use auto for obvious type; NFC

llvm-svn: 256393
diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
index 2486a49..eb6edeac 100644
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -785,7 +785,7 @@
     else
       pushRegion(Count, getStart(S));
 
-    if (const CaseStmt *CS = dyn_cast<CaseStmt>(S)) {
+    if (const auto *CS = dyn_cast<CaseStmt>(S)) {
       Visit(CS->getLHS());
       if (const Expr *RHS = CS->getRHS())
         Visit(RHS);