Add virtual destructor to WasmYAML::Section or avoid memory leak

[sbc100]

Summary

Tested locally with -DLLVM_USE_SANITIZER=Address

[dschuff]

include/llvm/ObjectYAML/WasmYAML.h

111

This probably should be out-of-line: http://llvm.org/docs/CodingStandards.html#provide-a-virtual-method-anchor-for-classes-in-headers

[sbc100]

• move virtual method to cpp file

include/llvm/ObjectYAML/WasmYAML.h

struct Signature {
   uint32_t Index;
   SignatureForm Form;
   std::vector<ValueType> ParamTypes;
   ValueType ReturnType;
 };
 
 struct Section {
   Section(SectionType SecType) : Type(SecType) {}
+  virtual ~Section();
 
   SectionType Type;
   std::vector<Relocation> Relocations;
 };
 
 struct CustomSection : Section {
   CustomSection() : Section(wasm::WASM_SEC_CUSTOM) {}
   static bool classof(const Section *S) {

lib/ObjectYAML/WasmYAML.cpp

 //===----------------------------------------------------------------------===//
 
 #include "llvm/ObjectYAML/WasmYAML.h"
 #include "llvm/Object/Wasm.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/MipsABIFlags.h"
 
 namespace llvm {
+
+namespace WasmYAML {
+
+// Declared here rather than in the header to comply with:
+// http://llvm.org/docs/CodingStandards.html#provide-a-virtual-method-anchor-for-classes-in-headers
+Section::~Section() {}
+
+} // end namespace WasmYAML
+
 namespace yaml {
 
 void MappingTraits<WasmYAML::FileHeader>::mapping(
     IO &IO, WasmYAML::FileHeader &FileHdr) {
   IO.mapRequired("Version", FileHdr.Version);
 }
 
 void MappingTraits<WasmYAML::Object>::mapping(IO &IO,