[clang] [LifetimeSafety] Flow origins from lifetimebound args in `gsl::Pointer` construction (PR #189907)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-analysis

Author: NeKon69

<details>
<summary>Changes</summary>

This PR adds origin flow from `[[clang::lifetimebound]]` constructor arguments during `gsl::Pointer` construction.

Fixes #<!-- -->175898

---
Full diff: https://github.com/llvm/llvm-project/pull/189907.diff


2 Files Affected:

- (modified) clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp (+4-4) 
- (modified) clang/test/Sema/warn-lifetime-analysis-nocfg.cpp (+5-7) 


``````````diff
diff --git a/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp b/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp
index 861e1f6fa8a33..b314ac45c5760 100644
--- a/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp
+++ b/clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp
@@ -704,10 +704,10 @@ void FactsGenerator::handleFunctionCall(const Expr *Call,
         assert(!Args[I]->isGLValue() || ArgList->getLength() >= 2);
         ArgList = getRValueOrigins(Args[I], ArgList);
       }
-      if (isGslOwnerType(Args[I]->getType())) {
-        // The constructed gsl::Pointer borrows from the Owner's storage, not
-        // from what the Owner itself borrows, so only the outermost origin is
-        // needed.
+      if (isGslOwnerType(Args[I]->getType()) || IsArgLifetimeBound(I)) {
+        // The constructed gsl::Pointer is dependent on the argument itself, not
+        // on anything the argument is dependent on, so only the outermost
+        // origin is needed.
         CurrentBlockFacts.push_back(FactMgr.createFact<OriginFlowFact>(
             CallList->getOuterOriginID(), ArgList->getOuterOriginID(),
             KillSrc));
diff --git a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
index d58f23e4b554c..0ed151b9db136 100644
--- a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
+++ b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp
@@ -931,13 +931,11 @@ struct [[gsl::Pointer]] Pointer {
   Pointer(const Bar & bar [[clang::lifetimebound]]);
 };
 Pointer test3(Bar bar) {
-  // FIXME: Detect this using the CFG-based lifetime analysis (constructor of a pointer).
-  //        https://github.com/llvm/llvm-project/issues/175898
-  Pointer p = Pointer(Bar()); // expected-warning {{temporary}}
-  use(p);
-  p = Pointer(Bar()); // expected-warning {{object backing}}
-  use(p);
-  return bar; // expected-warning {{address of stack}}
+  Pointer p = Pointer(Bar()); // expected-warning {{temporary}} cfg-warning {{object whose reference is captured does not live long enough}} cfg-note {{destroyed here}}
+  use(p);                     // cfg-note {{later used here}}
+  p = Pointer(Bar());         // expected-warning {{object backing}} cfg-warning {{object whose reference is captured does not live long enough}} cfg-note {{destroyed here}}
+  use(p);                     // cfg-note {{later used here}}
+  return bar;                 // expected-warning {{address of stack}} cfg-warning {{address of stack memory is returned later}} cfg-note {{returned here}}
 }
 
 template<typename T>

``````````

</details>


https://github.com/llvm/llvm-project/pull/189907