Make ELFYAML::Opt non-abstract

Author: chapuni

llvm/include/llvm/ObjectYAML/ELFYAML.h

@@ -778,8 +778,8 @@ struct Object {
 bool shouldAllocateFileSpace(ArrayRef<ProgramHeader> Phdrs,
                              const NoBitsSection &S);
 
-/// ELFYAML::Opt -- Abstract base class for ELFYAML to provide
-/// the interface for handling CustomRawConetentSection.
+/// ELFYAML::Opt -- Null base class for ELFYAML to provide the
+/// interface for handling CustomRawConetentSection.
 ///
 /// Users in ELFYAML should obtain the pointer with
 /// dyn_cast<ELFYAML::Opt> if IO::Opt is the instance from yaml::Opt.
@@ -801,15 +801,15 @@ class Opt : public yaml::IO::OptBase {
   /// This is called:
   ///   - Before preMapping for elf2yaml.
   ///   - After preMapping for yaml2elf.
+  /// Returns nullptr to delegate default actions.
   virtual std::unique_ptr<CustomRawContentSection>
-  makeCustomRawContentSection(StringRef Name) const = 0;
+  makeCustomRawContentSection(StringRef Name) const;
 
   /// Called before mapping sections for prettyprinting yaml.
-  virtual void preMapping(const ELFYAML::Object &Object, bool IsOutputting) = 0;
+  virtual void preMapping(const ELFYAML::Object &Object, bool IsOutputting);
 
   /// Called after mapping sections to gather members for the file format.
-  virtual void postMapping(const ELFYAML::Object &Object,
-                           bool IsOutputting) = 0;
+  virtual void postMapping(const ELFYAML::Object &Object, bool IsOutputting);
 
   /// Tell IO::OptBase to be this and derivered classes.
   static bool classof(const yaml::IO::OptBase *Obj) {

llvm/lib/ObjectYAML/ELFYAML.cpp

@@ -32,6 +32,19 @@ ELFYAML::Chunk::~Chunk() = default;
 ELFYAML::Opt::~Opt() = default;
 const char ELFYAML::Opt::ID = 'E';
 
+std::unique_ptr<ELFYAML::CustomRawContentSection>
+ELFYAML::Opt::makeCustomRawContentSection(StringRef Name) const {
+  return nullptr;
+}
+
+/// Called before mapping sections for prettyprinting yaml.
+void ELFYAML::Opt::preMapping(const ELFYAML::Object &Object,
+                              bool IsOutputting) {}
+
+/// Called after mapping sections to gather members for the file format.
+void ELFYAML::Opt::postMapping(const ELFYAML::Object &Object,
+                               bool IsOutputting) {}
+
 namespace ELFYAML {
 ELF_ELFOSABI Object::getOSAbi() const { return Header.OSABI; }
 

llvm/tools/obj2yaml/elf2yaml.cpp

@@ -22,19 +22,7 @@
 using namespace llvm;
 
 namespace {
-class DumperOpt : public ELFYAML::Opt {
-public:
-  std::unique_ptr<ELFYAML::CustomRawContentSection>
-  makeCustomRawContentSection(StringRef Name) const override {
-    return nullptr;
-  }
-  void preMapping(const ELFYAML::Object &Object, bool IsOutputting) override {
-    // Do nothing.
-  }
-  void postMapping(const ELFYAML::Object &Object, bool IsOutputting) override {
-    // Do nothing.
-  }
-};
+struct DumperOpt : public ELFYAML::Opt {};
 
 template <class ELFT>
 class ELFDumper {

llvm/tools/yaml2obj/yaml2obj.cpp

@@ -59,19 +59,7 @@ cl::opt<std::string> OutputFilename("o", cl::desc("Output filename"),
                                     cl::value_desc("filename"), cl::init("-"),
                                     cl::Prefix, cl::cat(Cat));
 
-class EmitterOpt : public ELFYAML::Opt {
-public:
-  std::unique_ptr<ELFYAML::CustomRawContentSection>
-  makeCustomRawContentSection(StringRef Name) const override {
-    return nullptr;
-  }
-  void preMapping(const ELFYAML::Object &Object, bool IsOutputting) override {
-    // Do nothing.
-  }
-  void postMapping(const ELFYAML::Object &Object, bool IsOutputting) override {
-    // Do nothing.
-  }
-};
+struct EmitterOpt : public ELFYAML::Opt {};
 } // namespace
 
 static std::optional<std::string> preprocess(StringRef Buf,