[clang] Don't emit bogus dangling diagnostics when [[gsl::Owner]] and [[clang::lifetimebound]] are used together.

[hokein]

In the GSL analysis, we don't track the this object if the conversion is not from gsl::owner to gsl pointer, we want to be conservative here to avoid triggering false positives.

Fixes #108272

[llvmbot]

@llvm/pr-subscribers-clang

Author: Haojian Wu (hokein)

Changes

Fixes #108272

---

Full diff: https://github.com/llvm/llvm-project/pull/108280.diff

3 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+2)
• (modified) clang/lib/Sema/CheckExprLifetime.cpp (+2-1)
• (modified) clang/test/Sema/warn-lifetime-analysis-nocfg.cpp (+34)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 59ccdf1e15cd81..3a8f159492d2d3 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -300,6 +300,8 @@ Improvements to Clang's diagnostics
 
 - Clang now diagnoses cases where a dangling ``GSLOwner<GSLPointer>`` object is constructed, e.g. ``std::vector<string_view> v = {std::string()};`` (#GH100526).
 
+- Don't emit bogus dangling diagnostics when ``[[gsl::Owner]]`` and `[[clang::lifetimebound]]` are used together (#GH108272).
+
 Improvements to Clang's time-trace
 ----------------------------------
 
diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp
index c8e703036c132c..80343905bcaa4d 100644
--- a/clang/lib/Sema/CheckExprLifetime.cpp
+++ b/clang/lib/Sema/CheckExprLifetime.cpp
@@ -289,7 +289,8 @@ static bool isGSLOwner(QualType T) {
 
 static bool shouldTrackImplicitObjectArg(const CXXMethodDecl *Callee) {
   if (auto *Conv = dyn_cast_or_null<CXXConversionDecl>(Callee))
-    if (isRecordWithAttr<PointerAttr>(Conv->getConversionType()))
+    if (isRecordWithAttr<PointerAttr>(Conv->getConversionType())
+        && Callee->getParent()->hasAttr<OwnerAttr>())
       return true;
   if (!isInStlNamespace(Callee->getParent()))
     return false;
diff --git a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
index 234e06f069074b..bc25c33bf9fed5 100644
--- a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
+++ b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
@@ -630,3 +630,37 @@ std::optional<std::string_view> test3(int i) {
 }
 
 } // namespace GH100526
+
+namespace GH108272 {
+template <typename T>
+struct [[gsl::Owner]] StatusOr {
+  const T &value() [[clang::lifetimebound]];
+};
+
+template <typename V>
+class Wrapper1 {
+ public:
+  operator V() const;
+  V value;
+};
+std::string_view test1() {
+  StatusOr<Wrapper1<std::string_view>> k;
+  // Be conservative in this case, as there is not enough information available
+  // to infer the lifetime relationship for the Wrapper1 type.
+  std::string_view good = StatusOr<Wrapper1<std::string_view>>().value();
+  return k.value();
+}
+
+template <typename V>
+class Wrapper2 {
+ public:
+  operator V() const [[clang::lifetimebound]];
+  V value;
+};
+std::string_view test2() {
+  StatusOr<Wrapper2<std::string_view>> k;
+  // We expect dangling issues as the conversion operator is lifetimebound。
+  std::string_view bad = StatusOr<Wrapper2<std::string_view>>().value(); // expected-warning {{temporary whose address is used as value of}}
+  return k.value(); // expected-warning {{address of stack memory associated}}
+}
+} // namespace GH108272

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[shafik]

Can you add some more details to the summary e.g. "The fix adds an additional check in isGSLOwner() for Owner attribute" or something along those lines.

[Xazax-hun]

LGTM!

[hokein]

Can you add some more details to the summary e.g. "The fix adds an additional check in isGSLOwner() for Owner attribute" or something along those lines.

Done.