From c81708e6ecf01443b437abb553845caed464e115 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanaka@apple.com>
Date: Mon, 24 Oct 2016 21:45:54 +0000
Subject: [Sema][ObjC] Warn about implicitly autoreleasing out-parameters
 captured by blocks.

Add a new warning "-Wblock-capture-autoreleasing". The warning warns
about implicitly autoreleasing out-parameters captured by blocks which
can introduce use-after-free bugs that are hard to debug.

rdar://problem/15377548

Differential Revision: https://reviews.llvm.org/D25844

llvm-svn: 285031
---
 clang/lib/Sema/SemaExpr.cpp | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'clang/lib/Sema/SemaExpr.cpp')

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index eddc4207dfc..7caa50e07cf 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -13502,6 +13502,23 @@ static bool captureInBlock(BlockScopeInfo *BSI, VarDecl *Var,
     }
     return false;
   }
+
+  // Warn about implicitly autoreleasing indirect parameters captured by blocks.
+  if (auto *PT = dyn_cast<PointerType>(CaptureType)) {
+    QualType PointeeTy = PT->getPointeeType();
+    if (isa<ObjCObjectPointerType>(PointeeTy.getCanonicalType()) &&
+        PointeeTy.getObjCLifetime() == Qualifiers::OCL_Autoreleasing &&
+        !isa<AttributedType>(PointeeTy)) {
+      if (BuildAndDiagnose) {
+        SourceLocation VarLoc = Var->getLocation();
+        S.Diag(Loc, diag::warn_block_capture_autoreleasing);
+        S.Diag(VarLoc, diag::note_declare_parameter_autoreleasing) <<
+            FixItHint::CreateInsertion(VarLoc, "__autoreleasing");
+        S.Diag(VarLoc, diag::note_declare_parameter_strong);
+      }
+    }
+  }
+
   const bool HasBlocksAttr = Var->hasAttr<BlocksAttr>();
   if (HasBlocksAttr || CaptureType->isReferenceType() ||
       (S.getLangOpts().OpenMP && S.IsOpenMPCapturedDecl(Var))) {
-- 
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