Re: [Tarantool-patches] [PATCH v4 5/10] Fix luacheck warnings in src/box/lua/

[Igor Munkin <imun@tarantool.org>]

Sergey,

Thanks for the patch! Please consider the comments I left below.

On 21.04.20, sergeyb@tarantool.org wrote:
> From: Sergey Bronnikov <sergeyb@tarantool.org>
> 
> Closes #4681
> 
> Reviewed-by: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
> Co-authored-by: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
> ---
>  .luacheckrc                     |  8 ++++++++
>  src/box/lua/console.lua         |  6 +++---
>  src/box/lua/feedback_daemon.lua |  2 +-
>  src/box/lua/key_def.lua         |  2 +-
>  src/box/lua/load_cfg.lua        | 25 +++++++++++------------
>  src/box/lua/net_box.lua         | 26 ++++++++----------------
>  src/box/lua/schema.lua          | 35 ++++++++++++++++-----------------
>  src/box/lua/tuple.lua           |  8 +++-----
>  src/box/lua/upgrade.lua         | 19 +++++++++---------
>  9 files changed, 62 insertions(+), 69 deletions(-)
> 
> diff --git a/.luacheckrc b/.luacheckrc
> index 60aedc842..64692b27c 100644
> --- a/.luacheckrc
> +++ b/.luacheckrc
> @@ -25,7 +25,15 @@ exclude_files = {
>      ".git/**/*.lua",
>  }
>  
> +files["**/*.lua"] = {
> +    globals = {"box", "_TARANTOOL", "help", "tutorial"},
> +    ignore = {"212/self", "122"}
> +}

Well, I can't figure out why these global suppressions are set in this
patch. By the way these suppressions don't work for
extra/dist/tarantoolctl.in.

Furthermore, IMHO, global suppression for (W122)[Setting a read-only
field of a global variable] is a bad practice.

>  files["extra/dist/tarantoolctl.in"] = {ignore = {"212/self", "122", "431"}}
>  files["src/lua/swim.lua"] = {ignore = {"431"}}
>  files["src/lua/fio.lua"] = {ignore = {"231"}}
>  files["src/lua/init.lua"] = {globals = {"dostring"}}
> +files["src/box/lua/console.lua"] = {ignore = {"212"}}

What is the reason to fix 3 (W211)[Unused local variable] warnings, but
leave and suppress 9 (W212)[Unused argument] warnings (at the same time
you fix this type of warnings in load_cfg.lua)?

> +files["src/box/lua/load_cfg.lua"] = {ignore = {"542"}}

It's a single empty branch warning, why it can't be fixed / suppressed
inline? Here is the diff:

================================================================================

diff --git a/.luacheckrc b/.luacheckrc
index 64692b27c..0c1f85766 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -29,11 +29,11 @@ files["**/*.lua"] = {
     globals = {"box", "_TARANTOOL", "help", "tutorial"},
     ignore = {"212/self", "122"}
 }
+
 files["extra/dist/tarantoolctl.in"] = {ignore = {"212/self", "122", "431"}}
 files["src/lua/swim.lua"] = {ignore = {"431"}}
 files["src/lua/fio.lua"] = {ignore = {"231"}}
 files["src/lua/init.lua"] = {globals = {"dostring"}}
 files["src/box/lua/console.lua"] = {ignore = {"212"}}
-files["src/box/lua/load_cfg.lua"] = {ignore = {"542"}}
 files["src/box/lua/net_box.lua"] = {ignore = {"431", "432", "231", "411", "212"}}
 files["src/box/lua/schema.lua"] = {ignore = {"431", "432", "542", "212"}}
diff --git a/src/box/lua/load_cfg.lua b/src/box/lua/load_cfg.lua
index 0926c7380..38c128e85 100644
--- a/src/box/lua/load_cfg.lua
+++ b/src/box/lua/load_cfg.lua
@@ -414,7 +414,7 @@ local function prepare_cfg(cfg, default_cfg, template_cfg, modify_cfg, prefix)
         elseif v == "" or v == nil then
             -- "" and NULL = ffi.cast('void *', 0) set option to default value
             v = default_cfg[k]
-        elseif template_cfg[k] == 'any' then
+        elseif template_cfg[k] == 'any' then -- luacheck: ignore
             -- any type is ok
         elseif type(template_cfg[k]) == 'table' then
             if type(v) ~= 'table' then

================================================================================

> +files["src/box/lua/net_box.lua"] = {ignore = {"431", "432", "231", "411", "212"}}

Again, I see suppressed (W212)[Unused argument] warnings *but*:
* they are well localized
* most of them will *never* be fixed and should be commented and
  protected from inquisitive persons
* others can be fixed with a trivial changes

Here is the diff:

================================================================================

diff --git a/.luacheckrc b/.luacheckrc
index 64692b27c..b05260d29 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -35,5 +35,5 @@ files["src/lua/fio.lua"] = {ignore = {"231"}}
 files["src/lua/init.lua"] = {globals = {"dostring"}}
 files["src/box/lua/console.lua"] = {ignore = {"212"}}
 files["src/box/lua/load_cfg.lua"] = {ignore = {"542"}}
-files["src/box/lua/net_box.lua"] = {ignore = {"431", "432", "231", "411", "212"}}
+files["src/box/lua/net_box.lua"] = {ignore = {"431", "432", "231", "411"}}
 files["src/box/lua/schema.lua"] = {ignore = {"431", "432", "542", "212"}}
diff --git a/src/box/lua/net_box.lua b/src/box/lua/net_box.lua
index 1e351bb31..8b3802749 100644
--- a/src/box/lua/net_box.lua
+++ b/src/box/lua/net_box.lua
@@ -56,18 +56,18 @@ local E_PROC_LUA             = box.error.PROC_LUA
 -- utility tables
 local is_final_state         = {closed = 1, error = 1}
 
-local function decode_nil(raw_data, raw_data_end)
+local function decode_nil(raw_data, raw_data_end) -- luacheck: no unused args
     return nil, raw_data_end
 end
 local function decode_data(raw_data)
     local response, raw_end = decode(raw_data)
     return response[IPROTO_DATA_KEY], raw_end
 end
-local function decode_tuple(raw_data, raw_data_end, format)
+local function decode_tuple(raw_data, raw_data_end, format) -- luacheck: no unused args
     local response, raw_end = internal.decode_select(raw_data, nil, format)
     return response[1], raw_end
 end
-local function decode_get(raw_data, raw_data_end, format)
+local function decode_get(raw_data, raw_data_end, format) -- luacheck: no unused args
     local body, raw_end = internal.decode_select(raw_data, nil, format)
     if body[2] then
         return nil, raw_end, box.error.MORE_THAN_ONE_TUPLE
@@ -110,7 +110,7 @@ local method_encoder = {
     max     = internal.encode_select,
     count   = internal.encode_call,
     -- inject raw data into connection, used by console and tests
-    inject = function(buf, id, bytes)
+    inject = function(buf, id, bytes) -- luacheck: no unused args
         local ptr = buf:reserve(#bytes)
         ffi.copy(ptr, bytes, #bytes)
         buf.wpos = ptr + #bytes
@@ -176,7 +176,7 @@ end
 -- Default action on push during a synchronous request -
 -- ignore.
 --
-local function on_push_sync_default(...) end
+local function on_push_sync_default() end
 
 --
 -- Basically, *transport* is a TCP connection speaking one of
@@ -1216,7 +1216,7 @@ function remote_methods:execute(query, parameters, sql_opts, netbox_opts)
                          sql_opts or {})
 end
 
-function remote_methods:prepare(query, parameters, sql_opts, netbox_opts)
+function remote_methods:prepare(query, parameters, sql_opts, netbox_opts) -- luacheck: no unused args
     check_remote_arg(self, "prepare")
     if type(query) ~= "string" then
         box.error(box.error.SQL_PREPARE, "expected string as SQL statement")
@@ -1581,7 +1581,7 @@ this_module.self = {
     timeout = function(self) return self end,
     wait_connected = function(self) return true end,
     is_connected = function(self) return true end,
-    call = function(_box, proc_name, args, opts)
+    call = function(_box, proc_name, args)
         check_remote_arg(_box, 'call')
         check_call_args(args)
         args = args or {}
@@ -1598,7 +1598,7 @@ this_module.self = {
             return handle_eval_result(pcall(proc, unpack(args)))
         end
     end,
-    eval = function(_box, expr, args, opts)
+    eval = function(_box, expr, args)
         check_remote_arg(_box, 'eval')
         check_eval_args(args)
         args = args or {}

================================================================================

Moreover a single (W231)[Local variable is set but never accessed]
warning is also supressed (but you fixed others in this file). Here is
the diff:

================================================================================

diff --git a/.luacheckrc b/.luacheckrc
index 64692b27c..b23ebfc60 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -35,5 +35,5 @@ files["src/lua/fio.lua"] = {ignore = {"231"}}
 files["src/lua/init.lua"] = {globals = {"dostring"}}
 files["src/box/lua/console.lua"] = {ignore = {"212"}}
 files["src/box/lua/load_cfg.lua"] = {ignore = {"542"}}
-files["src/box/lua/net_box.lua"] = {ignore = {"431", "432", "231", "411", "212"}}
+files["src/box/lua/net_box.lua"] = {ignore = {"431", "432", "411", "212"}}
 files["src/box/lua/schema.lua"] = {ignore = {"431", "432", "542", "212"}}
diff --git a/src/box/lua/net_box.lua b/src/box/lua/net_box.lua
index 1e351bb31..bcfec92bc 100644
--- a/src/box/lua/net_box.lua
+++ b/src/box/lua/net_box.lua
@@ -749,13 +749,12 @@ local function create_transport(host, port, user, password, callback,
             return iproto_schema_sm()
         end
         encode_auth(send_buf, new_request_id(), user, password, salt)
-        local err, hdr, body_rpos, body_end = send_and_recv_iproto()
+        local err, hdr, body_rpos = send_and_recv_iproto()
         if err then
             return error_sm(err, hdr)
         end
         if hdr[IPROTO_STATUS_KEY] ~= 0 then
-            local body
-            body, body_end = decode(body_rpos)
+            local body = decode(body_rpos)
             return error_sm(E_NO_CONNECTION, body[IPROTO_ERROR_KEY])
         end
         set_state('fetch_schema')

================================================================================

> +files["src/box/lua/schema.lua"] = {ignore = {"431", "432", "542", "212"}}

Again, it's a single empty branch warning, that can be suppressed
inline. Here is the diff:

================================================================================

diff --git a/.luacheckrc b/.luacheckrc
index 64692b27c..fa715fded 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -36,4 +36,4 @@ files["src/lua/init.lua"] = {globals = {"dostring"}}
 files["src/box/lua/console.lua"] = {ignore = {"212"}}
 files["src/box/lua/load_cfg.lua"] = {ignore = {"542"}}
 files["src/box/lua/net_box.lua"] = {ignore = {"431", "432", "231", "411", "212"}}
-files["src/box/lua/schema.lua"] = {ignore = {"431", "432", "542", "212"}}
+files["src/box/lua/schema.lua"] = {ignore = {"431", "432", "212"}}
diff --git a/src/box/lua/schema.lua b/src/box/lua/schema.lua
index de47b807e..5fad272ab 100644
--- a/src/box/lua/schema.lua
+++ b/src/box/lua/schema.lua
@@ -259,7 +259,7 @@ local function check_param_table(table, template)
         if template[k] == nil then
             box.error(box.error.ILLEGAL_PARAMS,
                       "unexpected option '" .. k .. "'")
-        elseif template[k] == 'any' then
+        elseif template[k] == 'any' then -- luacheck: ignore
             -- any type is ok
         elseif (string.find(template[k], ',') == nil) then
             -- one type

================================================================================

And the following simple diff fixes all remaining (W212)[Unused
argument] warnings reported for schema.lua:

================================================================================

diff --git a/.luacheckrc b/.luacheckrc
index 64692b27c..bfe144f64 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -36,4 +36,4 @@ files["src/lua/init.lua"] = {globals = {"dostring"}}
 files["src/box/lua/console.lua"] = {ignore = {"212"}}
 files["src/box/lua/load_cfg.lua"] = {ignore = {"542"}}
 files["src/box/lua/net_box.lua"] = {ignore = {"431", "432", "231", "411", "212"}}
-files["src/box/lua/schema.lua"] = {ignore = {"431", "432", "542", "212"}}
+files["src/box/lua/schema.lua"] = {ignore = {"431", "432", "542"}}
diff --git a/src/box/lua/schema.lua b/src/box/lua/schema.lua
index de47b807e..537443eeb 100644
--- a/src/box/lua/schema.lua
+++ b/src/box/lua/schema.lua
@@ -1229,12 +1229,12 @@ end
 
 local iterator_t = ffi.typeof('struct iterator')
 ffi.metatype(iterator_t, {
-    __tostring = function(iterator)
+    __tostring = function()
         return "<iterator state>"
     end;
 })
 
-local iterator_gen = function(param, state)
+local iterator_gen = function(param, state) -- luacheck: no unused args
     --[[
         index:pairs() mostly conforms to the Lua for-in loop conventions and
         tries to follow the best practices of Lua community.
@@ -1268,7 +1268,7 @@ local iterator_gen = function(param, state)
     end
 end
 
-local iterator_gen_luac = function(param, state)
+local iterator_gen_luac = function(param, state) -- luacheck: no unused args
     local tuple = internal.iterator_next(state)
     if tuple ~= nil then
         return state, tuple -- new state, value
@@ -1773,9 +1773,9 @@ local function wrap_schema_object_mt(name)
         __pairs = global_mt.__pairs
     }
     local mt_mt = {}
-    mt_mt.__newindex = function(t, k, v)
+    mt_mt.__newindex = function(self, k, v)
         mt_mt.__newindex = nil
-        mt.__index = function(t, k)
+        mt.__index = function(self, k)
             return mt[k] or box.schema[name][k]
         end
         rawset(mt, k, v)
@@ -2484,7 +2484,7 @@ local function revoke(uid, name, privilege, object_type, object_name, options)
     end
 end
 
-local function drop(uid, opts)
+local function drop(uid)
     -- recursive delete of user data
     local _vpriv = box.space[box.schema.VPRIV_ID]
     local spaces = box.space[box.schema.VSPACE_ID].index.owner:select{uid}
@@ -2563,7 +2563,7 @@ box.schema.user.drop = function(name, opts)
             box.error(box.error.DROP_USER, name,
                       "the user is active in the current session")
         end
-        return drop(uid, opts)
+        return drop(uid)
     end
     if not opts.if_exists then
         box.error(box.error.NO_SUCH_USER, name)

================================================================================

<snipped>

> diff --git a/src/box/lua/net_box.lua b/src/box/lua/net_box.lua
> index 07fa54c38..1e351bb31 100644
> --- a/src/box/lua/net_box.lua
> +++ b/src/box/lua/net_box.lua

<snipped>

> @@ -425,7 +421,7 @@ local function create_transport(host, port, user, password, callback,
>          state = new_state
>          last_errno = new_errno
>          last_error = new_error
> -        callback('state_changed', new_state, new_errno, new_error)
> +        callback('state_changed', new_state, new_error)

Please adjust the corresponding comment.

>          state_cond:broadcast()
>          if state == 'error' or state == 'error_reconnect' or
>             state == 'closed' then

<snipped>

> @@ -954,7 +945,7 @@ local function new_sm(host, port, opts, connection, greeting)
>      local remote = {host = host, port = port, opts = opts, state = 'initial'}
>      local function callback(what, ...)
>          if what == 'state_changed' then
> -            local state, errno, err = ...
> +            local state, err = ...
>              local was_connected = remote._is_connected
>              if state == 'active' then
>                  if not was_connected then
> diff --git a/src/box/lua/schema.lua b/src/box/lua/schema.lua
> index 85fcca562..de47b807e 100644
> --- a/src/box/lua/schema.lua
> +++ b/src/box/lua/schema.lua

<snipped>

> @@ -582,9 +580,9 @@ end
>  --
>  local function format_field_resolve(format, path, what)
>      assert(type(path) == 'number' or type(path) == 'string')
> -    local idx = nil
> +    local idx
>      local relative_path = nil
> -    local field_name = nil
> +    local field_name

You can simply move it down to its initialization.

>      -- Path doesn't require resolve.
>      if type(path) == 'number' then
>          idx = path

<snipped>

> -- 
> 2.23.0
> 

-- 
Best regards,
IM