From eff66cd2aa4e6cbce289ce61aa903ed3ee4b52fa Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Tue, 10 Dec 2019 15:12:50 -0500 Subject: [PATCH] PR c++/92847 - C++20 comparison ambiguity with class template. This testcase demonstrates that looking at cand->template_decl is not a good starting place for finding the most general template, as it is only set for primary templates. * call.c (cand_parms_match): Handle all templated functions. From-SVN: r279185 --- gcc/cp/ChangeLog | 3 ++ gcc/cp/call.c | 29 ++++++++++--------- .../g++.dg/cpp2a/spaceship-rewrite5.C | 15 ++++++++++ 3 files changed, 33 insertions(+), 14 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/spaceship-rewrite5.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 6b15fc306e2..c7760546142 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,5 +1,8 @@ 2019-12-10 Jason Merrill + PR c++/92847 - C++20 comparison ambiguity with class template. + * call.c (cand_parms_match): Handle all templated functions. + Fix C++20 structural type vs. private base. * class.c (build_base_field_1): Take access parameter. (build_base_field): Likewise. diff --git a/gcc/cp/call.c b/gcc/cp/call.c index 48d49b7ec87..cbd5747d6ca 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -11052,24 +11052,25 @@ joust_maybe_elide_copy (z_candidate *&cand) bool cand_parms_match (z_candidate *c1, z_candidate *c2) { - tree fn1 = c1->template_decl; - tree fn2 = c2->template_decl; - if (fn1 && fn2) - { - fn1 = most_general_template (TI_TEMPLATE (fn1)); - fn1 = DECL_TEMPLATE_RESULT (fn1); - fn2 = most_general_template (TI_TEMPLATE (fn2)); - fn2 = DECL_TEMPLATE_RESULT (fn2); - } - else - { - fn1 = c1->fn; - fn2 = c2->fn; - } + tree fn1 = c1->fn; + tree fn2 = c2->fn; if (fn1 == fn2) return true; if (identifier_p (fn1) || identifier_p (fn2)) return false; + /* We don't look at c1->template_decl because that's only set for primary + templates, not e.g. non-template member functions of class templates. */ + tree t1 = most_general_template (fn1); + tree t2 = most_general_template (fn2); + if (t1 || t2) + { + if (!t1 || !t2) + return false; + if (t1 == t2) + return true; + fn1 = DECL_TEMPLATE_RESULT (t1); + fn2 = DECL_TEMPLATE_RESULT (t2); + } return compparms (TYPE_ARG_TYPES (TREE_TYPE (fn1)), TYPE_ARG_TYPES (TREE_TYPE (fn2))); } diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-rewrite5.C b/gcc/testsuite/g++.dg/cpp2a/spaceship-rewrite5.C new file mode 100644 index 00000000000..d0424377e8e --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-rewrite5.C @@ -0,0 +1,15 @@ +// { dg-do compile { target c++11 } } + +template +struct A { + A() {} + + template + A(const A&) {} + + bool operator==(const A&) const { return true; } +}; + +A a; +A b; +auto c = (a == b); -- 2.30.2