Replace size calls on containers with empty calls where appropriate

[xazax.hun]

Summary

Replace size calls on containers with empty calls where appropriate. This patch is the result of applying the fixits of the recently committed readability-container-size-empty checker in clang tidy. A similar patch was committed to the backend already: http://reviews.llvm.org/rL226161

All the tests are passed on my machine.

[alexfh]

Looks good!

[alexfh]

Committed revision 226914.

examples/PrintFunctionNames/PrintFunctionNames.cpp

         return false;
       }
     }
-    if (args.size() && args[0] == "help")
+    if (!args.empty() && args[0] == "help")
       PrintHelp(llvm::errs());
 
     return true;

lib/CodeGen/BackendUtil.cpp

                                     BackendArgs.data());
 
   std::string FeaturesStr;
-  if (TargetOpts.Features.size()) {
+  if (!TargetOpts.Features.empty()) {
     SubtargetFeatures Features;
     for (std::vector<std::string>::const_iterator
            it = TargetOpts.Features.begin(),

lib/CodeGen/CGObjCGNU.cpp

   std::vector<llvm::Constant*> Elements;
   llvm::Constant *Statics = NULLPtr;
   // Generate statics list:
-  if (ConstantStrings.size()) {
+  if (!ConstantStrings.empty()) {
     llvm::ArrayType *StaticsArrayTy = llvm::ArrayType::get(PtrToInt8Ty,
         ConstantStrings.size() + 1);
     ConstantStrings.push_back(NULLPtr);

tools/libclang/CIndex.cpp

 
   CXTUResourceUsage usage = { (void*) entries.get(),
                             (unsigned) entries->size(),
-                            entries->size() ? &(*entries)[0] : nullptr };
+                            !entries->empty() ? &(*entries)[0] : nullptr };
   entries.release();
   return usage;
 }

utils/TableGen/ClangAttrEmitter.cpp

 static unsigned
 getSpellingListIndex(const std::vector<FlattenedSpelling> &SpellingList,
                      const FlattenedSpelling &Spelling) {
-  assert(SpellingList.size() && "Spelling list is empty!");
+  assert(!SpellingList.empty() && "Spelling list is empty!");
 
   for (unsigned Index = 0; Index < SpellingList.size(); ++Index) {
     const FlattenedSpelling &S = SpellingList[Index];

     std::vector<FlattenedSpelling> Spellings = 
       GetFlattenedSpellings(*Accessor);
     std::vector<FlattenedSpelling> SpellingList = GetFlattenedSpellings(R);
-    assert(SpellingList.size() &&
+    assert(!SpellingList.empty() &&
            "Attribute with empty spelling list can't have accessors!");
 
     OS << "  bool " << Name << "() const { return SpellingListIndex == ";

utils/TableGen/NeonEmitter.cpp

     }
   }
 
-  assert(Lines.size() && "Empty def?");
+  assert(!Lines.empty() && "Empty def?");
   if (!RetVar.getType().isVoid())
     Lines.back().insert(0, RetVar.getName() + " = ");