Diagnose attempts to add default function arguments to a

specialization. This completes C++ [temp.expl.spec]!

llvm-svn: 83980

Author: DougGregor

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -973,6 +973,9 @@ def note_instantiation_required_here : Note<
   "%select{implicit|explicit}0 instantiation first required here">;
 def err_template_spec_friend : Error<
   "template specialization declaration cannot be a friend">;
+def err_template_spec_default_arg : Error<
+  "default argument not permitted on an explicit "
+  "%select{instantiation|specialization}0 of function %1">;
 
 // C++ class template specializations and out-of-line definitions
 def err_template_spec_needs_header : Error<

clang/lib/Sema/SemaDeclCXX.cpp

@@ -296,6 +296,22 @@ bool Sema::MergeCXXFunctionDecl(FunctionDecl *New, FunctionDecl *Old) {
           << NewParam->getDefaultArgRange();
         Diag(Old->getLocation(), diag::note_template_prev_declaration)
           << false;
+      } else if (New->getTemplateSpecializationKind()
+                   != TSK_ImplicitInstantiation &&
+                 New->getTemplateSpecializationKind() != TSK_Undeclared) {
+        // C++ [temp.expr.spec]p21:
+        //   Default function arguments shall not be specified in a declaration
+        //   or a definition for one of the following explicit specializations:
+        //     - the explicit specialization of a function template;
+        //     — the explicit specialization of a member function template;
+        //     — the explicit specialization of a member function of a class 
+        //       template where the class template specialization to which the
+        //       member function specialization belongs is implicitly 
+        //       instantiated.
+        Diag(NewParam->getLocation(), diag::err_template_spec_default_arg)
+          << (New->getTemplateSpecializationKind() ==TSK_ExplicitSpecialization)
+          << New->getDeclName()
+          << NewParam->getDefaultArgRange();
       } else if (New->getDeclContext()->isDependentContext()) {
         // C++ [dcl.fct.default]p6 (DR217):
         //   Default arguments for a member function of a class template shall 

clang/test/CXX/temp/temp.spec/temp.expl.spec/p21.cpp

@@ -0,0 +1,30 @@
+// RUN: clang-cc -fsyntax-only -verify %s
+
+template<typename T>
+struct X {
+  void mf1(T);
+  template<typename U> void mf2(T, U); // expected-note{{previous}}
+};
+
+template<>
+void X<int>::mf1(int i = 17) // expected-error{{default}}
+{
+}
+
+template<> template<>
+void X<int>::mf2(int, int = 17) // expected-error{{default}}
+{ }
+
+template<> template<typename U> 
+void X<int>::mf2(int, U = U()) // expected-error{{default}}
+{
+}
+
+template<>
+struct X<float> {
+  void mf1(float);
+};
+
+void X<float>::mf1(float = 3.14f)  // okay
+{
+}

clang/www/cxx_status.html

@@ -2085,11 +2085,11 @@ <h1>C++ Support in Clang</h1>
 </tr>
 <tr>
   <td>&nbsp;&nbsp;&nbsp;&nbsp;14.7.3 [temp.expl.spec]</td>
-  <td class="advanced" align="center"></td>
-  <td class="medium" align="center"></td>
-  <td class="medium" align="center"></td>
-  <td class="broken" align="center"></td>
-  <td>O</td>
+  <td class="complete" align="center">&#x2713;</td>
+  <td class="complete" align="center">&#x2713;</td>
+  <td class="complete" align="center">&#x2713;</td>
+  <td class="complete" align="center"></td>
+  <td></td>
 </tr>
 <tr>
   <td>&nbsp;&nbsp;14.8 [temp.fct.spec]</td>