anchor.diff:  %% @spec file(File, Opts) -> CompRet
   %%            File = string()
   %%            Opts = [Opt]
  -%%            Opt  = {i,directory()} |
  -%%                   {type_specs, boolean()} | type_specs |
  +%%            Opt  = {type_specs, boolean()} | type_specs |
   %%                   {verify, optionally | always | never} |
  -%%                   {o,directory()} |
  +%%                   {copy_bytes, true | false | auto | integer() | float()} |
  +%%                   {i, directory()} |
  +%%                   {o, directory()} |
   %%                   binary |
  -%%                   {copy_bytes, true | false | auto | integer() | float()}
  +%%                   return | return_warnings | return_errors |
  +%%                   report | report_warnings | report_errors
   %%            CompRet = ModRet | BinRet | ErrRet
   %%            ModRet = ok | {ok, Warnings}
   %%            BinRet = {ok, ModuleName, Code} |
  
positive.code: %%   <dt>`true'</dt><dd>Always copy bytes/(sub-)binaries.</dd>
  %%   <dt>`auto'</dt><dd>Copy bytes/(sub-)binaries if the beam vm,
  %%           on which the compiler (this module) is running,
  %%           has the `binary:copy/1' function.</dd>
  %%   <dt>integer() | float()</dt><dd>Copy the bytes/(sub-)binaries if the
  %%           message this many times or more larger than the size of the
  %%           bytes/(sub-)binary.</dd>
  %% </dl>
  %%
  %% <dl>
  %%   <dt>`report_errors'/`report_warnings'</dt>
  
negative.code: %% `{gpb_type_error,Reason}'. Regardless of the `verify' option,
  %% a function, `verify_msg/1' is always generated.
  %%
  %% The `copy_bytes' option specifies whether when decoding data of
  %% type `bytes', the decoded bytes should be copied or not. Copying
  %% requires the `binary' module, which first appeared in Erlang
  