From 9845c52db38f15740861435f38f7e5ad8a8de2ec Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Thu, 30 Sep 2021 17:34:23 -0400 Subject: [PATCH] c++: __is_trivially_xible and multi-arg aggr paren init [PR102535] is_xible_helper assumes only 0- and 1-argument ctors can be trivial, but C++20 aggregate paren init means multi-arg ctors can now be trivial too. This patch relaxes the relevant early exit check accordingly. PR c++/102535 gcc/cp/ChangeLog: * method.c (is_xible_helper): Don't exit early for multi-arg ctors in C++20. gcc/testsuite/ChangeLog: * g++.dg/ext/is_trivially_constructible7.C: New test. --- gcc/cp/method.c | 4 +++- gcc/testsuite/g++.dg/ext/is_trivially_constructible7.C | 17 +++++++++++++++++ 2 files changed, 20 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/ext/is_trivially_constructible7.C diff --git a/gcc/cp/method.c b/gcc/cp/method.c index 3c34952..c38912a 100644 --- a/gcc/cp/method.c +++ b/gcc/cp/method.c @@ -2094,8 +2094,10 @@ is_xible_helper (enum tree_code code, tree to, tree from, bool trivial) tree expr; if (code == MODIFY_EXPR) expr = assignable_expr (to, from); - else if (trivial && from && TREE_CHAIN (from)) + else if (trivial && from && TREE_CHAIN (from) + && cxx_dialect < cxx20) return error_mark_node; // only 0- and 1-argument ctors can be trivial + // before C++20 aggregate paren init else if (TREE_CODE (to) == ARRAY_TYPE && !TYPE_DOMAIN (to)) return error_mark_node; // can't construct an array of unknown bound else diff --git a/gcc/testsuite/g++.dg/ext/is_trivially_constructible7.C b/gcc/testsuite/g++.dg/ext/is_trivially_constructible7.C new file mode 100644 index 0000000..f6fbf8f --- /dev/null +++ b/gcc/testsuite/g++.dg/ext/is_trivially_constructible7.C @@ -0,0 +1,17 @@ +// PR c++/102535 +// Verify __is_trivially_constructible works with multi-arg paren init of +// aggrs. + +struct A { int x; }; +struct B { float y; }; +struct C { char z; }; +struct D { A a; B b; C c; }; + +extern int n[1 + __is_trivially_constructible(D, A)]; +extern int n[1 + __is_trivially_constructible(D, A, B)]; +extern int n[1 + __is_trivially_constructible(D, A, B, C)]; +#if __cpp_aggregate_paren_init +extern int n[1 + true]; +#else +extern int n[1 + false]; +#endif -- 2.7.4