https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91353
--- Comment #8 from Marek Polacek <mpolacek at gcc dot gnu.org> --- Author: mpolacek Date: Thu Dec 5 20:13:03 2019 New Revision: 279019 URL: https://gcc.gnu.org/viewcvs?rev=279019&root=gcc&view=rev Log: PR c++/91353 - P1331R2: Allow trivial default init in constexpr contexts. This patch implements C++20 P1331, allowing trivial default initialization in constexpr contexts. * c-cppbuiltin.c (c_cpp_builtins): Adjust the value of __cpp_constexpr. * class.c (trivial_default_constructor_is_constexpr): Return true in C++20. * constexpr.c (cx_check_missing_mem_inits): Allow missing field initializers in C++20. (cxx_eval_call_expression): Don't clear CONSTRUCTOR_NO_CLEARING for constexpr constructors in C++20. (reduced_constant_expression_p): Don't set FIELD for union and array types. Skip empty class fields without initializers. * decl.c (check_for_uninitialized_const_var): Permit trivial default initialization in constexpr. (next_initializable_field): Don't skip vptr fields. * method.c (walk_field_subobs): Still consider a constructor that doesn't initialize all the members constexpr. * g++.dg/cpp0x/constexpr-array6.C: Adjust dg-error. * g++.dg/cpp0x/constexpr-ctor.C: Likewise. * g++.dg/cpp0x/constexpr-diag3.C: Likewise. * g++.dg/cpp0x/constexpr-diag4.C: Likewise. * g++.dg/cpp0x/constexpr-ex3.C: Likewise. * g++.dg/cpp0x/constexpr-template2.C: Likewise. * g++.dg/cpp0x/constexpr-union2.C: Likewise. * g++.dg/cpp0x/lambda/lambda-mangle.C: Rip out a piece of code ... * g++.dg/cpp0x/lambda/lambda-mangle6.C: ... and put it here. * g++.dg/cpp0x/pr79118.C: Adjust dg-error. * g++.dg/cpp1y/constexpr-83921-3.C: Likewise. * g++.dg/cpp1y/constexpr-neg1.C: Likewise. * g++.dg/cpp1z/constexpr-lambda12.C: Likewise. * g++.dg/cpp1z/feat-cxx1z.C: Use -std=c++17. * g++.dg/cpp2a/constexpr-init1.C: New test. * g++.dg/cpp2a/constexpr-init2.C: New test. * g++.dg/cpp2a/constexpr-init3.C: New test. * g++.dg/cpp2a/constexpr-init4.C: New test. * g++.dg/cpp2a/constexpr-init5.C: New test. * g++.dg/cpp2a/constexpr-init6.C: New test. * g++.dg/cpp2a/constexpr-init7.C: New test. * g++.dg/cpp2a/constexpr-init8.C: New test. * g++.dg/cpp2a/constexpr-init9.C: New test. * g++.dg/cpp2a/constexpr-init10.C: New test. * g++.dg/cpp2a/constexpr-init11.C: New test. * g++.dg/cpp2a/constexpr-init12.C: New test. * g++.dg/cpp2a/constexpr-init13.C: New test. * g++.dg/cpp2a/constexpr-init14.C: New test. * g++.dg/cpp2a/constexpr-init15.C: New test. * g++.dg/cpp2a/constexpr-try5.C: Adjust dg-error. * g++.dg/cpp2a/feat-cxx2a.C: Test __cpp_constexpr. * g++.dg/cpp2a/lambda-mangle.C: New test. * g++.dg/debug/dwarf2/pr44641.C: Skip for c++2a. * g++.dg/ext/stmtexpr21.C: Adjust dg-error. Added: trunk/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle6.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init10.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init11.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init12.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init13.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init14.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init15.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init2.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init3.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init4.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init5.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init6.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init7.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init8.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-init9.C trunk/gcc/testsuite/g++.dg/cpp2a/lambda-mangle.C Modified: trunk/gcc/c-family/ChangeLog trunk/gcc/c-family/c-cppbuiltin.c trunk/gcc/cp/ChangeLog trunk/gcc/cp/class.c trunk/gcc/cp/constexpr.c trunk/gcc/cp/decl.c trunk/gcc/cp/method.c trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-array6.C trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-ctor.C trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-diag4.C trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-ex3.C trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-template2.C trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-union2.C trunk/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle.C trunk/gcc/testsuite/g++.dg/cpp0x/pr79118.C trunk/gcc/testsuite/g++.dg/cpp1y/constexpr-83921-3.C trunk/gcc/testsuite/g++.dg/cpp1y/constexpr-neg1.C trunk/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda12.C trunk/gcc/testsuite/g++.dg/cpp2a/constexpr-try5.C trunk/gcc/testsuite/g++.dg/cpp2a/feat-cxx2a.C trunk/gcc/testsuite/g++.dg/debug/dwarf2/pr44641.C trunk/gcc/testsuite/g++.dg/ext/stmtexpr21.C
