https://github.com/hokein updated
https://github.com/llvm/llvm-project/pull/104556
>From ea86000bcba54e542a9a0f940451f15ac521e32b Mon Sep 17 00:00:00 2001
From: Haojian Wu <hokein...@gmail.com>
Date: Mon, 19 Aug 2024 13:46:16 +0200
Subject: [PATCH] [clang] Diagnose dangling issues for cases where a
gsl-pointer is construct from a gsl-owner object in a container.
---
clang/docs/ReleaseNotes.rst | 2 ++
clang/lib/Sema/CheckExprLifetime.cpp | 28 ++++++++++---------
.../Sema/warn-lifetime-analysis-nocfg.cpp | 28 +++++++++++++++++++
3 files changed, 45 insertions(+), 13 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index ffdd063ec99037..c9864abc593e5e 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -214,6 +214,8 @@ Improvements to Clang's diagnostics
- Clang now diagnoses the use of ``main`` in an ``extern`` context as invalid
according to [basic.start.main] p3. Fixes #GH101512.
+- Clang now diagnoses dangling cases where a gsl-pointer is constructed from a
gsl-owner object inside a container (#GH100384).
+
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/lib/Sema/CheckExprLifetime.cpp
b/clang/lib/Sema/CheckExprLifetime.cpp
index 7389046eaddde1..9c5b00da592417 100644
--- a/clang/lib/Sema/CheckExprLifetime.cpp
+++ b/clang/lib/Sema/CheckExprLifetime.cpp
@@ -328,13 +328,16 @@ static bool shouldTrackFirstArgument(const FunctionDecl
*FD) {
static void handleGslAnnotatedTypes(IndirectLocalPath &Path, Expr *Call,
LocalVisitor Visit) {
- auto VisitPointerArg = [&](const Decl *D, Expr *Arg, bool Value) {
+ auto VisitPointerArg = [&](const FunctionDecl *Callee, Expr *Arg) {
// We are not interested in the temporary base objects of gsl Pointers:
// Temp().ptr; // Here ptr might not dangle.
if (isa<MemberExpr>(Arg->IgnoreImpCasts()))
return;
- // Once we initialized a value with a reference, it can no longer dangle.
- if (!Value) {
+ auto ReturnType = Callee->getReturnType();
+ // Once we initialized a value with a non gsl-owner reference, it can no
+ // longer dangle.
+ if (ReturnType->isReferenceType() &&
+ !isRecordWithAttr<OwnerAttr>(ReturnType->getPointeeType())) {
for (const IndirectLocalPathEntry &PE : llvm::reverse(Path)) {
if (PE.Kind == IndirectLocalPathEntry::GslReferenceInit)
continue;
@@ -344,9 +347,11 @@ static void handleGslAnnotatedTypes(IndirectLocalPath
&Path, Expr *Call,
break;
}
}
- Path.push_back({Value ? IndirectLocalPathEntry::GslPointerInit
- : IndirectLocalPathEntry::GslReferenceInit,
- Arg, D});
+
+ Path.push_back({!ReturnType->isReferenceType()
+ ? IndirectLocalPathEntry::GslPointerInit
+ : IndirectLocalPathEntry::GslReferenceInit,
+ Arg, Callee});
if (Arg->isGLValue())
visitLocalsRetainedByReferenceBinding(Path, Arg, RK_ReferenceBinding,
Visit,
@@ -360,21 +365,18 @@ static void handleGslAnnotatedTypes(IndirectLocalPath
&Path, Expr *Call,
if (auto *MCE = dyn_cast<CXXMemberCallExpr>(Call)) {
const auto *MD = cast_or_null<CXXMethodDecl>(MCE->getDirectCallee());
if (MD && shouldTrackImplicitObjectArg(MD))
- VisitPointerArg(MD, MCE->getImplicitObjectArgument(),
- !MD->getReturnType()->isReferenceType());
+ VisitPointerArg(MD, MCE->getImplicitObjectArgument());
return;
} else if (auto *OCE = dyn_cast<CXXOperatorCallExpr>(Call)) {
FunctionDecl *Callee = OCE->getDirectCallee();
if (Callee && Callee->isCXXInstanceMember() &&
shouldTrackImplicitObjectArg(cast<CXXMethodDecl>(Callee)))
- VisitPointerArg(Callee, OCE->getArg(0),
- !Callee->getReturnType()->isReferenceType());
+ VisitPointerArg(Callee, OCE->getArg(0));
return;
} else if (auto *CE = dyn_cast<CallExpr>(Call)) {
FunctionDecl *Callee = CE->getDirectCallee();
if (Callee && shouldTrackFirstArgument(Callee))
- VisitPointerArg(Callee, CE->getArg(0),
- !Callee->getReturnType()->isReferenceType());
+ VisitPointerArg(Callee, CE->getArg(0));
return;
}
@@ -382,7 +384,7 @@ static void handleGslAnnotatedTypes(IndirectLocalPath
&Path, Expr *Call,
const auto *Ctor = CCE->getConstructor();
const CXXRecordDecl *RD = Ctor->getParent();
if (CCE->getNumArgs() > 0 && RD->hasAttr<PointerAttr>())
- VisitPointerArg(Ctor->getParamDecl(0), CCE->getArgs()[0], true);
+ VisitPointerArg(Ctor, CCE->getArgs()[0]);
}
}
diff --git a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
index 09dfb2b5d96a89..710eb361bfc915 100644
--- a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
+++ b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
@@ -275,6 +275,34 @@ int &danglingRawPtrFromLocal3() {
return *o; // expected-warning {{reference to stack memory associated with
local variable 'o' returned}}
}
+// GH100384
+std::string_view containerWithAnnotatedElements() {
+ std::string_view c1 = std::vector<std::string>().at(0); // expected-warning
{{object backing the pointer will be destroyed at the end of the
full-expression}}
+ c1 = std::vector<std::string>().at(0); // expected-warning {{object backing
the pointer}}
+
+ // no warning on constructing from gsl-pointer
+ std::string_view c2 = std::vector<std::string_view>().at(0);
+
+ std::vector<std::string> local;
+ return local.at(0); // expected-warning {{address of stack memory associated
with local variable}}
+}
+
+std::string_view localUniquePtr(int i) {
+ std::unique_ptr<std::string> c1;
+ if (i)
+ return *c1; // expected-warning {{address of stack memory associated with
local variable}}
+ std::unique_ptr<std::string_view> c2;
+ return *c2; // expect no-warning.
+}
+
+std::string_view localOptional(int i) {
+ std::optional<std::string> o;
+ if (i)
+ return o.value(); // expected-warning {{address of stack memory associated
with local variable}}
+ std::optional<std::string_view> abc;
+ return abc.value(); // expect no warning
+}
+
const char *danglingRawPtrFromTemp() {
return std::basic_string<char>().c_str(); // expected-warning {{returning
address of local temporary object}}
}
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