diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -5856,12 +5856,10 @@
       // expansion.
       OldType = Expansion->getPattern();
       IsPackExpansion = true;
-      Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
-      NewType = getDerived().TransformType(OldType);
-    } else {
-      NewType = getDerived().TransformType(OldType);
     }
 
+    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
+    NewType = getDerived().TransformType(OldType);
     if (NewType.isNull())
       return true;
 
diff --git a/clang/test/SemaTemplate/packs.cpp b/clang/test/SemaTemplate/packs.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaTemplate/packs.cpp
@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -ast-dump %s | FileCheck %s
+
+namespace pr56094 {
+template <typename... T> struct D {
+  template <typename... U> using B = int(int (*...p)(T, U));
+  template <typename U1, typename U2> D(B<U1, U2> *);
+};
+using t1 = D<float>::B<int>;
+// CHECK:      `-TypeAliasDecl 0x{{.*}} <{{.*}}> col:{{.*}} t1 'D<float>::B<int>':'int (int (*)(T, U)...)'
+// CHECK-NEXT:  `-ElaboratedType 0x{{.*}} 'D<float>::B<int>' sugar dependent
+// CHECK-NEXT:   `-TemplateSpecializationType 0x{{.*}} 'B<int>' sugar dependent alias B
+// CHECK-NEXT:     |-TemplateArgument type 'int'
+// CHECK-NEXT:     | `-BuiltinType 0x{{.*}} 'int'
+// CHECK-NEXT:     `-FunctionProtoType 0x{{.*}} 'int (int (*)(T, U)...)' dependent cdecl
+// CHECK-NEXT:       |-BuiltinType 0x{{.*}} 'int'
+// CHECK-NEXT:       `-PackExpansionType 0x{{.*}} 'int (*)(T, U)...' dependent
+// CHECK-NEXT:         `-PointerType 0x{{.*}} 'int (*)(T, U)' dependent contains_unexpanded_pack
+// CHECK-NEXT:           `-ParenType 0x{{.*}} 'int (T, U)' sugar dependent contains_unexpanded_pack
+// CHECK-NEXT:             `-FunctionProtoType 0x{{.*}} 'int (T, U)' dependent contains_unexpanded_pack cdecl
+// CHECK-NEXT:               |-BuiltinType 0x{{.*}} 'int'
+// CHECK-NEXT:               |-SubstTemplateTypeParmPackType 0x{{.*}} 'T' dependent contains_unexpanded_pack
+// CHECK-NEXT:               | |-TemplateTypeParmType 0x{{.*}} 'T' dependent contains_unexpanded_pack depth 0 index 0 pack
+// CHECK-NEXT:               | | `-TemplateTypeParm 0x{{.*}} 'T'
+// CHECK-NEXT:               | `-TemplateArgument pack
+// CHECK-NEXT:               |   `-TemplateArgument type 'float'
+// CHECK-NEXT:               |     `-BuiltinType 0x{{.*}} 'float'
+// CHECK-NEXT:               `-SubstTemplateTypeParmPackType 0x{{.*}} 'U' dependent contains_unexpanded_pack
+// CHECK-NEXT:                 |-TemplateTypeParmType 0x{{.*}} 'U' dependent contains_unexpanded_pack depth 1 index 0 pack
+// CHECK-NEXT:                 | `-TemplateTypeParm 0x{{.*}} 'U'
+// CHECK-NEXT:                 `-TemplateArgument pack
+// CHECK-NEXT:                   `-TemplateArgument type 'int'
+// CHECK-NEXT:                     `-BuiltinType 0x{{.*}} 'int'
+} // namespace pr56094