[analyzer] Add dispatch_data_create as a special case in RetainCountChecker.

This function receives a callback block. The analyzer suspects that this block
may be used to take care of releasing the libdispatch object returned from
the function. In fact, it doesn't - it only releases the raw data buffer.
Inform the analyzer about that. Fixes the resulting false negatives.

rdar://problem/22280098

Differential Revision: https://reviews.llvm.org/D27409

llvm-svn: 289047

1 files changed, 4 insertions, 1 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
index 6054b83e5cf..b7d1670999b 100644
--- a/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
@@ -953,7 +953,10 @@ void RetainSummaryManager::updateSummaryForCall(const RetainSummary *&S,
       if (IdentifierInfo *Name = FC->getDecl()->getIdentifier()) {
         // When the CGBitmapContext is deallocated, the callback here will free
         // the associated data buffer.
-        if (Name->isStr("CGBitmapContextCreateWithData"))
+        // The callback in dispatch_data_create frees the buffer, but not
+        // the data object.
+        if (Name->isStr("CGBitmapContextCreateWithData") ||
+            Name->isStr("dispatch_data_create"))
           RE = S->getRetEffect();
       }
     }