https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92812
--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:753b4679bc46f6806cf45d9afc3783c6d3b63589 commit r11-2999-g753b4679bc46f6806cf45d9afc3783c6d3b63589 Author: Marek Polacek <pola...@redhat.com> Date: Wed Aug 26 08:27:33 2020 -0400 c++: Fix P0960 in member init list and array [PR92812] This patch nails down the remaining P0960 case in PR92812: struct A { int ar[2]; A(): ar(1, 2) {} // doesn't work without this patch }; Note that when the target object is not of array type, this already works: struct S { int x, y; }; struct A { S s; A(): s(1, 2) { } // OK in C++20 }; because build_new_method_call_1 takes care of the P0960 magic. It proved to be quite hairy. When the ()-list has more than one element, we can always create a CONSTRUCTOR, because the code was previously invalid. But when the ()-list has just one element, it gets all kinds of difficult. As usual, we have to handle a("foo") so as not to wrap the STRING_CST in a CONSTRUCTOR. Always turning x(e) into x{e} would run into trouble as in c++/93790. Another issue was what to do about x({e}): previously, this would trigger "list-initializer for non-class type must not be parenthesized". I figured I'd make this work in C++20, so that given struct S { int x, y; }; you can do S a[2]; [...] A(): a({1, 2}) // initialize a[0] with {1, 2} and a[1] with {} It also turned out that, as an extension, we support compound literals: F (): m((S[1]) { 1, 2 }) so this has to keep working as before. Moreover, make sure not to trigger in compiler-generated code, like =default, where array assignment is allowed. I've factored out a function that turns a TREE_LIST into a CONSTRUCTOR to simplify handling of P0960. paren-init35.C also tests this with vector types. gcc/cp/ChangeLog: PR c++/92812 * cp-tree.h (do_aggregate_paren_init): Declare. * decl.c (do_aggregate_paren_init): New. (grok_reference_init): Use it. (check_initializer): Likewise. * init.c (perform_member_init): Handle initializing an array from a ()-list. Use do_aggregate_paren_init. gcc/testsuite/ChangeLog: PR c++/92812 * g++.dg/cpp0x/constexpr-array23.C: Adjust dg-error. * g++.dg/cpp0x/initlist69.C: Likewise. * g++.dg/diagnostic/mem-init1.C: Likewise. * g++.dg/init/array28.C: Likewise. * g++.dg/cpp2a/paren-init33.C: New test. * g++.dg/cpp2a/paren-init34.C: New test. * g++.dg/cpp2a/paren-init35.C: New test. * g++.old-deja/g++.brendan/crash60.C: Adjust dg-error. * g++.old-deja/g++.law/init10.C: Likewise. * g++.old-deja/g++.other/array3.C: Likewise.
