[clang] [clang][Sema] Deprecate `global`/`unknown` in `lifetime_capture_by` (PR #196635)
via cfe-commits
cfe-commits at lists.llvm.org
Wed Jul 8 12:51:30 PDT 2026
https://github.com/NeKon69 updated https://github.com/llvm/llvm-project/pull/196635
>From f80b7128ca6e4c83bcf23e5c1eba3ff24c658911 Mon Sep 17 00:00:00 2001
From: NeKon69 <nobodqwe at gmail.com>
Date: Wed, 8 Jul 2026 21:19:12 +0300
Subject: [PATCH 1/2] [LifetimeSafety] Add standalone lifetime_capture_by
spellings
---
clang/docs/ReleaseNotes.md | 8 +++
clang/include/clang/Basic/Attr.td | 12 +++-
clang/include/clang/Basic/AttrDocs.td | 15 +++--
.../clang/Basic/DiagnosticSemaKinds.td | 9 ++-
clang/lib/Sema/CheckExprLifetime.cpp | 14 +++--
clang/lib/Sema/SemaChecking.cpp | 5 +-
clang/lib/Sema/SemaDeclAttr.cpp | 62 ++++++++++++++-----
clang/test/Sema/LifetimeSafety/capture-by.cpp | 22 +++----
clang/test/Sema/LifetimeSafety/safety.cpp | 4 +-
.../test/SemaCXX/attr-lifetime-capture-by.cpp | 21 ++++---
10 files changed, 117 insertions(+), 55 deletions(-)
diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md
index b49a9db3d5fca..665642c23bfd5 100644
--- a/clang/docs/ReleaseNotes.md
+++ b/clang/docs/ReleaseNotes.md
@@ -553,6 +553,14 @@ latest release, please see the [Clang Web Site](https://clang.llvm.org) or the
- The `modular_format` attribute now supports the `fixed` aspect for C
ISO 18037 fixed-point `printf` specifiers.
+- The `lifetime_capture_by` attribute now accepts three new spelling forms:
+ `lifetime_capture_by_this`, `lifetime_capture_by_global`, and
+ `lifetime_capture_by_unknown`. These replace passing `this`, `global`, and
+ `unknown` as arguments to `lifetime_capture_by`; that argument form is now
+ deprecated because those names can conflict with user-defined parameters.
+ Multiple `lifetime_capture_by` attributes may also be written on the same
+ declaration.
+
- The `const` and `pure` attributes only apply to functions; they are now
diagnosed and ignored when applied to anything else.
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 3f57104d474a7..78ca15d564063 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -2137,9 +2137,19 @@ def LifetimeBound : DeclOrTypeAttr {
}
def LifetimeCaptureBy : DeclOrTypeAttr {
- let Spellings = [Clang<"lifetime_capture_by", 1>];
+ let Spellings = [Clang<"lifetime_capture_by">,
+ Clang<"lifetime_capture_by_this">,
+ Clang<"lifetime_capture_by_global">,
+ Clang<"lifetime_capture_by_unknown">];
let Subjects = SubjectList<[ParmVar, ImplicitObjectParameter], ErrorDiag>;
let Args = [VariadicParamOrParamIdxArgument<"Params">];
+ let Accessors = [Accessor<"isThis", [Clang<"lifetime_capture_by_this">]>,
+ Accessor<"isGlobal", [Clang<"lifetime_capture_by_global">]>,
+ Accessor<"isUnknown", [Clang<"lifetime_capture_by_unknown">]>,
+ Accessor<"isStandaloneSpecial",
+ [Clang<"lifetime_capture_by_this">,
+ Clang<"lifetime_capture_by_global">,
+ Clang<"lifetime_capture_by_unknown">]>];
let Documentation = [LifetimeCaptureByDocs];
let AdditionalMembers = [{
private:
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index b67a5b076237c..9cc5ed698a78c 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -4701,6 +4701,7 @@ have their lifetimes extended.
def LifetimeCaptureByDocs : Documentation {
let Category = DocCatFunction;
+ let Heading = "lifetime_capture_by, lifetime_capture_by_this, lifetime_capture_by_global, lifetime_capture_by_unknown";
let Content = [{
Similar to `lifetimebound`_, the ``lifetime_capture_by(X)`` attribute on a
function parameter or implicit object parameter indicates that the capturing
@@ -4746,28 +4747,30 @@ The capturing entity ``X`` can be one of the following:
s.insert(a);
}
-- ``this`` (in case of member functions).
+- ``this`` (in case of member functions), written as
+ ``lifetime_capture_by_this``.
.. code-block:: c++
class S {
- void addToSet(std::string_view a [[clang::lifetime_capture_by(this)]]) {
+ void addToSet(std::string_view a [[clang::lifetime_capture_by_this]]) {
s.insert(a);
}
std::set<std::string_view> s;
};
- Note: When applied to a constructor parameter, `[[clang::lifetime_capture_by(this)]]` is just an alias of `[[clang::lifetimebound]]`.
+ Note: When applied to a constructor parameter, `[[clang::lifetime_capture_by_this]]` is just an alias of `[[clang::lifetimebound]]`.
-- `global`, `unknown`.
+- ``global`` and ``unknown``, written as ``lifetime_capture_by_global`` and
+ ``lifetime_capture_by_unknown`` respectively.
.. code-block:: c++
std::set<std::string_view> s;
- void addToSet(std::string_view a [[clang::lifetime_capture_by(global)]]) {
+ void addToSet(std::string_view a [[clang::lifetime_capture_by_global]]) {
s.insert(a);
}
- void addSomewhere(std::string_view a [[clang::lifetime_capture_by(unknown)]]);
+ void addSomewhere(std::string_view a [[clang::lifetime_capture_by_unknown]]);
The attribute can be applied to the implicit ``this`` parameter of a member
function by writing the attribute after the function type:
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 3fa5bce9fb04f..00250dbe5d22d 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3556,18 +3556,21 @@ def err_callback_callee_is_variadic : Error<
def err_callback_implicit_this_not_available : Error<
"'callback' argument at position %0 references unavailable implicit 'this'">;
-def err_capture_by_attribute_multiple : Error<
- "multiple 'lifetime_capture' attributes specified">;
def err_capture_by_attribute_no_entity : Error<
"'lifetime_capture_by' attribute specifies no capturing entity">;
def err_capture_by_implicit_this_not_available : Error<
"'lifetime_capture_by' argument references unavailable implicit 'this'">;
+def err_capture_by_this_attr_without_implicit_this : Error<
+ "'lifetime_capture_by_this' attribute requires an implicit object parameter">;
def err_capture_by_attribute_argument_unknown : Error<
"'lifetime_capture_by' attribute argument %0 is not a known function parameter"
"; must be a function parameter, 'this', 'global' or 'unknown'">;
def err_capture_by_references_itself : Error<"'lifetime_capture_by' argument references itself">;
def err_capture_by_param_uses_reserved_name : Error<
- "parameter cannot be named '%select{global|unknown}0' while using 'lifetime_capture_by(%select{global|unknown}0)'">;
+ "parameter cannot be named '%0' while using 'lifetime_capture_by(%0)'">;
+def warn_deprecated_capture_by_special_entity : Warning<
+ "'lifetime_capture_by(%0)' is deprecated; use '%1' instead">,
+ InGroup<DeprecatedAttributes>;
def err_init_method_bad_return_type : Error<
"init methods must return an object pointer type, not %0">;
diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp
index d15b2c6518cec..fafee76ec18c3 100644
--- a/clang/lib/Sema/CheckExprLifetime.cpp
+++ b/clang/lib/Sema/CheckExprLifetime.cpp
@@ -502,12 +502,14 @@ static void visitFunctionCallArguments(IndirectLocalPath &Path, Expr *Call,
if (CheckCoroCall ||
CanonCallee->getParamDecl(I)->hasAttr<LifetimeBoundAttr>())
VisitLifetimeBoundArg(CanonCallee->getParamDecl(I), Arg);
- else if (const auto *CaptureAttr =
- CanonCallee->getParamDecl(I)->getAttr<LifetimeCaptureByAttr>();
- CaptureAttr && isa<CXXConstructorDecl>(CanonCallee) &&
- llvm::any_of(CaptureAttr->params(), [](int ArgIdx) {
- return ArgIdx == LifetimeCaptureByAttr::This;
- }))
+ else if (isa<CXXConstructorDecl>(CanonCallee) &&
+ llvm::any_of(CanonCallee->getParamDecl(I)
+ ->specific_attrs<LifetimeCaptureByAttr>(),
+ [](const LifetimeCaptureByAttr *CaptureAttr) {
+ return llvm::is_contained(
+ CaptureAttr->params(),
+ LifetimeCaptureByAttr::This);
+ }))
// `lifetime_capture_by(this)` in a class constructor has the same
// semantics as `lifetimebound`:
//
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index d52c12670a57b..d122b9050925e 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -4367,8 +4367,9 @@ void Sema::checkLifetimeCaptureBy(FunctionDecl *FD, bool IsMemberFunction,
}
};
for (unsigned I = 0; I < FD->getNumParams(); ++I)
- HandleCaptureByAttr(FD->getParamDecl(I)->getAttr<LifetimeCaptureByAttr>(),
- I + IsMemberFunction);
+ for (const auto *A :
+ FD->getParamDecl(I)->specific_attrs<LifetimeCaptureByAttr>())
+ HandleCaptureByAttr(A, I + IsMemberFunction);
// Check when the implicit object param is captured.
if (IsMemberFunction) {
TypeSourceInfo *TSI = FD->getTypeSourceInfo();
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index d3a1786bb8dbe..ebad76969fafb 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4404,17 +4404,41 @@ static void handleCallbackAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
LifetimeCaptureByAttr *Sema::ParseLifetimeCaptureByAttr(const ParsedAttr &AL,
StringRef ParamName) {
+ StringRef AttrName = AL.getAttrName()->getName();
+ StringRef SpecialEntity;
+ if (AttrName == "lifetime_capture_by_this")
+ SpecialEntity = "this";
+ else if (AttrName == "lifetime_capture_by_global")
+ SpecialEntity = "global";
+ else if (AttrName == "lifetime_capture_by_unknown")
+ SpecialEntity = "unknown";
+
+ if (!SpecialEntity.empty() && AL.getNumArgs() != 0) {
+ Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 0;
+ return nullptr;
+ }
+
// Atleast one capture by is required.
- if (AL.getNumArgs() == 0) {
+ if (SpecialEntity.empty() && AL.getNumArgs() == 0) {
Diag(AL.getLoc(), diag::err_capture_by_attribute_no_entity)
<< AL.getRange();
return nullptr;
}
- unsigned N = AL.getNumArgs();
+ unsigned N = SpecialEntity.empty() ? AL.getNumArgs() : 1;
auto ParamIdents =
MutableArrayRef<IdentifierInfo *>(new (Context) IdentifierInfo *[N], N);
auto ParamLocs =
MutableArrayRef<SourceLocation>(new (Context) SourceLocation[N], N);
+ if (!SpecialEntity.empty()) {
+ ParamIdents[0] = &Context.Idents.get(SpecialEntity);
+ ParamLocs[0] = AL.getRange().getEnd();
+ int FakeParamIndices[] = {LifetimeCaptureByAttr::Invalid};
+ auto *CapturedBy =
+ LifetimeCaptureByAttr::Create(Context, FakeParamIndices, 1, AL);
+ CapturedBy->setArgs(ParamIdents, ParamLocs);
+ return CapturedBy;
+ }
+
bool IsValid = true;
for (unsigned I = 0; I < N; ++I) {
if (AL.isArgExpr(I)) {
@@ -4426,6 +4450,17 @@ LifetimeCaptureByAttr *Sema::ParseLifetimeCaptureByAttr(const ParsedAttr &AL,
}
assert(AL.isArgIdent(I));
IdentifierLoc *IdLoc = AL.getArgAsIdent(I);
+ StringRef Name = IdLoc->getIdentifierInfo()->getName();
+ StringRef Replacement;
+ if (Name == "this")
+ Replacement = "lifetime_capture_by_this";
+ else if (Name == "global")
+ Replacement = "lifetime_capture_by_global";
+ else if (Name == "unknown")
+ Replacement = "lifetime_capture_by_unknown";
+ if (!Replacement.empty())
+ Diag(IdLoc->getLoc(), diag::warn_deprecated_capture_by_special_entity)
+ << Name << Replacement << IdLoc->getLoc();
if (IdLoc->getIdentifierInfo()->getName() == ParamName) {
Diag(IdLoc->getLoc(), diag::err_capture_by_references_itself)
<< IdLoc->getLoc();
@@ -4446,12 +4481,6 @@ LifetimeCaptureByAttr *Sema::ParseLifetimeCaptureByAttr(const ParsedAttr &AL,
static void handleLifetimeCaptureByAttr(Sema &S, Decl *D,
const ParsedAttr &AL) {
- // Do not allow multiple attributes.
- if (D->hasAttr<LifetimeCaptureByAttr>()) {
- S.Diag(AL.getLoc(), diag::err_capture_by_attribute_multiple)
- << AL.getRange();
- return;
- }
auto *PVD = dyn_cast<ParmVarDecl>(D);
assert(PVD);
auto *CaptureByAttr = S.ParseLifetimeCaptureByAttr(AL, PVD->getName());
@@ -4463,7 +4492,7 @@ void Sema::LazyProcessLifetimeCaptureByParams(FunctionDecl *FD) {
bool HasImplicitThisParam = hasImplicitObjectParameter(FD);
SmallVector<LifetimeCaptureByAttr *, 1> Attrs;
for (ParmVarDecl *PVD : FD->parameters())
- if (auto *A = PVD->getAttr<LifetimeCaptureByAttr>())
+ for (auto *A : PVD->specific_attrs<LifetimeCaptureByAttr>())
Attrs.push_back(A);
if (HasImplicitThisParam) {
TypeSourceInfo *TSI = FD->getTypeSourceInfo();
@@ -4493,7 +4522,7 @@ void Sema::LazyProcessLifetimeCaptureByParams(FunctionDecl *FD) {
for (const ParmVarDecl *PVD : FD->parameters())
if (PVD->getName() == Reserved)
Diag(PVD->getLocation(), diag::err_capture_by_param_uses_reserved_name)
- << (PVD->getName() == "unknown");
+ << PVD->getName();
};
for (auto *CapturedBy : Attrs) {
const auto &Entities = CapturedBy->getArgIdents();
@@ -4502,14 +4531,19 @@ void Sema::LazyProcessLifetimeCaptureByParams(FunctionDecl *FD) {
auto It = NameIdxMapping.find(Name);
if (It == NameIdxMapping.end()) {
auto Loc = CapturedBy->getArgLocs()[I];
- if (!HasImplicitThisParam && Name == "this")
- Diag(Loc, diag::err_capture_by_implicit_this_not_available) << Loc;
- else
+ if (!HasImplicitThisParam && Name == "this") {
+ unsigned DiagID =
+ CapturedBy->isStandaloneSpecial()
+ ? diag::err_capture_by_this_attr_without_implicit_this
+ : diag::err_capture_by_implicit_this_not_available;
+ Diag(Loc, DiagID) << Loc;
+ } else
Diag(Loc, diag::err_capture_by_attribute_argument_unknown)
<< Entities[I] << Loc;
continue;
}
- if (Name == "unknown" || Name == "global")
+ if ((Name == "unknown" || Name == "global") &&
+ !CapturedBy->isStandaloneSpecial())
DisallowReservedParams(Name);
CapturedBy->setParamIdx(I, It->second);
}
diff --git a/clang/test/Sema/LifetimeSafety/capture-by.cpp b/clang/test/Sema/LifetimeSafety/capture-by.cpp
index 2877d8d6cd5f9..285f50d61fa1d 100644
--- a/clang/test/Sema/LifetimeSafety/capture-by.cpp
+++ b/clang/test/Sema/LifetimeSafety/capture-by.cpp
@@ -145,7 +145,7 @@ void use() {
namespace temporary_capturing_object {
struct S {
- void add(const int& x [[clang::lifetime_capture_by(this)]]);
+ void add(const int& x [[clang::lifetime_capture_by_this]]);
};
void test() {
@@ -161,8 +161,8 @@ void test() {
// Capture by Global and Unknown.
// ****************************************************************************
namespace capture_by_global_unknown {
-void captureByGlobal(std::string_view s [[clang::lifetime_capture_by(global)]]);
-void captureByUnknown(std::string_view s [[clang::lifetime_capture_by(unknown)]]);
+void captureByGlobal(std::string_view s [[clang::lifetime_capture_by_global]]);
+void captureByUnknown(std::string_view s [[clang::lifetime_capture_by_unknown]]);
std::string_view getLifetimeBoundView(const std::string& s [[clang::lifetimebound]]);
@@ -188,8 +188,8 @@ void use() {
// ****************************************************************************
namespace capture_by_this {
struct S {
- void captureInt(const int& x [[clang::lifetime_capture_by(this)]]);
- void captureView(std::string_view sv [[clang::lifetime_capture_by(this)]]);
+ void captureInt(const int& x [[clang::lifetime_capture_by_this]]);
+ void captureView(std::string_view sv [[clang::lifetime_capture_by_this]]);
};
std::string_view getLifetimeBoundView(const std::string& s [[clang::lifetimebound]]);
std::string_view getNotLifetimeBoundView(const std::string& s);
@@ -248,8 +248,8 @@ void useCaptureDefaultArg() {
namespace containers_no_distinction {
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 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;
@@ -269,8 +269,8 @@ template<> struct IsPointerLikeTypeImpl<std::string_view> : std::true_type {};
template<typename T> concept IsPointerLikeType = std::is_pointer<T>::value || IsPointerLikeTypeImpl<T>::value;
template<class T> struct MyVector {
- void push_back(T&& t [[clang::lifetime_capture_by(this)]]) requires IsPointerLikeType<T>;
- void push_back(const T& t [[clang::lifetime_capture_by(this)]]) requires IsPointerLikeType<T>;
+ void push_back(T&& t [[clang::lifetime_capture_by_this]]) requires IsPointerLikeType<T>;
+ void push_back(const T& t [[clang::lifetime_capture_by_this]]) requires IsPointerLikeType<T>;
void push_back(T&& t) requires (!IsPointerLikeType<T>);
void push_back(const T& t) requires (!IsPointerLikeType<T>);
@@ -428,13 +428,13 @@ void use() {
namespace on_constructor {
struct T {
- T(const int& t [[clang::lifetime_capture_by(this)]]);
+ T(const int& t [[clang::lifetime_capture_by_this]]);
};
struct T2 {
T2(const int& t [[clang::lifetime_capture_by(x)]], int& x);
};
struct T3 {
- T3(const T& t [[clang::lifetime_capture_by(this)]]);
+ T3(const T& t [[clang::lifetime_capture_by_this]]);
};
int foo(const T& t);
diff --git a/clang/test/Sema/LifetimeSafety/safety.cpp b/clang/test/Sema/LifetimeSafety/safety.cpp
index 3c9b58c4e4957..0776fcdf05773 100644
--- a/clang/test/Sema/LifetimeSafety/safety.cpp
+++ b/clang/test/Sema/LifetimeSafety/safety.cpp
@@ -3978,7 +3978,7 @@ void test_reference_to_pointer() {
struct [[gsl::Pointer]] MyContainer {
View stored;
- void set(View s [[clang::lifetime_capture_by(this)]]);
+ void set(View s [[clang::lifetime_capture_by_this]]);
};
void member_capture() {
@@ -3993,7 +3993,7 @@ void member_capture() {
// FIXME: Add support for simple containers without annotations.
struct SimpleContainer {
View stored;
- void set(View s [[clang::lifetime_capture_by(this)]]);
+ void set(View s [[clang::lifetime_capture_by_this]]);
};
void member_capture_simple_container() {
diff --git a/clang/test/SemaCXX/attr-lifetime-capture-by.cpp b/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
index 6b3726a88c8b5..01a242199c5c4 100644
--- a/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
+++ b/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
@@ -2,7 +2,7 @@
struct S {
const int *x;
- void captureInt(const int&x [[clang::lifetime_capture_by(this)]]) { this->x = &x; }
+ void captureInt(const int&x [[clang::lifetime_capture_by_this]]) { this->x = &x; }
};
///////////////////////////
@@ -16,12 +16,13 @@ void nonMember(
const int &x2 [[clang::lifetime_capture_by(12345 + 12)]], // expected-error {{'lifetime_capture_by' attribute argument '12345 + 12' is not a known function parameter; must be a function parameter, 'this', 'global' or 'unknown'}}
const int &x3 [[clang::lifetime_capture_by(abcdefgh)]], // expected-error {{'lifetime_capture_by' attribute argument 'abcdefgh' is not a known function parameter; must be a function parameter, 'this', 'global' or 'unknown'}}
const int &x4 [[clang::lifetime_capture_by("abcdefgh")]], // expected-error {{'lifetime_capture_by' attribute argument '"abcdefgh"' is not a known function parameter; must be a function parameter, 'this', 'global' or 'unknown'}}
- const int &x5 [[clang::lifetime_capture_by(this)]], // expected-error {{'lifetime_capture_by' argument references unavailable implicit 'this'}}
+ const int &x5 [[clang::lifetime_capture_by_this]], // expected-error {{'lifetime_capture_by_this' attribute requires an implicit object parameter}}
const int &x6 [[clang::lifetime_capture_by()]], // expected-error {{'lifetime_capture_by' attribute specifies no capturing entity}}
const int& x7 [[clang::lifetime_capture_by(u,
- x7)]], // expected-error {{'lifetime_capture_by' argument references itself}}
- const int &x8 [[clang::lifetime_capture_by(global)]],
- const int &x9 [[clang::lifetime_capture_by(unknown)]],
+ x7)]], // expected-error {{'lifetime_capture_by' argument references itself}}
+ const int &x8 [[clang::lifetime_capture_by(global)]], // expected-warning {{'lifetime_capture_by(global)' is deprecated; use 'lifetime_capture_by_global' instead}}
+ const int &x9 [[clang::lifetime_capture_by(unknown)]], // expected-warning {{'lifetime_capture_by(unknown)' is deprecated; use 'lifetime_capture_by_unknown' instead}}
+ const int &x10 [[clang::lifetime_capture_by_global(s)]], // expected-error {{'clang::lifetime_capture_by_global' attribute takes no arguments}}
const int &test_memory_leak[[clang::lifetime_capture_by(x1,x2, x3, x4, x5, x6, x7, x8, x9)]],
const S& u
)
@@ -30,9 +31,9 @@ void nonMember(
}
void unknown_param_name(const int& unknown, // expected-error {{parameter cannot be named 'unknown' while using 'lifetime_capture_by(unknown)'}}
- const int& s [[clang::lifetime_capture_by(unknown)]]);
+ const int& s [[clang::lifetime_capture_by(unknown)]]); // expected-warning {{'lifetime_capture_by(unknown)' is deprecated; use 'lifetime_capture_by_unknown' instead}}
void global_param_name(const int& global, // expected-error {{parameter cannot be named 'global' while using 'lifetime_capture_by(global)'}}
- const int& s [[clang::lifetime_capture_by(global)]]);
+ const int& s [[clang::lifetime_capture_by(global)]]); // expected-warning {{'lifetime_capture_by(global)' is deprecated; use 'lifetime_capture_by_global' instead}}
void no_such_param(int i [[clang::lifetime_capture_by(no_such_param)]]); // expected-error {{'lifetime_capture_by' attribute argument 'no_such_param' is not a known function parameter; must be a function parameter, 'this', 'global' or 'unknown'}}
void use_no_such_param() { no_such_param(0); }
struct T {
@@ -41,12 +42,12 @@ struct T {
S &s,
S &t,
const int &y [[clang::lifetime_capture_by(s)]],
- const int &z [[clang::lifetime_capture_by(this, x, y)]],
- const int &u [[clang::lifetime_capture_by(global, unknown, x, s)]])
+ const int &z [[clang::lifetime_capture_by(x, y), clang::lifetime_capture_by_this]],
+ const int &u [[clang::lifetime_capture_by(global, unknown, x, s)]]) // expected-warning 2 {{deprecated}}
{
s.captureInt(x);
}
void explicit_this1(this T& self, const int &x [[clang::lifetime_capture_by(self)]]);
- void explicit_this2(this T& self, const int &x [[clang::lifetime_capture_by(this)]]); // expected-error {{argument references unavailable implicit 'this'}}
+ void explicit_this2(this T& self, const int &x [[clang::lifetime_capture_by(this)]]); // expected-warning {{'lifetime_capture_by(this)' is deprecated; use 'lifetime_capture_by_this' instead}} expected-error {{argument references unavailable implicit 'this'}}
};
>From 85fe259a3ab8062b4dc0c4c02e49794a78ebb695 Mon Sep 17 00:00:00 2001
From: NeKon69 <nobodqwe at gmail.com>
Date: Wed, 8 Jul 2026 22:51:16 +0300
Subject: [PATCH 2/2] add note, add 2 test cases
---
clang/docs/ReleaseNotes.md | 4 ++--
clang/test/Sema/LifetimeSafety/capture-by.cpp | 12 ++++++++++++
clang/test/SemaCXX/attr-lifetime-capture-by.cpp | 1 +
3 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md
index 665642c23bfd5..e1b3b75086f3a 100644
--- a/clang/docs/ReleaseNotes.md
+++ b/clang/docs/ReleaseNotes.md
@@ -558,8 +558,8 @@ latest release, please see the [Clang Web Site](https://clang.llvm.org) or the
`lifetime_capture_by_unknown`. These replace passing `this`, `global`, and
`unknown` as arguments to `lifetime_capture_by`; that argument form is now
deprecated because those names can conflict with user-defined parameters.
- Multiple `lifetime_capture_by` attributes may also be written on the same
- declaration.
+ They will be removed in the next release. Multiple `lifetime_capture_by`
+ attributes may also be written on the same declaration.
- The `const` and `pure` attributes only apply to functions; they are now
diagnosed and ignored when applied to anything else.
diff --git a/clang/test/Sema/LifetimeSafety/capture-by.cpp b/clang/test/Sema/LifetimeSafety/capture-by.cpp
index 285f50d61fa1d..bfe2a3a5589bc 100644
--- a/clang/test/Sema/LifetimeSafety/capture-by.cpp
+++ b/clang/test/Sema/LifetimeSafety/capture-by.cpp
@@ -85,6 +85,18 @@ void use() {
}
} // namespace capture_string_view
+namespace multiple_capture_by_attrs {
+struct X {} x1, x2;
+void capture(std::string_view s [[clang::lifetime_capture_by(x1),
+ clang::lifetime_capture_by(x2)]],
+ X &x1, X &x2);
+
+void use() {
+ capture(std::string(), // expected-warning {{object whose reference is captured by 'x1' will be destroyed at the end of the full-expression}} expected-warning {{object whose reference is captured by 'x2' will be destroyed at the end of the full-expression}}
+ x1, x2);
+}
+} // namespace multiple_capture_by_attrs
+
// ****************************************************************************
// Capture pointer (eg: std::string*)
// ****************************************************************************
diff --git a/clang/test/SemaCXX/attr-lifetime-capture-by.cpp b/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
index 01a242199c5c4..6a4e450294ba2 100644
--- a/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
+++ b/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
@@ -23,6 +23,7 @@ void nonMember(
const int &x8 [[clang::lifetime_capture_by(global)]], // expected-warning {{'lifetime_capture_by(global)' is deprecated; use 'lifetime_capture_by_global' instead}}
const int &x9 [[clang::lifetime_capture_by(unknown)]], // expected-warning {{'lifetime_capture_by(unknown)' is deprecated; use 'lifetime_capture_by_unknown' instead}}
const int &x10 [[clang::lifetime_capture_by_global(s)]], // expected-error {{'clang::lifetime_capture_by_global' attribute takes no arguments}}
+ const int &x11 [[clang::lifetime_capture_by(this)]], // expected-error {{'lifetime_capture_by' argument references unavailable implicit 'this'}} // expected-warning {{'lifetime_capture_by(this)' is deprecated; use 'lifetime_capture_by_this' instead}}
const int &test_memory_leak[[clang::lifetime_capture_by(x1,x2, x3, x4, x5, x6, x7, x8, x9)]],
const S& u
)
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