feat(prettier): add parens to conditional and arrow expr (#1530)

crates/oxc_ast/src/ast/js.rs

@@ -1611,6 +1611,18 @@ pub struct ArrowExpression<'a> {
     pub return_type: Option<Box<'a, TSTypeAnnotation<'a>>>,
 }
 
+impl<'a> ArrowExpression<'a> {
+    /// Get expression part of `ArrowExpression`: `() => expression_part`.
+    pub fn get_expression(&self) -> Option<&Expression<'a>> {
+        if self.expression {
+            if let Statement::ExpressionStatement(expr_stmt) = &self.body.statements[0] {
+                return Some(&expr_stmt.expression);
+            }
+        }
+        None
+    }
+}
+
 /// Generator Function Definitions
 #[derive(Debug, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize), serde(tag = "type"))]

crates/oxc_prettier/src/needs_parens.rs

@@ -11,7 +11,7 @@
 use oxc_ast::{
     ast::{
         AssignmentTarget, AssignmentTargetPattern, ChainElement, ExportDefaultDeclarationKind,
-        Expression, ModuleDeclaration, SimpleAssignmentTarget,
+        Expression, ModuleDeclaration, ObjectExpression, SimpleAssignmentTarget,
     },
     AstKind,
 };
@@ -40,6 +40,12 @@ impl<'a> Prettier<'a> {
 
         let parent_kind = self.parent_kind();
 
+        if let AstKind::ObjectExpression(e) = kind {
+            if self.check_object_expression(e) {
+                return true;
+            }
+        }
+
         if self.check_parent_kind(kind, parent_kind) {
             return true;
         }
@@ -72,8 +78,9 @@ impl<'a> Prettier<'a> {
             AstKind::Class(c) if c.is_expression() => self.check_object_function_class(c.span),
             AstKind::AssignmentExpression(assign_expr) => match parent_kind {
                 AstKind::ArrowExpression(arrow_expr)
-                    if arrow_expr.expression
-                        && arrow_expr.body.statements[0].span() == assign_expr.span =>
+                    if arrow_expr
+                        .get_expression()
+                        .is_some_and(|e| e.span() == assign_expr.span) =>
                 {
                     true
                 }
@@ -136,6 +143,24 @@ impl<'a> Prettier<'a> {
             AstKind::TSNonNullExpression(e) => {
                 self.check_member_call_tagged_template_ts_non_null(e.span)
             }
+            AstKind::ConditionalExpression(e) => match parent_kind {
+                AstKind::TaggedTemplateExpression(_)
+                | AstKind::UnaryExpression(_)
+                | AstKind::SpreadElement(_)
+                | AstKind::BinaryExpression(_)
+                | AstKind::LogicalExpression(_)
+                | AstKind::ModuleDeclaration(ModuleDeclaration::ExportDefaultDeclaration(_))
+                | AstKind::AwaitExpression(_)
+                | AstKind::JSXSpreadAttribute(_)
+                | AstKind::TSAsExpression(_)
+                | AstKind::TSSatisfiesExpression(_)
+                | AstKind::TSNonNullExpression(_) => true,
+                AstKind::CallExpression(call_expr) => call_expr.callee.span() == e.span,
+                AstKind::NewExpression(new_expr) => new_expr.callee.span() == e.span,
+                AstKind::ConditionalExpression(cond_expr) => cond_expr.test.span() == e.span,
+                AstKind::MemberExpression(member_expr) => member_expr.object().span() == e.span,
+                _ => false,
+            },
             AstKind::Function(e) if e.is_expression() => match parent_kind {
                 AstKind::CallExpression(call_expr) => call_expr.callee.span() == e.span,
                 AstKind::NewExpression(new_expr) => new_expr.callee.span() == e.span,
@@ -206,6 +231,29 @@ impl<'a> Prettier<'a> {
         false
     }
 
+    fn check_object_expression(&self, obj_expr: &ObjectExpression<'a>) -> bool {
+        let mut arrow_expr = None;
+        for kind in self.nodes.iter().rev() {
+            if let AstKind::ArrowExpression(e) = kind {
+                if e.get_expression().is_some_and(|e| e.span() == obj_expr.span) {
+                    arrow_expr = Some(e);
+                    break;
+                }
+            }
+        }
+        if let Some(arrow_expr) = arrow_expr {
+            if let Some(e) = arrow_expr.get_expression() {
+                if !matches!(e, Expression::SequenceExpression(_))
+                    && !matches!(e, Expression::AssignmentExpression(_))
+                    && Self::starts_with_no_lookahead_token(e, obj_expr.span)
+                {
+                    return true;
+                }
+            }
+        }
+        false
+    }
+
     fn check_object_function_class(&self, span: Span) -> bool {
         for ast_kind in self.nodes.iter().rev() {
             if let AstKind::ExpressionStatement(e) = ast_kind {

tasks/prettier_conformance/prettier.snap.md

@@ -1,4 +1,4 @@
-Compatibility: 152/597 (25.46%)
+Compatibility: 155/597 (25.96%)
 
 # Failed
 
@@ -442,7 +442,6 @@ Compatibility: 152/597 (25.46%)
 * module-blocks/worker.js
 
 ### new-expression
-* new-expression/new_expression.js
 * new-expression/with-member-expression.js
 
 ### new-target
@@ -554,9 +553,6 @@ Compatibility: 152/597 (25.46%)
 * sequence-expression/ignore.js
 * sequence-expression/parenthesized.js
 
-### spread
-* spread/spread.js
-
 ### strings
 * strings/escaped.js
 * strings/multiline-literal.js
@@ -577,7 +573,6 @@ Compatibility: 152/597 (25.46%)
 * template/graphql.js
 * template/indent.js
 * template/inline.js
-* template/parenthesis.js
 
 ### template-align
 * template-align/indent.js