fix(table,function): doc-commented function as table value

CHANGELOG.md

@@ -7,6 +7,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Correct indentation for a documented function defined as table value ([#942](https://github.com/JohnnyMorganz/StyLua/issues/942))
+
+```lua
+local t = {
+	plus_one =
+		---@param n number
+		---@return number
+		function(n)
+			return n + 1
+		end,
+}
+```
+
 ### Added
 
 - Luau: Added support for parsing user-defined type functions ([#938](https://github.com/JohnnyMorganz/StyLua/issues/938))

src/formatters/table.rs

@@ -34,7 +34,20 @@ pub enum TableType {
     Empty,
 }
 
+/// Detect function with leading comments/doc-comments when used as a table value
+/// Such (anonymous) function definition gets formatted differently, in a separate line line
+fn is_function_with_leading_trivia(expression: &Expression) -> bool {
+    match expression {
+        Expression::Function(anonymous_function) => {
+            !trivia_util::GetLeadingTrivia::leading_trivia(&anonymous_function.0).is_empty()
+        }
+        _ => false,
+    }
+}
+
 /// Formats an Expression value part of a k,v field pair
+/// If value is an anonymous function with trivia, will prepend a newline so the trivia will align
+/// to the function definition
 fn format_field_expression_value(
     ctx: &Context,
     expression: &Expression,
@@ -64,6 +77,14 @@ fn format_field_expression_value(
             }
         }
     } else {
+        if is_function_with_leading_trivia(expression) {
+            let incr_shape = shape.increment_additional_indent();
+            let incr_leading_trivia = vec![create_indent_trivia(ctx, incr_shape)];
+            let formatted_expr = format_expression(ctx, expression, incr_shape)
+                .update_trailing_trivia(trailing_trivia)
+                .update_leading_trivia(FormatTriviaType::Append(incr_leading_trivia));
+            return trivia_util::prepend_newline_indent(ctx, &formatted_expr, incr_shape);
+        }
         format_expression(ctx, expression, shape).update_trailing_trivia(trailing_trivia)
     }
 }
@@ -205,6 +226,15 @@ fn format_field(
             let shape = shape + (strip_trivia(&key).to_string().len() + 3); // 3 = " = "
             let value = format_field_expression_value(ctx, value, shape);
 
+            let equal = if is_function_with_leading_trivia(&value) {
+                // function definition goes in the next line, so we remove space between = and newline
+                equal.update_trailing_trivia(FormatTriviaType::Replace(vec![Token::new(
+                    TokenType::spaces(0),
+                )]))
+            } else {
+                equal
+            };
+
             Field::NameKey { key, equal, value }
         }
         Field::NoKey(expression) => {

tests/inputs/function-as-table-value-in-mixed-def.lua

@@ -0,0 +1,14 @@
+local mixed = {
+	--- identity
+	---@param n number
+	---@return number
+	function(n)
+		return n
+	end,
+	plus_one =
+		---@param n number
+		---@return number
+		function(n)
+			return n + 1
+		end,
+}

tests/inputs/function-as-table-value.lua

@@ -0,0 +1,9 @@
+-- https://github.com/JohnnyMorganz/StyLua/issues/942
+local t = {
+	plus_one =
+		---@param n number
+		---@return number
+		function(n)
+			return n + 1
+		end,
+}

tests/snapshots/tests__standard@function-as-table-value-in-mixed-def.lua.snap

@@ -0,0 +1,21 @@
+---
+source: tests/tests.rs
+assertion_line: 21
+expression: "format(&contents, LuaVersion::Lua51)"
+input_file: tests/inputs/function-as-table-value-in-mixed-def.lua
+---
+local mixed = {
+	--- identity
+	---@param n number
+	---@return number
+		function(n)
+		return n
+	end,
+	plus_one =
+		---@param n number
+		---@return number
+		function(n)
+			return n + 1
+		end,
+}
+

tests/snapshots/tests__standard@function-as-table-value.lua.snap

@@ -0,0 +1,16 @@
+---
+source: tests/tests.rs
+assertion_line: 18
+expression: "format(&contents, LuaVersion::Lua51)"
+input_file: tests/inputs/function-as-table-value.lua
+---
+-- https://github.com/JohnnyMorganz/StyLua/issues/942
+local t = {
+	plus_one =
+		---@param n number
+		---@return number
+		function(n)
+			return n + 1
+		end,
+}
+