[Sema] Implement DR777

A parameter pack after a default argument is now valid.

PR23029.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@233377 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index bb7ba943c60d47c4244a9ea9c3fd733b492b5a5c..aa1bfac7e06f61c03014beaeeff2be6d70134a3e 100644 (file)
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -697,16 +697,16 @@ void Sema::CheckCXXDefaultArguments(FunctionDecl *FD) {
       break;
   }
 
-  // C++ [dcl.fct.default]p4:
-  //   In a given function declaration, all parameters
-  //   subsequent to a parameter with a default argument shall
-  //   have default arguments supplied in this or previous
-  //   declarations. A default argument shall not be redefined
-  //   by a later declaration (not even to the same value).
+  // C++11 [dcl.fct.default]p4:
+  //   In a given function declaration, each parameter subsequent to a parameter
+  //   with a default argument shall have a default argument supplied in this or
+  //   a previous declaration or shall be a function parameter pack. A default
+  //   argument shall not be redefined by a later declaration (not even to the
+  //   same value).
   unsigned LastMissingDefaultArg = 0;
   for (; p < NumParams; ++p) {
     ParmVarDecl *Param = FD->getParamDecl(p);
-    if (!Param->hasDefaultArg()) {
+    if (!Param->hasDefaultArg() && !Param->isParameterPack()) {
       if (Param->isInvalidDecl())
         /* We already complained about this parameter. */;
       else if (Param->getIdentifier())

diff --git a/test/CXX/drs/dr7xx.cpp b/test/CXX/drs/dr7xx.cpp
new file mode 100644 (file)
index 0000000..a4ca74a
--- /dev/null
+++ b/test/CXX/drs/dr7xx.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -std=c++98 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++1z %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+
+namespace dr777 { // dr777: yes
+#if __cplusplus >= 201103L
+template <typename... T>
+void f(int i = 0, T ...args) {}
+void ff() { f(); }
+
+template <typename... T>
+void g(int i = 0, T ...args, T ...args2) {}
+
+template <typename... T>
+void h(int i = 0, T ...args, int j = 1) {}
+#endif
+}
+
+// expected-no-diagnostics

diff --git a/www/cxx_dr_status.html b/www/cxx_dr_status.html
index e70604f8cb5fca58bc098cb3c0befbb8fa0fe21e..66c65107d2cd26c16a3fcc666db83f0de62aa71b 100644 (file)
--- a/www/cxx_dr_status.html
+++ b/www/cxx_dr_status.html
@@ -4681,7 +4681,7 @@ and <I>POD class</I></td>
     <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#777">777</a></td>
     <td>CD2</td>
     <td>Default arguments and parameter packs</td>
-    <td class="none" align="center">Unknown</td>
+    <td class="full" align="center">Yes</td>
   </tr>
   <tr id="778">
     <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#778">778</a></td>