670 SourceLocation NewLoc) {
671 if (!getLangOpts().CXXExceptions)
672 return false;
673 return CheckEquivalentExceptionSpecImpl(*this, DiagID, NoteID, Old, OldLoc,
674 New, NewLoc);
675}
676
677bool Sema::handlerCanCatch(QualType HandlerType, QualType ExceptionType) {
678 // [except.handle]p3:
679 // A handler is a match for an exception object of type E if:
680
681 // HandlerType must be ExceptionType or derived from it, or pointer or
682 // reference to such types.
683 const ReferenceType *RefTy = HandlerType->getAs<ReferenceType>();
684 if (RefTy)
685 HandlerType = RefTy->getPointeeType();
686
687 // -- the handler is of type cv T or cv T& and E and T are the same type
688 if (Context.hasSameUnqualifiedType(ExceptionType, HandlerType))
689 return true;
690
691 // FIXME: ObjC pointer types?
692 if (HandlerType->isPointerType() || HandlerType->isMemberPointerType()) {
693 if (RefTy && (!HandlerType.isConstQualified() ||
694 HandlerType.isVolatileQualified()))
695 return false;
696
697 // -- the handler is of type cv T or const T& where T is a pointer or
698 // pointer to member type and E is std::nullptr_t
699 if (ExceptionType->isNullPtrType())
700 return true;
701
702 // -- the handler is of type cv T or const T& where T is a pointer or
703 // pointer to member type and E is a pointer or pointer to member type
704 // that can be converted to T by one or more of
705 // -- a qualification conversion
706 // -- a function pointer conversion
707 bool LifetimeConv;
708 QualType Result;
709 // FIXME: Should we treat the exception as catchable if a lifetime
710 // conversion is required?
711 if (IsQualificationConversion(ExceptionType, HandlerType, false,
712 LifetimeConv) ||
713 IsFunctionConversion(ExceptionType, HandlerType, Result))
714 return true;
715
716 // -- a standard pointer conversion [...]
717 if (!ExceptionType->isPointerType() || !HandlerType->isPointerType())
718 return false;
719
720 // Handle the "qualification conversion" portion.
721 Qualifiers EQuals, HQuals;
722 ExceptionType = Context.getUnqualifiedArrayType(
723 ExceptionType->getPointeeType(), EQuals);
724 HandlerType = Context.getUnqualifiedArrayType(
725 HandlerType->getPointeeType(), HQuals);
726 if (!HQuals.compatiblyIncludes(EQuals))
727 return false;
728
729 if (HandlerType->isVoidType() && ExceptionType->isObjectType())
730 return true;
731
732 // The only remaining case is a derived-to-base conversion.
733 }
734
735 // -- the handler is of type cg T or cv T& and T is an unambiguous public
736 // base class of E
737 if (!ExceptionType->isRecordType() || !HandlerType->isRecordType())
738 return false;
739 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
740 /*DetectVirtual=*/false);
741 if (!IsDerivedFrom(SourceLocation(), ExceptionType, HandlerType, Paths) ||
742 Paths.isAmbiguous(Context.getCanonicalType(HandlerType)))
743 return false;
744
745 // Do this check from a context without privileges.
746 switch (CheckBaseClassAccess(SourceLocation(), HandlerType, ExceptionType,
747 Paths.front(),
748 /*Diagnostic*/ 0,
749 /*ForceCheck*/ true,
750 /*ForceUnprivileged*/ true)) {
751 case AR_accessible: return true;
752 case AR_inaccessible: return false;
753 case AR_dependent:
754 llvm_unreachable("access check dependent for unprivileged context")__builtin_unreachable();
755 case AR_delayed:
756 llvm_unreachable("access check delayed in non-declaration")__builtin_unreachable();
757 }
758 llvm_unreachable("unexpected access check result")__builtin_unreachable();
759}
760
761/// CheckExceptionSpecSubset - Check whether the second function type's
762/// exception specification is a subset (or equivalent) of the first function
763/// type. This is used by override and pointer assignment checks.
764bool Sema::CheckExceptionSpecSubset(const PartialDiagnostic &DiagID,
765 const PartialDiagnostic &NestedDiagID,
766 const PartialDiagnostic &NoteID,
767 const PartialDiagnostic &NoThrowDiagID,
768 const FunctionProtoType *Superset,
769 SourceLocation SuperLoc,
770 const FunctionProtoType *Subset,
771 SourceLocation SubLoc) {
772
773 // Just auto-succeed under -fno-exceptions.
774 if (!getLangOpts().CXXExceptions)
775 return false;
776
777 // FIXME: As usual, we could be more specific in our error messages, but
778 // that better waits until we've got types with source locations.
779
780 if (!SubLoc.isValid())
781 SubLoc = SuperLoc;
782
783 // Resolve the exception specifications, if needed.
784 Superset = ResolveExceptionSpec(SuperLoc, Superset);
785 if (!Superset)
786 return false;
787 Subset = ResolveExceptionSpec(SubLoc, Subset);
788 if (!Subset)
789 return false;
790
791 ExceptionSpecificationType SuperEST = Superset->getExceptionSpecType();
792 ExceptionSpecificationType SubEST = Subset->getExceptionSpecType();
793 assert(!isUnresolvedExceptionSpec(SuperEST) &&(static_cast<void> (0))
794 !isUnresolvedExceptionSpec(SubEST) &&(static_cast<void> (0))
795 "Shouldn't see unknown exception specifications here")(static_cast<void> (0));
796
797 // If there are dependent noexcept specs, assume everything is fine. Unlike
798 // with the equivalency check, this is safe in this case, because we don't
799 // want to merge declarations. Checks after instantiation will catch any
800 // omissions we make here.
801 if (SuperEST == EST_DependentNoexcept || SubEST == EST_DependentNoexcept)
802 return false;
803
804 CanThrowResult SuperCanThrow = Superset->canThrow();
805 CanThrowResult SubCanThrow = Subset->canThrow();
806
807 // If the superset contains everything or the subset contains nothing, we're
808 // done.
809 if ((SuperCanThrow == CT_Can && SuperEST != EST_Dynamic) ||
810 SubCanThrow == CT_Cannot)
811 return CheckParamExceptionSpec(NestedDiagID, NoteID, Superset, SuperLoc,
812 Subset, SubLoc);
813
814 // Allow __declspec(nothrow) to be missing on redeclaration as an extension in
815 // some cases.
816 if (NoThrowDiagID.getDiagID() != 0 && SubCanThrow == CT_Can &&
817 SuperCanThrow == CT_Cannot && SuperEST == EST_NoThrow) {
818 Diag(SubLoc, NoThrowDiagID);
819 if (NoteID.getDiagID() != 0)
820 Diag(SuperLoc, NoteID);
821 return true;
822 }
823
824 // If the subset contains everything or the superset contains nothing, we've
825 // failed.
826 if ((SubCanThrow == CT_Can && SubEST != EST_Dynamic) ||
827 SuperCanThrow == CT_Cannot) {
828 Diag(SubLoc, DiagID);
829 if (NoteID.getDiagID() != 0)
830 Diag(SuperLoc, NoteID);
831 return true;
832 }
833
834 assert(SuperEST == EST_Dynamic && SubEST == EST_Dynamic &&(static_cast<void> (0))
835 "Exception spec subset: non-dynamic case slipped through.")(static_cast<void> (0));
836
837 // Neither contains everything or nothing. Do a proper comparison.
838 for (QualType SubI : Subset->exceptions()) {
839 if (const ReferenceType *RefTy = SubI->getAs<ReferenceType>())
840 SubI = RefTy->getPointeeType();
841
842 // Make sure it's in the superset.
843 bool Contained = false;
844 for (QualType SuperI : Superset->exceptions()) {
845 // [except.spec]p5:
846 // the target entity shall allow at least the exceptions allowed by the
847 // source
848 //
849 // We interpret this as meaning that a handler for some target type would
850 // catch an exception of each source type.
851 if (handlerCanCatch(SuperI, SubI)) {
852 Contained = true;
853 break;
854 }
855 }
856 if (!Contained) {
857 Diag(SubLoc, DiagID);
858 if (NoteID.getDiagID() != 0)
859 Diag(SuperLoc, NoteID);
860 return true;
861 }
862 }
863 // We've run half the gauntlet.
864 return CheckParamExceptionSpec(NestedDiagID, NoteID, Superset, SuperLoc,
865 Subset, SubLoc);
866}
867
868static bool
869CheckSpecForTypesEquivalent(Sema &S, const PartialDiagnostic &DiagID,
870 const PartialDiagnostic &NoteID, QualType Target,
871 SourceLocation TargetLoc, QualType Source,
872 SourceLocation SourceLoc) {
873 const FunctionProtoType *TFunc = GetUnderlyingFunction(Target);
874 if (!TFunc)
875 return false;
876 const FunctionProtoType *SFunc = GetUnderlyingFunction(Source);
877 if (!SFunc)
878 return false;
879
880 return S.CheckEquivalentExceptionSpec(DiagID, NoteID, TFunc, TargetLoc,
881 SFunc, SourceLoc);
882}
883
884/// CheckParamExceptionSpec - Check if the parameter and return types of the
885/// two functions have equivalent exception specs. This is part of the
886/// assignment and override compatibility check. We do not check the parameters
887/// of parameter function pointers recursively, as no sane programmer would
888/// even be able to write such a function type.
889bool Sema::CheckParamExceptionSpec(const PartialDiagnostic &DiagID,
890 const PartialDiagnostic &NoteID,
891 const FunctionProtoType *Target,
892 SourceLocation TargetLoc,
893 const FunctionProtoType *Source,
894 SourceLocation SourceLoc) {
895 auto RetDiag = DiagID;
896 RetDiag << 0;
897 if (CheckSpecForTypesEquivalent(
898 *this, RetDiag, PDiag(),
899 Target->getReturnType(), TargetLoc, Source->getReturnType(),
900 SourceLoc))
901 return true;
902
903 // We shouldn't even be testing this unless the arguments are otherwise
904 // compatible.
905 assert(Target->getNumParams() == Source->getNumParams() &&(static_cast<void> (0))
906 "Functions have different argument counts.")(static_cast<void> (0));
907 for (unsigned i = 0, E = Target->getNumParams(); i != E; ++i) {
908 auto ParamDiag = DiagID;
909 ParamDiag << 1;
910 if (CheckSpecForTypesEquivalent(
911 *this, ParamDiag, PDiag(),
912 Target->getParamType(i), TargetLoc, Source->getParamType(i),
913 SourceLoc))
914 return true;
915 }
916 return false;
917}
918
919bool Sema::CheckExceptionSpecCompatibility(Expr *From, QualType ToType) {
920 // First we check for applicability.
921 // Target type must be a function, function pointer or function reference.
922 const FunctionProtoType *ToFunc = GetUnderlyingFunction(ToType);
923 if (!ToFunc || ToFunc->hasDependentExceptionSpec())
924 return false;
925
926 // SourceType must be a function or function pointer.
927 const FunctionProtoType *FromFunc = GetUnderlyingFunction(From->getType());
928 if (!FromFunc || FromFunc->hasDependentExceptionSpec())
929 return false;
930
931 unsigned DiagID = diag::err_incompatible_exception_specs;
932 unsigned NestedDiagID = diag::err_deep_exception_specs_differ;
933 // This is not an error in C++17 onwards, unless the noexceptness doesn't
934 // match, but in that case we have a full-on type mismatch, not just a
935 // type sugar mismatch.
936 if (getLangOpts().CPlusPlus17) {
937 DiagID = diag::warn_incompatible_exception_specs;
938 NestedDiagID = diag::warn_deep_exception_specs_differ;
939 }
940
941 // Now we've got the correct types on both sides, check their compatibility.
942 // This means that the source of the conversion can only throw a subset of
943 // the exceptions of the target, and any exception specs on arguments or
944 // return types must be equivalent.
945 //
946 // FIXME: If there is a nested dependent exception specification, we should
947 // not be checking it here. This is fine:
948 // template<typename T> void f() {
949 // void (*p)(void (*) throw(T));
950 // void (*q)(void (*) throw(int)) = p;
951 // }
952 // ... because it might be instantiated with T=int.
953 return CheckExceptionSpecSubset(
954 PDiag(DiagID), PDiag(NestedDiagID), PDiag(), PDiag(), ToFunc,
955 From->getSourceRange().getBegin(), FromFunc, SourceLocation()) &&
956 !getLangOpts().CPlusPlus17;
957}
958
959bool Sema::CheckOverridingFunctionExceptionSpec(const CXXMethodDecl *New,
960 const CXXMethodDecl *Old) {
961 // If the new exception specification hasn't been parsed yet, skip the check.
962 // We'll get called again once it's been parsed.
963 if (New->getType()->castAs<FunctionProtoType>()->getExceptionSpecType() ==
964 EST_Unparsed)
965 return false;
966
967 // Don't check uninstantiated template destructors at all. We can only
968 // synthesize correct specs after the template is instantiated.
969 if (isa<CXXDestructorDecl>(New) && New->getParent()->isDependentType())
970 return false;
971
972 // If the old exception specification hasn't been parsed yet, or the new
973 // exception specification can't be computed yet, remember that we need to
974 // perform this check when we get to the end of the outermost
975 // lexically-surrounding class.
976 if (exceptionSpecNotKnownYet(Old) || exceptionSpecNotKnownYet(New)) {
977 DelayedOverridingExceptionSpecChecks.push_back({New, Old});
978 return false;
979 }
980
981 unsigned DiagID = diag::err_override_exception_spec;
982 if (getLangOpts().MSVCCompat)
983 DiagID = diag::ext_override_exception_spec;
984 return CheckExceptionSpecSubset(PDiag(DiagID),
985 PDiag(diag::err_deep_exception_specs_differ),
986 PDiag(diag::note_overridden_virtual_function),
987 PDiag(diag::ext_override_exception_spec),
988 Old->getType()->castAs<FunctionProtoType>(),
989 Old->getLocation(),
990 New->getType()->castAs<FunctionProtoType>(),
991 New->getLocation());
992}
993
994static CanThrowResult canSubStmtsThrow(Sema &Self, const Stmt *S) {
995 CanThrowResult R = CT_Cannot;
996 for (const Stmt *SubStmt : S->children()) {
997 if (!SubStmt)
998 continue;
999 R = mergeCanThrow(R, Self.canThrow(SubStmt));
1000 if (R == CT_Can)
1001 break;
1002 }
1003 return R;
1004}
1005
1006CanThrowResult Sema::canCalleeThrow(Sema &S, const Expr *E, const Decl *D,
1007 SourceLocation Loc) {
1008 // As an extension, we assume that __attribute__((nothrow)) functions don't
1009 // throw.
1010 if (D && isa<FunctionDecl>(D) && D->hasAttr<NoThrowAttr>())
1011 return CT_Cannot;
1012
1013 QualType T;
1014
1015 // In C++1z, just look at the function type of the callee.
1016 if (S.getLangOpts().CPlusPlus17 && E && isa<CallExpr>(E)) {
1017 E = cast<CallExpr>(E)->getCallee();
1018 T = E->getType();
1019 if (T->isSpecificPlaceholderType(BuiltinType::BoundMember)) {
1020 // Sadly we don't preserve the actual type as part of the "bound member"
1021 // placeholder, so we need to reconstruct it.
1022 E = E->IgnoreParenImpCasts();
1023
1024 // Could be a call to a pointer-to-member or a plain member access.
1025 if (auto *Op = dyn_cast<BinaryOperator>(E)) {
1026 assert(Op->getOpcode() == BO_PtrMemD || Op->getOpcode() == BO_PtrMemI)(static_cast<void> (0));
1027 T = Op->getRHS()->getType()
1028 ->castAs<MemberPointerType>()->getPointeeType();
1029 } else {
1030 T = cast<MemberExpr>(E)->getMemberDecl()->getType();
1031 }
1032 }
1033 } else if (const ValueDecl *VD = dyn_cast_or_null<ValueDecl>(D))
1034 T = VD->getType();
1035 else
1036 // If we have no clue what we're calling, assume the worst.
1037 return CT_Can;
1038
1039 const FunctionProtoType *FT;
1040 if ((FT = T->getAs<FunctionProtoType>())) {
1041 } else if (const PointerType *PT = T->getAs<PointerType>())
1042 FT = PT->getPointeeType()->getAs<FunctionProtoType>();
1043 else if (const ReferenceType *RT = T->getAs<ReferenceType>())
1044 FT = RT->getPointeeType()->getAs<FunctionProtoType>();
1045 else if (const MemberPointerType *MT = T->getAs<MemberPointerType>())
1046 FT = MT->getPointeeType()->getAs<FunctionProtoType>();
1047 else if (const BlockPointerType *BT = T->getAs<BlockPointerType>())
1048 FT = BT->getPointeeType()->getAs<FunctionProtoType>();
1049
1050 if (!FT)
1051 return CT_Can;
1052
1053 if (Loc.isValid() || (Loc.isInvalid() && E))
1054 FT = S.ResolveExceptionSpec(Loc.isInvalid() ? E->getBeginLoc() : Loc, FT);
1055 if (!FT)
1056 return CT_Can;
1057
1058 return FT->canThrow();
1059}
1060
1061static CanThrowResult canVarDeclThrow(Sema &Self, const VarDecl *VD) {
1062 CanThrowResult CT = CT_Cannot;
1063
1064 // Initialization might throw.
1065 if (!VD->isUsableInConstantExpressions(Self.Context))
1066 if (const Expr *Init = VD->getInit())
1067 CT = mergeCanThrow(CT, Self.canThrow(Init));
1068
1069 // Destructor might throw.
1070 if (VD->needsDestruction(Self.Context) == QualType::DK_cxx_destructor) {
1071 if (auto *RD =
1072 VD->getType()->getBaseElementTypeUnsafe()->getAsCXXRecordDecl()) {
1073 if (auto *Dtor = RD->getDestructor()) {
1074 CT = mergeCanThrow(
1075 CT, Sema::canCalleeThrow(Self, nullptr, Dtor, VD->getLocation()));
1076 }
1077 }
1078 }
1079
1080 // If this is a decomposition declaration, bindings might throw.
1081 if (auto *DD = dyn_cast<DecompositionDecl>(VD))
1082 for (auto *B : DD->bindings())
1083 if (auto *HD = B->getHoldingVar())
1084 CT = mergeCanThrow(CT, canVarDeclThrow(Self, HD));
1085
1086 return CT;
1087}
1088
1089static CanThrowResult canDynamicCastThrow(const CXXDynamicCastExpr *DC) {
1090 if (DC->isTypeDependent())
1091 return CT_Dependent;
1092
1093 if (!DC->getTypeAsWritten()->isReferenceType())
1094 return CT_Cannot;
1095
1096 if (DC->getSubExpr()->isTypeDependent())
1097 return CT_Dependent;
1098
1099 return DC->getCastKind() == clang::CK_Dynamic? CT_Can : CT_Cannot;
1100}
1101
1102static CanThrowResult canTypeidThrow(Sema &S, const CXXTypeidExpr *DC) {
1103 if (DC->isTypeOperand())
1104 return CT_Cannot;
1105
1106 Expr *Op = DC->getExprOperand();
1107 if (Op->isTypeDependent())
1108 return CT_Dependent;
1109
1110 const RecordType *RT = Op->getType()->getAs<RecordType>();
1111 if (!RT)
1112 return CT_Cannot;
1113
1114 if (!cast<CXXRecordDecl>(RT->getDecl())->isPolymorphic())
1115 return CT_Cannot;
1116
1117 if (Op->Classify(S.Context).isPRValue())
1118 return CT_Cannot;
1119
1120 return CT_Can;
1121}
1122
1123CanThrowResult Sema::canThrow(const Stmt *S) {
1124 // C++ [expr.unary.noexcept]p3:
1125 // [Can throw] if in a potentially-evaluated context the expression would
1126 // contain:
1127 switch (S->getStmtClass()) {
1128 case Expr::ConstantExprClass:
1129 return canThrow(cast<ConstantExpr>(S)->getSubExpr());
1130
1131 case Expr::CXXThrowExprClass:
1132 // - a potentially evaluated throw-expression
1133 return CT_Can;
1134
1135 case Expr::CXXDynamicCastExprClass: {
1136 // - a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
1137 // where T is a reference type, that requires a run-time check
1138 auto *CE = cast<CXXDynamicCastExpr>(S);
1139 // FIXME: Properly determine whether a variably-modified type can throw.
1140 if (CE->getType()->isVariablyModifiedType())
1141 return CT_Can;
1142 CanThrowResult CT = canDynamicCastThrow(CE);
1143 if (CT == CT_Can)
1144 return CT;
1145 return mergeCanThrow(CT, canSubStmtsThrow(*this, CE));
1146 }
1147
1148 case Expr::CXXTypeidExprClass:
1149 // - a potentially evaluated typeid expression applied to a glvalue
1150 // expression whose type is a polymorphic class type
1151 return canTypeidThrow(*this, cast<CXXTypeidExpr>(S));
1152
1153 // - a potentially evaluated call to a function, member function, function
1154 // pointer, or member function pointer that does not have a non-throwing
1155 // exception-specification
1156 case Expr::CallExprClass:
1157 case Expr::CXXMemberCallExprClass:
1158 case Expr::CXXOperatorCallExprClass:
1159 case Expr::UserDefinedLiteralClass: {
1160 const CallExpr *CE = cast<CallExpr>(S);
1161 CanThrowResult CT;
1162 if (CE->isTypeDependent())
1163 CT = CT_Dependent;
1164 else if (isa<CXXPseudoDestructorExpr>(CE->getCallee()->IgnoreParens()))
1165 CT = CT_Cannot;
1166 else
1167 CT = canCalleeThrow(*this, CE, CE->getCalleeDecl());
1168 if (CT == CT_Can)
1169 return CT;
1170 return mergeCanThrow(CT, canSubStmtsThrow(*this, CE));
1171 }
1172
1173 case Expr::CXXConstructExprClass:
1174 case Expr::CXXTemporaryObjectExprClass: {
1175 auto *CE = cast<CXXConstructExpr>(S);
1176 // FIXME: Properly determine whether a variably-modified type can throw.
1177 if (CE->getType()->isVariablyModifiedType())
1178 return CT_Can;
1179 CanThrowResult CT = canCalleeThrow(*this, CE, CE->getConstructor());
1180 if (CT == CT_Can)
1181 return CT;
1182 return mergeCanThrow(CT, canSubStmtsThrow(*this, CE));
1183 }
1184
1185 case Expr::CXXInheritedCtorInitExprClass: {
1186 auto *ICIE = cast<CXXInheritedCtorInitExpr>(S);
1187 return canCalleeThrow(*this, ICIE, ICIE->getConstructor());
1188 }
1189
1190 case Expr::LambdaExprClass: {
1191 const LambdaExpr *Lambda = cast<LambdaExpr>(S);
1192 CanThrowResult CT = CT_Cannot;
1193 for (LambdaExpr::const_capture_init_iterator
1194 Cap = Lambda->capture_init_begin(),
1195 CapEnd = Lambda->capture_init_end();
1196 Cap != CapEnd; ++Cap)
1197 CT = mergeCanThrow(CT, canThrow(*Cap));
1198 return CT;
1199 }
1200
1201 case Expr::CXXNewExprClass: {
1202 auto *NE = cast<CXXNewExpr>(S);
1203 CanThrowResult CT;
1204 if (NE->isTypeDependent())
1205 CT = CT_Dependent;
1206 else
1207 CT = canCalleeThrow(*this, NE, NE->getOperatorNew());
1208 if (CT == CT_Can)
1209 return CT;
1210 return mergeCanThrow(CT, canSubStmtsThrow(*this, NE));
1211 }
1212
1213 case Expr::CXXDeleteExprClass: {
1214 auto *DE = cast<CXXDeleteExpr>(S);
1215 CanThrowResult CT;
1216 QualType DTy = DE->getDestroyedType();
1217 if (DTy.isNull() || DTy->isDependentType()) {
1218 CT = CT_Dependent;
1219 } else {
1220 CT = canCalleeThrow(*this, DE, DE->getOperatorDelete());
1221 if (const RecordType *RT = DTy->getAs<RecordType>()) {
1222 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1223 const CXXDestructorDecl *DD = RD->getDestructor();
1224 if (DD)
1225 CT = mergeCanThrow(CT, canCalleeThrow(*this, DE, DD));
1226 }
1227 if (CT == CT_Can)
1228 return CT;
1229 }
1230 return mergeCanThrow(CT, canSubStmtsThrow(*this, DE));
1231 }
1232
1233 case Expr::CXXBindTemporaryExprClass: {
1234 auto *BTE = cast<CXXBindTemporaryExpr>(S);
1235 // The bound temporary has to be destroyed again, which might throw.
1236 CanThrowResult CT =
1237 canCalleeThrow(*this, BTE, BTE->getTemporary()->getDestructor());
1238 if (CT == CT_Can)
1239 return CT;
1240 return mergeCanThrow(CT, canSubStmtsThrow(*this, BTE));
1241 }
1242
1243 case Expr::PseudoObjectExprClass: {
1244 auto *POE = cast<PseudoObjectExpr>(S);
1245 CanThrowResult CT = CT_Cannot;
1246 for (const Expr *E : POE->semantics()) {
1247 CT = mergeCanThrow(CT, canThrow(E));
1248 if (CT == CT_Can)
1249 break;
1250 }
1251 return CT;
1252 }
1253
1254 // ObjC message sends are like function calls, but never have exception
1255 // specs.
1256 case Expr::ObjCMessageExprClass:
1257 case Expr::ObjCPropertyRefExprClass:
1258 case Expr::ObjCSubscriptRefExprClass:
1259 return CT_Can;
1260
1261 // All the ObjC literals that are implemented as calls are
1262 // potentially throwing unless we decide to close off that
1263 // possibility.
1264 case Expr::ObjCArrayLiteralClass:
1265 case Expr::ObjCDictionaryLiteralClass:
1266 case Expr::ObjCBoxedExprClass:
1267 return CT_Can;
1268
1269 // Many other things have subexpressions, so we have to test those.
1270 // Some are simple:
1271 case Expr::CoawaitExprClass:
1272 case Expr::ConditionalOperatorClass:
1273 case Expr::CoyieldExprClass:
1274 case Expr::CXXRewrittenBinaryOperatorClass:
1275 case Expr::CXXStdInitializerListExprClass:
1276 case Expr::DesignatedInitExprClass:
1277 case Expr::DesignatedInitUpdateExprClass:
1278 case Expr::ExprWithCleanupsClass:
1279 case Expr::ExtVectorElementExprClass:
1280 case Expr::InitListExprClass:
1281 case Expr::ArrayInitLoopExprClass:
1282 case Expr::MemberExprClass:
1283 case Expr::ObjCIsaExprClass:
1284 case Expr::ObjCIvarRefExprClass:
1285 case Expr::ParenExprClass:
1286 case Expr::ParenListExprClass:
1287 case Expr::ShuffleVectorExprClass:
1288 case Expr::StmtExprClass:
1289 case Expr::ConvertVectorExprClass:
1290 case Expr::VAArgExprClass:
1291 return canSubStmtsThrow(*this, S);
1292
1293 case Expr::CompoundLiteralExprClass:
1294 case Expr::CXXConstCastExprClass:
1295 case Expr::CXXAddrspaceCastExprClass:
1296 case Expr::CXXReinterpretCastExprClass:
1297 case Expr::BuiltinBitCastExprClass:
1298 // FIXME: Properly determine whether a variably-modified type can throw.
1299 if (cast<Expr>(S)->getType()->isVariablyModifiedType())
1300 return CT_Can;
1301 return canSubStmtsThrow(*this, S);
1302
1303 // Some might be dependent for other reasons.
1304 case Expr::ArraySubscriptExprClass:
1305 case Expr::MatrixSubscriptExprClass:
1306 case Expr::OMPArraySectionExprClass:
1307 case Expr::OMPArrayShapingExprClass:
1308 case Expr::OMPIteratorExprClass:
1309 case Expr::BinaryOperatorClass:
1310 case Expr::DependentCoawaitExprClass:
1311 case Expr::CompoundAssignOperatorClass:
1312 case Expr::CStyleCastExprClass:
1313 case Expr::CXXStaticCastExprClass:
1314 case Expr::CXXFunctionalCastExprClass:
1315 case Expr::ImplicitCastExprClass:
1316 case Expr::MaterializeTemporaryExprClass:
1317 case Expr::UnaryOperatorClass: {
1318 // FIXME: Properly determine whether a variably-modified type can throw.
1319 if (auto *CE = dyn_cast<CastExpr>(S))
1320 if (CE->getType()->isVariablyModifiedType())
1321 return CT_Can;
1322 CanThrowResult CT =
1323 cast<Expr>(S)->isTypeDependent() ? CT_Dependent : CT_Cannot;
1324 return mergeCanThrow(CT, canSubStmtsThrow(*this, S));
1325 }
1326
1327 case Expr::CXXDefaultArgExprClass:
1328 return canThrow(cast<CXXDefaultArgExpr>(S)->getExpr());
1329
1330 case Expr::CXXDefaultInitExprClass:
1331 return canThrow(cast<CXXDefaultInitExpr>(S)->getExpr());
1332
1333 case Expr::ChooseExprClass: {
1334 auto *CE = cast<ChooseExpr>(S);
1335 if (CE->isTypeDependent() || CE->isValueDependent())
1336 return CT_Dependent;
1337 return canThrow(CE->getChosenSubExpr());
1338 }
1339
1340 case Expr::GenericSelectionExprClass:
1341 if (cast<GenericSelectionExpr>(S)->isResultDependent())
1342 return CT_Dependent;
1343 return canThrow(cast<GenericSelectionExpr>(S)->getResultExpr());
1344
1345 // Some expressions are always dependent.
1346 case Expr::CXXDependentScopeMemberExprClass:
1347 case Expr::CXXUnresolvedConstructExprClass:
1348 case Expr::DependentScopeDeclRefExprClass:
1349 case Expr::CXXFoldExprClass:
1350 case Expr::RecoveryExprClass:
1351 return CT_Dependent;
1352
1353 case Expr::AsTypeExprClass:
1354 case Expr::BinaryConditionalOperatorClass:
1355 case Expr::BlockExprClass:
1356 case Expr::CUDAKernelCallExprClass:
1357 case Expr::DeclRefExprClass:
1358 case Expr::ObjCBridgedCastExprClass:
1359 case Expr::ObjCIndirectCopyRestoreExprClass:
1360 case Expr::ObjCProtocolExprClass:
1361 case Expr::ObjCSelectorExprClass:
1362 case Expr::ObjCAvailabilityCheckExprClass:
1363 case Expr::OffsetOfExprClass:
1364 case Expr::PackExpansionExprClass:
1365 case Expr::SubstNonTypeTemplateParmExprClass:
1366 case Expr::SubstNonTypeTemplateParmPackExprClass:
1367 case Expr::FunctionParmPackExprClass:
1368 case Expr::UnaryExprOrTypeTraitExprClass:
1369 case Expr::UnresolvedLookupExprClass:
1370 case Expr::UnresolvedMemberExprClass:
1371 case Expr::TypoExprClass:
1372 // FIXME: Many of the above can throw.
1373 return CT_Cannot;
1374
1375 case Expr::AddrLabelExprClass:
1376 case Expr::ArrayTypeTraitExprClass:
1377 case Expr::AtomicExprClass:
1378 case Expr::TypeTraitExprClass:
1379 case Expr::CXXBoolLiteralExprClass:
1380 case Expr::CXXNoexceptExprClass:
1381 case Expr::CXXNullPtrLiteralExprClass:
1382 case Expr::CXXPseudoDestructorExprClass:
1383 case Expr::CXXScalarValueInitExprClass:
1384 case Expr::CXXThisExprClass:
1385 case Expr::CXXUuidofExprClass:
1386 case Expr::CharacterLiteralClass:
1387 case Expr::ExpressionTraitExprClass:
1388 case Expr::FloatingLiteralClass:
1389 case Expr::GNUNullExprClass:
1390 case Expr::ImaginaryLiteralClass:
1391 case Expr::ImplicitValueInitExprClass:
1392 case Expr::IntegerLiteralClass:
1393 case Expr::FixedPointLiteralClass:
1394 case Expr::ArrayInitIndexExprClass:
1395 case Expr::NoInitExprClass:
1396 case Expr::ObjCEncodeExprClass:
1397 case Expr::ObjCStringLiteralClass:
1398 case Expr::ObjCBoolLiteralExprClass:
1399 case Expr::OpaqueValueExprClass:
1400 case Expr::PredefinedExprClass:
1401 case Expr::SizeOfPackExprClass:
1402 case Expr::StringLiteralClass:
1403 case Expr::SourceLocExprClass:
1404 case Expr::ConceptSpecializationExprClass:
1405 case Expr::RequiresExprClass:
1406 // These expressions can never throw.
1407 return CT_Cannot;
1408
1409 case Expr::MSPropertyRefExprClass:
1410 case Expr::MSPropertySubscriptExprClass:
1411 llvm_unreachable("Invalid class for expression")__builtin_unreachable();
1412
1413 // Most statements can throw if any substatement can throw.
1414 case Stmt::AttributedStmtClass:
1415 case Stmt::BreakStmtClass:
1416 case Stmt::CapturedStmtClass:
1417 case Stmt::CaseStmtClass:
1418 case Stmt::CompoundStmtClass:
1419 case Stmt::ContinueStmtClass:
1420 case Stmt::CoreturnStmtClass:
1421 case Stmt::CoroutineBodyStmtClass:
1422 case Stmt::CXXCatchStmtClass:
1423 case Stmt::CXXForRangeStmtClass:
1424 case Stmt::DefaultStmtClass:
1425 case Stmt::DoStmtClass:
1426 case Stmt::ForStmtClass:
1427 case Stmt::GCCAsmStmtClass:
1428 case Stmt::GotoStmtClass:
1429 case Stmt::IndirectGotoStmtClass:
1430 case Stmt::LabelStmtClass:
1431 case Stmt::MSAsmStmtClass:
1432 case Stmt::MSDependentExistsStmtClass:
1433 case Stmt::NullStmtClass:
1434 case Stmt::ObjCAtCatchStmtClass:
1435 case Stmt::ObjCAtFinallyStmtClass:
1436 case Stmt::ObjCAtSynchronizedStmtClass:
1437 case Stmt::ObjCAutoreleasePoolStmtClass:
1438 case Stmt::ObjCForCollectionStmtClass:
1439 case Stmt::OMPAtomicDirectiveClass:
1440 case Stmt::OMPBarrierDirectiveClass:
1441 case Stmt::OMPCancelDirectiveClass:
1442 case Stmt::OMPCancellationPointDirectiveClass:
1443 case Stmt::OMPCriticalDirectiveClass:
1444 case Stmt::OMPDistributeDirectiveClass:
1445 case Stmt::OMPDistributeParallelForDirectiveClass:
1446 case Stmt::OMPDistributeParallelForSimdDirectiveClass:
1447 case Stmt::OMPDistributeSimdDirectiveClass:
1448 case Stmt::OMPFlushDirectiveClass:
1449 case Stmt::OMPDepobjDirectiveClass:
1450 case Stmt::OMPScanDirectiveClass:
1451 case Stmt::OMPForDirectiveClass:
1452 case Stmt::OMPForSimdDirectiveClass:
1453 case Stmt::OMPMasterDirectiveClass:
1454 case Stmt::OMPMasterTaskLoopDirectiveClass:
1455 case Stmt::OMPMasterTaskLoopSimdDirectiveClass:
1456 case Stmt::OMPOrderedDirectiveClass:
1457 case Stmt::OMPCanonicalLoopClass:
1458 case Stmt::OMPParallelDirectiveClass:
1459 case Stmt::OMPParallelForDirectiveClass:
1460 case Stmt::OMPParallelForSimdDirectiveClass:
1461 case Stmt::OMPParallelMasterDirectiveClass:
1462 case Stmt::OMPParallelMasterTaskLoopDirectiveClass:
1463 case Stmt::OMPParallelMasterTaskLoopSimdDirectiveClass:
1464 case Stmt::OMPParallelSectionsDirectiveClass:
1465 case Stmt::OMPSectionDirectiveClass:
1466 case Stmt::OMPSectionsDirectiveClass:
1467 case Stmt::OMPSimdDirectiveClass:
1468 case Stmt::OMPTileDirectiveClass:
1469 case Stmt::OMPUnrollDirectiveClass:
1470 case Stmt::OMPSingleDirectiveClass:
1471 case Stmt::OMPTargetDataDirectiveClass:
1472 case Stmt::OMPTargetDirectiveClass:
1473 case Stmt::OMPTargetEnterDataDirectiveClass:
1474 case Stmt::OMPTargetExitDataDirectiveClass:
1475 case Stmt::OMPTargetParallelDirectiveClass:
1476 case Stmt::OMPTargetParallelForDirectiveClass:
1477 case Stmt::OMPTargetParallelForSimdDirectiveClass:
1478 case Stmt::OMPTargetSimdDirectiveClass:
1479 case Stmt::OMPTargetTeamsDirectiveClass:
1480 case Stmt::OMPTargetTeamsDistributeDirectiveClass:
1481 case Stmt::OMPTargetTeamsDistributeParallelForDirectiveClass:
1482 case Stmt::OMPTargetTeamsDistributeParallelForSimdDirectiveClass:
1483 case Stmt::OMPTargetTeamsDistributeSimdDirectiveClass:
1484 case Stmt::OMPTargetUpdateDirectiveClass:
1485 case Stmt::OMPTaskDirectiveClass:
1486 case Stmt::OMPTaskgroupDirectiveClass:
1487 case Stmt::OMPTaskLoopDirectiveClass:
1488 case Stmt::OMPTaskLoopSimdDirectiveClass:
1489 case Stmt::OMPTaskwaitDirectiveClass:
1490 case Stmt::OMPTaskyieldDirectiveClass:
1491 case Stmt::OMPTeamsDirectiveClass:
1492 case Stmt::OMPTeamsDistributeDirectiveClass:
1493 case Stmt::OMPTeamsDistributeParallelForDirectiveClass:
1494 case Stmt::OMPTeamsDistributeParallelForSimdDirectiveClass:
1495 case Stmt::OMPTeamsDistributeSimdDirectiveClass:
1496 case Stmt::OMPInteropDirectiveClass:
1497 case Stmt::OMPDispatchDirectiveClass:
1498 case Stmt::OMPMaskedDirectiveClass:
1499 case Stmt::ReturnStmtClass:
1500 case Stmt::SEHExceptStmtClass:
1501 case Stmt::SEHFinallyStmtClass:
1502 case Stmt::SEHLeaveStmtClass:
1503 case Stmt::SEHTryStmtClass:
1504 case Stmt::SwitchStmtClass:
1505 case Stmt::WhileStmtClass:
1506 return canSubStmtsThrow(*this, S);
1507
1508 case Stmt::DeclStmtClass: {
1509 CanThrowResult CT = CT_Cannot;
1510 for (const Decl *D : cast<DeclStmt>(S)->decls()) {
1511 if (auto *VD = dyn_cast<VarDecl>(D))
1512 CT = mergeCanThrow(CT, canVarDeclThrow(*this, VD));
1513
1514 // FIXME: Properly determine whether a variably-modified type can throw.
1515 if (auto *TND = dyn_cast<TypedefNameDecl>(D))
1516 if (TND->getUnderlyingType()->isVariablyModifiedType())
1517 return CT_Can;
1518 if (auto *VD = dyn_cast<ValueDecl>(D))
1519 if (VD->getType()->isVariablyModifiedType())
1520 return CT_Can;
1521 }
1522 return CT;
1523 }
1524
1525 case Stmt::IfStmtClass: {
1526 auto *IS = cast<IfStmt>(S);
1527 CanThrowResult CT = CT_Cannot;
1528 if (const Stmt *Init = IS->getInit())
1529 CT = mergeCanThrow(CT, canThrow(Init));
1530 if (const Stmt *CondDS = IS->getConditionVariableDeclStmt())
1531 CT = mergeCanThrow(CT, canThrow(CondDS));
1532 CT = mergeCanThrow(CT, canThrow(IS->getCond()));
1533
1534 // For 'if constexpr', consider only the non-discarded case.
1535 // FIXME: We should add a DiscardedStmt marker to the AST.
1536 if (Optional<const Stmt *> Case = IS->getNondiscardedCase(Context))
1537 return *Case ? mergeCanThrow(CT, canThrow(*Case)) : CT;
1538
1539 CanThrowResult Then = canThrow(IS->getThen());
1540 CanThrowResult Else = IS->getElse() ? canThrow(IS->getElse()) : CT_Cannot;
1541 if (Then == Else)
1542 return mergeCanThrow(CT, Then);
1543
1544 // For a dependent 'if constexpr', the result is dependent if it depends on
1545 // the value of the condition.
1546 return mergeCanThrow(CT, IS->isConstexpr() ? CT_Dependent
1547 : mergeCanThrow(Then, Else));
1548 }
1549
1550 case Stmt::CXXTryStmtClass: {
1551 auto *TS = cast<CXXTryStmt>(S);
1552 // try /*...*/ catch (...) { H } can throw only if H can throw.
1553 // Any other try-catch can throw if any substatement can throw.
1554 const CXXCatchStmt *FinalHandler = TS->getHandler(TS->getNumHandlers() - 1);
1555 if (!FinalHandler->getExceptionDecl())
1556 return canThrow(FinalHandler->getHandlerBlock());
1557 return canSubStmtsThrow(*this, S);
1558 }
1559
1560 case Stmt::ObjCAtThrowStmtClass:
1561 return CT_Can;
1562
1563 case Stmt::ObjCAtTryStmtClass: {
1564 auto *TS = cast<ObjCAtTryStmt>(S);
1565
1566 // @catch(...) need not be last in Objective-C. Walk backwards until we
1567 // see one or hit the @try.
1568 CanThrowResult CT = CT_Cannot;
1569 if (const Stmt *Finally = TS->getFinallyStmt())
1570 CT = mergeCanThrow(CT, canThrow(Finally));
1571 for (unsigned I = TS->getNumCatchStmts(); I != 0; --I) {
1572 const ObjCAtCatchStmt *Catch = TS->getCatchStmt(I - 1);
1573 CT = mergeCanThrow(CT, canThrow(Catch));
1574 // If we reach a @catch(...), no earlier exceptions can escape.
1575 if (Catch->hasEllipsis())
1576 return CT;
1577 }
1578
1579 // Didn't find an @catch(...). Exceptions from the @try body can escape.
1580 return mergeCanThrow(CT, canThrow(TS->getTryBody()));
1581 }
1582
1583 case Stmt::SYCLUniqueStableNameExprClass:
1584 return CT_Cannot;
1585 case Stmt::NoStmtClass:
1586 llvm_unreachable("Invalid class for statement")__builtin_unreachable();
1587 }
1588 llvm_unreachable("Bogus StmtClass")__builtin_unreachable();
1589}
1590
1591} // end namespace clang