Add diagnostic warning about any global (#1)

* Add warning for any global variable via diagnostic
* Add messages in en-US
  TODO: add messages in languages other than en-us as well
* fallback: enable/disable diagnostics w/ annotation
* Add tests for the new diagnostic
* Add diagnostic and group to config.md

16 files changed, 247 insertions, 0 deletions

diff --git a/doc/en-us/config.md b/doc/en-us/config.md
index 2d519824..0e5d09ee 100644
--- a/doc/en-us/config.md
+++ b/doc/en-us/config.md
@@ -238,6 +238,7 @@ Array<string>
 * ``"err-nonstandard-symbol"``
 * ``"err-then-as-do"``
 * ``"exp-in-action"``
+* ``"global-element"``
 * ``"global-in-nil-env"``
 * ``"index-in-func-name"``
 * ``"invisible"``
@@ -468,6 +469,10 @@ object<string, string>
     */
     "strict": "Fallback",
     /*
+    * global-element
+    */
+    "strict-convention": "None",
+    /*
     * no-unknown
     */
     "strong": "Fallback",
@@ -587,6 +592,10 @@ object<string, string>
     */
     "strict": "Fallback",
     /*
+    * global-element
+    */
+    "strict-convention": "Fallback",
+    /*
     * no-unknown
     */
     "strong": "Fallback",
@@ -775,6 +784,10 @@ object<string, string>
     */
     "empty-block": "Opened",
     /*
+    Enable diagnostics to warn about global elements.
+    */
+    "global-element": "None",
+    /*
     Enable cannot use global variables （ `_ENV` is set to `nil`） diagnostics.
     */
     "global-in-nil-env": "Any",
@@ -1023,6 +1036,10 @@ object<string, string>
     */
     "empty-block": "Hint",
     /*
+    Enable diagnostics to warn about global elements.
+    */
+    "global-element": "Warning",
+    /*
     Enable cannot use global variables （ `_ENV` is set to `nil`） diagnostics.
     */
     "global-in-nil-env": "Warning",
diff --git a/doc/pt-br/config.md b/doc/pt-br/config.md
index 24cf8d3b..762f2259 100644
--- a/doc/pt-br/config.md
+++ b/doc/pt-br/config.md
@@ -238,6 +238,7 @@ Array<string>
 * ``"err-nonstandard-symbol"``
 * ``"err-then-as-do"``
 * ``"exp-in-action"``
+* ``"global-element"``
 * ``"global-in-nil-env"``
 * ``"index-in-func-name"``
 * ``"invisible"``
@@ -468,6 +469,10 @@ object<string, string>
     */
     "strict": "Fallback",
     /*
+    * global-element
+    */
+    "strict-convention": "None",
+    /*
     * no-unknown
     */
     "strong": "Fallback",
@@ -587,6 +592,10 @@ object<string, string>
     */
     "strict": "Fallback",
     /*
+    * global-element
+    */
+    "strict-convention": "Fallback",
+    /*
     * no-unknown
     */
     "strong": "Fallback",
@@ -775,6 +784,10 @@ object<string, string>
     */
     "empty-block": "Opened",
     /*
+    Enable diagnostics to warn about global elements.
+    */
+    "global-element": "None",
+    /*
     不能使用全局变量（ `_ENV` 被设置为了 `nil`）
     */
     "global-in-nil-env": "Any",
@@ -1023,6 +1036,10 @@ object<string, string>
     */
     "empty-block": "Hint",
     /*
+    Enable diagnostics to warn about global elements.
+    */
+    "global-element": "Warning",
+    /*
     不能使用全局变量（ `_ENV` 被设置为了 `nil`）
     */
     "global-in-nil-env": "Warning",
diff --git a/doc/zh-cn/config.md b/doc/zh-cn/config.md
index 991932b6..869e2506 100644
--- a/doc/zh-cn/config.md
+++ b/doc/zh-cn/config.md
@@ -238,6 +238,7 @@ Array<string>
 * ``"err-nonstandard-symbol"``
 * ``"err-then-as-do"``
 * ``"exp-in-action"``
+* ``"global-element"``
 * ``"global-in-nil-env"``
 * ``"index-in-func-name"``
 * ``"invisible"``
@@ -468,6 +469,10 @@ object<string, string>
     */
     "strict": "Fallback",
     /*
+    * global-element
+    */
+    "strict-convention": "None",
+    /*
     * no-unknown
     */
     "strong": "Fallback",
@@ -587,6 +592,10 @@ object<string, string>
     */
     "strict": "Fallback",
     /*
+    * global-element
+    */
+    "strict-convention": "Fallback",
+    /*
     * no-unknown
     */
     "strong": "Fallback",
@@ -775,6 +784,10 @@ object<string, string>
     */
     "empty-block": "Opened",
     /*
+    Enable diagnostics to warn about global elements.
+    */
+    "global-element": "None",
+    /*
     不能使用全局变量（ `_ENV` 被设置为了 `nil`）
     */
     "global-in-nil-env": "Any",
@@ -1022,6 +1035,10 @@ object<string, string>
     */
     "empty-block": "Hint",
     /*
+    Enable diagnostics to warn about global elements.
+    */
+    "global-element": "Warning",
+    /*
     不能使用全局变量（ `_ENV` 被设置为了 `nil`）
     */
     "global-in-nil-env": "Warning",
diff --git a/doc/zh-tw/config.md b/doc/zh-tw/config.md
index 83cef315..c922ad6b 100644
--- a/doc/zh-tw/config.md
+++ b/doc/zh-tw/config.md
@@ -238,6 +238,7 @@ Array<string>
 * ``"err-nonstandard-symbol"``
 * ``"err-then-as-do"``
 * ``"exp-in-action"``
+* ``"global-element"``
 * ``"global-in-nil-env"``
 * ``"index-in-func-name"``
 * ``"invisible"``
@@ -468,6 +469,10 @@ object<string, string>
     */
     "strict": "Fallback",
     /*
+    * global-element
+    */
+    "strict-convention": "None",
+    /*
     * no-unknown
     */
     "strong": "Fallback",
@@ -587,6 +592,10 @@ object<string, string>
     */
     "strict": "Fallback",
     /*
+    * global-element
+    */
+    "strict-convention": "Fallback",
+    /*
     * no-unknown
     */
     "strong": "Fallback",
@@ -775,6 +784,10 @@ object<string, string>
     */
     "empty-block": "Opened",
     /*
+    Enable diagnostics to warn about global elements.
+    */
+    "global-element": "None",
+    /*
     不能使用全域變數（ `_ENV` 被設定為 `nil`）
     */
     "global-in-nil-env": "Any",
@@ -1022,6 +1035,10 @@ object<string, string>
     */
     "empty-block": "Hint",
     /*
+    Enable diagnostics to warn about global elements.
+    */
+    "global-element": "Warning",
+    /*
     不能使用全域變數（ `_ENV` 被設定為 `nil`）
     */
     "global-in-nil-env": "Warning",
diff --git a/locale/en-us/script.lua b/locale/en-us/script.lua
index 4b74fa51..2a13214f 100644
--- a/locale/en-us/script.lua
+++ b/locale/en-us/script.lua
@@ -150,6 +150,8 @@ DIAG_INVISIBLE_PROTECTED              =
 'Field `{field}` is protected, it can only be accessed in class `{class}` and its subclasses.'
 DIAG_INVISIBLE_PACKAGE                =
 'Field `{field}` can only be accessed in same file `{uri}`.'
+DIAG_GLOBAL_ELEMENT                  =
+'Element is global.'
 
 MWS_NOT_SUPPORT         =
 '{} does not support multi workspace for now, I may need to restart to support the new workspace ...'
diff --git a/locale/en-us/setting.lua b/locale/en-us/setting.lua
index 18840e94..9f606cd7 100644
--- a/locale/en-us/setting.lua
+++ b/locale/en-us/setting.lua
@@ -415,6 +415,8 @@ config.diagnostics['unknown-operator']      =
 'Enable diagnostics for unknown operators.'
 config.diagnostics['unreachable-code']      =
 'Enable diagnostics for unreachable code.'
+config.diagnostics['global-element']       =
+'Enable diagnostics to warn about global elements.'
 config.typeFormat.config                    =
 'Configures the formatting behavior while typing Lua code.'
 config.typeFormat.config.auto_complete_end  =
diff --git a/locale/pt-br/script.lua b/locale/pt-br/script.lua
index d2a7c314..affcd893 100644
--- a/locale/pt-br/script.lua
+++ b/locale/pt-br/script.lua
@@ -150,6 +150,8 @@ DIAG_INVISIBLE_PROTECTED              = -- TODO: need translate!
 'Field `{field}` is protected, it can only be accessed in class `{class}` and its subclasses.'
 DIAG_INVISIBLE_PACKAGE                = -- TODO: need translate!
 'Field `{field}` can only be accessed in same file `{uri}`.'
+DIAG_GLOBAL_ELEMENT                  = -- TODO: need translate!
+'Element is global.'
 
 MWS_NOT_SUPPORT         =
 '{} não é suportado múltiplos espaços de trabalho por enquanto, posso precisar reiniciar para estabelecer um novo espaço de trabalho ...'
diff --git a/locale/pt-br/setting.lua b/locale/pt-br/setting.lua
index 75904872..95f26b76 100644
--- a/locale/pt-br/setting.lua
+++ b/locale/pt-br/setting.lua
@@ -415,6 +415,8 @@ config.diagnostics['unknown-operator']      = -- TODO: need translate!
 'Enable diagnostics for unknown operators.'
 config.diagnostics['unreachable-code']      = -- TODO: need translate!
 'Enable diagnostics for unreachable code.'
+config.diagnostics['global-element']       = -- TODO: need translate!
+'Enable diagnostics to warn about global elements.'
 config.typeFormat.config                    = -- TODO: need translate!
 'Configures the formatting behavior while typing Lua code.'
 config.typeFormat.config.auto_complete_end  = -- TODO: need translate!
diff --git a/locale/zh-cn/script.lua b/locale/zh-cn/script.lua
index 531b54ae..f6f639ea 100644
--- a/locale/zh-cn/script.lua
+++ b/locale/zh-cn/script.lua
@@ -150,6 +150,8 @@ DIAG_INVISIBLE_PROTECTED              =
 '字段 `{field}` 受到保护，只能在 `{class}` 类极其子类中才能访问。'
 DIAG_INVISIBLE_PACKAGE                =
 '字段 `{field}` 只能在相同的文件 `{uri}` 中才能访问。'
+DIAG_GLOBAL_ELEMENT                  = -- TODO: need translate!
+'Element is global.'
 
 MWS_NOT_SUPPORT         =
 '{} 目前还不支持多工作目录，我可能需要重启才能支持新的工作目录...'
diff --git a/locale/zh-cn/setting.lua b/locale/zh-cn/setting.lua
index d488ac3f..731190e2 100644
--- a/locale/zh-cn/setting.lua
+++ b/locale/zh-cn/setting.lua
@@ -414,6 +414,8 @@ config.diagnostics['unknown-operator']      = -- TODO: need translate!
 'Enable diagnostics for unknown operators.'
 config.diagnostics['unreachable-code']      = -- TODO: need translate!
 'Enable diagnostics for unreachable code.'
+config.diagnostics['global-element']       = -- TODO: need translate!
+'Enable diagnostics to warn about global elements.'
 config.typeFormat.config                    = -- TODO: need translate!
 'Configures the formatting behavior while typing Lua code.'
 config.typeFormat.config.auto_complete_end  = -- TODO: need translate!
diff --git a/locale/zh-tw/script.lua b/locale/zh-tw/script.lua
index d6e93a43..4d9a89ad 100644
--- a/locale/zh-tw/script.lua
+++ b/locale/zh-tw/script.lua
@@ -150,6 +150,8 @@ DIAG_INVISIBLE_PROTECTED              = -- TODO: need translate!
 'Field `{field}` is protected, it can only be accessed in class `{class}` and its subclasses.'
 DIAG_INVISIBLE_PACKAGE                = -- TODO: need translate!
 'Field `{field}` can only be accessed in same file `{uri}`.'
+DIAG_GLOBAL_ELEMENT                  = -- TODO: need translate!
+'Element is global.'
 
 MWS_NOT_SUPPORT         =
 '{} 目前還不支援多工作目錄，我可能需要重新啟動才能支援新的工作目錄...'
diff --git a/locale/zh-tw/setting.lua b/locale/zh-tw/setting.lua
index 8c74668d..fd363d3f 100644
--- a/locale/zh-tw/setting.lua
+++ b/locale/zh-tw/setting.lua
@@ -414,6 +414,8 @@ config.diagnostics['unknown-operator']      = -- TODO: need translate!
 'Enable diagnostics for unknown operators.'
 config.diagnostics['unreachable-code']      = -- TODO: need translate!
 'Enable diagnostics for unreachable code.'
+config.diagnostics['global-element']       = -- TODO: need translate!
+'Enable diagnostics to warn about global elements.'
 config.typeFormat.config                    = -- TODO: need translate!
 'Configures the formatting behavior while typing Lua code.'
 config.typeFormat.config.auto_complete_end  = -- TODO: need translate!
diff --git a/script/core/diagnostics/global-element.lua b/script/core/diagnostics/global-element.lua
new file mode 100644
index 00000000..e9dd46ce
--- /dev/null
+++ b/script/core/diagnostics/global-element.lua
@@ -0,0 +1,57 @@
+local files     = require 'files'
+local guide     = require 'parser.guide'
+local lang      = require 'language'
+local config    = require 'config'
+local vm        = require 'vm'
+local util      = require 'utility'
+
+local function isDocClass(source)
+    if not source.bindDocs then
+        return false
+    end
+    for _, doc in ipairs(source.bindDocs) do
+        if doc.type == 'doc.class' then
+            return true
+        end
+    end
+    return false
+end
+
+-- If global elements are discouraged by coding convention, this diagnostic helps with reminding about that
+-- Exceptions may be added to Lua.diagnostics.globals
+return function (uri, callback)
+    local ast = files.getState(uri)
+    if not ast then
+        return
+    end
+
+    local definedGlobal = util.arrayToHash(config.get(uri, 'Lua.diagnostics.globals'))
+
+    guide.eachSourceType(ast.ast, 'setglobal', function (source)
+        local name = guide.getKeyName(source)
+        if not name or definedGlobal[name] then
+            return
+        end
+        -- If the assignment is marked as doc.class, then it is considered allowed 
+        if isDocClass(source) then
+            return
+        end
+        if definedGlobal[name] == nil then
+            definedGlobal[name] = false
+            local global = vm.getGlobal('variable', name)
+            if global then
+                for _, set in ipairs(global:getSets(uri)) do
+                    if vm.isMetaFile(guide.getUri(set)) then
+                        definedGlobal[name] = true
+                        return
+                    end
+                end
+            end
+        end
+        callback {
+            start   = source.start,
+            finish  = source.finish,
+            message = lang.script.DIAG_GLOBAL_ELEMENT,
+        }
+    end)
+end
diff --git a/script/proto/diagnostic.lua b/script/proto/diagnostic.lua
index ceb42f8b..bea7c160 100644
--- a/script/proto/diagnostic.lua
+++ b/script/proto/diagnostic.lua
@@ -172,6 +172,14 @@ m.register {
 }
 
 m.register {
+    'global-element',
+} {
+    group   = 'strict-conventions',
+    severity = 'Warning',
+    status = 'None'
+}
+
+m.register {
     'duplicate-index',
 } {
     group    = 'duplicate',
diff --git a/test/diagnostics/global-element.lua b/test/diagnostics/global-element.lua
new file mode 100644
index 00000000..176fda79
--- /dev/null
+++ b/test/diagnostics/global-element.lua
@@ -0,0 +1,97 @@
+local config = require 'config'
+local util   = require 'utility'
+
+-- disable all default groups to make isolated tests
+config.set(nil, 'Lua.diagnostics.groupFileStatus', 
+{
+    ['ambiguity']     = 'None',
+    ['await']         = 'None',
+    ['codestyle']     = 'None',
+    ['strict-conventions']   = 'None',
+    ['duplicate']     = 'None',
+    ['global']        = 'None',
+    ['luadoc']        = 'None',
+    ['redefined']     = 'None',
+    ['strict']        = 'None',
+    ['strong']        = 'None',
+    ['type-check']    = 'None',
+    ['unbalanced']    = 'None',
+    ['unused']        = 'None'
+})
+
+-- enable single diagnostic that is to be tested
+config.set(nil, 'Lua.diagnostics.neededFileStatus',
+{
+    ['global-element'] = 'Any!' -- override groupFileStatus
+})
+
+-- check that local elements are not warned about
+TEST [[
+local x = 123
+x = 321
+<!Y!> = "global"
+<!z!> = "global"
+]]
+
+TEST [[
+local function test1()
+    print()
+end
+
+function <!Test2!>()
+    print()
+end
+]]
+
+TEST [[
+local function closure1()
+    local elem1 = 1
+    <!elem2!> = 2
+end
+
+function <!Closure2!>()
+    local elem1 = 1
+    <!elem2!> = 2
+end
+]]
+
+-- add elements to exemption list
+config.set(nil, 'Lua.diagnostics.globals',
+{
+    'GLOBAL1',
+    'GLOBAL2',
+    'GLOBAL_CLOSURE'
+})
+
+TEST [[
+GLOBAL1 = "allowed"
+<!global2!> = "not allowed"
+<!GLOBAL3!> = "not allowed"
+]]
+
+TEST [[
+function GLOBAL1()
+    print()
+end
+]]
+
+TEST [[
+local function closure1()
+    local elem1 = 1
+    GLOBAL1 = 2
+end
+
+function GLOBAL_CLOSURE()
+    local elem1 = 1
+    GLOBAL2 = 2
+    <!elem2!> = 2
+end
+]]
+
+-- reset configurations
+config.set(nil, 'Lua.diagnostics.groupFileStatus', 
+{})
+config.set(nil, 'Lua.diagnostics.neededFileStatus',
+{})
+config.set(nil, 'Lua.diagnostics.globals',
+{})
\ No newline at end of file
diff --git a/test/diagnostics/init.lua b/test/diagnostics/init.lua
index 827d4d08..4025dd8c 100644
--- a/test/diagnostics/init.lua
+++ b/test/diagnostics/init.lua
@@ -86,3 +86,4 @@ end
 
 require 'diagnostics.common'
 require 'diagnostics.type-check'
+require 'diagnostics.global-element'
\ No newline at end of file