commit c0536c8294fc4453f0f1d1cf24a62bfc725fd492
author Richard Smith <richard-llvm@metafoo.co.uk> Wed Jan 25 02:14:59 2012 +0000
committer Richard Smith <richard-llvm@metafoo.co.uk> Wed Jan 25 02:14:59 2012 +0000
tree 2facdc4b4477c42d6a4d61a976cd44a3fc05b708
parent 5d613b57972a761973861f7c38b3e6442243a6ab

Fix PR11848: decree that an alias template contains an unexpanded parameter pack
iff its substitution contains an unexpanded parameter pack. This has the effect
that we now reject declarations such as this (which we used to crash when
expanding):

  template<typename T> using Int = int;
  template<typename ...Ts> void f(Int<Ts> ...ints);

The standard is inconsistent on how this case should be treated.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148905 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/Type.cpp

diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 7b30c50..b6ce59e 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -1889,7 +1889,9 @@
          Canon.isNull()? T.isDependent() : Canon->isDependentType(),
          Canon.isNull()? T.isDependent() 
                        : Canon->isInstantiationDependentType(),
-         false, T.containsUnexpandedParameterPack()),
+         false,
+         Canon.isNull()? T.containsUnexpandedParameterPack()
+                       : Canon->containsUnexpandedParameterPack()),
     Template(T), NumArgs(NumArgs) {
   assert(!T.getAsDependentTemplateName() && 
          "Use DependentTemplateSpecializationType for dependent template-name");
@@ -1922,7 +1924,7 @@
     if (Args[Arg].getKind() == TemplateArgument::Type &&
         Args[Arg].getAsType()->isVariablyModifiedType())
       setVariablyModified();
-    if (Args[Arg].containsUnexpandedParameterPack())
+    if (Canon.isNull() && Args[Arg].containsUnexpandedParameterPack())
       setContainsUnexpandedParameterPack();
 
     new (&TemplateArgs[Arg]) TemplateArgument(Args[Arg]);

lib/Sema/SemaTemplateInstantiate.cpp

diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 2b96a1c..e183f1f 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1510,7 +1510,7 @@
   // FIXME: When OldParm is a parameter pack and NewParm is not a parameter
   // pack, we actually have a set of instantiated locations. Maintain this set!
   if (OldParm->isParameterPack() && !NewParm->isParameterPack()) {
-    // Add the new parameter to 
+    // Add the new parameter to the instantiated parameter pack.
     CurrentInstantiationScope->InstantiatedLocalPackArg(OldParm, NewParm);
   } else {
     // Introduce an Old -> New mapping

test/SemaTemplate/alias-templates.cpp

diff --git a/test/SemaTemplate/alias-templates.cpp b/test/SemaTemplate/alias-templates.cpp
index 79d6849..c0f9e21 100644
--- a/test/SemaTemplate/alias-templates.cpp
+++ b/test/SemaTemplate/alias-templates.cpp
@@ -68,3 +68,36 @@
 
 itt::rebind<bool> btr;
 itt::rebind_thing<bool> btt(btr);
+
+namespace PR11848 {
+  template<typename T> using U = int;
+
+  template<typename T, typename ...Ts>
+  void f(U<T> i, U<Ts> ...is) { // expected-error {{type 'U<Ts>' (aka 'int') of function parameter pack does not contain any unexpanded parameter packs}}
+    return i + f<Ts...>(is...); // expected-error {{pack expansion does not contain any unexpanded parameter packs}}
+  }
+
+  template<typename ...Ts>
+  struct S {
+    S(U<Ts>...ts); // expected-error {{does not contain any unexpanded parameter packs}}
+  };
+
+  template<typename T>
+  struct Hidden1 {
+    template<typename ...Ts>
+    Hidden1(typename T::template U<Ts> ...ts);
+  };
+
+  template<typename T, typename ...Ts>
+  struct Hidden2 {
+    Hidden2(typename T::template U<Ts> ...ts);
+  };
+
+  struct Hide {
+    template<typename T> using U = int;
+  };
+
+  // FIXME: This case crashes clang at the moment.
+  //Hidden1<Hide> h1;
+  Hidden2<Hide, double, char> h2(1, 2);
+}