[dataflow] fix compile on gcc7

Reported on https://reviews.llvm.org/D153674
This returned expression is move-eligible, this is a bug in old GCC.

diff --git a/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp b/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
index d290872..9e48df1 100644 (file)
--- a/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ b/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -583,7 +583,7 @@ runTypeErasedDataflowAnalysis(
     }
   }
 
-  return BlockStates;
+  return std::move(BlockStates);
 }
 
 } // namespace dataflow