[PATCH] D65050: [SemaTemplate] Mark a function type as dependent when its parameter list contains pack expansion

[S. B. Tam via Phabricator via cfe-commits]

cpplearner created this revision.
cpplearner added reviewers: doug.gregor, eli.friedman, lvoufo, rsmith.
Herald added subscribers: cfe-commits, dexonsmith.
Herald added a project: clang.

Given `template<class> using Int = int;`, the type `void(Int<Ts>...)` should be treated as a dependent type, even though `Int<Ts>` is not dependent.

This fixes https://bugs.llvm.org/show_bug.cgi?id=42654


Repository:
  rC Clang

https://reviews.llvm.org/D65050

Files:
  clang/lib/AST/Type.cpp
  clang/test/SemaTemplate/alias-templates.cpp


Index: clang/test/SemaTemplate/alias-templates.cpp
===================================================================
--- clang/test/SemaTemplate/alias-templates.cpp
+++ clang/test/SemaTemplate/alias-templates.cpp
@@ -267,3 +267,34 @@
     int z = Bar(); // expected-error {{use of template template parameter 'Bar' requires template arguments}}
   }
 }
+
+namespace PR42654 {
+  template<typename> struct function { };
+
+  template<typename...T>
+  struct thing {
+    void f(function<void(T...)>) { }
+  };
+
+  template<typename ...Ts>
+  struct Environment
+  {
+    template<typename T>
+    using Integer = int;
+
+    using Function = function<void(Integer<Ts>...)>;
+    using MyTuple = thing<Integer<Ts>...>;
+
+    void run(Function func)
+    {
+      MyTuple t;
+      t.f(func);
+    }
+  };
+
+  void f()
+  {
+    Environment<int, double> env;
+    env.run({});
+  }
+}
Index: clang/lib/AST/Type.cpp
===================================================================
--- clang/lib/AST/Type.cpp
+++ clang/lib/AST/Type.cpp
@@ -2912,7 +2912,7 @@
   // Fill in the trailing argument array.
   auto *argSlot = getTrailingObjects<QualType>();
   for (unsigned i = 0; i != getNumParams(); ++i) {
-    if (params[i]->isDependentType())
+    if (params[i]->isDependentType() || params[i]->getAs<PackExpansionType>())
       setDependent();
     else if (params[i]->isInstantiationDependentType())
       setInstantiationDependent();


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