Don't crash if we deserialize a pack expansion type whose pattern

contains no packs.

Fixes a regression from 740a164dec.

clang/include/clang/AST/TypeProperties.td

@@ -722,7 +722,8 @@ let Class = PackExpansionType in {
   }
 
   def : Creator<[{
-    return ctx.getPackExpansionType(pattern, numExpansions);
+    return ctx.getPackExpansionType(pattern, numExpansions,
+                                    /*ExpectPackInType*/false);
   }]>;
 }
 

clang/lib/AST/ASTImporter.cpp

@@ -1498,7 +1498,8 @@ ASTNodeImporter::VisitPackExpansionType(const PackExpansionType *T) {
     return ToPatternOrErr.takeError();
 
   return Importer.getToContext().getPackExpansionType(*ToPatternOrErr,
-                                                      T->getNumExpansions());
+                                                      T->getNumExpansions(),
+                                                      /*ExpactPack=*/false);
 }
 
 ExpectedType ASTNodeImporter::VisitDependentTemplateSpecializationType(

clang/test/PCH/cxx-variadic-templates.cpp

@@ -19,3 +19,8 @@ shared_ptr<int> spi = shared_ptr<int>::allocate_shared(1, 2);
 template<int> struct A {};
 template<int> struct B {};
 outer<int, int>::inner<1, 2, A, B> i(A<1>{}, B<2>{});
+
+void test_nondependent_pack() {
+  take_nondependent_pack<int, int>(nullptr, nullptr);
+  take_nondependent_pack_2<int, int>({});
+}

clang/test/PCH/cxx-variadic-templates.h

@@ -23,3 +23,8 @@ template<typename...Ts> struct outer {
   };
 };
 template struct outer<int, int>;
+
+template<typename ...T> void take_nondependent_pack(int (...arr)[sizeof(sizeof(T))]);
+
+template<typename T> using hide = int;
+template<typename ...T> void take_nondependent_pack_2(outer<hide<T>...>);

clang/test/PCH/cxx1y-lambdas.mm

@@ -39,6 +39,8 @@ int init_capture(T t) {
   return [&, x(t)] { return sizeof(x); };
 }
 
+auto with_pack = [](auto ...xs){};
+
 #else
 
 // CHECK-PRINT: T add_slowly
@@ -55,4 +57,6 @@ int add(int x, int y) {
 // CHECK-PRINT: init_capture
 // CHECK-PRINT: [&, x(t)]
 
+void use_with_pack() { with_pack(1, 2, 3); }
+
 #endif

clang/test/PCH/cxx2a-constraints.cpp

@@ -24,6 +24,8 @@ template <SizedLike<char> T> void h(T) {}
 template <SizedLike<int> T> void i(T) {}
 template <SizedLike T> void i(T) {}
 
+void j(SizedLike<int> auto ...ints) {}
+
 #else /*included pch*/
 
 int main() {
@@ -35,6 +37,7 @@ int main() {
   (void)h(1);
   (void)i('1');
   (void)i(1);
+  (void)j(1, 2, 3);
 }
 
 #endif // HEADER