implement dim dead code

Author: CapsAdmin

language_server/editor_helper.lua

@@ -474,6 +474,78 @@ function META:Recompile(path, lol, diagnostics, on_save_path)
 		end
 	end
 
+	-- Add diagnostics for unreachable code (dimmed with Unnecessary tag)
+	local file_data = self:IsLoaded(path) and self:GetFile(path)
+
+	if file_data and file_data.compiler and file_data.compiler.SyntaxTree then
+		local code_obj = file_data.code
+		local diag_name = code_obj and code_obj:GetName()
+
+		if diag_name then
+			local function collect_unreachable(node)
+				if not node then return end
+
+				if node.statements then
+					for _, child in ipairs(node.statements) do
+						if type(child) == "table" then
+							if child.Type then
+								-- It's a statement node
+								if child.Unreachable == true then
+									local start, stop = child:GetStartStop()
+
+									if start and stop then
+										diagnostics[diag_name] = diagnostics[diag_name] or {}
+										table.insert(
+											diagnostics[diag_name],
+											{
+												severity = "hint",
+												code = code_obj,
+												start = start,
+												stop = stop,
+												message = "unreachable code",
+												unreachable = true,
+											}
+										)
+									end
+								end
+
+								collect_unreachable(child)
+							else
+								-- It's an array of statements (e.g., if branch)
+								for _, stmt in ipairs(child) do
+									if type(stmt) == "table" and stmt.Type then
+										if stmt.Unreachable == true then
+											local start, stop = stmt:GetStartStop()
+
+											if start and stop then
+												diagnostics[diag_name] = diagnostics[diag_name] or {}
+												table.insert(
+													diagnostics[diag_name],
+													{
+														severity = "hint",
+														code = code_obj,
+														start = start,
+														stop = stop,
+														message = "unreachable code",
+														unreachable = true,
+													}
+												)
+											end
+										end
+
+										collect_unreachable(stmt)
+									end
+								end
+							end
+						end
+					end
+				end
+			end
+
+			collect_unreachable(file_data.compiler.SyntaxTree)
+		end
+	end
+
 	for name, data in pairs(diagnostics) do
 		if #data > 0 then
 			self:OnDiagnostics(name, data)

language_server/lsp.lua

@@ -131,7 +131,7 @@ function editor_helper:OnDiagnostics(path, data)
 		local range = get_range(v.code, v.start, v.stop)
 		local tags
 
-		if v.message:find("is never used") then tags = {1} end
+		if v.message:find("is never used") or v.unreachable then tags = {1} end
 
 		diagnostics[i] = {
 			severity = DiagnosticSeverity[v.severity],
@@ -254,7 +254,6 @@ lsp.methods["textDocument/codeAction"] = function(params)
 
 	return actions
 end
-
 lsp.methods["nattlua/format"] = function(params)
 	local path = to_fs_path(params.textDocument.uri)
 	local code = editor_helper:Format(params.code, path)
@@ -828,4 +827,4 @@ function lsp.Call(params)
 	if lsp.methods[params.method] then lsp.methods[params.method](params) end
 end
 
-return lsp
+return lsp

nattlua/analyzer/statements/if.lua

@@ -73,6 +73,10 @@ return {
 									self:ConstantIfExpressionWarning(nil, og_statement.tokens["if/else/elseif"][i])
 									self:PopCurrentExpression()
 								end
+
+								for _, stmt in ipairs(statements) do
+									if stmt.Unreachable == nil then stmt:SetUnreachable(true) end
+								end
 							end
 						end
 					else

test/tests/language_server/integration.lua

@@ -298,3 +298,100 @@ do
 	test_hover("local a = |(1)", "1")
 	test_hover("local a = (|1)", "1")
 end
+
+-- Test unreachable code is dimmed via Unnecessary diagnostic tag
+do
+	local client = LSPClient.New()
+	local root_uri = "file:///workspace"
+	client:SetWorkingDirectory("/workspace")
+	client:Initialize(lsp, root_uri)
+	local file_uri = root_uri .. "/test.nlua"
+	local code = [[
+if false then
+	local www = "hello"
+end
+]]
+	client:ClearNotifications()
+	client:Notify(
+		lsp,
+		"textDocument/didOpen",
+		{
+			textDocument = {
+				uri = file_uri,
+				languageId = "nattlua",
+				version = 1,
+				text = code,
+			},
+		}
+	)
+	local diag_notifications = client:GetNotifications("textDocument/publishDiagnostics")
+	assert(#diag_notifications > 0, "Should have publishDiagnostics notifications")
+	local found_unnecessary = false
+
+	for _, notif in ipairs(diag_notifications) do
+		for _, diag in ipairs(notif.params.diagnostics) do
+			if diag.tags then
+				for _, tag in ipairs(diag.tags) do
+					if tag == 1 and diag.message:find("unreachable") then
+						found_unnecessary = true
+					end
+				end
+			end
+		end
+	end
+
+	assert(
+		found_unnecessary,
+		"Unreachable code inside 'if false' should produce a diagnostic with Unnecessary tag (1)"
+	)
+end
+
+-- Test unreachable code in else-branch when condition is always true
+do
+	local client = LSPClient.New()
+	local root_uri = "file:///workspace"
+	client:SetWorkingDirectory("/workspace")
+	client:Initialize(lsp, root_uri)
+	local file_uri = root_uri .. "/test.nlua"
+	local code = [[
+local x = true
+if x then
+	local alive = "reachable"
+else
+	local dead = "unreachable"
+end
+]]
+	client:ClearNotifications()
+	client:Notify(
+		lsp,
+		"textDocument/didOpen",
+		{
+			textDocument = {
+				uri = file_uri,
+				languageId = "nattlua",
+				version = 1,
+				text = code,
+			},
+		}
+	)
+	local diag_notifications = client:GetNotifications("textDocument/publishDiagnostics")
+	assert(#diag_notifications > 0, "Should have publishDiagnostics notifications")
+	local found_unnecessary = false
+
+	for _, notif in ipairs(diag_notifications) do
+		for _, diag in ipairs(notif.params.diagnostics) do
+			if diag.tags then
+				for _, tag in ipairs(diag.tags) do
+					if tag == 1 and diag.message:find("unreachable") then
+						found_unnecessary = true
+					end
+				end
+			end
+		end
+	end
+
+	assert(
+		found_unnecessary,
+		"Unreachable else-branch when condition is always true should produce a diagnostic with Unnecessary tag (1)"
+	)
+end