From 4df86402990e2f45e02a367f1734a22ebc041e98 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Thu, 13 Jun 2024 10:02:43 -0400 Subject: c++: ICE w/ ambig and non-strictly-viable cands [PR115239] Here during overload resolution we have two strictly viable ambiguous candidates #1 and #2, and two non-strictly viable candidates #3 and #4 which we hold on to ever since r14-6522. These latter candidates have an empty second arg conversion since the first arg conversion was deemed bad, and this trips up joust when called on #3 and #4 which assumes all arg conversions are there. We can fix this by making joust robust to empty arg conversions, but in this situation we shouldn't need to compare #3 and #4 at all given that we have a strictly viable candidate. To that end, this patch makes tourney shortcut considering non-strictly viable candidates upon encountering ambiguity between two strictly viable candidates (taking advantage of the fact that the candidates list is sorted according to viability via splice_viable). PR c++/115239 gcc/cp/ChangeLog: * call.cc (tourney): Don't consider a non-strictly viable candidate as the champ if there was ambiguity between two strictly viable candidates. gcc/testsuite/ChangeLog: * g++.dg/overload/error7.C: New test. Reviewed-by: Jason Merrill (cherry picked from commit 7fed7e9bbc57d502e141e079a6be2706bdbd4560) --- gcc/cp/call.cc | 3 ++- gcc/testsuite/g++.dg/overload/error7.C | 10 ++++++++++ 2 files changed, 12 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/overload/error7.C diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc index 38b9c4f..f5584c9 100644 --- a/gcc/cp/call.cc +++ b/gcc/cp/call.cc @@ -13488,7 +13488,8 @@ tourney (struct z_candidate *candidates, tsubst_flags_t complain) { previous_worse_champ = nullptr; champ = &(*challenger)->next; - if (!*champ || !(*champ)->viable) + if (!*champ || !(*champ)->viable + || (*champ)->viable < (*challenger)->viable) { champ = nullptr; break; diff --git a/gcc/testsuite/g++.dg/overload/error7.C b/gcc/testsuite/g++.dg/overload/error7.C new file mode 100644 index 0000000..de50ce5 --- /dev/null +++ b/gcc/testsuite/g++.dg/overload/error7.C @@ -0,0 +1,10 @@ +// PR c++/115239 + +bool foo(char *, long); // #1, strictly viable, ambig with #2 +bool foo(char *, unsigned); // #2, strictly viable, ambig with #1 +bool foo(char, long); // #3, non-strictly viable +bool foo(char, unsigned); // #4, non-strictly viable + +int main() { + foo((char *)0, 0); // { dg-error "ambiguous" } +} -- cgit v1.1