/usr/share/lua/5.1/luacheck/analyze.lua is in lua-check 0.17.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 | local core_utils = require "luacheck.core_utils"
local utils = require "luacheck.utils"
local function register_value(values_per_var, var, value)
if not values_per_var[var] then
values_per_var[var] = {}
end
table.insert(values_per_var[var], value)
end
local function add_resolution(line, item, var, value, mutation)
register_value(item.used_values, var, value)
value[mutation and "mutated" or "used"] = true
value.using_lines[line] = true
if value.secondaries then
value.secondaries.used = true
end
end
local function in_scope(var, index)
return (var.scope_start <= index) and (index <= var.scope_end)
end
-- Called when value of var is live at an item, maybe several times.
-- Registers value as live where variable is accessed or liveness propogation stops.
-- Stops when out of scope of variable, at another assignment to it or at an item
-- encountered already.
-- When stopping at a visited item, only save value if the item is in the current stack
-- of items, i.e. when propogation followed some path from it to previous item
local function value_propogation_callback(line, stack, index, item, visited, var, value)
if not item then
register_value(line.last_live_values, var, value)
return true
end
if not visited[index] then
if item.accesses and item.accesses[var] then
add_resolution(line, item, var, value)
end
if item.mutations and item.mutations[var] then
add_resolution(line, item, var, value, true)
end
end
if stack[index] or (not visited[index] and (not in_scope(var, index) or item.set_variables and item.set_variables[var])) then
if not item.live_values then
item.live_values = {}
end
register_value(item.live_values, var, value)
return true
end
if visited[index] then
return true
end
visited[index] = true
end
-- For each node accessing variables, adds table {var = {values}} to field `used_values`.
-- A pair `var = {values}` in this table means that accessed local variable `var` can contain one of values `values`.
-- Values that can be accessed locally are marked as used.
local function propogate_values(line)
-- {var = values} live at the end of line.
line.last_live_values = {}
-- It is not very clever to simply propogate every single assigned value.
-- Fortunately, performance hit seems small (can be compenstated by inlining a few functions in lexer).
for i, item in ipairs(line.items) do
if item.set_variables then
for var, value in pairs(item.set_variables) do
if var.line == line then
-- Values are only live at the item after assignment.
core_utils.walk_line(line, i + 1, value_propogation_callback, {}, var, value)
end
end
end
end
end
-- Called when closure (subline) is live at index.
-- Updates variable resolution:
-- When a closure accessing upvalue is live at item where a value of the variable is live,
-- the access can resolve to the value.
-- When a closure setting upvalue is live at item where the variable is accessed,
-- the access can resolve to the value.
-- Live values are only stored when their liveness ends. However, as closure propogation is unrestricted,
-- if there is an intermediate item where value is factually live and closure is live, closure will at some
-- point be propogated to where value liveness ends and is stored as live.
-- (Chances that I will understand this comment six months later: non-existent)
local function closure_propogation_callback(line, _, item, subline)
local live_values
if not item then
live_values = line.last_live_values
else
live_values = item.live_values
end
if live_values then
for _, var_map in ipairs({subline.accessed_upvalues, subline.mutated_upvalues}) do
for var, accessing_items in pairs(var_map) do
if var.line == line then
if live_values[var] then
for _, accessing_item in ipairs(accessing_items) do
for _, value in ipairs(live_values[var]) do
add_resolution(subline, accessing_item, var, value, var_map == subline.mutated_upvalues)
end
end
end
end
end
end
end
if not item then
return true
end
for _, action_key in ipairs({"accesses", "mutations"}) do
local item_var_map = item[action_key]
if item_var_map then
for var, setting_items in pairs(subline.set_upvalues) do
if var.line == line then
if item_var_map[var] then
for _, setting_item in ipairs(setting_items) do
add_resolution(line, item, var, setting_item.set_variables[var], action_key == "mutations")
end
end
end
end
end
end
end
-- Updates variable resolution to account for closures and upvalues.
local function propogate_closures(line)
for i, item in ipairs(line.items) do
if item.lines then
for _, subline in ipairs(item.lines) do
-- Closures are considered live at the item they are created.
core_utils.walk_line_once(line, {}, i, closure_propogation_callback, subline)
end
end
end
-- It is assumed that all closures are live at the end of the line.
-- Therefore, all accesses and sets inside closures can resolve to each other.
for _, subline in ipairs(line.lines) do
for _, var_map in ipairs({subline.accessed_upvalues, subline.mutated_upvalues}) do
for var, accessing_items in pairs(var_map) do
if var.line == line then
for _, accessing_item in ipairs(accessing_items) do
for _, another_subline in ipairs(line.lines) do
if another_subline.set_upvalues[var] then
for _, setting_item in ipairs(another_subline.set_upvalues[var]) do
add_resolution(subline, accessing_item, var, setting_item.set_variables[var], var_map == subline.mutated_upvalues)
end
end
end
end
end
end
end
end
end
local function analyze_line(line)
propogate_values(line)
propogate_closures(line)
end
local function is_function_var(var)
return (#var.values == 1 and var.values[1].type == "func") or (
#var.values == 2 and var.values[1].empty and var.values[2].type == "func")
end
local externally_accessible_tags = utils.array_to_set({"Id", "Index", "Call", "Invoke", "Op", "Paren", "Dots"})
local function externally_accessible(value)
return value.type ~= "var" or (value.node and externally_accessible_tags[value.node.tag])
end
-- Emits warnings for variable.
local function check_var(chstate, var)
if is_function_var(var) then
local value = var.values[2] or var.values[1]
if not value.used then
chstate:warn_unused_variable(value)
end
elseif #var.values == 1 then
if not var.values[1].used then
if var.values[1].mutated then
if not externally_accessible(var.values[1]) then
chstate:warn_unaccessed(var, true)
end
else
chstate:warn_unused_variable(var.values[1], nil, nil, var.values[1].empty)
end
elseif var.values[1].empty then
var.empty = true
chstate:warn_unset(var)
end
elseif not var.accessed and not var.mutated then
chstate:warn_unaccessed(var)
else
local no_values_externally_accessible = true
for _, value in ipairs(var.values) do
if externally_accessible(value) then
no_values_externally_accessible = false
end
end
if not var.accessed and no_values_externally_accessible then
chstate:warn_unaccessed(var, true)
end
for _, value in ipairs(var.values) do
if not value.empty then
if not value.used and not value.mutated then
chstate:warn_unused_value(value)
elseif not value.used and not externally_accessible(value) then
if var.accessed or not no_values_externally_accessible then
chstate:warn_unused_value(value, true)
end
end
end
end
end
end
-- Emits warnings for unused variables and values and unset variables in line.
local function check_for_warnings(chstate, line)
for _, item in ipairs(line.items) do
if item.tag == "Local" then
for var in pairs(item.set_variables) do
-- Do not check implicit top level vararg.
if var.location then
check_var(chstate, var)
end
end
end
end
end
local function mark_reachable_lines(edges, marked, line)
for connected_line in pairs(edges[line]) do
if not marked[connected_line] then
marked[connected_line] = true
mark_reachable_lines(edges, marked, connected_line)
end
end
end
-- Detects unused recursive and mutually recursive functions.
local function check_unused_recursive_funcs(chstate, line)
-- Build a graph of usage relations of all closures.
-- Closure A is used by closure B iff either B is parent
-- of A and A is not assigned to a local/upvalue, or
-- B uses local/upvalue value that is A.
-- Closures not reachable from root closure are unused,
-- report corresponding values/variables if not done already.
-- Initialize edges maps.
local forward_edges = {[line] = {}}
local backward_edges = {[line] = {}}
for _, nested_line in ipairs(line.lines) do
forward_edges[nested_line] = {}
backward_edges[nested_line] = {}
end
-- Add edges leading to each nested line.
for _, nested_line in ipairs(line.lines) do
if nested_line.node.value then
for using_line in pairs(nested_line.node.value.using_lines) do
forward_edges[using_line][nested_line] = true
backward_edges[nested_line][using_line] = true
end
elseif nested_line.parent then
forward_edges[nested_line.parent][nested_line] = true
backward_edges[nested_line][nested_line.parent] = true
end
end
-- Recursively mark all closures reachable from root closure and unused closures.
-- Closures reachable from main chunk are used; closure reachable from unused closures
-- depend on that closure; that is, fixing warning about parent unused closure
-- fixes warning about the child one, so issuing a warning for the child is superfluous.
local marked = {[line] = true}
mark_reachable_lines(forward_edges, marked, line)
for _, nested_line in ipairs(line.lines) do
if nested_line.node.value and not nested_line.node.value.used then
marked[nested_line] = true
mark_reachable_lines(forward_edges, marked, nested_line)
end
end
-- Deal with unused closures.
for _, nested_line in ipairs(line.lines) do
local value = nested_line.node.value
if value and value.used and not marked[nested_line] then
-- This closure is used by some closure, but is not marked as reachable
-- from main chunk or any of reported closures.
-- Find candidate group of mutually recursive functions containing this one:
-- mark sets of closures reachable from it by forward and backward edges,
-- intersect them. Ignore already marked closures in the process to avoid
-- issuing superfluous, dependent warnings.
local forward_marked = setmetatable({}, {__index = marked})
local backward_marked = setmetatable({}, {__index = marked})
mark_reachable_lines(forward_edges, forward_marked, nested_line)
mark_reachable_lines(backward_edges, backward_marked, nested_line)
-- Iterate over closures in the group.
for mut_rec_line in pairs(forward_marked) do
if rawget(backward_marked, mut_rec_line) then
marked[mut_rec_line] = true
value = mut_rec_line.node.value
if value then
-- Report this closure as simply recursive or mutually recursive.
local simply_recursive = forward_edges[mut_rec_line][mut_rec_line]
if is_function_var(value.var) then
chstate:warn_unused_variable(value, true, simply_recursive)
else
chstate:warn_unused_value(value, true, simply_recursive)
end
end
end
end
end
end
end
-- Finds reaching assignments for all variable accesses.
-- Emits warnings: unused variable, unused value, unset variable.
local function analyze(chstate, line)
analyze_line(line)
for _, nested_line in ipairs(line.lines) do
analyze_line(nested_line)
end
check_for_warnings(chstate, line)
for _, nested_line in ipairs(line.lines) do
check_for_warnings(chstate, nested_line)
end
check_unused_recursive_funcs(chstate, line)
end
return analyze
|