This fixes two cases where variably-modified types were not recognized as such. The first is when building composite types and the other when a type is reconstructed for the 'vector' attribute. Construction of types in the C FE is reorganized to use c_build_* functions which are responsible for setting C_TYPE_VARIABLE_SIZE, C_TYPE_VARIABLY_MODIFIED and TYPE_TYPELESS_STORAGE based on the properties of the type itself and these replace all other logic elsewhere (e.g. in grokdeclarator). A new 'c_reconstruct_complex_type' based on these functions is introduced which is called via a language hook when the 'vector' attribute is processed (as for C++). One problem is are arrays of unspecified size 'T[*]' which were represented identically to zero-sized arrays but with C_TYPE_VARIABLE_SIZE set. To avoid having to create distinct type copies for this, the representation was changed to make it a natural VLA by giving it an upper bound of '(0, 0)'. This also then allows fixing of PR100420 where such arrays were printed as 'T[0]'. Finally, a new function 'c_verify_type' checks consistency of properties specific to C FE and is called when checking is on. PR c/117145 PR c/117245 PR c/100420 gcc/c/ChangeLog: * c-decl.cc (c_build_pointer_type): Move to c-typeck.cc (grokdeclarator): Simplify logic. (match_builtin_function_types): Adapt. (push_decl): Adapt. (implicitly_declare): Adapt. (c_update_type_canonical): Adapt. (c_make_fname_decl): Adapt. (start_function): Adapt. * c-objc-common.h: Add LANG_HOOKS_RECONSTRUCT_COMPLEX_TYPE. * c-tree.h: Add prototypes. * c-typeck.cc (c_verify_type): New function. (c_set_type_bits). New function. (c_build_pointer_type): Moved from c-decl.cc. (c_build_pointer_type_for_mode): New function. (c_build_function_type): New function. (c_build_array_type): New function. (c_build_type_attribute_variant): New function. (c_reconstruct_complex_type): New function. (c_build_functype_attribute_variant): Renamed. (array_to_pointer_conversion): Simplify logic. (composite_type_internal): Simplify logic.. (build_unary_op): Simplify logic.. (comptypes_verify): Add checking assertions. (c_build_qualified_type): Add checking assertions. (c_build_function_call_vec): Adapt. (qualify_type): Adapt. (build_functype_attribute_variant): Adapt. (common_pointer_type): Adapt. (c_common_type): Adapt. (convert_for_assignment): Adapt. (type_or_builtin_type): Adapt. (build_access_with_size_for_counted_by): Adapt. (build_conditional_expr): Adapt. (build_modify_expr): Adapt. (build_binary_op): Adapt. (build_omp_array_section): Adapt. (handle_omp_array_sections): Adapt. (c_finish_omp_clauses): Adapt. * c-parser.cc (c_parser_typeof_specifier): Adapt. (c_parser_generic_selection): Adapt. gcc/c-family/ChangeLog: * c-pretty-print.cc (c_pretty_printer::direct_abstract_declarator): Detect arrays of unspecified size. gcc/testsuite/ChangeLog: * gcc.dg/c23-tag-composite-11.c: New test. * gcc.dg/Warray-parameter-4.c: Resolve xfails. * gcc.dg/Wvla-parameter-2.c: Resolve xfails. * gcc.dg/Wvla-parameter-3.c: Resolve xfails. * gcc.dg/pr117145-1.c: New test. * gcc.dg/pr117145-2.c: New test. * gcc.dg/pr117245.c: New test.