Check for inline comments that will force hanging in function arguments

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed goto not being recognised for LuaJIT ([#986](https://github.com/JohnnyMorganz/StyLua/issues/986))
 - Fixed semicolon removed after a statement ending with an if-expression leading to ambiguous syntax when the next line begins with parentheses ([#1010](https://github.com/JohnnyMorganz/StyLua/issues/1010))
 - Luau: Fixed malformed formatting when there is a comment after a type specifier in a local assignment ([#995](https://github.com/JohnnyMorganz/StyLua/issues/995))
+- Fixed malformed formatting when a binary expression inside of a function call with comments around the operators is incorrectly collapsed onto one line ([#996](https://github.com/JohnnyMorganz/StyLua/issues/996))
 
 ## [2.1.0] - 2025-04-21
 

src/formatters/functions.rs

@@ -147,11 +147,13 @@ fn function_args_contains_comments(
         true
     } else {
         arguments.pairs().any(|argument| {
-            // Leading / Trailing trivia of expression (ignore inline comments)
+            // Leading / Trailing trivia of expression
             argument.value().leading_trivia()
                 .iter()
                 .chain(argument.value().trailing_trivia().iter())
                 .any(function_trivia_contains_comments)
+            // Inline comments that will force hanging
+            || argument.value().has_inline_comments()
             // Punctuation contains comments
             || argument
                 .punctuation()

tests/inputs/hang-binop-comments-3.lua

@@ -0,0 +1,10 @@
+-- https://github.com/JohnnyMorganz/StyLua/issues/996
+
+local function f()
+  local a = "ab"
+  a = a:gsub("a".. -- "
+    'b', function() return "c" end)
+  print(a)
+end
+
+f()

tests/snapshots/tests__standard@hang-binop-comments-3.lua.snap

@@ -0,0 +1,20 @@
+---
+source: tests/tests.rs
+expression: "format(&contents, LuaVersion::Lua51)"
+input_file: tests/inputs/hang-binop-comments-3.lua
+---
+-- https://github.com/JohnnyMorganz/StyLua/issues/996
+
+local function f()
+	local a = "ab"
+	a = a:gsub(
+		"a" -- "
+			.. "b",
+		function()
+			return "c"
+		end
+	)
+	print(a)
+end
+
+f()