c++: Fix regression introduced by r15-3796 [PR116722]

Jason pointed out that the fix I made for PR116722 via r15-3796
introduces a regression when running constexpr-dynamic10.C with
-fimplicit-constexpr.

The problem is that my change makes us leave cxx_eval_call_expression
early, and bypass the call to cxx_eval_thunk_call (through a recursive
call to cxx_eval_call_expression) that used to emit an error for that
testcase with -fimplicit-constexpr.

This patch emits the error if !ctx->quiet before bailing out because the
{con,de}structor belongs to a class with virtual bases.

	PR c++/116722

gcc/cp/ChangeLog:

	* constexpr.cc (cxx_bind_parameters_in_call): When !ctx->quiet,
	emit error before bailing out due to a call to {con,de}structor
	for a class with virtual bases.

1 files changed, 6 insertions, 0 deletions

diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 5c66967..4e4df94 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -1867,6 +1867,12 @@ cxx_bind_parameters_in_call (const constexpr_ctx *ctx, tree t, tree fun,
      with virtual bases.  */
   if (DECL_HAS_IN_CHARGE_PARM_P (fun) || DECL_HAS_VTT_PARM_P (fun))
     {
+      if (!ctx->quiet)
+	{
+	  error_at (cp_expr_loc_or_input_loc (t),
+		    "call to non-%<constexpr%> function %qD", fun);
+	  explain_invalid_constexpr_fn (fun);
+	}
       *non_constant_p = true;
       return binds;
     }