https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96090
--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Nathaniel Shead <nsh...@gcc.gnu.org>: https://gcc.gnu.org/g:4719b6f5ae4d758f193a17bbd5fb6cbacd702a23 commit r14-6395-g4719b6f5ae4d758f193a17bbd5fb6cbacd702a23 Author: Nathaniel Shead <nathanielosh...@gmail.com> Date: Sat Oct 28 16:04:52 2023 +1100 c++: Fix noexcept checking for trivial operations [PR96090] This patch stops eager folding of trivial operations (construction and assignment) from occurring when checking for noexceptness. This was previously done in PR c++/53025, but only for copy/move construction, and the __is_nothrow_xible builtins did not receive the same treatment when they were added. To handle `is_nothrow_default_constructible`, the patch also ensures that when no parameters are passed we do value initialisation instead of just building the constructor call: in particular, value-initialisation doesn't necessarily actually invoke the constructor for trivial default constructors, and so we need to handle this case as well. This is contrary to the proposed resolution of CWG2820; for now we just ensure it matches the behaviour of the `noexcept` operator and create testcases formalising this, and if that issue gets accepted we can revisit. PR c++/96090 PR c++/100470 gcc/cp/ChangeLog: * call.cc (build_over_call): Prevent folding of trivial special members when checking for noexcept. * method.cc (constructible_expr): Perform value-initialisation for empty parameter lists. (is_nothrow_xible): Treat as noexcept operator. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/noexcept81.C: New test. * g++.dg/ext/is_nothrow_constructible7.C: New test. * g++.dg/ext/is_nothrow_constructible8.C: New test. Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
