Super Strict

Introduction

Super Strict is a Lua library (compatible with Lua 5.1, 5.2, 5.3 and LuaJIT) that finds undeclared variables and other minor mistakes in your source code. Super Strict tests your Lua scripts during loading using static analysis.
The source code is available on GitHub and the documentation is hosted on 2dengine.com

Installation

Super Strict does not depend on third party modules or binaries. Just require the "sstrict.lua" file and any subsequent calls to "require","dofile","loadfile" or "loadstring" will be checked through Super Strict.

require('sstrict.lua')

Continuous Integration

Super Strict provides a reusable workflow that allows you to validate all new commits pushed to your GitHub repository. First, make sure that GitHub Actions are enabled for your repository. Create a file in your repository titled ".github/workflows/validate.yml" and paste the following code:

name: Lua Validation
on: [workflow_dispatch,push]
jobs:
  lua-validation:
    uses: 2dengine/sstrict.lua/.github/workflows/validate.yml@main
    with:
      lua-version: "5.1"

You may need to change the "lua-version" input depending on your environment (for example, LuaJIT uses 5.1) Lastly, go to the "Actions" tab of your repository to confirm that your code has passed the validation successfully. Here is what the validation scan looks like:

	+==========================================================+
	| 1. /utils/pure/speak.lua                                 |
	| 2. /utils/pure/oo.lua                                    |
	| /utils/pure/oo.lua:40: undefined variable 'global'       |
	| /utils/pure/oo.lua:41: undefined variable 'test'         |
	| 3. /ux/scrollbar.lua                                     |
	| 4. /ux/slider.lua                                        |
	| 5. /ux/window.lua                                        |
	+==========================================================+
	| 5 files scanned                                          |
	+==========================================================+
	| /utils/pure/oo.lua.lua:40: undefined variable 'global'   |
	| /utils/pure/oo.lua.lua:41: undefined variable 'test'     |
	+==========================================================+
	| 2 errors found                                           |
	+==========================================================+

You can also trigger the validation manually by clicking on the "Run Workflow" button.

Usage

In most cases you should not run Super Script in production code. Static analysis is CPU intensive and can potentially slow down your scripts. A better option is to write a script that iterates and checks all of the .lua files in your project during development. Here is a script that recursively scans all .lua files within a specific directory using the LuaFileSystem module:

local lfs = require('lfs')
local ss = require('sstrict')
local function scan(path)
  for file in lfs.dir(path) do
    if file ~= '.' and file ~= '..' then
      local full = path..'/'..file
      local attr = lfs.attributes(full)
      if attr.mode == 'directory' then
        scan(full)
      else
        if file:match('%.lua$') then
          print(full)
          assert(ss.parseFile(full))
        end
      end
    end
  end
end
print('scanning...')
scan('.')

To exclude a specific Lua file from being checked place the line "--!strict" at the top of your source code.

Examples

Undefined and unused variables

function foo()
  a = 5 -- undefined variable 'a'
end
function bar(a, b)
  local c = a + b -- unused variable 'c'
  return a + b
end

Redefinition of variable names

for i = 1, 10 do
  for i = 1, 10 do
    -- variable name 'i' redefinition
  end
end

Empty and unnecessary code blocks

for i = 1, 3 do
  -- empty code block error
end
function baz()
  local n = 5
  n = n - 1 -- unnecessary code block error
end

Constant conditions

if 5+5 > 11 then
  -- constant condition error in if/else statement
end

Too many values in assignment

a = 1, 2 -- too many values on the right-hand side in assignment

Duplicate variables, arguments and table fields

t =
{ 
  ['a'] = 100,
  a = 100 -- duplicate field 'a' in table constructor
}
for b, b in pairs(t) do
  -- duplicate lvariable 'b'
end
c, c = 1, 2 -- duplicate variable 'c'
function foo(d, d)
  -- duplicate argument 'd'
end

Credits

grump, pgimeno, MrFariator and the rest of the Love2D community
sstrict.lua is not related in any way to the strict.lua library
Please support our work so we can release more free software in the future.