[lld][WebAssembly] Fix stub library parsing with windows line endings

[sbc100]

Summary

Also, fix checking of first line in ::parse. We can't use the
::getLines helper here since that already does comment stripping
internally.

[sbc100]

• revert

[dschuff]

lld/wasm/InputFiles.cpp

696

I think the SmallVector docs (https://llvm.org/doxygen/classllvm_1_1SmallVector.html#details) recommend leaving out the 2nd template parameter if we don't have a particular best choice for it. 0 seems too small since we know there will be at least a few lines (or maybe just use std::vector since it seems likely there will be heap allocation anyway?)

[sbc100]

• feedback

lld/test/wasm/Inputs/.gitattributes

+# ensures that we test parsing of stub libraries that contain
+# windows line endings
+libstub.so text eol=crlf

lld/wasm/Driver.cpp

case file_magic::archive: {
     files.push_back(make<ArchiveFile>(mbref));
     return;
   }
   case file_magic::bitcode:
   case file_magic::wasm_object:
     files.push_back(createObjectFile(mbref));
     break;
   case file_magic::unknown:
-    if (mbref.getBuffer().starts_with("#STUB\n")) {
+    if (mbref.getBuffer().starts_with("#STUB")) {
       files.push_back(make<StubFile>(mbref));
       break;
     }
     [[fallthrough]];
   default:
     error("unknown file type: " + mbref.getBufferIdentifier());
   }
 }

lld/wasm/InputFiles.cpp

StringRef strip(StringRef s) {
   }
   while (s.ends_with(" ")) {
     s = s.drop_back();
   }
   return s;
 }
 
 void StubFile::parse() {
-  bool first = false;
+  bool first = true;
+
+  SmallVector<StringRef> lines;
+  mb.getBuffer().split(lines, '\n');
+  for (StringRef line : lines) {
+    line = line.trim();
 
-  for (StringRef line : args::getLines(mb)) {
     // File must begin with #STUB
     if (first) {
-      assert(line == "#STUB\n");
+      assert(line == "#STUB");
       first = false;
     }
 
     // Lines starting with # are considered comments
     if (line.startswith("#"))
       continue;
 
     StringRef sym;
     StringRef rest;
     std::tie(sym, rest) = line.split(':');
     sym = strip(sym);
     rest = strip(rest);
 
     symbolDependencies[sym] = {};
 
     while (rest.size()) {
-      StringRef first;
-      std::tie(first, rest) = rest.split(',');
-      first = strip(first);
-      symbolDependencies[sym].push_back(first);
+      StringRef dep;
+      std::tie(dep, rest) = rest.split(',');
+      dep = strip(dep);
+      symbolDependencies[sym].push_back(dep);
     }
   }
 }
 
 void ArchiveFile::parse() {
   // Parse a MemoryBufferRef as an archive file.
   LLVM_DEBUG(dbgs() << "Parsing library: " << toString(this) << "\n");
   file = CHECK(Archive::create(mb), toString(this));