Fix unstable formatting around comments in type declarations

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed shape calculation of the RHS of a binary expression not correctly reset when hanging, causing it to expand unnecessarily ([#432](https://github.com/JohnnyMorganz/StyLua/issues/432))
 - Fixed unstable formatting of tables at column width boundary ([#436](https://github.com/JohnnyMorganz/StyLua/issues/436))
 - Fixed assignments no longer hanging at equals token if a comment is present, but the expression is not hangable at a binop. ([#439](https://github.com/JohnnyMorganz/StyLua/issues/439))
+- Fixed unstable formatting around comments within type declarations ([#397](https://github.com/JohnnyMorganz/StyLua/issues/397), [#430](https://github.com/JohnnyMorganz/StyLua/issues/430))
 
 ## [0.13.0] - 2022-03-31
 ### Added

src/formatters/trivia.rs

@@ -884,6 +884,28 @@ define_update_leading_trivia!(GenericDeclarationParameter, |this, leading| {
     this.to_owned().with_parameter(parameter_info)
 });
 
+#[cfg(feature = "luau")]
+define_update_trailing_trivia!(GenericDeclarationParameter, |this, trailing| {
+    if let Some(default_type) = this.default_type() {
+        let default_type = default_type.update_trailing_trivia(trailing);
+        this.to_owned()
+            .with_default(Some((this.equals().unwrap().to_owned(), default_type)))
+    } else {
+        let parameter_info = match this.parameter() {
+            GenericParameterInfo::Name(token) => {
+                GenericParameterInfo::Name(token.update_trailing_trivia(trailing))
+            }
+            GenericParameterInfo::Variadic { name, ellipse } => GenericParameterInfo::Variadic {
+                name: name.to_owned(),
+                ellipse: ellipse.update_trailing_trivia(trailing),
+            },
+            other => panic!("unknown node {:?}", other),
+        };
+
+        this.to_owned().with_parameter(parameter_info)
+    }
+});
+
 #[cfg(feature = "luau")]
 define_update_leading_trivia!(IfExpression, |this, leading| {
     this.to_owned()

src/formatters/trivia_util.rs

@@ -6,7 +6,10 @@ use crate::{
 #[cfg(feature = "luau")]
 use full_moon::ast::span::ContainedSpan;
 #[cfg(feature = "luau")]
-use full_moon::ast::types::{IndexedTypeInfo, TypeArgument, TypeDeclaration, TypeInfo};
+use full_moon::ast::types::{
+    GenericDeclarationParameter, GenericParameterInfo, IndexedTypeInfo, TypeArgument,
+    TypeDeclaration, TypeInfo,
+};
 use full_moon::ast::{Block, FunctionBody, Parameter};
 use full_moon::{
     ast::{
@@ -225,6 +228,38 @@ pub fn type_info_trailing_trivia(type_info: &TypeInfo) -> Vec<Token> {
     }
 }
 
+#[cfg(feature = "luau")]
+fn generic_declaration_parameter_trailing_trivia(
+    parameter: &GenericDeclarationParameter,
+) -> Vec<Token> {
+    if let Some(default_type) = parameter.default_type() {
+        type_info_trailing_trivia(default_type)
+    } else {
+        match parameter.parameter() {
+            GenericParameterInfo::Name(token) => token.trailing_trivia().cloned().collect(),
+            GenericParameterInfo::Variadic { ellipse, .. } => {
+                ellipse.trailing_trivia().cloned().collect()
+            }
+            other => panic!("unknown node {:?}", other),
+        }
+    }
+}
+
+#[cfg(feature = "luau")]
+pub fn take_generic_parameter_trailing_comments(
+    parameter: &GenericDeclarationParameter,
+) -> (GenericDeclarationParameter, Vec<Token>) {
+    let trailing_comments = generic_declaration_parameter_trailing_trivia(parameter)
+        .iter()
+        .filter(|x| trivia_is_comment(x))
+        .cloned()
+        .collect();
+    (
+        parameter.update_trailing_trivia(FormatTriviaType::Replace(vec![])),
+        trailing_comments,
+    )
+}
+
 fn var_trailing_trivia(var: &Var) -> Vec<Token> {
     match var {
         Var::Name(token_reference) => token_reference

tests/inputs-luau/type-comments-2.lua

@@ -0,0 +1,39 @@
+-- https://github.com/JohnnyMorganz/StyLua/issues/397
+
+--[[opening type comment]]
+type Doo<
+	T --[[ per-generic argument comment]]
+> =
+	--[[ opening RHS comment]]
+	string --[[ per-RHS comment]]
+
+type Foo<T = --[[leading]]
+string
+--[[trailing]]> = { baz: T, }
+
+type Bar<T
+--[[ Trailing comment ]]> = {}
+
+-- This is a comment before
+type Foo = --[[ Comment before Bar ]]
+Bar<--[[ Before X ]]
+X, --[[ After X ]]
+--[[ Before Y ]]
+Y, --[[ After Y ]]
+--[[ Before Z ]]
+Z
+--[[ After Z ]]> -- This is a comment after
+
+--[[comment]]
+type Doo
+--[[comment]]
+<
+--[[comment]]
+T
+--[[comment]]
+>
+--[[comment]]
+=
+--[[comment]]
+string
+--[[comment]]

tests/snapshots/tests__luau@type-comments-2.lua.snap

@@ -0,0 +1,47 @@
+---
+source: tests/tests.rs
+assertion_line: 30
+expression: format(&contents)
+
+---
+-- https://github.com/JohnnyMorganz/StyLua/issues/397
+
+--[[opening type comment]]
+type Doo<
+	T--[[ per-generic argument comment]]
+> =
+	--[[ opening RHS comment]]
+	string --[[ per-RHS comment]]
+
+type Foo<
+	T = --[[leading]]
+		string
+	--[[trailing]]
+> = { baz: T }
+
+type Bar<
+	T
+	--[[ Trailing comment ]]
+> = {}
+
+-- This is a comment before
+type Foo = --[[ Comment before Bar ]]
+	Bar<--[[ Before X ]]
+		X, --[[ After X ]]
+		--[[ Before Y ]]
+		Y, --[[ After Y ]]
+		--[[ Before Z ]]
+		Z
+		--[[ After Z ]]
+	> -- This is a comment after
+
+--[[comment]]
+type Doo --[[comment]] <
+	--[[comment]]
+	T
+	--[[comment]]
+> --[[comment]] =
+	--[[comment]]
+	string
+--[[comment]]
+

tests/snapshots/tests__luau@type-multiline-comments.lua.snap

@@ -6,25 +6,26 @@ expression: format(&contents)
 ---
 -- Shouldn't hang since multiline comments arent an issue
 
-export type GraphQLEnumType =  --[[ <T> ]]{
-	name: string,
-	description: string?,
-	extensions: ReadOnlyObjMap<any>?,
-	astNode: EnumTypeDefinitionNode?,
-	extensionASTNodes: Array<EnumTypeExtensionNode>?,
+export type GraphQLEnumType = --[[ <T> ]]
+	{
+		name: string,
+		description: string?,
+		extensions: ReadOnlyObjMap<any>?,
+		astNode: EnumTypeDefinitionNode?,
+		extensionASTNodes: Array<EnumTypeExtensionNode>?,
 
-	_values: Array<GraphQLEnumValue --[[ <T> ]]>,
-	_valueLookup: Map<any --[[ T ]], GraphQLEnumValue>,
-	_nameLookup: ObjMap<GraphQLEnumValue>,
-	-- ROBLOX deviation: add self parameter for all ':' operator methods
-	getValues: (self: GraphQLEnumType) -> Array<GraphQLEnumValue --[[ <T> ]]>,
-	getValue: (self: GraphQLEnumType, string) -> GraphQLEnumValue?,
-	serialize: (
-		self: GraphQLEnumType,
-		any --[[ T ]]
-	) -> string?,
-	parseValue: (self: GraphQLEnumType, any) -> any?, --[[ T ]]
-	parseLiteral: (self: GraphQLEnumType, ValueNode, ObjMap<any>?) -> any?, --[[ T ]]
-	toConfig: (self: GraphQLEnumType) -> GraphQLEnumTypeNormalizedConfig,
-}
+		_values: Array<GraphQLEnumValue --[[ <T> ]]>,
+		_valueLookup: Map<any --[[ T ]], GraphQLEnumValue>,
+		_nameLookup: ObjMap<GraphQLEnumValue>,
+		-- ROBLOX deviation: add self parameter for all ':' operator methods
+		getValues: (self: GraphQLEnumType) -> Array<GraphQLEnumValue --[[ <T> ]]>,
+		getValue: (self: GraphQLEnumType, string) -> GraphQLEnumValue?,
+		serialize: (
+			self: GraphQLEnumType,
+			any --[[ T ]]
+		) -> string?,
+		parseValue: (self: GraphQLEnumType, any) -> any?, --[[ T ]]
+		parseLiteral: (self: GraphQLEnumType, ValueNode, ObjMap<any>?) -> any?, --[[ T ]]
+		toConfig: (self: GraphQLEnumType) -> GraphQLEnumTypeNormalizedConfig,
+	}