Provided by: erlang-dialyzer_20.2.2+dfsg-1ubuntu2_amd64 bug


       dialyzer - Dialyzer, a DIscrepancy AnaLYZer for ERlang programs.


       Dialyzer  is  a  static  analysis  tool  that  identifies  software discrepancies, such as
       definite type errors, code that has become dead  or  unreachable  because  of  programming
       error, and unnecessary tests, in single Erlang modules or entire (sets of) applications.

       Dialyzer  starts  its  analysis  from  either  debug-compiled BEAM bytecode or from Erlang
       source code. The file and  line  number  of  a  discrepancy  is  reported  along  with  an
       indication of what the discrepancy is about. Dialyzer bases its analysis on the concept of
       success typings, which allows for sound warnings (no false positives).


       Dialyzer has a command-line version for automated  use.  This  section  provides  a  brief
       description  of the options. The same information can be obtained by writing the following
       in a shell:

       dialyzer --help

       For more details about the operation of Dialyzer, see section  Using Dialyzer from the GUI
       in the User's Guide.

       Exit status of the command-line version:

           No problems were found during the analysis and no warnings were emitted.

           Problems were found during the analysis.

           No problems were found during the analysis, but warnings were emitted.


       dialyzer [--add_to_plt] [--apps applications] [--build_plt]
                [--check_plt] [-Ddefine]* [-Dname] [--dump_callgraph file]
                [files_or_dirs] [--fullpath] [--get_warnings] [--gui] [--help]
                [-I include_dir]* [--no_check_plt] [--no_native]
                [--no_native_cache] [-o outfile] [--output_plt file] [-pa dir]*
                [--plt plt] [--plt_info] [--plts plt*] [--quiet] [-r dirs]
                [--raw] [--remove_from_plt] [--shell] [--src] [--statistics]
                [--verbose] [--version] [-Wwarn]*

       * denotes that multiple occurrences of the option are possible.


           The  PLT  is extended to also include the files specified with -c and -r. Use --plt to
           specify which PLT to start from, and --output_plt to specify where  to  put  the  PLT.
           Notice that the analysis possibly can include files from the PLT if they depend on the
           new files. This option only works for BEAM files.

         --apps applications:
           This option is typically used when building or modifying a PLT as in:

         dialyzer --build_plt --apps erts kernel stdlib mnesia ...

           to  refer  conveniently  to  library  applications  corresponding  to  the  Erlang/OTP
           installation.  However, this option is general and can also be used during analysis to
           refer to Erlang/OTP applications. File or directory names can also be included, as in:

         dialyzer --apps inets ssl ./ebin ../other_lib/ebin/my_module.beam

           The analysis starts from an empty PLT and creates a new one from the  files  specified
           with  -c  and  -r.  This option only works for BEAM files. To override the default PLT
           location, use --plt or --output_plt.

           Check the PLT for consistency and rebuild it if it is not up-to-date.

         -Dname (or -Dname=value):
           When analyzing from source, pass the define to Dialyzer. (**)

         --dump_callgraph file:
           Dump the call graph into the specified file whose format is determined by the filename
           extension.  Supported  extensions  are: raw, dot, and ps. If something else is used as
           filename extension, default format .raw is used.

         files_or_dirs (for backward compatibility also as -c files_or_dirs):
           Use Dialyzer from the command line  to  detect  defects  in  the  specified  files  or
           directories containing .erl or .beam files, depending on the type of the analysis.

           Display the full path names of files for which warnings are emitted.

           Make  Dialyzer emit warnings even when manipulating the PLT. Warnings are only emitted
           for files that are analyzed.

           Use the GUI.

         --help (or -h):
           Print this message and exit.

         -I include_dir:
           When analyzing from source, pass the include_dir to Dialyzer. (**)

           Skip the PLT check when running Dialyzer. This is useful when working  with  installed
           PLTs that never change.

         --no_native (or -nn):
           Bypass  the  native  code  compilation  of  some key files that Dialyzer heuristically
           performs when dialyzing many files. This avoids the compilation time, but  can  result
           in (much) longer analysis time.

           By   default,   Dialyzer  caches  the  results  of  native  compilation  in  directory
           $XDG_CACHE_HOME/erlang/dialyzer_hipe_cache. XDG_CACHE_HOME defaults  to  $HOME/.cache.
           Use this option to disable caching.

         -o outfile (or --output outfile):
           When  using Dialyzer from the command line, send the analysis results to the specified
           outfile rather than to stdout.

         --output_plt file:
           Store the PLT at the specified file after building it.

         -pa dir:
           Include dir in the path for Erlang. This is useful  when  analyzing  files  that  have
           -include_lib() directives.

         --plt plt:
           Use the specified PLT as the initial PLT. If the PLT was built during setup, the files
           are checked for consistency.

           Make Dialyzer print information about the PLT and then quit. The PLT can be  specified
           with --plt(s).

         --plts plt*:
           Merge  the  specified  PLTs to create the initial PLT. This requires that the PLTs are
           disjoint (that is, do not have any module appearing in more than one  PLT).  The  PLTs
           are created in the usual way:

         dialyzer --build_plt --output_plt plt_1 files_to_include
         dialyzer --build_plt --output_plt plt_n files_to_include

           They can then be used in either of the following ways:

         dialyzer files_to_analyze --plts plt_1 ... plt_n


         dialyzer --plts plt_1 ... plt_n -- files_to_analyze

           Notice the -- delimiter in the second case.

         --quiet (or -q):
           Make Dialyzer a bit more quiet.

         -r dirs:
           Same  as  files_or_dirs,  but  the  specified directories are searched recursively for
           subdirectories containing .erl or .beam files  in  them,  depending  on  the  type  of

           When  using  Dialyzer  from  the command line, output the raw analysis results (Erlang
           terms) instead of the formatted result. The raw format is easier to post-process  (for
           example, to filter warnings or to output HTML pages).

           The  information  from  the  files  specified  with -c and -r is removed from the PLT.
           Notice that this can cause a reanalysis of the remaining dependent files.

           Do not disable the Erlang shell while running the GUI.

           Override the default, which is to analyze BEAM files, and analyze starting from Erlang
           source code instead.

           Print  information  about  the  progress  of execution (analysis phases, time spent in
           each, and size of the relative input).

           Make Dialyzer a bit more verbose.

         --version (or -v):
           Print the Dialyzer version and some more information and exit.

           A family of options that selectively turn on/off warnings. (For help on the  names  of
           warnings,  use  dialyzer -Whelp.) Notice that the options can also be specified in the
           file with a -dialyzer() attribute. For details, see section Requesting or  Suppressing
           Warnings in Source Files.

       **  options  -D and -I work both from the command line and in the Dialyzer GUI; the syntax
       of defines and includes is the same as that used by erlc(1).

       Warning options:

         -Werror_handling (***):
           Include warnings for functions that only return by an exception.

           Suppress warnings about behavior callbacks that drift from the  published  recommended

           Suppress warnings about invalid contracts.

           Suppress warnings for failing calls.

           Suppress warnings for fun applications that will fail.

           Suppress warnings for construction of improper lists.

           Suppress warnings for patterns that are unused or cannot match.

           Suppress warnings about calls to missing functions.

           Suppress warnings for violations of opacity of data types.

           Suppress warnings for functions that will never return a value.

           Suppress  warnings  about  behaviors  that  have  no  -callback  attributes  for their

           Suppress warnings for unused functions.

         -Wrace_conditions (***):
           Include warnings for possible race conditions. Notice that  the  analysis  that  finds
           data  races  performs intra-procedural data flow analysis and can sometimes explode in
           time. Enable it at your own risk.

         -Wunderspecs (***):
           Warn about underspecified functions (the specification is strictly more allowing  than
           the success typing).

         -Wunknown (***):
           Let  warnings about unknown functions and types affect the exit status of the command-
           line version. The default is to ignore warnings about unknown functions and types when
           setting  the  exit  status.  When  using  Dialyzer from Erlang, warnings about unknown
           functions and types are returned; the default is not to return these warnings.

         -Wunmatched_returns (***):
           Include warnings for function calls that ignore a structured return value  or  do  not
           match against one of many possible return value(s).

       The  following  options  are  also  available,  but their use is not recommended (they are
       mostly for Dialyzer developers and internal debugging):

         -Woverspecs (***):
           Warn about overspecified functions (the specification is strictly less  allowing  than
           the success typing).

         -Wspecdiffs (***):
           Warn when the specification is different than the success typing.

       *** denotes options that turn on warnings rather than turning them off.


       Dialyzer  can be used directly from Erlang. Both the GUI and the command-line versions are
       also available. The options are similar to the ones  given  from  the  command  line,  see
       section  Using Dialyzer from the Command Line.


       Attribute  -dialyzer()  can  be  used  for  turning off warnings in a module by specifying
       functions or warning options. For example, to turn off all warnings for the function  f/0,
       include the following line:

       -dialyzer({nowarn_function, f/0}).

       To turn off warnings for improper lists, add the following line to the source file:


       Attribute  -dialyzer() is allowed after function declarations. Lists of warning options or
       functions are allowed:

       -dialyzer([{nowarn_function, [f/0]}, no_improper_lists]).

       Warning options can be restricted to functions:

       -dialyzer({no_improper_lists, g/0}).

       -dialyzer({[no_return, no_match], [g/0, h/0]}).

       For help on the warning options, use dialyzer -Whelp. The options are also enumerated, see
       function gui/1 below (WarnOpts).

       Warning option -Wrace_conditions has no effect when set in source files.

       Attribute  -dialyzer()  can also be used for turning on warnings. For example, if a module
       has been fixed regarding unmatched returns, adding the following line can help in assuring
       that no new unmatched return warnings are introduced:



       format_warning(Msg) -> string()


                 Msg = {Tag, Id, msg()}
                   See run/1.

              Get a string from warnings as returned by run/1.

       gui() -> ok | {error, Msg}
       gui(OptList) -> ok | {error, Msg}


                   See below.

              Dialyzer GUI version.

              OptList  :: [Option]
              Option   :: {files,          [Filename :: string()]}
                        | {files_rec,      [DirName :: string()]}
                        | {defines,        [{Macro :: atom(), Value :: term()}]}
                        | {from,           src_code | byte_code}
                                             %% Defaults to byte_code
                        | {init_plt,       FileName :: string()}
                                             %% If changed from default
                        | {plts,           [FileName :: string()]}
                                             %% If changed from default
                        | {include_dirs,   [DirName :: string()]}
                        | {output_file,    FileName :: string()}
                        | {output_plt,     FileName :: string()}
                        | {check_plt,      boolean()},
                        | {analysis_type,  'succ_typings' |
                                           'plt_add' |
                                           'plt_build' |
                                           'plt_check' |
                        | {warnings,       [WarnOpts]}
                        | {get_warnings,   bool()}

              WarnOpts :: error_handling
                        | no_behaviours
                        | no_contracts
                        | no_fail_call
                        | no_fun_app
                        | no_improper_lists
                        | no_match
                     | no_missing_calls
                        | no_opaque
                     | no_return
                        | no_undefined_callbacks
                        | no_unused
                        | race_conditions
                        | underspecs
                        | unknown
                        | unmatched_returns
                        | overspecs
                        | specdiffs

       plt_info(string()) -> {'ok', [{atom(), any()}]} | {'error', atom()}

              Returns information about the specified PLT.

       run(OptList) -> Warnings


                   See gui/0,1.
                   See below.

              Dialyzer command-line version.

              Warnings :: [{Tag, Id, Msg}]
              Tag      :: 'warn_behaviour'
                        | 'warn_bin_construction'
                        | 'warn_callgraph'
                        | 'warn_contract_not_equal'
                        | 'warn_contract_range'
                        | 'warn_contract_subtype'
                        | 'warn_contract_supertype'
                        | 'warn_contract_syntax'
                        | 'warn_contract_types'
                        | 'warn_failing_call'
                        | 'warn_fun_app'
                        | 'warn_matching'
                        | 'warn_non_proper_list'
                        | 'warn_not_called'
                        | 'warn_opaque'
                        | 'warn_race_condition'
                        | 'warn_return_no_exit'
                        | 'warn_return_only_exit'
                        | 'warn_umatched_return'
                        | 'warn_undefined_callbacks'
                        | 'warn_unknown'
              Id  = {File :: string(), Line :: integer()}
              Msg = msg() -- Undefined