Don't try to instantiate REFLECT_EXPR_HANDLE of REFLECT_ANNOTATION REFLECT_EXPR.

gcc/cp/pt.cc

@@ -23016,6 +23016,11 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	reflect_kind kind = REFLECT_EXPR_KIND (t);
 	if (TYPE_P (h) || TREE_CODE (h) == NAMESPACE_DECL)
 	  h = tsubst (h, args, complain, in_decl);
+	else if (kind == REFLECT_ANNOTATION)
+	  /* annotations_of should be called on reflections of already
+	     instantiated entities and so no need to tsubst the annotation
+	     attribute and we rely on pointer equality of that.  */
+	  ;
 	else
 	  {
 	    /* [expr.reflect] The id-expression of a reflect-expression is

gcc/testsuite/g++.dg/reflect/annotations8.C

@@ -0,0 +1,16 @@
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+
+struct [[=42]] A {};
+template <auto I>
+inline auto b = [] (auto &&x) { x.template operator () <I> (); };
+
+int
+main ()
+{
+  auto l = [&] <auto> {};
+  auto w = b <annotations_of (^^A)[0]>;
+  w (l);
+}