https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105838
--- Comment #18 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jason Merrill <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:d081807d8d70e3e87eae41e1560e54d503f4d465 commit r13-4564-gd081807d8d70e3e87eae41e1560e54d503f4d465 Author: Jason Merrill <ja...@redhat.com> Date: Tue Dec 6 09:51:51 2022 -0500 c++: avoid initializer_list<string> [PR105838] When constructing a vector<string> from { "strings" }, first is built an initializer_list<string>, which is then copied into the strings in the vector. But this is inefficient: better would be treat the { "strings" } as a range and construct the strings in the vector directly from the string-literals. We can do this transformation for standard library classes because we know the design patterns they follow. PR c++/105838 gcc/cp/ChangeLog: * call.cc (list_ctor_element_type): New. (braced_init_element_type): New. (has_non_trivial_temporaries): New. (maybe_init_list_as_array): New. (maybe_init_list_as_range): New. (build_user_type_conversion_1): Use maybe_init_list_as_range. * parser.cc (cp_parser_braced_list): Call recompute_constructor_flags. * cp-tree.h (find_temps_r): Declare. gcc/testsuite/ChangeLog: * g++.dg/tree-ssa/initlist-opt1.C: New test.
