poly_int was written before the switch to C++11 and so couldn't use explicit default constructors. This led to an awkward split between poly_int_pod and poly_int. poly_int simply inherited from poly_int_pod and added constructors, with the argumentless constructor having an empty body. But inheritance meant that poly_int had to repeat the assignment operators from poly_int_pod (again, no C++11, so no "using" to inherit base-class implementations). All that goes away if we switch to using default constructors. The main complication is ensuring that braced initialisation still gives a constexpr, so that static variables can be initialised without runtime code. The two problems here are: (1) When initialising a poly_int<N, wide_int> with fewer than N coefficients, the other coefficients need to be a zero of the same precision as the explicit coefficients. This was previously done in a for loop using wi::ints_for<...>::zero, but C++11 constexpr constructors can't have function bodies. The patch instead uses a series of delegated initialisers to fill in the implicit coefficients. (2) The initialisation in: void f(int x) { unsigned int foo {x}; } produces the warning: warning: narrowing conversion of 'x' from 'int' to 'unsigned int' [-Wnarrowing] whereas: void f(int x) { unsigned int foo = x; } does not. So switching to direct initialisation of the coeffs array would mean that: poly_uin64_t x = 0; would trigger a warning for using 0 rather than 0u. That seemed overly pedantic, so the patch adds explicit casts to the constructor. The complication is to do that without adding extra code to wide-int versions. The patch uses a new init_cast type for that. gcc/ * poly-int.h (poly_int_pod): Delete. (poly_coeff_traits::init_cast): New type. (poly_int_full, poly_int_hungry, poly_int_fullness): New structures. (poly_int): Replace constructors that take 1 and 2 coefficients with a general one that takes an arbitrary number of coefficients. Delegate initialization to two new private constructors, one of which uses the coefficients as-is and one of which adds an extra zero of the appropriate type (and precision, where applicable). (gt_ggc_mx, gt_pch_nx): Operate on poly_ints rather than poly_int_pods. * poly-int-types.h (poly_uint16_pod, poly_int64_pod, poly_uint64_pod) (poly_offset_int_pod, poly_wide_int_pod, poly_widest_int_pod): Delete. * gengtype.cc (main): Don't register poly_int64_pod. * calls.cc (initialize_argument_information): Use poly_int rather than poly_int_pod. (combine_pending_stack_adjustment_and_call): Likewise. * config/aarch64/aarch64.cc (pure_scalable_type_info): Likewise. * data-streamer.h (bp_unpack_poly_value): Likewise. * dwarf2cfi.cc (struct dw_trace_info): Likewise. (struct queued_reg_save): Likewise. * dwarf2out.h (struct dw_cfa_location): Likewise. * emit-rtl.h (struct incoming_args): Likewise. (struct rtl_data): Likewise. * expr.cc (get_bit_range): Likewise. (get_inner_reference): Likewise. * expr.h (get_bit_range): Likewise. * fold-const.cc (split_address_to_core_and_offset): Likewise. (ptr_difference_const): Likewise. * fold-const.h (ptr_difference_const): Likewise. * function.cc (try_fit_stack_local): Likewise. (instantiate_new_reg): Likewise. * function.h (struct expr_status): Likewise. (struct args_size): Likewise. * genmodes.cc (ZERO_COEFFS): Likewise. (mode_size_inline): Likewise. (mode_nunits_inline): Likewise. (emit_mode_precision): Likewise. (emit_mode_size): Likewise. (emit_mode_nunits): Likewise. * gimple-fold.cc (get_base_constructor): Likewise. * gimple-ssa-store-merging.cc (struct symbolic_number): Likewise. * inchash.h (class hash): Likewise. * ipa-modref-tree.cc (modref_access_node::dump): Likewise. * ipa-modref.cc (modref_access_analysis::merge_call_side_effects): Likewise. * ira-int.h (ira_spilled_reg_stack_slot): Likewise. * lra-eliminations.cc (self_elim_offsets): Likewise. * machmode.h (mode_size, mode_precision, mode_nunits): Likewise. * omp-low.cc (omplow_simd_context): Likewise. * pretty-print.cc (pp_wide_integer): Likewise. * pretty-print.h (pp_wide_integer): Likewise. * reload.cc (struct decomposition): Likewise. * reload.h (struct reload): Likewise. * reload1.cc (spill_stack_slot_width): Likewise. (struct elim_table): Likewise. (offsets_at): Likewise. (init_eliminable_invariants): Likewise. * rtl.h (union rtunion): Likewise. (poly_int_rtx_p): Likewise. (strip_offset): Likewise. (strip_offset_and_add): Likewise. * rtlanal.cc (strip_offset): Likewise. * tree-dfa.cc (get_ref_base_and_extent): Likewise. (get_addr_base_and_unit_offset_1): Likewise. (get_addr_base_and_unit_offset): Likewise. * tree-dfa.h (get_ref_base_and_extent): Likewise. (get_addr_base_and_unit_offset_1): Likewise. (get_addr_base_and_unit_offset): Likewise. * tree-ssa-loop-ivopts.cc (struct iv_use): Likewise. (strip_offset): Likewise. * tree-ssa-sccvn.h (struct vn_reference_op_struct): Likewise. * tree.cc (ptrdiff_tree_p): Likewise. * tree.h (poly_int_tree_p): Likewise. (ptrdiff_tree_p): Likewise. (get_inner_reference): Likewise. gcc/testsuite/ * gcc.dg/plugin/poly-int-tests.h (test_num_coeffs_extra): Use poly_int rather than poly_int_pod.