From a988a398d6daef3072cd2d07a21980911d8f93fc Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Mon, 7 Dec 2020 17:21:47 -0500 Subject: [PATCH] c++: Distinguish ambiguity from no valid candidate Several recent C++ features are specified to try overload resolution, and if no viable candidate is found, do something else. But our error return doesn't distinguish between that situation and finding multiple viable candidates that end up being ambiguous. We're already trying to separately return the single function we found even if it ends up being ill-formed for some reason; for ambiguity let's pass back error_mark_node, to be distinguished from NULL_TREE meaning no viable candidate. gcc/cp/ChangeLog: * call.c (build_new_op_1): Set *overload for ambiguity. (build_new_method_call_1): Likewise. --- gcc/cp/call.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/gcc/cp/call.c b/gcc/cp/call.c index f1e0bcb796b..221e3de0c70 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -6357,6 +6357,8 @@ build_new_op_1 (const op_location_t &loc, enum tree_code code, int flags, print_z_candidates (loc, candidates); } result = error_mark_node; + if (overload) + *overload = error_mark_node; } else if (TREE_CODE (cand->fn) == FUNCTION_DECL) { @@ -10438,6 +10440,8 @@ build_new_method_call_1 (tree instance, tree fns, vec **args, free (pretty_name); } call = error_mark_node; + if (fn_p) + *fn_p = error_mark_node; } else { -- 2.30.2