https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71093
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Jason Merrill <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:90bc2d09b5bfcc913f79543c3b65202e7246e162 commit r14-6508-g90bc2d09b5bfcc913f79543c3b65202e7246e162 Author: Nathaniel Shead <nathanielosh...@gmail.com> Date: Fri Nov 3 12:18:29 2023 +1100 c++: End lifetime of objects in constexpr after destructor call [PR71093] This patch adds checks for using objects after they've been manually destroyed via explicit destructor call. Currently this is only implemented for 'top-level' objects; FIELD_DECLs and individual elements of arrays will need a lot more work to track correctly and are left for a future patch. The other limitation is that destruction of parameter objects is checked too 'early', happening at the end of the function call rather than the end of the owning full-expression as they should be for consistency; see cpp2a/constexpr-lifetime2.C. This is because I wasn't able to find a good way to link the constructed parameter declarations with the variable declarations that are actually destroyed later on to propagate their lifetime status, so I'm leaving this for a later patch. PR c++/71093 gcc/cp/ChangeLog: * constexpr.cc (constexpr_global_ctx::get_value_ptr): Don't return NULL_TREE for objects we're initializing. (constexpr_global_ctx::destroy_value): Rename from remove_value. Only mark real variables as outside lifetime. (constexpr_global_ctx::clear_value): New function. (destroy_value_checked): New function. (cxx_eval_call_expression): Defer complaining about non-constant arg0 for operator delete. Use remove_value_safe. (cxx_fold_indirect_ref_1): Handle conversion to 'as base' type. (outside_lifetime_error): Include name of object we're accessing. (cxx_eval_store_expression): Handle clobbers. Improve error messages. (cxx_eval_constant_expression): Use remove_value_safe. Clear bind variables before entering body. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/constexpr-lifetime1.C: Improve error message. * g++.dg/cpp1y/constexpr-lifetime2.C: Likewise. * g++.dg/cpp1y/constexpr-lifetime3.C: Likewise. * g++.dg/cpp1y/constexpr-lifetime4.C: Likewise. * g++.dg/cpp2a/bitfield2.C: Likewise. * g++.dg/cpp2a/constexpr-new3.C: Likewise. New check. * g++.dg/cpp1y/constexpr-lifetime7.C: New test. * g++.dg/cpp2a/constexpr-lifetime1.C: New test. * g++.dg/cpp2a/constexpr-lifetime2.C: New test. Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
