[clang] [clang] Implement lifetime analysis for lifetime_capture_by(X) (PR #115921)
Utkarsh Saxena via cfe-commits
cfe-commits at lists.llvm.org
Wed Nov 13 02:24:58 PST 2024
https://github.com/usx95 updated https://github.com/llvm/llvm-project/pull/115921
>From 2cef37ecdb81452a8f5882dfe765167c1e45b7b6 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Wed, 13 Nov 2024 10:24:33 +0000
Subject: [PATCH] Implement semantics for lifetime analysis
---
clang/include/clang/Basic/DiagnosticGroups.td | 2 +
.../clang/Basic/DiagnosticSemaKinds.td | 7 +-
clang/include/clang/Sema/Sema.h | 3 +
clang/lib/Sema/CheckExprLifetime.cpp | 66 ++++++++---
clang/lib/Sema/CheckExprLifetime.h | 13 +++
clang/lib/Sema/SemaChecking.cpp | 47 +++++++-
.../Sema/warn-lifetime-analysis-nocfg.cpp | 105 ++++++++++++++++++
clang/test/SemaCXX/attr-lifetimebound.cpp | 4 +-
8 files changed, 228 insertions(+), 19 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 72eada50a56cc9..df9bf94b5d0398 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -453,6 +453,7 @@ def ShiftOpParentheses: DiagGroup<"shift-op-parentheses">;
def OverloadedShiftOpParentheses: DiagGroup<"overloaded-shift-op-parentheses">;
def DanglingAssignment: DiagGroup<"dangling-assignment">;
def DanglingAssignmentGsl : DiagGroup<"dangling-assignment-gsl">;
+def DanglingCapture : DiagGroup<"dangling-capture">;
def DanglingElse: DiagGroup<"dangling-else">;
def DanglingField : DiagGroup<"dangling-field">;
def DanglingInitializerList : DiagGroup<"dangling-initializer-list">;
@@ -462,6 +463,7 @@ def ReturnStackAddress : DiagGroup<"return-stack-address">;
def : DiagGroup<"return-local-addr", [ReturnStackAddress]>;
def Dangling : DiagGroup<"dangling", [DanglingAssignment,
DanglingAssignmentGsl,
+ DanglingCapture,
DanglingField,
DanglingInitializerList,
DanglingGsl,
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 2f5d672e2f0035..58745d450ed63f 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10132,10 +10132,10 @@ def err_lifetimebound_ctor_dtor : Error<
"%select{constructor|destructor}0">;
def err_lifetimebound_parameter_void_return_type : Error<
"'lifetimebound' attribute cannot be applied to a parameter of a function "
- "that returns void">;
+ "that returns void; did you mean 'lifetime_capture_by(X)'">;
def err_lifetimebound_implicit_object_parameter_void_return_type : Error<
"'lifetimebound' attribute cannot be applied to an implicit object "
- "parameter of a function that returns void">;
+ "parameter of a function that returns void; did you mean 'lifetime_capture_by(X)'">;
// CHECK: returning address/reference of stack memory
def warn_ret_stack_addr_ref : Warning<
@@ -10230,6 +10230,9 @@ def warn_dangling_pointer_assignment : Warning<
"object backing %select{|the pointer }0%1 "
"will be destroyed at the end of the full-expression">,
InGroup<DanglingAssignment>;
+def warn_dangling_reference_captured : Warning<
+ "object captured by '%0' will be destroyed at the end of the full-expression">,
+ InGroup<DanglingCapture>;
// For non-floating point, expressions of the form x == x or x != x
// should result in a warning, since these always evaluate to a constant.
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index d6f3508a5243f3..6ea6c67447b6f0 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -2323,6 +2323,9 @@ class Sema final : public SemaBase {
bool BuiltinVectorMath(CallExpr *TheCall, QualType &Res, bool FPOnly = false);
bool BuiltinVectorToScalarMath(CallExpr *TheCall);
+ void checkLifetimeCaptureBy(FunctionDecl *FDecl, bool IsMemberFunction,
+ const Expr *ThisArg, ArrayRef<const Expr *> Args);
+
/// Handles the checks for format strings, non-POD arguments to vararg
/// functions, NULL arguments passed to non-NULL parameters, diagnose_if
/// attributes and AArch64 SME attributes.
diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp
index a1a402b4a2b530..81e26f48fb8851 100644
--- a/clang/lib/Sema/CheckExprLifetime.cpp
+++ b/clang/lib/Sema/CheckExprLifetime.cpp
@@ -45,10 +45,14 @@ enum LifetimeKind {
/// a default member initializer), the program is ill-formed.
LK_MemInitializer,
- /// The lifetime of a temporary bound to this entity probably ends too soon,
+ /// The lifetime of a temporary bound to this entity may end too soon,
/// because the entity is a pointer and we assign the address of a temporary
/// object to it.
LK_Assignment,
+
+ /// The lifetime of a temporary bound to this entity may end too soon,
+ /// because the entity may capture the reference to a temporary object.
+ LK_LifetimeCapture,
};
using LifetimeResult =
llvm::PointerIntPair<const InitializedEntity *, 3, LifetimeKind>;
@@ -193,6 +197,7 @@ struct IndirectLocalPathEntry {
VarInit,
LValToRVal,
LifetimeBoundCall,
+ LifetimeCapture,
TemporaryCopy,
LambdaCaptureInit,
GslReferenceInit,
@@ -249,9 +254,10 @@ static void visitLocalsRetainedByReferenceBinding(IndirectLocalPath &Path,
LocalVisitor Visit);
template <typename T> static bool isRecordWithAttr(QualType Type) {
- if (auto *RD = Type->getAsCXXRecordDecl())
- return RD->hasAttr<T>();
- return false;
+ CXXRecordDecl *RD = Type.getNonReferenceType()->getAsCXXRecordDecl();
+ if (!RD)
+ return false;
+ return RD->hasAttr<T>();
}
// Decl::isInStdNamespace will return false for iterators in some STL
@@ -1049,6 +1055,7 @@ static SourceRange nextPathEntryRange(const IndirectLocalPath &Path, unsigned I,
case IndirectLocalPathEntry::AddressOf:
case IndirectLocalPathEntry::LValToRVal:
case IndirectLocalPathEntry::LifetimeBoundCall:
+ case IndirectLocalPathEntry::LifetimeCapture:
case IndirectLocalPathEntry::TemporaryCopy:
case IndirectLocalPathEntry::GslReferenceInit:
case IndirectLocalPathEntry::GslPointerInit:
@@ -1082,6 +1089,7 @@ static bool pathOnlyHandlesGslPointer(const IndirectLocalPath &Path) {
case IndirectLocalPathEntry::VarInit:
case IndirectLocalPathEntry::AddressOf:
case IndirectLocalPathEntry::LifetimeBoundCall:
+ case IndirectLocalPathEntry::LifetimeCapture:
continue;
case IndirectLocalPathEntry::GslPointerInit:
case IndirectLocalPathEntry::GslReferenceInit:
@@ -1110,12 +1118,13 @@ static bool shouldRunGSLAssignmentAnalysis(const Sema &SemaRef,
isAssignmentOperatorLifetimeBound(Entity.AssignmentOperator)));
}
-static void checkExprLifetimeImpl(Sema &SemaRef,
- const InitializedEntity *InitEntity,
- const InitializedEntity *ExtendingEntity,
- LifetimeKind LK,
- const AssignedEntity *AEntity, Expr *Init) {
+static void
+checkExprLifetimeImpl(Sema &SemaRef, const InitializedEntity *InitEntity,
+ const InitializedEntity *ExtendingEntity, LifetimeKind LK,
+ const AssignedEntity *AEntity,
+ const CapturingEntity *CapEntity, Expr *Init) {
assert((AEntity && LK == LK_Assignment) ||
+ (CapEntity && LK == LK_LifetimeCapture) ||
(InitEntity && LK != LK_Assignment));
// If this entity doesn't have an interesting lifetime, don't bother looking
// for temporaries within its initializer.
@@ -1199,6 +1208,17 @@ static void checkExprLifetimeImpl(Sema &SemaRef,
break;
}
+ case LK_LifetimeCapture: {
+ if (!MTE)
+ return false;
+ assert(shouldLifetimeExtendThroughPath(Path) ==
+ PathLifetimeKind::NoExtend &&
+ "No lifetime extension in function calls");
+ SemaRef.Diag(DiagLoc, diag::warn_dangling_reference_captured)
+ << CapEntity->Entity << DiagRange;
+ return false;
+ }
+
case LK_Assignment: {
if (!MTE || pathContainsInit(Path))
return false;
@@ -1359,6 +1379,7 @@ static void checkExprLifetimeImpl(Sema &SemaRef,
break;
case IndirectLocalPathEntry::LifetimeBoundCall:
+ case IndirectLocalPathEntry::LifetimeCapture:
case IndirectLocalPathEntry::TemporaryCopy:
case IndirectLocalPathEntry::GslPointerInit:
case IndirectLocalPathEntry::GslReferenceInit:
@@ -1411,7 +1432,7 @@ static void checkExprLifetimeImpl(Sema &SemaRef,
// warnings or errors on inner temporaries within this one's initializer.
return false;
};
-
+ bool HasReferenceBinding = Init->isGLValue();
llvm::SmallVector<IndirectLocalPathEntry, 8> Path;
if (LK == LK_Assignment &&
shouldRunGSLAssignmentAnalysis(SemaRef, *AEntity)) {
@@ -1420,9 +1441,18 @@ static void checkExprLifetimeImpl(Sema &SemaRef,
? IndirectLocalPathEntry::LifetimeBoundCall
: IndirectLocalPathEntry::GslPointerAssignment,
Init});
+ } else if (LK == LK_LifetimeCapture) {
+ Path.push_back({IndirectLocalPathEntry::LifetimeCapture, Init});
+ if (isRecordWithAttr<PointerAttr>(Init->getType()))
+ HasReferenceBinding = false;
+ // Skip the top MTE if it is a temporary object of the pointer-like type
+ // itself.
+ if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(Init);
+ MTE && isPointerLikeType(Init->getType()))
+ Init = MTE->getSubExpr();
}
- if (Init->isGLValue())
+ if (HasReferenceBinding)
visitLocalsRetainedByReferenceBinding(Path, Init, RK_ReferenceBinding,
TemporaryVisitor);
else
@@ -1438,13 +1468,13 @@ void checkExprLifetime(Sema &SemaRef, const InitializedEntity &Entity,
LifetimeKind LK = LTResult.getInt();
const InitializedEntity *ExtendingEntity = LTResult.getPointer();
checkExprLifetimeImpl(SemaRef, &Entity, ExtendingEntity, LK,
- /*AEntity*/ nullptr, Init);
+ /*AEntity*/ nullptr, /*CapEntity=*/nullptr, Init);
}
void checkExprLifetimeMustTailArg(Sema &SemaRef,
const InitializedEntity &Entity, Expr *Init) {
checkExprLifetimeImpl(SemaRef, &Entity, nullptr, LK_MustTail,
- /*AEntity*/ nullptr, Init);
+ /*AEntity*/ nullptr, /*CapEntity=*/nullptr, Init);
}
void checkExprLifetime(Sema &SemaRef, const AssignedEntity &Entity,
@@ -1460,7 +1490,15 @@ void checkExprLifetime(Sema &SemaRef, const AssignedEntity &Entity,
checkExprLifetimeImpl(SemaRef, /*InitEntity=*/nullptr,
/*ExtendingEntity=*/nullptr, LK_Assignment, &Entity,
- Init);
+ /*CapEntity=*/nullptr, Init);
+}
+
+void checkExprLifetime(Sema &SemaRef, const CapturingEntity &Entity,
+ Expr *Init) {
+ return checkExprLifetimeImpl(SemaRef, /*InitEntity=*/nullptr,
+ /*ExtendingEntity=*/nullptr, LK_LifetimeCapture,
+ /*AEntity=*/nullptr,
+ /*CapEntity=*/&Entity, Init);
}
} // namespace clang::sema
diff --git a/clang/lib/Sema/CheckExprLifetime.h b/clang/lib/Sema/CheckExprLifetime.h
index 903f312f3533e5..e109b73b280e9e 100644
--- a/clang/lib/Sema/CheckExprLifetime.h
+++ b/clang/lib/Sema/CheckExprLifetime.h
@@ -25,6 +25,16 @@ struct AssignedEntity {
CXXMethodDecl *AssignmentOperator = nullptr;
};
+struct CapturingEntity {
+ // In an function call involving a lifetime capture, this would be the
+ // argument capturing the lifetime of another argument.
+ // void addToSet(std::string_view sv [[clang::lifetime_capture_by(setsv)]],
+ // set<std::string_view>& setsv);
+ // set<std::string_view> setsv;
+ // addToSet(std::string(), setsv); // Here 'setsv' is the 'Entity'.
+ Expr *Entity = nullptr;
+};
+
/// Check that the lifetime of the given expr (and its subobjects) is
/// sufficient for initializing the entity, and perform lifetime extension
/// (when permitted) if not.
@@ -35,6 +45,9 @@ void checkExprLifetime(Sema &SemaRef, const InitializedEntity &Entity,
/// sufficient for assigning to the entity.
void checkExprLifetime(Sema &SemaRef, const AssignedEntity &Entity, Expr *Init);
+void checkExprLifetime(Sema &SemaRef, const CapturingEntity &Entity,
+ Expr *Init);
+
/// Check that the lifetime of the given expr (and its subobjects) is
/// sufficient, assuming that it is passed as an argument to a musttail
/// function.
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 96008b14225a4c..27edb56df3abc7 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -11,6 +11,7 @@
//
//===----------------------------------------------------------------------===//
+#include "CheckExprLifetime.h"
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
@@ -3229,6 +3230,49 @@ void Sema::CheckArgAlignment(SourceLocation Loc, NamedDecl *FDecl,
<< ParamName << (FDecl != nullptr) << FDecl;
}
+void Sema::checkLifetimeCaptureBy(FunctionDecl *FD, bool IsMemberFunction,
+ const Expr *ThisArg,
+ ArrayRef<const Expr *> Args) {
+ auto GetArgAt = [&](int Idx) {
+ if (IsMemberFunction && Idx == 0)
+ return const_cast<Expr *>(ThisArg);
+ return const_cast<Expr *>(Args[Idx - int(IsMemberFunction)]);
+ };
+ for (unsigned I = 0; I < FD->getNumParams(); ++I) {
+ auto *CapturedByAttr =
+ FD->getParamDecl(I)->getAttr<LifetimeCaptureByAttr>();
+ if (!CapturedByAttr)
+ continue;
+ for (int CapturingParamIdx : CapturedByAttr->params()) {
+ Expr *Capturing = GetArgAt(CapturingParamIdx);
+ Expr *Captured = GetArgAt(I + IsMemberFunction);
+ CapturingEntity CE{Capturing};
+ // Ensure that 'Captured' outlives the 'Capturing' entity.
+ checkExprLifetime(*this, CE, Captured);
+ }
+ }
+ // Check when the 'this' object is captured.
+ if (IsMemberFunction) {
+ TypeSourceInfo *TSI = FD->getTypeSourceInfo();
+ if (!TSI)
+ return;
+ AttributedTypeLoc ATL;
+ for (TypeLoc TL = TSI->getTypeLoc();
+ (ATL = TL.getAsAdjusted<AttributedTypeLoc>());
+ TL = ATL.getModifiedLoc()) {
+ auto *CapturedByAttr = ATL.getAttrAs<LifetimeCaptureByAttr>();
+ if (!CapturedByAttr)
+ continue;
+ Expr *Captured = GetArgAt(0);
+ for (int CapturingParamIdx : CapturedByAttr->params()) {
+ Expr *Capturing = GetArgAt(CapturingParamIdx);
+ CapturingEntity CE{Capturing};
+ checkExprLifetime(*this, CE, Captured);
+ }
+ }
+ }
+}
+
void Sema::checkCall(NamedDecl *FDecl, const FunctionProtoType *Proto,
const Expr *ThisArg, ArrayRef<const Expr *> Args,
bool IsMemberFunction, SourceLocation Loc,
@@ -3269,7 +3313,8 @@ void Sema::checkCall(NamedDecl *FDecl, const FunctionProtoType *Proto,
}
}
}
-
+ if (FD)
+ checkLifetimeCaptureBy(FD, IsMemberFunction, ThisArg, Args);
if (FDecl || Proto) {
CheckNonNullArguments(*this, FDecl, Proto, Args, Loc);
diff --git a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
index 6a2af01ea5116c..49bbc05c009ff9 100644
--- a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
+++ b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
@@ -793,3 +793,108 @@ void test13() {
}
} // namespace GH100526
+
+namespace lifetime_capture_by {
+struct S {
+ const int *x;
+ void captureInt(const int&x [[clang::lifetime_capture_by(this)]]) { this->x = &x; }
+ void captureSV(std::string_view sv [[clang::lifetime_capture_by(this)]]);
+};
+///////////////////////////
+// Detect dangling cases.
+///////////////////////////
+void captureInt(const int&x [[clang::lifetime_capture_by(s)]], S&s);
+void captureRValInt(int&&x [[clang::lifetime_capture_by(s)]], S&s);
+void noCaptureInt(int x [[clang::lifetime_capture_by(s)]], S&s);
+std::string_view substr(const std::string& s [[clang::lifetimebound]]);
+std::string_view strcopy(const std::string& s);
+void captureSV(std::string_view x [[clang::lifetime_capture_by(s)]], S&s);
+void captureRValSV(std::string_view&& x [[clang::lifetime_capture_by(s)]], S&s);
+void noCaptureSV(std::string_view x, S&s);
+void captureS(const std::string& x [[clang::lifetime_capture_by(s)]], S&s);
+void captureRValS(std::string&& x [[clang::lifetime_capture_by(s)]], S&s);
+const std::string* getPointerLB(const std::string& s[[clang::lifetimebound]]);
+const std::string* getPointerNoLB(const std::string& s);
+void capturePointer(const std::string* x [[clang::lifetime_capture_by(s)]], S&s);
+struct ThisIsCaptured {
+ void capture(S& s) [[clang::lifetime_capture_by(s)]];
+ void bar(S& s) [[clang::lifetime_capture_by(abcd)]]; // expected-error {{'lifetime_capture_by' attribute argument 'abcd' is not a known function parameter}}
+ void baz(S& s) [[clang::lifetime_capture_by(this)]]; // expected-error {{'lifetime_capture_by' argument references itself}}
+};
+void use() {
+ std::string_view local_sv;
+ std::string local_s;
+ S s;
+ // Capture an 'int'.
+ int local;
+ captureInt(1, // expected-warning {{object captured by 's' will be destroyed at the end of the full-expression}}
+ s);
+ captureRValInt(1, s); // expected-warning {{object captured by 's'}}
+ captureInt(local, s);
+ noCaptureInt(1, s);
+ noCaptureInt(local, s);
+
+ // Capture lifetimebound pointer.
+ capturePointer(getPointerLB(std::string()), s); // expected-warning {{object captured by 's'}}
+ capturePointer(getPointerLB(*getPointerLB(std::string())), s); // expected-warning {{object captured by 's'}}
+ capturePointer(getPointerNoLB(std::string()), s);
+
+ // Capture using std::string_view.
+ captureSV(local_sv, s);
+ captureSV(std::string(), // expected-warning {{object captured by 's'}}
+ s);
+ captureSV(substr(
+ std::string() // expected-warning {{object captured by 's'}}
+ ), s);
+ captureSV(substr(local_s), s);
+ captureSV(strcopy(std::string()), s);
+ captureRValSV(std::move(local_sv), s);
+ captureRValSV(std::string(), s); // expected-warning {{object captured by 's'}}
+ captureRValSV(std::string_view{"abcd"}, s);
+ captureRValSV(substr(local_s), s);
+ captureRValSV(substr(std::string()), s); // expected-warning {{object captured by 's'}}
+ captureRValSV(strcopy(std::string()), s);
+ noCaptureSV(local_sv, s);
+ noCaptureSV(std::string(), s);
+ noCaptureSV(substr(std::string()), s);
+
+ // Capture using std::string.
+ captureS(std::string(), s); // expected-warning {{object captured by 's'}}
+ captureS(local_s, s);
+ captureRValS(std::move(local_s), s);
+ captureRValS(std::string(), s); // expected-warning {{object captured by 's'}}
+
+ // Member functions.
+ s.captureInt(1); // expected-warning {{object captured by 's'}}
+ s.captureSV(std::string()); // expected-warning {{object captured by 's'}}
+ s.captureSV(substr(std::string())); // expected-warning {{object captured by 's'}}
+ s.captureSV(strcopy(std::string()));
+
+ // 'this' is captured.
+ ThisIsCaptured{}.capture(s); // expected-warning {{object captured by 's'}}
+ ThisIsCaptured TIS;
+ TIS.capture(s);
+}
+class [[gsl::Pointer()]] my_string_view : public std::string_view {};
+class my_string_view_not_pointer : public std::string_view {};
+std::optional<std::string_view> getOptionalSV();
+std::optional<std::string> getOptionalS();
+std::optional<my_string_view> getOptionalMySV();
+std::optional<my_string_view_not_pointer> getOptionalMySVNotP();
+my_string_view getMySV();
+my_string_view_not_pointer getMySVNotP();
+
+template<class T>
+struct MySet {
+void insert(T&& t [[clang::lifetime_capture_by(this)]]);
+void insert(const T& t [[clang::lifetime_capture_by(this)]]);
+};
+void user_defined_containers() {
+ MySet<int> set_of_int;
+ set_of_int.insert(1); // expected-warning {{object captured by 'set_of_int' will be destroyed}}
+ MySet<std::string_view> set_of_sv;
+ set_of_sv.insert(std::string()); // expected-warning {{object captured by 'set_of_sv' will be destroyed}}
+}
+} // namespace lifetime_capture_by
+// Test for templated code.
+// 2 nested function calls foo(sv, bar(sv, setsv));
\ No newline at end of file
diff --git a/clang/test/SemaCXX/attr-lifetimebound.cpp b/clang/test/SemaCXX/attr-lifetimebound.cpp
index 81e9193cf76a04..f89b556f5bba08 100644
--- a/clang/test/SemaCXX/attr-lifetimebound.cpp
+++ b/clang/test/SemaCXX/attr-lifetimebound.cpp
@@ -1,7 +1,7 @@
// RUN: %clang_cc1 -std=c++23 -verify %s
namespace usage_invalid {
- void void_return(int ¶m [[clang::lifetimebound]]); // expected-error {{'lifetimebound' attribute cannot be applied to a parameter of a function that returns void}}
+ void void_return(int ¶m [[clang::lifetimebound]]); // expected-error {{'lifetimebound' attribute cannot be applied to a parameter of a function that returns void; did you mean 'lifetime_capture_by(X)'}}
int *not_class_member() [[clang::lifetimebound]]; // expected-error {{non-member function has no implicit object parameter}}
struct A {
@@ -11,7 +11,7 @@ namespace usage_invalid {
int *explicit_object(this A&) [[clang::lifetimebound]]; // expected-error {{explicit object member function has no implicit object parameter}}
int not_function [[clang::lifetimebound]]; // expected-error {{only applies to parameters and implicit object parameters}}
int [[clang::lifetimebound]] also_not_function; // expected-error {{cannot be applied to types}}
- void void_return_member() [[clang::lifetimebound]]; // expected-error {{'lifetimebound' attribute cannot be applied to an implicit object parameter of a function that returns void}}
+ void void_return_member() [[clang::lifetimebound]]; // expected-error {{'lifetimebound' attribute cannot be applied to an implicit object parameter of a function that returns void; did you mean 'lifetime_capture_by(X)'}}
};
int *attr_with_param(int ¶m [[clang::lifetimebound(42)]]); // expected-error {{takes no arguments}}
}
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