diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index 0709695fd08..30fccc46678 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -2747,6 +2747,7 @@ tsubst_constraint (tree t, tree args, tsubst_flags_t complain, tree in_decl)
   /* We also don't want to evaluate concept-checks when substituting the
      constraint-expressions of a declaration.  */
   processing_constraint_expression_sentinel s;
+  cp_unevaluated u;
   tree expr = tsubst_expr (t, args, complain, in_decl, false);
   return expr;
 }
@@ -3005,7 +3006,10 @@ satisfy_atom (tree t, tree args, sat_info info)
 
   /* Compute the value of the constraint.  */
   if (info.noisy ())
-    result = cxx_constant_value (result);
+    {
+      iloc_sentinel ils (EXPR_LOCATION (result));
+      result = cxx_constant_value (result);
+    }
   else
     {
       result = maybe_constant_value (result, NULL_TREE,
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index bd99529f98e..85c05af42ed 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -13203,6 +13203,8 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
       else
 	result = tsubst (pattern, args, complain, in_decl);
       result = make_pack_expansion (result, complain);
+      PACK_EXPANSION_LOCAL_P (result) = PACK_EXPANSION_LOCAL_P (t);
+      PACK_EXPANSION_SIZEOF_P (result) = PACK_EXPANSION_SIZEOF_P (t);
       if (PACK_EXPANSION_AUTO_P (t))
 	{
 	  /* This is a fake auto... pack expansion created in add_capture with
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-ctad4.C b/gcc/testsuite/g++.dg/cpp2a/concepts-ctad4.C
new file mode 100644
index 00000000000..4f04cb3f43b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-ctad4.C
@@ -0,0 +1,25 @@
+// PR c++/100138
+// { dg-do compile { target c++20 } }
+
+template <class T>
+struct A {
+  A(T, auto... xs) requires (sizeof...(xs) != 0);
+};
+
+constexpr bool f(...) { return true; }
+
+template <class T>
+struct B {
+  B(T, auto... xs) requires (f(xs...)); // { dg-error "constant expression" }
+};
+
+template <class T>
+struct C {
+  C(T, auto x) requires (f(x)); // { dg-error "constant expression" }
+};
+
+int main() {
+  A x{1, 2}; // { dg-bogus "" }
+  B y{1, 2}; // { dg-error "deduction|no match" }
+  C z{1, 2}; // { dg-error "deduction|no match" }
+}