Awesome

lualint performs luac-based static analysis of global variable usage in Lua source code.

Usage: lualint [-r|-s] filename.lua [ [-r|-s] [filename.lua] ...]

Description

lualint uses luac's bytecode listing. It reports all accesses to undeclared global variables, which catches many typing errors in variable names. For example:

local really_aborting
local function abort() os.exit(1) end
if not os.getenv("HOME") then
  realy_aborting = true
  abortt()
end
reports:

/tmp/example.lua:4: *** global SET of realy_aborting
/tmp/example.lua:5: global get of abortt

It is primarily designed for use on LTN7-style modules, where each source file only exports one global symbol. (A module contained in the file "foobar.lua" should only export the symbol "foobar".)

A "relaxed" mode is available for source not in LTN7 style. It only detects reads from globals that were never set. The switch "-r" puts lualint into relaxed mode for the following files; "-s" switches back to strict.

Required packages are tracked, although not recursively. If you call "myext.process()" you should require "myext", and not depend on other dependencies to load it. LUA_PATH is followed as usual to find requirements.

Some (not strictly LTN7) modules may wish to export other variables into the global environment. To do so, use the declare function:

declare "xpairs"
function xpairs(node)
  [...]

Similarly, to quiet warnings about reading global variables you are aware may be unavailable:

lint_ignore "lua_fltk_version"
if lua_fltk_version then print("fltk loaded") end

One way of defining these is in a module "declare.lua":

function declare(s)
end
declare "lint_ignore"
function lint_ignore(s)
end

(Setting declare is OK, because it's in the "declare" module.) These functions don't have to do anything, or in fact actually exist! They can be in dead code:

if false then declare "xpairs" end

This is because lualint only performs a rather primitive and cursory scan of the bytecode. Perhaps declarations should only be allowed in the main chunk.

TODO

The errors don't come out in any particular order.

Should switch to RiciLake's parser, which should do a much better job of this and allow detection of some other common situations.

CREDITS

JayCarlson (nop@nop.com)

This is all Ben Jackson's (ben@ben.com) fault, who did some similar tricks in MOO.