From a8de832470f78a40a0e2c8de866a471bf74bf0ab Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Mon, 30 Aug 2021 09:44:28 -0400 Subject: c++: fold function template args sooner [PR101460] As discussed in the PR, we were giving a lot of unnecessary errors for this testcase because we didn't try to do constant evaluation until convert_nontype_argument, which happens for each of the candidates. But when looking at a template-id as the function operand of a call, we can try to fold arguments before we get into overload resolution. PR c++/101460 gcc/cp/ChangeLog: * cp-tree.h (cxx_constant_value_sfinae): Declare. * constexpr.c (cxx_constant_value_sfinae): New. * pt.c (fold_targs_r, maybe_fold_fn_template_args): New. (tsubst_copy_and_build) [CALL_EXPR]: Call maybe_fold_fn_template_args. gcc/testsuite/ChangeLog: * g++.dg/template/explicit-args6.C: New test. --- gcc/cp/constexpr.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'gcc/cp/constexpr.c') diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index b9c0062..9606719 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -7458,6 +7458,18 @@ cxx_constant_value (tree t, tree decl) return cxx_eval_outermost_constant_expr (t, false, true, true, false, decl); } +/* As above, but respect SFINAE. */ + +tree +cxx_constant_value_sfinae (tree t, tsubst_flags_t complain) +{ + bool sfinae = !(complain & tf_error); + tree r = cxx_eval_outermost_constant_expr (t, sfinae, true, true); + if (sfinae && !TREE_CONSTANT (r)) + r = error_mark_node; + return r; +} + /* Like cxx_constant_value, but used for evaluation of constexpr destructors of constexpr variables. The actual initializer of DECL is not modified. */ -- cgit v1.1