luacheck - Online in the Cloud

PROGRAM:

NAME

luacheck - luacheck Documentation

Contents:

LIST OF WARNINGS

Warnings produced by Luacheck are categorized using three-digit warning codes. Warning
codes can be displayed in CLI output using --codes CLI option or codes config option.
Errors also have codes starting with zero.

┌─────┬──────────────────────────────────┐
│Code │ Description │
├─────┼──────────────────────────────────┤
│011 │ A syntax error. │
├─────┼──────────────────────────────────┤
│021 │ An invalid inline option. │
├─────┼──────────────────────────────────┤
│022 │ An upaired inline push │
│ │ directive. │
├─────┼──────────────────────────────────┤
│023 │ An upaired inline pop directive. │
├─────┼──────────────────────────────────┤
│111 │ Setting an undefined global │
│ │ variable. │
├─────┼──────────────────────────────────┤
│112 │ Mutating an undefined global │
│ │ variable. │
├─────┼──────────────────────────────────┤
│113 │ Accessing an undefined global │
│ │ variable. │
├─────┼──────────────────────────────────┤
│121 │ Setting a read-only global │
│ │ variable. │
├─────┼──────────────────────────────────┤
│122 │ Mutating a read-only global │
│ │ variable. │
├─────┼──────────────────────────────────┤
│131 │ Unused implicitly defined global │
│ │ variable. │
├─────┼──────────────────────────────────┤
│211 │ Unused local variable. │
├─────┼──────────────────────────────────┤
│212 │ Unused argument. │
├─────┼──────────────────────────────────┤
│213 │ Unused loop variable. │
├─────┼──────────────────────────────────┤
│221 │ Local variable is accessed but │
│ │ never set. │
├─────┼──────────────────────────────────┤
│231 │ Local variable is set but never │
│ │ accessed. │
├─────┼──────────────────────────────────┤
│232 │ An argument is set but never │
│ │ accessed. │
├─────┼──────────────────────────────────┤
│233 │ Loop variable is set but never │
│ │ accessed. │
├─────┼──────────────────────────────────┤
│311 │ Value assigned to a local │
│ │ variable is unused. │
└─────┴──────────────────────────────────┘

│312 │ Value of an argument is unused. │
├─────┼──────────────────────────────────┤
│313 │ Value of a loop variable is │
│ │ unused. │
├─────┼──────────────────────────────────┤
│321 │ Accessing uninitialized local │
│ │ variable. │
├─────┼──────────────────────────────────┤
│411 │ Redefining a local variable. │
├─────┼──────────────────────────────────┤
│412 │ Redefining an argument. │
├─────┼──────────────────────────────────┤
│413 │ Redefining a loop variable. │
├─────┼──────────────────────────────────┤
│421 │ Shadowing a local variable. │
├─────┼──────────────────────────────────┤
│422 │ Shadowing an argument. │
├─────┼──────────────────────────────────┤
│423 │ Shadowing a loop variable. │
├─────┼──────────────────────────────────┤
│431 │ Shadowing an upvalue. │
├─────┼──────────────────────────────────┤
│432 │ Shadowing an upvalue argument. │
├─────┼──────────────────────────────────┤
│433 │ Shadowing an upvalue loop │
│ │ variable. │
├─────┼──────────────────────────────────┤
│511 │ Unreachable code. │
├─────┼──────────────────────────────────┤
│512 │ Loop can be executed at most │
│ │ once. │
├─────┼──────────────────────────────────┤
│521 │ Unused label. │
├─────┼──────────────────────────────────┤
│531 │ Left-hand side of an assignment │
│ │ is too short. │
├─────┼──────────────────────────────────┤
│532 │ Left-hand side of an assignment │
│ │ is too long. │
├─────┼──────────────────────────────────┤
│541 │ An empty do end block. │
├─────┼──────────────────────────────────┤
│542 │ An empty if branch. │
├─────┼──────────────────────────────────┤
│551 │ An empty statement. │
└─────┴──────────────────────────────────┘

Global variables
For each file, Luacheck builds list of defined globals which can be used there. By default
only globals from Lua standard library are defined; custom globals can be added using
--globals CLI option or globals config option, and version of standard library can be
selected using --std CLI option or std config option. When an undefined global is set,
mutated or accessed, Luacheck produces a warning.

Read-only globals
By default, all standard globals except _G and package are marked as read-only, so that
setting or mutating them produces a warning. Custom read-only globals can be added using
--read-globals CLI option or read_globals config option.

Implicitly defined globals
Luacheck can be configured to consider globals assigned under some conditions to be
defined implicitly. When -d/--allow_defined CLI option or allow_defined config option is
used, all assignments to globals define them; when -t/--allow_defined_top CLI option or
allow_defined_top config option is used, assignments to globals in the top level function
scope (also known as main chunk) define them. A warning is produced when an implicitly
defined global is not accessed anywhere.

Modules
Files can be marked as modules using -m/--module CLI option or module config option to
simulate semantics of the deprecated module function. Globals implicitly defined inside a
module are considired part of its interface, are not visible outside and are not reported
as unused. Assignments to other globals are not allowed, even to defined ones.

Unused variables and values
Luacheck generates warnings for all unused local variables except one named _. It also
detects variables which are set but never accessed or accessed but never set.

Unused values and uninitialized variables
For each value assigned to a local variable, Luacheck computes set of expressions where it
could be used. Warnings are produced for unused values (when a value can't be used
anywhere) and for accessing uninitialized variables (when no values can reach an
expression). E.g. in the following snippet value assigned to foo on line 1 is unused, and
variable bar is uninitialized on line 9:

local foo = expr1()
local bar

if condition() then
foo = expr2()
bar = expr3()
else
foo = expr4()
print(bar)
end

return foo, bar

Secondary values and variables
Unused value assigned to a local variable is secondary if its origin is the last item on
the RHS of assignment, and another value from that item is used. Secondary values
typically appear when result of a function call is put into locals, and only some of them
are later used. For example, here value assigned to b is secondary, value assigned to c is
used, and value assigned to a is simply unused:

local a, b, c = f(), g()

return c

A variable is secondary if all values assigned to it are secondary. In the snippet above,
b is a secondary variable.

Warnings related to unused secondary values and variables can be removed using
-s/--no-unused-secondaries CLI option or unused_secondaries config option.

Shadowing declarations
Luacheck detects declarations of local variables shadowing previous declarations, unless
the variable is named _. If the previous declaration is in the same scope as the new one,
it is called redefining.

Note that it is not necessary to define a new local variable when overwriting an argument:

local function f(x)
local x = x or "default" -- bad
end

local function f(x)
x = x or "default" -- good
end

Control flow and data flow issues
The following control flow and data flow issues are detected:

· Unreachable code and loops that can be executed at most once (e.g. due to an
unconditional break);

· Unused labels;

· Unbalanced assignments;

· Empty blocks.

· Empty statements (semicolons without preceding statements).

COMMAND LINE INTERFACE

luacheck program accepts files, directories and rockspecs as arguments.

· Given a file, luacheck will check it.

· Given -, luacheck will check stdin.

· Given a directory, luacheck will check all files within it, selecting only files with
.lua extension unless --include-files option is used. This feature requires
LuaFileSystem (installed automatically if LuaRocks was used to install Luacheck).

· Given a rockspec (a file with .rockspec extension), luacheck will check all files with
.lua extension mentioned in the rockspec in build.install.lua, build.install.bin and
build.modules tables.

The output of luacheck consists of separate reports for each checked file and ends with a
summary:

$ luacheck src
Checking src/bad_code.lua 5 warnings

src/bad_code.lua:3:16: unused variable helper
src/bad_code.lua:3:23: unused variable length argument
src/bad_code.lua:7:10: setting non-standard global variable embrace
src/bad_code.lua:8:10: variable opt was previously defined as an argument on line 7
src/bad_code.lua:9:11: accessing undefined variable hepler

Checking src/good_code.lua OK
Checking src/python_code.lua 1 error

src/python_code.lua:1:6: expected '=' near '__future__'

Checking src/unused_code.lua 9 warnings

src/unused_code.lua:3:18: unused argument baz
src/unused_code.lua:4:8: unused loop variable i
src/unused_code.lua:5:13: unused variable q
src/unused_code.lua:7:11: unused loop variable a
src/unused_code.lua:7:14: unused loop variable b
src/unused_code.lua:7:17: unused loop variable c
src/unused_code.lua:13:7: value assigned to variable x is unused
src/unused_code.lua:14:1: value assigned to variable x is unused
src/unused_code.lua:22:1: value assigned to variable z is unused

Total: 14 warnings / 1 error in 4 files

luacheck exits with 0 if no warnings or errors occured and with a positive number
otherwise.

Command line options
Short options that do not take an argument can be combined into one, so that -qqu is
equivalent to -q -q -u. For long options, both --option value or --option=value can be
used.

Options taking several arguments can be used several times; --ignore foo --ignore bar is
equivalent to --ignore foo bar.

Note that options that may take several arguments, such as --globals, should not be used
immediately before positional arguments; given --globals foo bar file.lua, luacheck will
consider all foo, bar and file.lua global and then panic as there are no file names left.

┌─────────────────────────────────┬──────────────────────────────────┐
│Option │ Meaning │
├─────────────────────────────────┼──────────────────────────────────┤
│-g | --no-global │ Filter out warnings related to │
│ │ global variables. │
├─────────────────────────────────┼──────────────────────────────────┤
│-u | --no-unused │ Filter out warnings related to │
│ │ unused variables and values. │
├─────────────────────────────────┼──────────────────────────────────┤
│-r | --no-redefined │ Filter out warnings related to │
│ │ redefined variables. │
├─────────────────────────────────┼──────────────────────────────────┤
│-a | --no-unused-args │ Filter out warnings related to │
│ │ unused arguments and loop │
│ │ variables. │
├─────────────────────────────────┼──────────────────────────────────┤
│-s | --no-unused-secondaries │ Filter out warnings related to │
│ │ unused variables set together │
│ │ with used ones. │
│ │ │
│ │ See secondaryvaluesandvariables │
├─────────────────────────────────┼──────────────────────────────────┤
│--no-self │ Filter out warnings related to │
│ │ implicit self argument. │
└─────────────────────────────────┴──────────────────────────────────┘

│--std <std> │ Set standard globals. <std> can │
│ │ be one of: │
│ │ │
│ │ · _G - globals of the Lua │
│ │ interpreter luacheck │
│ │ runs on (default); │
│ │ │
│ │ · lua51 - globals of Lua │
│ │ 5.1; │
│ │ │
│ │ · lua52 - globals of Lua │
│ │ 5.2; │
│ │ │
│ │ · lua52c - globals of Lua │
│ │ 5.2 compiled with │
│ │ LUA_COMPAT_ALL; │
│ │ │
│ │ · lua53 - globals of Lua │
│ │ 5.3; │
│ │ │
│ │ · lua53c - globals of Lua │
│ │ 5.3 compiled with │
│ │ LUA_COMPAT_5_2; │
│ │ │
│ │ · luajit - globals of │
│ │ LuaJIT 2.0; │
│ │ │
│ │ · ngx_lua - globals of │
│ │ Openresty │
│ │ lua-nginx-module with │
│ │ LuaJIT 2.0; │
│ │ │
│ │ · min - intersection of │
│ │ globals of Lua 5.1, Lua │
│ │ 5.2 and LuaJIT 2.0; │
│ │ │
│ │ · max - union of globals │
│ │ of Lua 5.1, Lua 5.2 and │
│ │ LuaJIT 2.0; │
│ │ │
│ │ · busted - globals added │
│ │ by Busted 2.0; │
│ │ │
│ │ · none - no standard │
│ │ globals. │
│ │ │
│ │ See Sets of standard │
│ │ globals │
├─────────────────────────────────┼──────────────────────────────────┤
│--globals [<global>] ... │ Add custom globals on top of │
│ │ standard ones. │
├─────────────────────────────────┼──────────────────────────────────┤
│--read-globals [<global>] ... │ Add read-only globals. │
├─────────────────────────────────┼──────────────────────────────────┤
│--new-globals [<global>] ... │ Set custom globals. Removes │
│ │ custom globals added previously. │
├─────────────────────────────────┼──────────────────────────────────┤
│--new-read-globals [<global>] │ Set read-only globals. Removes │
│... │ read-only globals added │
│ │ previously. │
├─────────────────────────────────┼──────────────────────────────────┤
│-c | --compat │ Equivalent to --std max. │
└─────────────────────────────────┴──────────────────────────────────┘

│-d | --allow-defined │ Allow defining globals │
│ │ implicitly by setting them. │
│ │ │
│ │ See implicitlydefinedglobals │
├─────────────────────────────────┼──────────────────────────────────┤
│-t | --allow-defined-top │ Allow defining globals │
│ │ implicitly by setting them in │
│ │ the top level scope. │
│ │ │
│ │ See implicitlydefinedglobals │
├─────────────────────────────────┼──────────────────────────────────┤
│-m | --module │ Limit visibility of implicitly │
│ │ defined globals to their files. │
│ │ │
│ │ See modules │
├─────────────────────────────────┼──────────────────────────────────┤
│--ignore | -i <patt> [<patt>] │ Filter out warnings matching │
│... │ patterns. │
├─────────────────────────────────┼──────────────────────────────────┤
│--enable | -e <patt> [<patt>] │ Do not filter out warnings │
│... │ matching patterns. │
├─────────────────────────────────┼──────────────────────────────────┤
│--only | -o <patt> [<patt>] ... │ Filter out warnings not matching │
│ │ patterns. │
├─────────────────────────────────┼──────────────────────────────────┤
│--no-inline │ Disable inline options. │
├─────────────────────────────────┼──────────────────────────────────┤
│--config <config> │ Path to custom configuration │
│ │ file (default: .luacheckrc). │
├─────────────────────────────────┼──────────────────────────────────┤
│--no-config │ Do not look up custom │
│ │ configuration file. │
├─────────────────────────────────┼──────────────────────────────────┤
│--filename <filename> │ Use another filename in output, │
│ │ for selecting configuration │
│ │ overrides and for file │
│ │ filtering. │
├─────────────────────────────────┼──────────────────────────────────┤
│--exclude-files <glob> [<glob>] │ Do not check files matching │
│... │ these globbing patterns. │
│ │ Recursive globs such as **/*.lua │
│ │ are supported. │
├─────────────────────────────────┼──────────────────────────────────┤
│--include-files <glob> [<glob>] │ Do not check files not matching │
│... │ these globbing patterns. │
├─────────────────────────────────┼──────────────────────────────────┤
│--cache [<cache>] │ Path to cache file. (default: │
│ │ .luacheckcache). See Caching │
├─────────────────────────────────┼──────────────────────────────────┤
│--no-cache │ Do not use cache. │
├─────────────────────────────────┼──────────────────────────────────┤
│-j | --jobs │ Check <jobs> files in parallel. │
│ │ Requires LuaLanes. │
└─────────────────────────────────┴──────────────────────────────────┘

│--formatter <formatter> │ Use custom formatter. │
│ │ <formatter> must be a module │
│ │ name or one of: │
│ │ │
│ │ · TAP - Test Anything │
│ │ Protocol formatter; │
│ │ │
│ │ · JUnit - JUnit XML │
│ │ formatter; │
│ │ │
│ │ · plain - simple │
│ │ warning-per-line │
│ │ formatter; │
│ │ │
│ │ · default - standard │
│ │ formatter. │
├─────────────────────────────────┼──────────────────────────────────┤
│-q | --quiet │ Suppress report output for files │
│ │ without warnings. │
│ │ │
│ │ · -qq - Suppress output │
│ │ of warnings. │
│ │ │
│ │ · -qqq - Only output │
│ │ summary. │
├─────────────────────────────────┼──────────────────────────────────┤
│--codes │ Show warning codes. │
├─────────────────────────────────┼──────────────────────────────────┤
│--ranges │ Show ranges of columns related │
│ │ to warnings. │
├─────────────────────────────────┼──────────────────────────────────┤
│--no-color │ Do not colorize output. │
├─────────────────────────────────┼──────────────────────────────────┤
│-v | --version │ Show version of Luacheck and its │
│ │ dependencies and exit. │
├─────────────────────────────────┼──────────────────────────────────┤
│-h | --help │ Show help and exit. │
└─────────────────────────────────┴──────────────────────────────────┘

Patterns
CLI options --ignore, --enable and --only and corresponding config options allow filtering
warnings using pattern matching on warning codes, variable names or both. If a pattern
contains a slash, the part before slash matches warning code and the part after matches
variable name. Otherwise, if a pattern contains a letter or underscore, it matches
variable name. Otherwise, it matches warning code. E.g.:

┌────────┬──────────────────────────────────┐
│Pattern │ Matching warnings │
├────────┼──────────────────────────────────┤
│4.2 │ Shadowing declarations of │
│ │ arguments or redefining them. │
├────────┼──────────────────────────────────┤
│.*_ │ Warnings related to variables │
│ │ with _ suffix. │
├────────┼──────────────────────────────────┤
│4.2/.*_ │ Shadowing declarations of │
│ │ arguments with _ suffix or │
│ │ redefining them. │
└────────┴──────────────────────────────────┘

Unless already anchored, patterns matching variable names are anchored at both sides and
patterns matching warning codes are anchored at their beginnings. This allows one to
filter warnings by category (e.g. --only 1 focuses luacheck on global-related warnings).

Sets of standard globals
CLI option --stds allows combining built-in sets described above using +. For example,
--std max is equivalent to --std=lua51+lua52+lua53. Leading plus sign adds new sets to
default one instead of replacing it. For instance, --std +busted is suitable for checking
test files that use Busted testing framework. Custom sets of globals can be defined by
mutating global variable stds in config. See custom_stds

Formatters
CLI option --formatter allows selecting a custom formatter for luacheck output. A custom
formatter is a Lua module returning a function with three arguments: report as returned by
luacheck module (see report), array of file names and table of options. Options contain
values assigned to quiet, color, limit, codes, ranges and formatter options in CLI or
config. Formatter function must return a string.

Caching
If LuaFileSystem is available, Luacheck can cache results of checking files. On subsequent
checks, only files which have changed since the last check will be rechecked, improving
run time significantly. Changing options (e.g. defining additional globals) does not
invalidate cache. Caching can be enabled by using --cache <cache> option or cache config
option. Using --cache without an argument or setting cache config option to true sets
.luacheckcache as the cache file. Note that --cache must be used every time luacheck is
run, not on the first run only.

Stable interface for editor plugins and tools
Command-line interface of Luacheck can change between minor releases. Starting from 0.11.0
version, the following interface is guaranteed at least till 1.0.0 version, and should be
used by tools using Luacheck output, e.g. editor plugins.

· Luacheck should be started from the directory containing the checked file.

· File can be passed through stdin using - as argument or using a temporary file. Real
filename should be passed using --filename option.

· Plain formatter should be used. It outputs one issue (warning or error) per line.

· To get precise error location, --ranges option can be used. Each line starts with real
filename (passed using --filename), followed by :<line>:<start_column>-<end_column>:,
where <line> is line number on which issue occurred and <start_column>-<end_column> is
inclusive range of columns of token related to issue. Numbering starts from 1. If
--ranges is not used, end column and dash is not printed.

· To get warning and error codes, --codes option can be used. For each line, substring
between parentheses contains three digit issue code, prefixed with E for errors and W
for warnings. Lack of such substring indicates a fatal error (e.g. I/O error).

· The rest of the line is warning message.

If compatibility with older Luacheck version is desired, output of luacheck --help can be
used to get its version. If it contains string 0.<minor>.<patch>, where <minor> is at
least 11 and patch is any number, interface described above should be used.

CONFIGURATION FILE

luacheck tries to load configuration from .luacheckrc file in the current directory. If
not found, it will look for it in the parent directory and so on, going up until it
reaches file system root. Path to config can be set using --config option, in which case
it will be used during recursive loading. Config loading can be disabled using --no-config
flag.

Config is simply a Lua script executed by luacheck. It may set various options by
assigning to globals or by returning a table with option names as keys.

Config options
┌───────────────────┬──────────────────────────┬─────────────────────┐
│Option │ Type │ Default value │
├───────────────────┼──────────────────────────┼─────────────────────┤
│color │ Boolean │ true │
├───────────────────┼──────────────────────────┼─────────────────────┤
│codes │ Boolean │ false │
└───────────────────┴──────────────────────────┴─────────────────────┘

│formatter │ String or function │ "default" │
├───────────────────┼──────────────────────────┼─────────────────────┤
│cache │ Boolean or string │ false │
├───────────────────┼──────────────────────────┼─────────────────────┤
│jobs │ Positive integer │ 1 │
├───────────────────┼──────────────────────────┼─────────────────────┤
│exclude_files │ Array of strings │ {} │
├───────────────────┼──────────────────────────┼─────────────────────┤
│include_files │ Array of strings │ (Include all files) │
├───────────────────┼──────────────────────────┼─────────────────────┤
│global │ Boolean │ true │
├───────────────────┼──────────────────────────┼─────────────────────┤
│unused │ Boolean │ true │
├───────────────────┼──────────────────────────┼─────────────────────┤
│redefined │ Boolean │ true │
├───────────────────┼──────────────────────────┼─────────────────────┤
│unused_args │ Boolean │ true │
├───────────────────┼──────────────────────────┼─────────────────────┤
│unused_secondaries │ Boolean │ true │
├───────────────────┼──────────────────────────┼─────────────────────┤
│self │ Boolean │ true │
├───────────────────┼──────────────────────────┼─────────────────────┤
│std │ String or set of │ "_G" │
│ │ standard globals │ │
├───────────────────┼──────────────────────────┼─────────────────────┤
│globals │ Array of strings │ {} │
├───────────────────┼──────────────────────────┼─────────────────────┤
│new_globals │ Array of strings │ (Do not overwrite) │
├───────────────────┼──────────────────────────┼─────────────────────┤
│read_globals │ Array of strings │ {} │
├───────────────────┼──────────────────────────┼─────────────────────┤
│new_read_globals │ Array of strings │ (Do not overwrite) │
├───────────────────┼──────────────────────────┼─────────────────────┤
│compat │ Boolean │ false │
├───────────────────┼──────────────────────────┼─────────────────────┤
│allow_defined │ Boolean │ false │
├───────────────────┼──────────────────────────┼─────────────────────┤
│allow_defined_top │ Boolean │ false │
├───────────────────┼──────────────────────────┼─────────────────────┤
│module │ Boolean │ false │
├───────────────────┼──────────────────────────┼─────────────────────┤
│ignore │ Array of patterns (see │ {} │
│ │ patterns) │ │
├───────────────────┼──────────────────────────┼─────────────────────┤
│enable │ Array of patterns │ {} │
├───────────────────┼──────────────────────────┼─────────────────────┤
│only │ Array of patterns │ (Do not filter) │
├───────────────────┼──────────────────────────┼─────────────────────┤
│inline │ Boolean │ true │
└───────────────────┴──────────────────────────┴─────────────────────┘

An example of a config which makes luacheck ensure that only globals from the portable
intersection of Lua 5.1, Lua 5.2, Lua 5.3 and LuaJIT 2.0 are used, as well as disables
detection of unused arguments:

std = "min"
ignore = {"212"}

Custom sets of globals
std option allows setting a custom standard set of globals using a table. In that table,
string keys are globals, and string in array part are read-only globals.

Additionally, custom sets can be given names by mutating global stds variable. For
example, when using LPEG library, it makes sense to access its functions tersely using
globals. In that case, the following config allows removing false positives related to
global access easily:

stds.lpeg = require "lpeg"

local lpeg = require "lpeg"

local function parse1(...)
-- This function only uses lpeg functions as globals.
local _ENV = lpeg
-- luacheck: std lpeg
local digit, space = R "09", S " "
-- ...
end

local function parse2(...)
-- This function uses lpeg functions as well as standard globals.
local _ENV = setmetatable({}, {__index = function(_, k) return _ENV[k] or lpeg[k] end})
-- luacheck: std +lpeg
local digit, space = R "09", S " "
local number = C(digit^1) / tonumber
-- ...
end

Per-file and per-path overrides
The environment in which luacheck loads the config contains a special global files. When
checking a file <path>, luacheck will override options from the main config with entries
from files[<path>] and files[<parent_path>], applying entries for shorter paths first. For
example, the following config re-enables detection of unused arguments only for files in
src/dir, but not for src/dir/myfile.lua, and allows using Busted globals within spec/:

std = "min"
ignore = {"212"}
files["src/dir"] = {enable = {"212"}}
files["src/dir/myfile.lua"] = {ignore = {"212"}}
files["spec"] = {std = "+busted"}

Note that files table supports autovivification, so that

files["myfile.lua"].ignore = {"212"}

and

files["myfile.lua"] = {ignore = {"212"}}

are equivalent.

INLINE OPTIONS

Luacheck supports setting some options directly in the checked files using inline
configuration comments. An inline configuration comment starts with luacheck: label,
possibly after some whitespace. The body of the comment should contain comma separated
options, where option invocation consists of its name plus space separated arguments. The
following options are supported:

┌───────────────────┬──────────────────────────────────┐
│Option │ Number of arguments │
├───────────────────┼──────────────────────────────────┤
│global │ 0 │
├───────────────────┼──────────────────────────────────┤
│unused │ 0 │
├───────────────────┼──────────────────────────────────┤
│redefined │ 0 │
├───────────────────┼──────────────────────────────────┤
│unused args │ 0 │
├───────────────────┼──────────────────────────────────┤
│unused secondaries │ 0 │
├───────────────────┼──────────────────────────────────┤
│self │ 0 │
└───────────────────┴──────────────────────────────────┘

│compat │ 0 │
├───────────────────┼──────────────────────────────────┤
│module │ 0 │
├───────────────────┼──────────────────────────────────┤
│allow defined │ 0 │
├───────────────────┼──────────────────────────────────┤
│allow defined top │ 0 │
├───────────────────┼──────────────────────────────────┤
│std │ 1 │
├───────────────────┼──────────────────────────────────┤
│globals │ 0+ │
├───────────────────┼──────────────────────────────────┤
│new globals │ 0+ │
├───────────────────┼──────────────────────────────────┤
│read globals │ 0+ │
├───────────────────┼──────────────────────────────────┤
│new read globals │ 0+ │
├───────────────────┼──────────────────────────────────┤
│ignore │ 0+ (without arguments everything │
│ │ is ignored) │
├───────────────────┼──────────────────────────────────┤
│enable │ 1+ │
├───────────────────┼──────────────────────────────────┤
│only │ 1+ │
└───────────────────┴──────────────────────────────────┘

Options that take no arguments can be prefixed with no to invert their meaning. E.g.
--luacheck: no unused args disables unused argument warnings.

Part of the file affected by inline option dependes on where it is placed. If there is any
code on the line with the option, only that line is affected; otherwise, everthing till
the end of the current closure is. In particular, inline options at the top of the file
affect all of it:

-- luacheck: globals g1 g2, ignore foo
local foo = g1(g2) -- No warnings emitted.

-- The following unused function is not reported.
local function f() -- luacheck: ignore
-- luacheck: globals g3
g3() -- No warning.
end

g3() -- Warning is emitted as the inline option defining g3 only affected function f.

For fine-grained control over inline option visibility use luacheck: push and luacheck:
pop directives:

-- luacheck: push ignore foo
foo() -- No warning.
-- luacheck: pop
foo() -- Warning is emitted.

Inline options can be completely disabled using --no-inline CLI option or inline config
option.

LUACHECK MODULE

Use local luacheck = require "luacheck" to import luacheck module. It contains the
following functions:

· luacheck.get_report(source): Given source string, returns analysis data (a table).

· luacheck.process_reports(reports, options): Processes array of analysis reports and
applies options. reports[i] uses options, options[i], options[i][1], options[i][2], ...
as options, overriding each other in that order. Options table is a table with fields
similar to config options; see options. Analysis reports with field fatal are ignored.
process_reports returns final report, see Report format.

· luacheck.check_strings(sources, options): Checks array of sources using options, returns
final report. Tables with field fatal within sources array are ignored.

· luacheck.check_files(files, options): Checks array of files using options, returns final
report. Open file handles can passed instead of filenames, in which case they will be
read till EOF and closed.

· luacheck.get_message(issue): Returns a string message for an issue, see Report format.

luacheck._VERSION contains Luacheck version as a string in MAJOR.MINOR.PATCH format.

Using luacheck as a function is equivalent to calling luacheck.check_files.

Report format
A final report is an array of file reports plus fields warnings, errors and fatals
containing total number of warnings, errors and fatal errors, correspondingly.

A file report is an array of issues (warnings or errors). If a fatal error occured while
checking a file, its report will have fatal field containing error type.

An issue is a table with field code indicating its type (see warnings), and fields line,
column and end_column pointing to the source of the warning. name field may contain name
of relate variable. Issues of some types can also have additional fields:

┌──────┬──────────────────────────────────┐
│Codes │ Additional fields │
├──────┼──────────────────────────────────┤
│011 │ msg field contains syntax error │
│ │ message. │
├──────┼──────────────────────────────────┤
│111 │ module field indicates that │
│ │ assignment is to a non-module │
│ │ global variable. │
├──────┼──────────────────────────────────┤
│211 │ func field indicates that unused │
│ │ variable is a function. │
├──────┼──────────────────────────────────┤
│4.. │ prev_line and prev_column fields │
│ │ contain location of the │
│ │ overwritten definition. │
└──────┴──────────────────────────────────┘

Other fields may be present for internal reasons.

This is documentation for 0.13.0 version of Luacheck, a linter for Lua.

Use luacheck online using onworks.net services