[WebAssembly] Do not use default argument.

[ruiu]

Summary

I don't think blank name is an appropriate default, but is this code
correct in the first place? Don't Code and data segments have name
in WebAssembly?

[sbc100]

Hmm. I wonder if its worth making a CustomSection subclass. Names make no sense unless the type is WASM_SEC_CUSTOM so perhaps the baseclass could take only a type and the custom section could take only a string, otherwise this is going to lead to all the section constructors passing empty string. See Writer::createSyntheticSection too.

[sbc100]

In answer to your question in the description. No, the only sections that have names are the custom sections. The 10 different types of builtin section can only occur once and are identified by number only.

[sbc100]

Still want to land this?

lld/wasm/OutputSections.h

 std::string toString(const wasm::OutputSection &Section);
 
 namespace wasm {
 
 class OutputSegment;
 
 class OutputSection {
 public:
-  OutputSection(uint32_t Type, std::string Name = "")
-      : Type(Type), Name(Name) {}
+  OutputSection(uint32_t Type, std::string Name) : Type(Type), Name(Name) {}
   virtual ~OutputSection() = default;
 
   std::string getSectionName() const;
   void setOffset(size_t NewOffset) {
     log("setOffset: " + toString(*this) + ": " + Twine(NewOffset));
     Offset = NewOffset;
   }
   void createHeader(size_t BodySize);

lld/wasm/OutputSections.cpp

void OutputSection::createHeader(size_t BodySize) {
   encodeULEB128(Type, OS);
   writeUleb128(OS, BodySize, "section size");
   OS.flush();
   log("createHeader: " + toString(*this) + " body=" + Twine(BodySize) +
       " total=" + Twine(getSize()));
 }
 
 CodeSection::CodeSection(ArrayRef<InputFunction *> Functions)
-    : OutputSection(WASM_SEC_CODE), Functions(Functions) {
+    : OutputSection(WASM_SEC_CODE, ""), Functions(Functions) {
   assert(Functions.size() > 0);
 
   raw_string_ostream OS(CodeSectionHeader);
   writeUleb128(OS, Functions.size(), "function count");
   OS.flush();
   BodySize = CodeSectionHeader.size();
 
   for (InputChunk *Func : Functions) {

 }
 
 void CodeSection::writeRelocations(raw_ostream &OS) const {
   for (const InputChunk *C : Functions)
     C->writeRelocations(OS);
 }
 
 DataSection::DataSection(ArrayRef<OutputSegment *> Segments)
-    : OutputSection(WASM_SEC_DATA), Segments(Segments) {
+    : OutputSection(WASM_SEC_DATA, ""), Segments(Segments) {
   raw_string_ostream OS(DataSectionHeader);
 
   writeUleb128(OS, Segments.size(), "data segment count");
   OS.flush();
   BodySize = DataSectionHeader.size();
 
   for (OutputSegment *Segment : Segments) {
     raw_string_ostream OS(Segment->Header);