You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: diag_data.rs
    path of file: ./repos/Project-47/pr47-core/src/diag
    
    the code of the file until where you have to start completion: #![allow(non_upper_case_globals)]

// notes
pub const note_commence_placeholder: u32 = 1000;

// errors
pub const err_commence_placeholder: u32 = 2000;
pub const err_unexpected_control_char_0: u32 = 2001;
    
pub const fn diag_message(code: u32) -> &'static str {
    if code > warn_commence_placeholder {
        match code {
            warn_space_character_0_ignored => "unicode space character '?0' ignored",
            warn_underscored_id_reserved =>
                "identifiers starting with underscore (`_`) are considered reserved",
            _ => "INVALID_ERROR_CODE"
        }
    } else if code > err_commence_placeholder {
        match code {
            err_unexpected_control_char_0 => "unexpected control character '?0'",
            err_unclosed_string_literal => "unclosed string literal",
            err_reserved_identifier_0 => "unexpected use of reserved identifier `?0`",
            err_reserved_symbol_0 => "unexpected use of reserved symbol `?0`",
            err_expected_token_0_got_1 => "expected ?0, got ?1",
            err_unexpected_eoi => "unexpected end of input",
            err_import_decl_disallow_attr => "cannot add attribute to `import`s",
            err_export_decl_disallow_attr => "cannot add attribute to `export`s",
            err_expected_any_of_0_got_1 => "expected any of ?0, got ?1",
            err_no_top_level_var_decl => "variable declaration cannot appear at top level",
            err_expected_unqual_id => "expected unqualified identifier",
            err_missing_type_got_0 => "missing type specifier, got ?0",
            err_bad_num_literal_hex_oct_bin =>
                "expected '0x', '0o' or '0b' for hex, oct or bin literals",
            err_empty_literal => "empty literal",
            err_empty_float_exponent => "empty float exponent",
            err_bad_escape => "bad escape sequence \\?0",
            err_unclosed_string => "unclosed string literal",
            err_duplicate_syntax_action_name_0 => "duplicate syntax action name `?0`",
            err_undefined_identifier_0 => "undefined identifier `?0`",
            _ => "INVALID_ERROR_CODE"
        }
    } else /* if code > note_commence_placeholder */ {
        match code {
            _ => "INVALID_ERROR_CODE"
        }
    }
}