[llvm-branch-commits] [clang] release/20.x: [clang] Fix false positive regression for lifetime analysis warning. (#127460) (PR #127618)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/127618

Backport 9c49b188b8e1434eb774ee8422124ad3e8870dce

Requested by: @hokein

>From 31928865025e07919548e21abf657c9f5aeab429 Mon Sep 17 00:00:00 2001
From: Haojian Wu <hokein.wu at gmail.com>
Date: Mon, 17 Feb 2025 14:40:31 +0100
Subject: [PATCH] [clang] Fix false positive regression for lifetime analysis
 warning. (#127460)

This fixes a false positive caused by #114044.

For `GSLPointer*` types, it's less clear whether the lifetime issue is
about the GSLPointer object itself or the owner it points to. To avoid
false positives, we take a conservative approach in our heuristic.

Fixes #127195

(This will be backported to release 20).

(cherry picked from commit 9c49b188b8e1434eb774ee8422124ad3e8870dce)
---
 clang/lib/Sema/CheckExprLifetime.cpp          |  5 ++--
 clang/test/Sema/Inputs/lifetime-analysis.h    |  2 ++
 .../Sema/warn-lifetime-analysis-nocfg.cpp     | 24 +++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp
index 8963cad86dbca..1f87001f35b57 100644
--- a/clang/lib/Sema/CheckExprLifetime.cpp
+++ b/clang/lib/Sema/CheckExprLifetime.cpp
@@ -1239,11 +1239,12 @@ static AnalysisResult analyzePathForGSLPointer(const IndirectLocalPath &Path,
     }
     // Check the return type, e.g.
     //   const GSLOwner& func(const Foo& foo [[clang::lifetimebound]])
+    //   GSLOwner* func(cosnt Foo& foo [[clang::lifetimebound]])
     //   GSLPointer func(const Foo& foo [[clang::lifetimebound]])
     if (FD &&
-        ((FD->getReturnType()->isReferenceType() &&
+        ((FD->getReturnType()->isPointerOrReferenceType() &&
           isRecordWithAttr<OwnerAttr>(FD->getReturnType()->getPointeeType())) ||
-         isPointerLikeType(FD->getReturnType())))
+         isGLSPointerType(FD->getReturnType())))
       return Report;
 
     return Abandon;
diff --git a/clang/test/Sema/Inputs/lifetime-analysis.h b/clang/test/Sema/Inputs/lifetime-analysis.h
index d318033ff0cc4..2072e4603cead 100644
--- a/clang/test/Sema/Inputs/lifetime-analysis.h
+++ b/clang/test/Sema/Inputs/lifetime-analysis.h
@@ -61,6 +61,7 @@ struct basic_string_view {
   basic_string_view();
   basic_string_view(const T *);
   const T *begin() const;
+  const T *data() const;
 };
 using string_view = basic_string_view<char>;
 
@@ -80,6 +81,7 @@ struct basic_string {
   const T *c_str() const;
   operator basic_string_view<T> () const;
   using const_iterator = iter<T>;
+  const T *data() const;
 };
 using string = basic_string<char>;
 
diff --git a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
index 04bb1330ded4c..66a2a19ceb321 100644
--- a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
+++ b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
@@ -852,3 +852,27 @@ struct Test {
 };
 
 } // namespace GH120543
+
+namespace GH127195 {
+template <typename T>
+struct StatusOr {
+  T* operator->() [[clang::lifetimebound]];
+  T* value() [[clang::lifetimebound]];
+};
+
+const char* foo() {
+  StatusOr<std::string> s;
+  return s->data(); // expected-warning {{address of stack memory associated with local variable}}
+  
+  StatusOr<std::string_view> s2;
+  return s2->data();
+
+  StatusOr<StatusOr<std::string_view>> s3;
+  return s3.value()->value()->data();
+
+  // FIXME: nested cases are not supported now.
+  StatusOr<StatusOr<std::string>> s4;
+  return s4.value()->value()->data();
+}
+
+} // namespace GH127195