https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109431
--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:173cf7c9b8c0d61bb2cb0bd3a9e3150b393ab59a commit r15-7810-g173cf7c9b8c0d61bb2cb0bd3a9e3150b393ab59a Author: Marek Polacek <pola...@redhat.com> Date: Thu Feb 27 17:42:49 2025 -0500 c++: ICE with RANGE_EXPR and array init [PR109431] We crash because we generate {[0 ... 1]={.low=0, .high=1}, [1]={.low=0, .high=1}} which output_constructor_regular_field doesn't want to see. This happens since r9-1483: process_init_constructor_array can now create a RANGE_EXPR. But the bug isn't in that patch; the problem is that build_vec_init doesn't handle RANGE_EXPRs. build_vec_init has a FOR_EACH_CONSTRUCTOR_ELT loop which populates const_vec. In this case it loops over the elements of {[0 ... 1]={.low=0, .high=1}} but assumes that each element initializes one element. So after the loop num_initialized_elts was 1, and then below: HOST_WIDE_INT last = tree_to_shwi (maxindex); if (num_initialized_elts <= last) { tree field = size_int (num_initialized_elts); if (num_initialized_elts != last) field = build2 (RANGE_EXPR, sizetype, field, size_int (last)); CONSTRUCTOR_APPEND_ELT (const_vec, field, e); } we added the extra initializer. It seemed convenient to use range_expr_nelts like below. PR c++/109431 gcc/cp/ChangeLog: * cp-tree.h (range_expr_nelts): Declare. * init.cc (build_vec_init): If the CONSTRUCTOR's index is a RANGE_EXPR, use range_expr_nelts to count how many elements were initialized. gcc/testsuite/ChangeLog: * g++.dg/init/array67.C: New test. Reviewed-by: Jason Merrill <ja...@redhat.com>
