Fix a case when the TemplateArgs vector can be empty.

llvm-svn: 72911

clang/lib/Sema/SemaTemplate.cpp

@@ -2271,7 +2271,7 @@ Sema::ActOnExplicitInstantiation(Scope *S, SourceLocation TemplateLoc,
   // template.
   llvm::SmallVector<TemplateArgument, 16> ConvertedTemplateArgs;
   if (CheckTemplateArgumentList(ClassTemplate, TemplateNameLoc, LAngleLoc, 
-                                &TemplateArgs[0], TemplateArgs.size(),
+                                TemplateArgs.data(), TemplateArgs.size(),
                                 RAngleLoc, ConvertedTemplateArgs))
     return true;
 

clang/test/SemaTemplate/default-arguments.cpp

@@ -10,3 +10,6 @@ X<> *x3; // expected-error{{too few template arguments for class template 'X'}}
 template<typename U = float, int M> struct X;
 
 X<> *x4;
+
+template<typename T = int> struct Z;
+template struct Z<>;