More explicit template instantiation. Now we're checking for more

cases where an explicit instantiation requires a definition; the
remainder of these checks will come with the implementation of
paragraph 4 of [temp.explicit].


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@84181 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 71 insertions, 6 deletions

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index b1222a3f84..c9803da719 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1112,6 +1112,8 @@ def err_explicit_instantiation_without_qualified_id_quals : Error<
   "qualifier in explicit instantiation of '%0%1' requires a template-id">;
 def err_explicit_instantiation_unqualified_wrong_namespace : Error<
   "explicit instantiation of %q0 must occur in %1">;
+def err_explicit_instantiation_undefined_member_class : Error<
+  "explicit instantiation of undefined member class %0 of class template %1">;
 
 // C++ typename-specifiers
 def err_typename_nested_not_found : Error<"no type named %0 in %1">;
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index ab0bbe081d..04580b70b8 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -3651,12 +3651,20 @@ Sema::ActOnExplicitInstantiation(Scope *S,
   CheckExplicitInstantiationScope(*this, Record, NameLoc, true);
 
   if (!Record->getDefinition(Context)) {
-    // If the class has a definition, instantiate it (and all of its
-    // members, recursively).
-    Pattern = cast_or_null<CXXRecordDecl>(Pattern->getDefinition(Context));
-    if (Pattern && InstantiateClass(TemplateLoc, Record, Pattern,
-                                    getTemplateInstantiationArgs(Record),
-                                    TSK))
+    // C++ [temp.explicit]p3:
+    //   A definition of a member class of a class template shall be in scope 
+    //   at the point of an explicit instantiation of the member class.
+    CXXRecordDecl *Def 
+      = cast_or_null<CXXRecordDecl>(Pattern->getDefinition(Context));
+    if (!Def) {
+      Diag(TemplateLoc, diag::err_explicit_instantiation_undefined_member_class)
+        << Record->getDeclName() << Record->getDeclContext();
+      Diag(Pattern->getLocation(), diag::note_forward_declaration)
+        << Pattern;
+      return true;
+    } else if (InstantiateClass(TemplateLoc, Record, Def,
+                                getTemplateInstantiationArgs(Record),
+                                TSK))
       return true;
   } else // Instantiate all of the members of the class.
     InstantiateClassMembers(TemplateLoc, Record,
diff --git a/test/CXX/temp/temp.spec/temp.explicit/p3.cpp b/test/CXX/temp/temp.spec/temp.explicit/p3.cpp
new file mode 100644
index 0000000000..2bd781bbed
--- /dev/null
+++ b/test/CXX/temp/temp.spec/temp.explicit/p3.cpp
@@ -0,0 +1,55 @@
+// RUN: clang-cc -fsyntax-only -verify %s
+
+// A declaration of a function template shall be in scope at the point of the 
+// explicit instantiation of the function template.
+template<typename T> void f0(T) { }
+template void f0(int); // okay
+
+// A definition of the class or class template containing a member function 
+// template shall be in scope at the point of the explicit instantiation of 
+// the member function template.
+struct X0; // expected-note 2{{forward declaration}}
+template<typename> struct X1; // expected-note 2{{declared here}} \
+                              // expected-note 3{{forward declaration}}
+
+// FIXME: Repeated diagnostics here!
+template void X0::f0<int>(int); // expected-error 2{{incomplete type}} \
+  // expected-error{{invalid token after}}
+template void X1<int>::f0<int>(int); // expected-error{{implicit instantiation of undefined template}} \
+  // expected-error{{incomplete type}} \\
+  // expected-error{{invalid token}}
+
+// A definition of a class template or class member template shall be in scope 
+// at the point of the explicit instantiation of the class template or class 
+// member template.
+template struct X1<float>; // expected-error{{explicit instantiation of undefined template}}
+
+template<typename T>
+struct X2 { // expected-note 4{{refers here}}
+  template<typename U>
+  struct Inner; // expected-note{{declared here}}
+  
+  struct InnerClass; // expected-note{{forward declaration}}
+};
+
+template struct X2<int>::Inner<float>; // expected-error{{explicit instantiation of undefined template}}
+
+// A definition of a class template shall be in scope at the point of an 
+// explicit instantiation of a member function or a static data member of the
+// class template.
+template void X1<int>::f1(int); // expected-error{{incomplete type}} \
+                                // expected-error{{does not refer}}
+
+template int X1<int>::member; // expected-error{{incomplete type}} \
+                              // expected-error{{does not refer}}
+
+// A definition of a member class of a class template shall be in scope at the 
+// point of an explicit instantiation of the member class.
+template struct X2<float>::InnerClass; // expected-error{{undefined member}}
+
+// If the declaration of the explicit instantiation names an implicitly-declared 
+// special member function (Clause 12), the program is ill-formed.
+template X2<int>::X2(); // expected-error{{not an instantiation}}
+template X2<int>::X2(const X2&); // expected-error{{not an instantiation}}
+template X2<int>::~X2(); // expected-error{{not an instantiation}}
+template X2<int> &X2<int>::operator=(const X2<int>&); // expected-error{{not an instantiation}}