std_move false positive

Author: usx95

clang/include/clang/Analysis/Analyses/LifetimeSafety/FactsGenerator.h

@@ -101,6 +101,8 @@ class FactsGenerator : public ConstStmtVisitor<FactsGenerator> {
   // corresponding to the left-hand side is updated to be a "write", thereby
   // exempting it from the check.
   llvm::DenseMap<const DeclRefExpr *, UseFact *> UseFacts;
+
+  llvm::DenseSet<const ValueDecl* > MovedDecls;
 };
 
 } // namespace clang::lifetimes::internal

clang/lib/Analysis/LifetimeSafety/FactsGenerator.cpp

@@ -163,9 +163,21 @@ void FactsGenerator::VisitCXXMemberCallExpr(const CXXMemberCallExpr *MCE) {
   }
 }
 
+static bool isStdMove(const FunctionDecl *FD) {
+  return FD && FD->isInStdNamespace() && FD->getIdentifier() &&
+         FD->getName() == "move";
+}
+
 void FactsGenerator::VisitCallExpr(const CallExpr *CE) {
   handleFunctionCall(CE, CE->getDirectCallee(),
                      {CE->getArgs(), CE->getNumArgs()});
+  // Remember accessPath which moved using std::move.
+  // TODO: If there is need, this could flow-sensitive
+  if (isStdMove(CE->getDirectCallee()))
+    if (CE->getNumArgs() == 1)
+      if (auto *DRE =
+              dyn_cast<DeclRefExpr>(CE->getArg(0)->IgnoreParenImpCasts()))
+        MovedDecls.insert(DRE->getDecl());
 }
 
 void FactsGenerator::VisitCXXNullPtrLiteralExpr(
@@ -341,6 +353,8 @@ void FactsGenerator::handleLifetimeEnds(const CFGLifetimeEnds &LifetimeEnds) {
   // Iterate through all loans to see if any expire.
   for (const auto &Loan : FactMgr.getLoanMgr().getLoans()) {
     const AccessPath &LoanPath = Loan.Path;
+    if (MovedDecls.contains(LoanPath.D))
+      continue;
     // Check if the loan is for a stack variable and if that variable
     // is the one being destructed.
     if (LoanPath.D == LifetimeEndsVD)