dialyzer(3erl) Erlang Module Definition dialyzer(3erl)
NAME
dialyzer - Dialyzer, a DIscrepancy AnaLYZer for ERlang programs.
DESCRIPTION
Dialyzer is a static analysis tool that identifies software discrepan-
cies, such as definite type errors, code that has become dead or un-
reachable because of programming error, and unnecessary tests, in sin-
gle 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).
USING DIALYZER FROM THE COMMAND LINE
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:
0:
No problems were found during the analysis and no warnings were
emitted.
1:
Problems were found during the analysis.
2:
No problems were found during the analysis, but warnings were emit-
ted.
Usage:
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_indentation] [--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]*
Note:
* denotes that multiple occurrences of the option are possible.
Options:
--add_to_plt:
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
--build_plt:
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 --out-
put_plt.
--check_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 deter-
mined by the filename extension. Supported extensions are: raw,
dot, and ps. If something else is used as filename extension, de-
fault 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 speci-
fied files or directories containing .erl or .beam files, depending
on the type of the analysis.
--fullpath:
Display the full path names of files for which warnings are emit-
ted.
--get_warnings:
Make Dialyzer emit warnings even when manipulating the PLT. Warn-
ings are only emitted for files that are analyzed.
--gui:
Use the GUI.
--help (or -h):
Print this message and exit.
-I include_dir:
When analyzing from source, pass the include_dir to Dialyzer. (**)
--no_check_plt:
Skip the PLT check when running Dialyzer. This is useful when work-
ing with installed PLTs that never change.
--no_indentation:
Do not insert line breaks in types, contracts, and Erlang Code when
formatting warnings.
--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.
--no_native_cache:
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 re-
sults 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 dur-
ing setup, the files are checked for consistency.
--plt_info:
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 appear-
ing 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
or
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 analysis.
--raw:
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).
--remove_from_plt:
The information from the files specified with -c and -r is removed
from the PLT. Notice that this can cause a reanalysis of the re-
maining dependent files.
--shell:
Do not disable the Erlang shell while running the GUI.
--src:
Override the default, which is to analyze BEAM files, and analyze
starting from Erlang source code instead.
--statistics:
Print information about the progress of execution (analysis phases,
time spent in each, and size of the relative input).
--verbose:
Make Dialyzer a bit more verbose.
--version (or -v):
Print the Dialyzer version and some more information and exit.
-Wwarn:
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 Warn-
ings in Source Files.
Note:
** options -D and -I work both from the command line and in the Dia-
lyzer 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.
-Wno_behaviours:
Suppress warnings about behavior callbacks that drift from the pub-
lished recommended interfaces.
-Wno_contracts:
Suppress warnings about invalid contracts.
-Wno_fail_call:
Suppress warnings for failing calls.
-Wno_fun_app:
Suppress warnings for fun applications that will fail.
-Wno_improper_lists:
Suppress warnings for construction of improper lists.
-Wno_match:
Suppress warnings for patterns that are unused or cannot match.
-Wno_missing_calls:
Suppress warnings about calls to missing functions.
-Wno_opaque:
Suppress warnings for violations of opacity of data types.
-Wno_return:
Suppress warnings for functions that will never return a value.
-Wno_undefined_callbacks:
Suppress warnings about behaviors that have no -callback attributes
for their callbacks.
-Wno_unused:
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 sta-
tus 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 warn-
ings.
-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 recom-
mended (they are mostly for Dialyzer developers and internal debug-
ging):
-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.
Note:
*** denotes options that turn on warnings rather than turning them off.
USING DIALYZER FROM ERLANG
Dialyzer can be used directly from Erlang. Both the GUI and the com-
mand-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.
REQUESTING OR SUPPRESSING WARNINGS IN SOURCE FILES
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:
-dialyzer(no_improper_lists).
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).
Note:
Warning option -Wrace_conditions has no effect when set in source
files.
Attribute -dialyzer() can also be used for turning on warnings. For ex-
ample, 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:
-dialyzer(unmatched_returns).
EXPORTS
format_warning(Msg) -> string()
Types:
Msg = {Tag, Id, msg()}
See run/1.
Get a string from warnings as returned by run/1.
format_warning(Msg, Options) -> string()
Types:
Msg = {Tag, Id, msg()}
See run/1.
Options = [{indent_opt, boolean()}]
Get a string from warnings as returned by run/1.
If indent_opt is set to true (default), line breaks are inserted
in types, contracts, and Erlang code to improve readability.
gui() -> ok | {error, Msg}
gui(OptList) -> ok | {error, Msg}
Types:
OptList
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' |
'plt_remove'}
| {warnings, [WarnOpts]}
| {get_warnings, boolean()}
| {native, boolean()}
%% Defaults to false when invoked from Erlang
| {native_cache, boolean()}
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
Types:
OptList
See gui/0,1.
Warnings
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
Ericsson AB dialyzer 4.2 dialyzer(3erl)