[clang] [clang] Implement lifetime analysis for lifetime_capture_by(X) (PR #115921)
Utkarsh Saxena via cfe-commits
cfe-commits at lists.llvm.org
Tue Nov 12 22:57:15 PST 2024
https://github.com/usx95 updated https://github.com/llvm/llvm-project/pull/115921
>From 3c233df64906972016c26909263cfd53940d87a0 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Tue, 12 Nov 2024 04:28:37 +0000
Subject: [PATCH 1/4] Reapply "[clang] Introduce
[[clang::lifetime_capture_by(X)]] (#111499)"
This reverts commit 3a03513fc6ef8f3272d33be19164243c9dbf0452.
---
clang/docs/ReleaseNotes.rst | 3 +
clang/include/clang/Basic/Attr.td | 33 ++++++
clang/include/clang/Basic/AttrDocs.td | 69 +++++++++++
.../clang/Basic/DiagnosticSemaKinds.td | 14 +++
clang/include/clang/Sema/Sema.h | 8 ++
clang/lib/AST/TypePrinter.cpp | 15 +++
clang/lib/Sema/SemaDecl.cpp | 1 +
clang/lib/Sema/SemaDeclAttr.cpp | 111 ++++++++++++++++++
clang/lib/Sema/SemaType.cpp | 13 ++
clang/test/AST/attr-lifetime-capture-by.cpp | 9 ++
.../test/SemaCXX/attr-lifetime-capture-by.cpp | 46 ++++++++
11 files changed, 322 insertions(+)
create mode 100644 clang/test/AST/attr-lifetime-capture-by.cpp
create mode 100644 clang/test/SemaCXX/attr-lifetime-capture-by.cpp
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 4ef48bed58d95c..482b30848b57e8 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -449,6 +449,9 @@ Attribute Changes in Clang
- Fix a bug where clang doesn't automatically apply the ``[[gsl::Owner]]`` or
``[[gsl::Pointer]]`` to STL explicit template specialization decls. (#GH109442)
+- Clang now supports ``[[clang::lifetime_capture_by(X)]]``. Similar to lifetimebound, this can be
+ used to specify when a reference to a function parameter is captured by another capturing entity ``X``.
+
Improvements to Clang's diagnostics
-----------------------------------
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index a631e81d40aa68..6a77967c32cbcb 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1889,6 +1889,39 @@ def LifetimeBound : DeclOrTypeAttr {
let SimpleHandler = 1;
}
+def LifetimeCaptureBy : DeclOrTypeAttr {
+ let Spellings = [Clang<"lifetime_capture_by", 0>];
+ let Subjects = SubjectList<[ParmVar, ImplicitObjectParameter], ErrorDiag>;
+ let Args = [VariadicParamOrParamIdxArgument<"Params">];
+ let Documentation = [LifetimeCaptureByDocs];
+ let AdditionalMembers = [{
+private:
+ SmallVector<IdentifierInfo*, 1> ArgIdents;
+ SmallVector<SourceLocation, 1> ArgLocs;
+
+public:
+ static constexpr int THIS = 0;
+ static constexpr int INVALID = -1;
+ static constexpr int UNKNOWN = -2;
+ static constexpr int GLOBAL = -3;
+
+ void setArgs(SmallVector<IdentifierInfo*>&& Idents,
+ SmallVector<SourceLocation>&& Locs) {
+ assert(Idents.size() == Locs.size());
+ assert(Idents.size() == params_Size);
+ ArgIdents = std::move(Idents);
+ ArgLocs = std::move(Locs);
+ }
+
+ ArrayRef<IdentifierInfo*> getArgIdents() const { return ArgIdents; }
+ ArrayRef<SourceLocation> getArgLocs() const { return ArgLocs; }
+ void setParamIdx(size_t Idx, int Val) {
+ assert(Idx < params_Size);
+ params_[Idx] = Val;
+ }
+}];
+}
+
def TrivialABI : InheritableAttr {
// This attribute does not have a C [[]] spelling because it requires the
// CPlusPlus language option.
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index b64dbef6332e6a..21fcd183e8969c 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -3918,6 +3918,75 @@ have their lifetimes extended.
}];
}
+def LifetimeCaptureByDocs : Documentation {
+ let Category = DocCatFunction;
+ let Content = [{
+ Similar to `lifetimebound`_, the ``lifetime_capture_by(X)`` attribute on a function
+parameter or implicit object parameter indicates that that objects that are referred to
+by that parameter may also be referred to by the capturing entity ``X``.
+
+By default, a reference is considered to refer to its referenced object, a
+pointer is considered to refer to its pointee, a ``std::initializer_list<T>``
+is considered to refer to its underlying array, and aggregates (arrays and
+simple ``struct``\s) are considered to refer to all objects that their
+transitive subobjects refer to.
+
+The capturing entity ``X`` can be one of the following:
+- Another (named) function parameter.
+
+ .. code-block:: c++
+
+ void addToSet(std::string_view a [[clang::lifetime_capture_by(s)]], std::set<std::string_view>& s) {
+ s.insert(a);
+ }
+
+- ``this`` (in case of member functions).
+
+ .. code-block:: c++
+
+ class S {
+ void addToSet(std::string_view a [[clang::lifetime_capture_by(this)]]) {
+ s.insert(a);
+ }
+ std::set<std::string_view> s;
+ };
+
+- 'global', 'unknown' (without quotes).
+
+ .. code-block:: c++
+
+ std::set<std::string_view> s;
+ 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)]]);
+
+The attribute can be applied to the implicit ``this`` parameter of a member
+function by writing the attribute after the function type:
+
+.. code-block:: c++
+
+ struct S {
+ const char *data(std::set<S*>& s) [[clang::lifetime_capture_by(s)]] {
+ s.insert(this);
+ }
+ };
+
+The attribute supports specifying more than one capturing entities:
+
+.. code-block:: c++
+
+ void addToSets(std::string_view a [[clang::lifetime_capture_by(s1, s2)]],
+ std::set<std::string_view>& s1,
+ std::set<std::string_view>& s2) {
+ s1.insert(a);
+ s2.insert(a);
+ }
+
+.. _`lifetimebound`: https://clang.llvm.org/docs/AttributeReference.html#lifetimebound
+ }];
+}
+
def TrivialABIDocs : Documentation {
let Category = DocCatDecl;
let Content = [{
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index a5d97d7e545ffd..f4452fbb57e736 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3383,6 +3383,20 @@ def err_callback_callee_is_variadic : Error<
"'callback' attribute callee may not be variadic">;
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_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)'">;
+
def err_init_method_bad_return_type : Error<
"init methods must return an object pointer type, not %0">;
def err_attribute_invalid_size : Error<
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index fad446a05e782f..d6f3508a5243f3 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -1760,6 +1760,14 @@ class Sema final : public SemaBase {
/// Add [[gsl::Pointer]] attributes for std:: types.
void inferGslPointerAttribute(TypedefNameDecl *TD);
+ LifetimeCaptureByAttr *ParseLifetimeCaptureByAttr(const ParsedAttr &AL,
+ StringRef ParamName);
+ // Processes the argument 'X' in [[clang::lifetime_capture_by(X)]]. Since 'X'
+ // can be the name of a function parameter, we need to parse the function
+ // declaration and rest of the parameters before processesing 'X'. Therefore
+ // do this lazily instead of processing while parsing the annotation itself.
+ void LazyProcessLifetimeCaptureByParams(FunctionDecl *FD);
+
/// Add _Nullable attributes for std:: types.
void inferNullableClassAttribute(CXXRecordDecl *CRD);
diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
index 6d8db5cf4ffd22..a073a6a4b7d454 100644
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -25,6 +25,7 @@
#include "clang/AST/TextNodeDumper.h"
#include "clang/AST/Type.h"
#include "clang/Basic/AddressSpaces.h"
+#include "clang/Basic/AttrKinds.h"
#include "clang/Basic/ExceptionSpecificationType.h"
#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/LLVM.h"
@@ -1909,6 +1910,19 @@ void TypePrinter::printAttributedAfter(const AttributedType *T,
OS << " [[clang::lifetimebound]]";
return;
}
+ if (T->getAttrKind() == attr::LifetimeCaptureBy) {
+ OS << " [[clang::lifetime_capture_by(";
+ if (auto *attr = dyn_cast_or_null<LifetimeCaptureByAttr>(T->getAttr())) {
+ auto Idents = attr->getArgIdents();
+ for (unsigned I = 0; I < Idents.size(); ++I) {
+ OS << Idents[I]->getName();
+ if (I != Idents.size() - 1)
+ OS << ", ";
+ }
+ }
+ OS << ")]]";
+ return;
+ }
// The printing of the address_space attribute is handled by the qualifier
// since it is still stored in the qualifier. Return early to prevent printing
@@ -1976,6 +1990,7 @@ void TypePrinter::printAttributedAfter(const AttributedType *T,
case attr::SizedBy:
case attr::SizedByOrNull:
case attr::LifetimeBound:
+ case attr::LifetimeCaptureBy:
case attr::TypeNonNull:
case attr::TypeNullable:
case attr::TypeNullableResult:
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 61c29e320d5c73..a3bc8e4191c819 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16687,6 +16687,7 @@ void Sema::AddKnownFunctionAttributes(FunctionDecl *FD) {
}
}
+ LazyProcessLifetimeCaptureByParams(FD);
inferLifetimeBoundAttribute(FD);
AddKnownFunctionAttributesForReplaceableGlobalAllocationFunction(FD);
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index d05d326178e1b8..b4aaa58c082002 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -14,6 +14,7 @@
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTMutationListener.h"
#include "clang/AST/CXXInheritance.h"
+#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
@@ -3867,6 +3868,113 @@ static void handleCallbackAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
S.Context, AL, EncodingIndices.data(), EncodingIndices.size()));
}
+LifetimeCaptureByAttr *Sema::ParseLifetimeCaptureByAttr(const ParsedAttr &AL,
+ StringRef ParamName) {
+ // Atleast one capture by is required.
+ if (AL.getNumArgs() == 0) {
+ Diag(AL.getLoc(), diag::err_capture_by_attribute_no_entity)
+ << AL.getRange();
+ return nullptr;
+ }
+ SmallVector<IdentifierInfo *, 1> ParamIdents;
+ SmallVector<SourceLocation, 1> ParamLocs;
+ for (unsigned I = 0; I < AL.getNumArgs(); ++I) {
+ if (AL.isArgExpr(I)) {
+ Expr *E = AL.getArgAsExpr(I);
+ Diag(E->getExprLoc(), diag::err_capture_by_attribute_argument_unknown)
+ << E << E->getExprLoc();
+ continue;
+ }
+ assert(AL.isArgIdent(I));
+ IdentifierLoc *IdLoc = AL.getArgAsIdent(I);
+ if (IdLoc->Ident->getName() == ParamName) {
+ Diag(IdLoc->Loc, diag::err_capture_by_references_itself) << IdLoc->Loc;
+ continue;
+ }
+ ParamIdents.push_back(IdLoc->Ident);
+ ParamLocs.push_back(IdLoc->Loc);
+ }
+ SmallVector<int, 1> FakeParamIndices(ParamIdents.size(),
+ LifetimeCaptureByAttr::INVALID);
+ LifetimeCaptureByAttr *CapturedBy = ::new (Context) LifetimeCaptureByAttr(
+ Context, AL, FakeParamIndices.data(), FakeParamIndices.size());
+ CapturedBy->setArgs(std::move(ParamIdents), std::move(ParamLocs));
+ return CapturedBy;
+}
+
+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());
+ if (CaptureByAttr)
+ D->addAttr(CaptureByAttr);
+}
+
+void Sema::LazyProcessLifetimeCaptureByParams(FunctionDecl *FD) {
+ bool HasImplicitThisParam = isInstanceMethod(FD);
+
+ llvm::StringMap<int> NameIdxMapping;
+ NameIdxMapping["global"] = LifetimeCaptureByAttr::GLOBAL;
+ NameIdxMapping["unknown"] = LifetimeCaptureByAttr::UNKNOWN;
+ int Idx = 0;
+ if (HasImplicitThisParam) {
+ NameIdxMapping["this"] = 0;
+ Idx++;
+ }
+ for (const ParmVarDecl *PVD : FD->parameters())
+ NameIdxMapping[PVD->getName()] = Idx++;
+ auto DisallowReservedParams = [&](StringRef Reserved) {
+ for (const ParmVarDecl *PVD : FD->parameters())
+ if (PVD->getName() == Reserved)
+ Diag(PVD->getLocation(), diag::err_capture_by_param_uses_reserved_name)
+ << (PVD->getName() == "unknown");
+ };
+ auto HandleCaptureBy = [&](LifetimeCaptureByAttr *CapturedBy) {
+ if (!CapturedBy)
+ return;
+ const auto &Entities = CapturedBy->getArgIdents();
+ for (size_t I = 0; I < Entities.size(); ++I) {
+ StringRef Name = Entities[I]->getName();
+ 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
+ Diag(Loc, diag::err_capture_by_attribute_argument_unknown)
+ << Entities[I] << Loc;
+ continue;
+ }
+ if (Name == "unknown" || Name == "global")
+ DisallowReservedParams(Name);
+ CapturedBy->setParamIdx(I, It->second);
+ }
+ };
+ for (ParmVarDecl *PVD : FD->parameters())
+ HandleCaptureBy(PVD->getAttr<LifetimeCaptureByAttr>());
+ if (!HasImplicitThisParam)
+ return;
+ TypeSourceInfo *TSI = FD->getTypeSourceInfo();
+ if (!TSI)
+ return;
+ AttributedTypeLoc ATL;
+ for (TypeLoc TL = TSI->getTypeLoc();
+ (ATL = TL.getAsAdjusted<AttributedTypeLoc>());
+ TL = ATL.getModifiedLoc()) {
+ auto *A = ATL.getAttrAs<LifetimeCaptureByAttr>();
+ if (!A)
+ continue;
+ HandleCaptureBy(const_cast<LifetimeCaptureByAttr *>(A));
+ }
+}
+
static bool isFunctionLike(const Type &T) {
// Check for explicit function types.
// 'called_once' is only supported in Objective-C and it has
@@ -6644,6 +6752,9 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
case ParsedAttr::AT_Callback:
handleCallbackAttr(S, D, AL);
break;
+ case ParsedAttr::AT_LifetimeCaptureBy:
+ HandleLifetimeCaptureByAttr(S, D, AL);
+ break;
case ParsedAttr::AT_CalledOnce:
handleCalledOnceAttr(S, D, AL);
break;
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 515b9f689a248a..eb7516b3ef1ece 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -8609,6 +8609,15 @@ static void HandleLifetimeBoundAttr(TypeProcessingState &State,
}
}
+static void HandleLifetimeCaptureByAttr(TypeProcessingState &State,
+ QualType &CurType, ParsedAttr &PA) {
+ if (State.getDeclarator().isDeclarationOfFunction()) {
+ auto *Attr = State.getSema().ParseLifetimeCaptureByAttr(PA, "this");
+ if (Attr)
+ CurType = State.getAttributedType(Attr, CurType, CurType);
+ }
+}
+
static void HandleHLSLParamModifierAttr(TypeProcessingState &State,
QualType &CurType,
const ParsedAttr &Attr, Sema &S) {
@@ -8770,6 +8779,10 @@ static void processTypeAttrs(TypeProcessingState &state, QualType &type,
if (TAL == TAL_DeclChunk)
HandleLifetimeBoundAttr(state, type, attr);
break;
+ case ParsedAttr::AT_LifetimeCaptureBy:
+ if (TAL == TAL_DeclChunk)
+ HandleLifetimeCaptureByAttr(state, type, attr);
+ break;
case ParsedAttr::AT_NoDeref: {
// FIXME: `noderef` currently doesn't work correctly in [[]] syntax.
diff --git a/clang/test/AST/attr-lifetime-capture-by.cpp b/clang/test/AST/attr-lifetime-capture-by.cpp
new file mode 100644
index 00000000000000..da2eb0cf3d592e
--- /dev/null
+++ b/clang/test/AST/attr-lifetime-capture-by.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 %s -ast-dump | FileCheck %s
+
+// Verify that we print the [[clang::lifetime_capture_by(X)]] attribute.
+
+struct S {
+ void foo(int &a, int &b) [[clang::lifetime_capture_by(a, b, global)]];
+};
+
+// CHECK: CXXMethodDecl {{.*}}clang::lifetime_capture_by(a, b, global)
diff --git a/clang/test/SemaCXX/attr-lifetime-capture-by.cpp b/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
new file mode 100644
index 00000000000000..3115dc8d6150c9
--- /dev/null
+++ b/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
@@ -0,0 +1,46 @@
+// RUN: %clang_cc1 -std=c++23 -verify %s
+
+struct S {
+ const int *x;
+ void captureInt(const int&x [[clang::lifetime_capture_by(this)]]) { this->x = &x; }
+};
+
+///////////////////////////
+// Test for valid usages.
+///////////////////////////
+[[clang::lifetime_capture_by(unknown)]] // expected-error {{'lifetime_capture_by' attribute only applies to parameters and implicit object parameters}}
+void nonMember(
+ const int &x1 [[clang::lifetime_capture_by(s, t)]],
+ S &s,
+ S &t,
+ 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 &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)]],
+ const S& u
+ )
+{
+ s.captureInt(x1);
+}
+
+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)]]);
+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)]]);
+struct T {
+ void member(
+ const int &x [[clang::lifetime_capture_by(s)]],
+ 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)]])
+ {
+ s.captureInt(x);
+ }
+};
>From 28a5f099a05c83251fd2bfa2c4b4c0a46c0ad12f Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Tue, 12 Nov 2024 06:18:54 +0000
Subject: [PATCH 2/4] Fix compile time regression and memory leak
---
clang/include/clang/Basic/Attr.td | 17 ++---
clang/lib/Sema/SemaDeclAttr.cpp | 71 ++++++++++---------
.../test/SemaCXX/attr-lifetime-capture-by.cpp | 1 +
3 files changed, 46 insertions(+), 43 deletions(-)
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 6a77967c32cbcb..d385651dbe207d 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1896,8 +1896,8 @@ def LifetimeCaptureBy : DeclOrTypeAttr {
let Documentation = [LifetimeCaptureByDocs];
let AdditionalMembers = [{
private:
- SmallVector<IdentifierInfo*, 1> ArgIdents;
- SmallVector<SourceLocation, 1> ArgLocs;
+ IdentifierInfo** ArgIdents;
+ SourceLocation* ArgLocs;
public:
static constexpr int THIS = 0;
@@ -1905,16 +1905,13 @@ public:
static constexpr int UNKNOWN = -2;
static constexpr int GLOBAL = -3;
- void setArgs(SmallVector<IdentifierInfo*>&& Idents,
- SmallVector<SourceLocation>&& Locs) {
- assert(Idents.size() == Locs.size());
- assert(Idents.size() == params_Size);
- ArgIdents = std::move(Idents);
- ArgLocs = std::move(Locs);
+ void setArgs(IdentifierInfo **Idents, SourceLocation *Locs) {
+ ArgIdents = Idents;
+ ArgLocs = Locs;
}
- ArrayRef<IdentifierInfo*> getArgIdents() const { return ArgIdents; }
- ArrayRef<SourceLocation> getArgLocs() const { return ArgLocs; }
+ auto getArgIdents() const { return ArrayRef<IdentifierInfo*>(ArgIdents, params_Size); }
+ auto getArgLocs() const { return ArrayRef<SourceLocation>(ArgLocs, params_Size); }
void setParamIdx(size_t Idx, int Val) {
assert(Idx < params_Size);
params_[Idx] = Val;
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index b4aaa58c082002..03b57c5e9440fd 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -65,6 +65,7 @@
#include "llvm/ADT/StringExtras.h"
#include "llvm/Demangle/Demangle.h"
#include "llvm/IR/Assumptions.h"
+#include "llvm/IR/DerivedTypes.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MathExtras.h"
@@ -3876,33 +3877,38 @@ LifetimeCaptureByAttr *Sema::ParseLifetimeCaptureByAttr(const ParsedAttr &AL,
<< AL.getRange();
return nullptr;
}
- SmallVector<IdentifierInfo *, 1> ParamIdents;
- SmallVector<SourceLocation, 1> ParamLocs;
- for (unsigned I = 0; I < AL.getNumArgs(); ++I) {
+ unsigned N = AL.getNumArgs();
+ IdentifierInfo **ParamIdents = new (Context) IdentifierInfo *[N];
+ SourceLocation *ParamLocs = new (Context) SourceLocation[N];
+ bool IsValid = true;
+ for (unsigned I = 0; I < N; ++I) {
if (AL.isArgExpr(I)) {
Expr *E = AL.getArgAsExpr(I);
Diag(E->getExprLoc(), diag::err_capture_by_attribute_argument_unknown)
<< E << E->getExprLoc();
+ IsValid = false;
continue;
}
assert(AL.isArgIdent(I));
IdentifierLoc *IdLoc = AL.getArgAsIdent(I);
if (IdLoc->Ident->getName() == ParamName) {
Diag(IdLoc->Loc, diag::err_capture_by_references_itself) << IdLoc->Loc;
+ IsValid = false;
continue;
}
- ParamIdents.push_back(IdLoc->Ident);
- ParamLocs.push_back(IdLoc->Loc);
+ ParamIdents[I] = IdLoc->Ident;
+ ParamLocs[I] = IdLoc->Loc;
}
- SmallVector<int, 1> FakeParamIndices(ParamIdents.size(),
- LifetimeCaptureByAttr::INVALID);
+ if (!IsValid)
+ return nullptr;
+ SmallVector<int> FakeParamIndices(N, LifetimeCaptureByAttr::INVALID);
LifetimeCaptureByAttr *CapturedBy = ::new (Context) LifetimeCaptureByAttr(
Context, AL, FakeParamIndices.data(), FakeParamIndices.size());
- CapturedBy->setArgs(std::move(ParamIdents), std::move(ParamLocs));
+ CapturedBy->setArgs(ParamIdents, ParamLocs);
return CapturedBy;
}
-static void HandleLifetimeCaptureByAttr(Sema &S, Decl *D,
+static void handleLifetimeCaptureByAttr(Sema &S, Decl *D,
const ParsedAttr &AL) {
// Do not allow multiple attributes.
if (D->hasAttr<LifetimeCaptureByAttr>()) {
@@ -3919,10 +3925,27 @@ static void HandleLifetimeCaptureByAttr(Sema &S, Decl *D,
void Sema::LazyProcessLifetimeCaptureByParams(FunctionDecl *FD) {
bool HasImplicitThisParam = isInstanceMethod(FD);
-
- llvm::StringMap<int> NameIdxMapping;
- NameIdxMapping["global"] = LifetimeCaptureByAttr::GLOBAL;
- NameIdxMapping["unknown"] = LifetimeCaptureByAttr::UNKNOWN;
+ SmallVector<LifetimeCaptureByAttr *, 1> Attrs;
+ for (ParmVarDecl *PVD : FD->parameters())
+ if (auto *A = PVD->getAttr<LifetimeCaptureByAttr>())
+ Attrs.push_back(A);
+ if (HasImplicitThisParam) {
+ TypeSourceInfo *TSI = FD->getTypeSourceInfo();
+ if (!TSI)
+ return;
+ AttributedTypeLoc ATL;
+ for (TypeLoc TL = TSI->getTypeLoc();
+ (ATL = TL.getAsAdjusted<AttributedTypeLoc>());
+ TL = ATL.getModifiedLoc()) {
+ if (auto *A = ATL.getAttrAs<LifetimeCaptureByAttr>())
+ Attrs.push_back(const_cast<LifetimeCaptureByAttr *>(A));
+ }
+ }
+ if (Attrs.empty())
+ return;
+ llvm::StringMap<int> NameIdxMapping = {
+ {"global", LifetimeCaptureByAttr::GLOBAL},
+ {"unknown", LifetimeCaptureByAttr::UNKNOWN}};
int Idx = 0;
if (HasImplicitThisParam) {
NameIdxMapping["this"] = 0;
@@ -3936,9 +3959,7 @@ void Sema::LazyProcessLifetimeCaptureByParams(FunctionDecl *FD) {
Diag(PVD->getLocation(), diag::err_capture_by_param_uses_reserved_name)
<< (PVD->getName() == "unknown");
};
- auto HandleCaptureBy = [&](LifetimeCaptureByAttr *CapturedBy) {
- if (!CapturedBy)
- return;
+ for (auto *CapturedBy : Attrs) {
const auto &Entities = CapturedBy->getArgIdents();
for (size_t I = 0; I < Entities.size(); ++I) {
StringRef Name = Entities[I]->getName();
@@ -3956,22 +3977,6 @@ void Sema::LazyProcessLifetimeCaptureByParams(FunctionDecl *FD) {
DisallowReservedParams(Name);
CapturedBy->setParamIdx(I, It->second);
}
- };
- for (ParmVarDecl *PVD : FD->parameters())
- HandleCaptureBy(PVD->getAttr<LifetimeCaptureByAttr>());
- if (!HasImplicitThisParam)
- return;
- TypeSourceInfo *TSI = FD->getTypeSourceInfo();
- if (!TSI)
- return;
- AttributedTypeLoc ATL;
- for (TypeLoc TL = TSI->getTypeLoc();
- (ATL = TL.getAsAdjusted<AttributedTypeLoc>());
- TL = ATL.getModifiedLoc()) {
- auto *A = ATL.getAttrAs<LifetimeCaptureByAttr>();
- if (!A)
- continue;
- HandleCaptureBy(const_cast<LifetimeCaptureByAttr *>(A));
}
}
@@ -6753,7 +6758,7 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
handleCallbackAttr(S, D, AL);
break;
case ParsedAttr::AT_LifetimeCaptureBy:
- HandleLifetimeCaptureByAttr(S, D, AL);
+ handleLifetimeCaptureByAttr(S, D, AL);
break;
case ParsedAttr::AT_CalledOnce:
handleCalledOnceAttr(S, D, AL);
diff --git a/clang/test/SemaCXX/attr-lifetime-capture-by.cpp b/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
index 3115dc8d6150c9..be1cd730ed40ce 100644
--- a/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
+++ b/clang/test/SemaCXX/attr-lifetime-capture-by.cpp
@@ -22,6 +22,7 @@ void nonMember(
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)]],
+ const int &test_memory_leak[[clang::lifetime_capture_by(x1,x2, x3, x4, x5, x6, x7, x8, x9)]],
const S& u
)
{
>From 3392c6edf9e561c1469cc1205a32aeccec98e804 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Tue, 12 Nov 2024 17:21:07 +0000
Subject: [PATCH 3/4] use interleaveComma
---
clang/lib/AST/TypePrinter.cpp | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
index a073a6a4b7d454..df9acd387bf770 100644
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -1912,14 +1912,9 @@ void TypePrinter::printAttributedAfter(const AttributedType *T,
}
if (T->getAttrKind() == attr::LifetimeCaptureBy) {
OS << " [[clang::lifetime_capture_by(";
- if (auto *attr = dyn_cast_or_null<LifetimeCaptureByAttr>(T->getAttr())) {
- auto Idents = attr->getArgIdents();
- for (unsigned I = 0; I < Idents.size(); ++I) {
- OS << Idents[I]->getName();
- if (I != Idents.size() - 1)
- OS << ", ";
- }
- }
+ if (auto *attr = dyn_cast_or_null<LifetimeCaptureByAttr>(T->getAttr()))
+ llvm::interleaveComma(attr->getArgIdents(), OS,
+ [&](auto it) { OS << it->getName(); });
OS << ")]]";
return;
}
>From f66ab055ccac7c925f1a152f7a20863b6a599261 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Tue, 12 Nov 2024 18:20:06 +0000
Subject: [PATCH 4/4] [clang] Implement lifetime analysis for
lifetime_capture_by(X)
format
---
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 f4452fbb57e736..3d71f1f9b1da6c 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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