When resolving default template arguments, it should be done in the declaration context
of the template what we are going to instantiate.

Fixes various crashes of rdar://11242625 & http://llvm.org/PR11421.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@155576 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index d4b0975..b9ea055 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -2512,6 +2512,7 @@
                                      Converted.size(),
                                      SourceRange(TemplateLoc, RAngleLoc));
 
+    Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
     ArgType = SemaRef.SubstType(ArgType, AllTemplateArgs,
                                 Param->getDefaultArgumentLoc(),
                                 Param->getDeclName());
@@ -2560,6 +2561,7 @@
                                    Converted.size(),
                                    SourceRange(TemplateLoc, RAngleLoc));
 
+  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
   return SemaRef.SubstExpr(Param->getDefaultArgument(), AllTemplateArgs);
 }
 
@@ -2607,6 +2609,7 @@
                                    Converted.size(),
                                    SourceRange(TemplateLoc, RAngleLoc));
 
+  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
   // Substitute into the nested-name-specifier first, 
   QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
   if (QualifierLoc) {
diff --git a/test/SemaTemplate/dependent-names.cpp b/test/SemaTemplate/dependent-names.cpp
index 36e1ad8..924bad9 100644
--- a/test/SemaTemplate/dependent-names.cpp
+++ b/test/SemaTemplate/dependent-names.cpp
@@ -292,3 +292,35 @@
     template void f<S>(); // expected-note {{here}}
   }
 }
+
+namespace rdar11242625 {
+
+template <typename T>
+struct Main {
+  struct default_names {
+    typedef int id;
+  };
+
+  template <typename T2 = typename default_names::id>
+  struct TS {
+    T2 q;
+  };
+};
+
+struct Sub : public Main<int> {
+  TS<> ff;
+};
+
+int arr[sizeof(Sub)];
+
+}
+
+namespace PR11421 {
+template < unsigned > struct X {
+  static const unsigned dimension = 3;
+  template<unsigned dim=dimension> 
+  struct Y: Y<dim> { }; // expected-error {{incomplete type}} expected-note {{is not complete until the closing}}
+};
+typedef X<3> X3;
+X3::Y<>::iterator it; // expected-note {{requested here}}
+}