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

1 files changed, 57 insertions, 0 deletions

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