feat(formatter): correct printing for TSConditionalType

crates/oxc_formatter/src/formatter/comments.rs

@@ -128,17 +128,29 @@ pub struct Comments<'a> {
     /// The index of the type cast comment that has been printed already.
     /// Used to prevent duplicate processing of special TypeScript type cast comments.
     handled_type_cast_comment: usize,
+    /// Optional limit for the unprinted_comments view.
+    ///
+    /// When set, [`Self::unprinted_comments()`] will only return comments up to this index,
+    /// effectively hiding comments beyond this point from the formatter.
+    pub view_limit: Option<usize>,
 }
 
 impl<'a> Comments<'a> {
     pub fn new(source_text: SourceText<'a>, comments: &'a [Comment]) -> Self {
-        Comments { source_text, comments, printed_count: 0, handled_type_cast_comment: 0 }
+        Comments {
+            source_text,
+            comments,
+            printed_count: 0,
+            handled_type_cast_comment: 0,
+            view_limit: None,
+        }
     }
 
     /// Returns comments that have not been printed yet.
     #[inline]
     pub fn unprinted_comments(&self) -> &'a [Comment] {
-        &self.comments[self.printed_count..]
+        let end = self.view_limit.unwrap_or(self.comments.len());
+        &self.comments[self.printed_count..end]
     }
 
     /// Returns comments that have already been printed.
@@ -486,6 +498,34 @@ impl<'a> Comments<'a> {
     pub fn is_already_handled_type_cast_comment(&self) -> bool {
         self.printed_count == self.handled_type_cast_comment
     }
+
+    /// Temporarily limits the unprinted comments view to only those before the given position.
+    /// Returns the previous view limit to allow restoration.
+    pub fn limit_comments_up_to(&mut self, end_pos: u32) -> Option<usize> {
+        // Save the original limit for restoration
+        let original_limit = self.view_limit;
+
+        // Find the index of the first comment that starts at or after end_pos
+        // Using binary search would be more efficient for large comment arrays
+        let limit_index = self.comments[self.printed_count..]
+            .iter()
+            .position(|c| c.span.start >= end_pos)
+            .map_or(self.comments.len(), |idx| self.printed_count + idx);
+
+        // Only update if we're actually limiting the view
+        if limit_index < self.comments.len() {
+            self.view_limit = Some(limit_index);
+        }
+
+        original_limit
+    }
+
+    /// Restores the view limit to a previously saved value.
+    /// This is typically used after temporarily limiting the view with `limit_comments_up_to`.
+    #[inline]
+    pub fn restore_view_limit(&mut self, limit: Option<usize>) {
+        self.view_limit = limit;
+    }
 }
 
 /// Checks if a pattern matches at the given position.

crates/oxc_formatter/src/utils/conditional.rs

@@ -7,7 +7,7 @@ use crate::{
     Format, FormatResult, FormatWrite,
     formatter::{Formatter, prelude::*, trivia::FormatTrailingComments},
     generated::ast_nodes::{AstNode, AstNodes},
-    utils::expression::FormatExpressionWithoutTrailingComments,
+    utils::format_node_without_trailing_comments::FormatNodeWithoutTrailingComments,
     write,
 };
 
@@ -171,32 +171,35 @@ impl<'a> FormatConditionalLike<'a, '_> {
     fn layout(&self, f: &mut Formatter<'_, 'a>) -> ConditionalLayout {
         let self_span = self.span();
 
-        let (is_test, is_consequent) = match self.parent() {
+        match self.parent() {
             AstNodes::ConditionalExpression(parent) => {
                 let parent_expr = parent.as_ref();
-                (parent_expr.test.span() == self_span, parent_expr.consequent.span() == self_span)
+                if parent_expr.test.span() == self_span {
+                    ConditionalLayout::NestedTest
+                } else if parent_expr.consequent.span() == self_span {
+                    ConditionalLayout::NestedConsequent
+                } else {
+                    ConditionalLayout::NestedAlternate
+                }
             }
             AstNodes::TSConditionalType(parent) => {
                 let parent_type = parent.as_ref();
                 // For TS conditional types, both check_type and extends_type are part of the test
                 let is_test = parent_type.check_type.span() == self_span
                     || parent_type.extends_type.span() == self_span;
-                let is_consequent = parent_type.true_type.span() == self_span;
-                (is_test, is_consequent)
+                if is_test {
+                    ConditionalLayout::NestedTest
+                } else if parent_type.true_type.span() == self_span {
+                    ConditionalLayout::NestedConsequent
+                } else {
+                    ConditionalLayout::NestedAlternate
+                }
             }
             _ => {
                 let jsx_chain =
                     f.context().source_type().is_jsx() && self.is_jsx_conditional_chain();
-                return ConditionalLayout::Root { jsx_chain };
+                ConditionalLayout::Root { jsx_chain }
             }
-        };
-
-        if is_test {
-            ConditionalLayout::NestedTest
-        } else if is_consequent {
-            ConditionalLayout::NestedConsequent
-        } else {
-            ConditionalLayout::NestedAlternate
         }
     }
 
@@ -374,7 +377,7 @@ impl<'a> FormatConditionalLike<'a, '_> {
     ) -> FormatResult<()> {
         let format_inner = format_with(|f| match self.conditional {
             ConditionalLike::ConditionalExpression(conditional) => {
-                write!(f, FormatExpressionWithoutTrailingComments(conditional.test()))?;
+                write!(f, FormatNodeWithoutTrailingComments(conditional.test()))?;
                 format_trailing_comments(
                     conditional.test.span().end,
                     conditional.consequent.span().start,
@@ -390,8 +393,15 @@ impl<'a> FormatConditionalLike<'a, '_> {
                         space(),
                         "extends",
                         space(),
-                        conditional.extends_type()
+                        FormatNodeWithoutTrailingComments(conditional.extends_type())
                     ]
+                )?;
+
+                format_trailing_comments(
+                    conditional.extends_type.span().end,
+                    conditional.true_type.span().start,
+                    b'?',
+                    f,
                 )
             }
         });
@@ -411,53 +421,60 @@ impl<'a> FormatConditionalLike<'a, '_> {
     ) -> FormatResult<()> {
         write!(f, [soft_line_break_or_space(), "?", space()])?;
 
-        let format_consequent = format_with(|f| match self.conditional {
-            ConditionalLike::ConditionalExpression(conditional) => {
-                let is_consequent_nested = match self.conditional {
+        let format_consequent = format_with(|f| {
+            let format_consequent_with_trailing_comments =
+                format_once(|f| match self.conditional {
                     ConditionalLike::ConditionalExpression(conditional) => {
-                        matches!(conditional.consequent, Expression::ConditionalExpression(_))
+                        write!(f, FormatNodeWithoutTrailingComments(conditional.consequent()))?;
+                        format_trailing_comments(
+                            conditional.consequent.span().end,
+                            conditional.alternate.span().start,
+                            b':',
+                            f,
+                        )
                     }
                     ConditionalLike::TSConditionalType(conditional) => {
-                        matches!(conditional.true_type, TSType::TSConditionalType(_))
-                    }
-                };
-
-                let format_consequent = format_once(|f| {
-                    write!(f, FormatExpressionWithoutTrailingComments(conditional.consequent()))?;
-                    format_trailing_comments(
-                        conditional.consequent.span().end,
-                        conditional.alternate.span().start,
-                        b':',
-                        f,
-                    )
-                });
-
-                let format_consequent = format_with(|f| {
-                    if f.options().indent_style.is_space() {
-                        write!(f, [align(2, &format_consequent)])
-                    } else {
-                        write!(f, [indent(&format_consequent)])
+                        write!(f, FormatNodeWithoutTrailingComments(conditional.true_type()))?;
+                        format_trailing_comments(
+                            conditional.true_type.span().end,
+                            conditional.false_type.span().start,
+                            b':',
+                            f,
+                        )
                     }
                 });
 
-                if is_consequent_nested {
-                    // Add parentheses around the consequent if it is a conditional expression and fits on the same line
-                    // so that it's easier to identify the parts that belong to a conditional expression.
-                    // `a ? b ? c: d : e` -> `a ? (b ? c: d) : e`
-                    write!(
-                        f,
-                        [
-                            if_group_fits_on_line(&text("(")),
-                            format_consequent,
-                            if_group_fits_on_line(&text(")"))
-                        ]
-                    )
+            let format_consequent_with_proper_indentation = format_with(|f| {
+                if f.options().indent_style.is_space() {
+                    write!(f, [align(2, &format_consequent_with_trailing_comments)])
                 } else {
-                    write!(f, format_consequent)
+                    write!(f, [indent(&format_consequent_with_trailing_comments)])
                 }
-            }
-            ConditionalLike::TSConditionalType(conditional) => {
-                write!(f, [conditional.true_type()])
+            });
+
+            let is_nested_consequent = match self.conditional {
+                ConditionalLike::ConditionalExpression(conditional) => {
+                    matches!(conditional.consequent, Expression::ConditionalExpression(_))
+                }
+                ConditionalLike::TSConditionalType(conditional) => {
+                    matches!(conditional.true_type, TSType::TSConditionalType(_))
+                }
+            };
+
+            if is_nested_consequent {
+                // Add parentheses around the consequent if it is a conditional expression and fits on the same line
+                // so that it's easier to identify the parts that belong to a conditional expression.
+                // `a ? b ? c: d : e` -> `a ? (b ? c: d) : e`
+                write!(
+                    f,
+                    [
+                        if_group_fits_on_line(&text("(")),
+                        format_consequent_with_proper_indentation,
+                        if_group_fits_on_line(&text(")"))
+                    ]
+                )
+            } else {
+                write!(f, format_consequent_with_proper_indentation)
             }
         });
 
@@ -662,7 +679,7 @@ impl<'a> Format<'a> for FormatJsxChainExpression<'a, '_> {
                 }
                 .fmt(f)
             } else {
-                FormatExpressionWithoutTrailingComments(self.expression).fmt(f)
+                FormatNodeWithoutTrailingComments(self.expression).fmt(f)
             }
         });