fix(codegen): dedupe pure annotation comments (#4862)

Close https://github.com/oxc-project/oxc/issues/4843

crates/oxc_codegen/src/annotation_comment.rs

@@ -1,6 +1,7 @@
 use daachorse::DoubleArrayAhoCorasick;
 use once_cell::sync::Lazy;
 use oxc_ast::{Comment, CommentKind};
+use oxc_span::Span;
 
 use crate::Codegen;
 static MATCHER: Lazy<DoubleArrayAhoCorasick<usize>> = Lazy::new(|| {
@@ -9,8 +10,46 @@ static MATCHER: Lazy<DoubleArrayAhoCorasick<usize>> = Lazy::new(|| {
     DoubleArrayAhoCorasick::new(patterns).unwrap()
 });
 
+bitflags::bitflags! {
+    /// In theory this should be a enum,but using bitflags is easy to merge many flags into one
+    /// bitset, which is used to unique annotation comment in codegen
+    #[derive(Debug, Default, Clone, Copy)]
+    pub(crate) struct AnnotationKind: u8 {
+        const NO_SIDE_EFFECTS = 1 << 0;
+        const PURE = 1 << 1;
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct AnnotationComment {
+    pub(crate) annotation_kind: AnnotationKind,
+    pub(crate) comment: Comment,
+}
+
+impl AnnotationComment {
+    pub fn annotation_kind(&self) -> AnnotationKind {
+        self.annotation_kind
+    }
+
+    pub fn span(&self) -> Span {
+        self.comment.span
+    }
+    pub fn kind(&self) -> CommentKind {
+        self.comment.kind
+    }
+}
+
+impl From<(Comment, AnnotationKind)> for AnnotationComment {
+    fn from(value: (Comment, AnnotationKind)) -> Self {
+        Self { annotation_kind: value.1, comment: value.0 }
+    }
+}
+
 impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
-    pub(crate) fn get_leading_annotate_comment(&mut self, node_start: u32) -> Option<Comment> {
+    pub(crate) fn get_leading_annotate_comment(
+        &mut self,
+        node_start: u32,
+    ) -> Option<AnnotationComment> {
         let maybe_leading_comment = self.try_get_leading_comment(node_start);
         let comment = maybe_leading_comment?;
         if self.latest_consumed_comment_end >= comment.span.end {
@@ -26,8 +65,13 @@ impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
         if content_between.chars().all(|ch| ch.is_ascii_whitespace()) {
             let comment_content =
                 &source_code[comment.span.start as usize..comment.span.end as usize];
-            if MATCHER.find_iter(&comment_content).next().is_some() {
+            if let Some(m) = MATCHER.find_iter(&comment_content).next() {
-                return Some(*comment);
+                let annotation_kind = match m.value() {
+                    0 | 1 => AnnotationKind::NO_SIDE_EFFECTS,
+                    2 | 3 => AnnotationKind::PURE,
+                    _ => unreachable!(),
+                };
+                return Some((*comment, annotation_kind).into());
             }
             None
         } else {
@@ -35,7 +79,7 @@ impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
         }
     }
 
-    pub(crate) fn print_comment(&mut self, comment: Comment) {
+    pub(crate) fn print_comment(&mut self, comment: AnnotationComment) {
         // ```js
         // /*#__PURE__*/
         // Object.getOwnPropertyNames(Symbol)
@@ -48,15 +92,16 @@ impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
         // ```
         // in this example, `Object.getOwnPropertyNames(Symbol)` and `Object.getOwnPropertyNames(Symbol).filter()`, `Object.getOwnPropertyNames(Symbol).filter().map()`
         // share the same leading comment. since they both are call expr and has same span start, we need to avoid print the same comment multiple times.
-        if self.latest_consumed_comment_end >= comment.span.end {
+        let comment_span = comment.span();
+        if self.latest_consumed_comment_end >= comment_span.end {
             return;
         }
-        self.latest_consumed_comment_end = comment.span.end;
+        self.latest_consumed_comment_end = comment_span.end;
-        match comment.kind {
+        match comment.kind() {
             CommentKind::SingleLine => {
                 self.print_str("//");
                 self.print_range_of_source_code(
-                    comment.span.start as usize..comment.span.end as usize,
+                    comment_span.start as usize..comment_span.end as usize,
                 );
                 self.print_soft_newline();
                 self.print_indent();
@@ -64,7 +109,7 @@ impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
             CommentKind::MultiLine => {
                 self.print_str("/*");
                 self.print_range_of_source_code(
-                    comment.span.start as usize..comment.span.end as usize,
+                    comment_span.start as usize..comment_span.end as usize,
                 );
                 self.print_str("*/");
                 self.print_soft_space();
@@ -74,16 +119,25 @@ impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
         self.start_of_default_export = self.code_len();
     }
 
-    pub(crate) fn gen_comment(&mut self, node_start: u32) {
+    pub(crate) fn gen_comments(&mut self, node_start: u32) {
         if !self.comment_options.preserve_annotate_comments {
             return;
         }
+        let mut annotation_kind_set = AnnotationKind::empty();
         if let Some(comment) = self.try_take_moved_comment(node_start) {
-            self.print_comment(comment);
+            let kind = comment.annotation_kind();
+            if !annotation_kind_set.intersects(kind) {
+                annotation_kind_set.insert(kind);
+                self.print_comment(comment);
+            }
         }
         let maybe_leading_annotate_comment = self.get_leading_annotate_comment(node_start);
         if let Some(comment) = maybe_leading_annotate_comment {
-            self.print_comment(comment);
+            let kind = comment.annotation_kind();
+            if !annotation_kind_set.intersects(kind) {
+                annotation_kind_set.insert(kind);
+                self.print_comment(comment);
+            }
         }
     }
 }

crates/oxc_codegen/src/gen.rs

@@ -632,7 +632,7 @@ impl<'a, const MINIFY: bool> Gen<MINIFY> for Function<'a> {
     fn gen(&self, p: &mut Codegen<{ MINIFY }>, ctx: Context) {
         let n = p.code_len();
         let wrap = self.is_expression() && (p.start_of_stmt == n || p.start_of_default_export == n);
-        p.gen_comment(self.span.start);
+        p.gen_comments(self.span.start);
         p.wrap(wrap, |p| {
             p.print_space_before_identifier();
             p.add_source_mapping(self.span.start);
@@ -868,7 +868,7 @@ impl<'a, const MINIFY: bool> Gen<MINIFY> for ExportNamedDeclaration<'a> {
         if p.comment_options.preserve_annotate_comments {
             match &self.declaration {
                 Some(Declaration::FunctionDeclaration(_)) => {
-                    p.gen_comment(self.span.start);
+                    p.gen_comments(self.span.start);
                 }
                 Some(Declaration::VariableDeclaration(var_decl))
                     if matches!(var_decl.kind, VariableDeclarationKind::Const) =>
@@ -1638,7 +1638,7 @@ impl<'a, const MINIFY: bool> Gen<MINIFY> for PropertyKey<'a> {
 impl<'a, const MINIFY: bool> GenExpr<MINIFY> for ArrowFunctionExpression<'a> {
     fn gen_expr(&self, p: &mut Codegen<{ MINIFY }>, precedence: Precedence, ctx: Context) {
         p.wrap(precedence >= Precedence::Assign, |p| {
-            p.gen_comment(self.span.start);
+            p.gen_comments(self.span.start);
             if self.r#async {
                 p.add_source_mapping(self.span.start);
                 p.print_str("async");

crates/oxc_codegen/src/lib.rs

@@ -35,6 +35,8 @@ pub use crate::{
     gen::{Gen, GenExpr},
 };
 
+use self::annotation_comment::AnnotationComment;
+
 /// Code generator without whitespace removal.
 pub type CodeGenerator<'a> = Codegen<'a, false>;
 
@@ -519,7 +521,7 @@ impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
     }
 }
 
-pub(crate) type MoveCommentMap = FxHashMap<u32, Comment>;
+pub(crate) type MoveCommentMap = FxHashMap<u32, AnnotationComment>;
 
 // Comment related
 impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
@@ -543,7 +545,7 @@ impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
     ///
     ///  }, b = 10000;
     /// ```
-    fn move_comment(&mut self, position: u32, full_comment_info: Comment) {
+    fn move_comment(&mut self, position: u32, full_comment_info: AnnotationComment) {
         self.move_comment_map.insert(position, full_comment_info);
     }
 
@@ -551,7 +553,7 @@ impl<'a, const MINIFY: bool> Codegen<'a, MINIFY> {
         self.trivias.comments_range(0..start).next_back()
     }
 
-    fn try_take_moved_comment(&mut self, node_start: u32) -> Option<Comment> {
+    fn try_take_moved_comment(&mut self, node_start: u32) -> Option<AnnotationComment> {
         self.move_comment_map.remove(&node_start)
     }
 }

crates/oxc_codegen/tests/integration/pure_comments.rs

@@ -184,4 +184,18 @@ const builtInSymbols = new Set(
     test("(/* @__PURE__ */ new Foo()).bar();\n", "(/* @__PURE__ */ new Foo()).bar();\n");
 
     test("(/* @__PURE__ */ Foo()).bar();\n", "(/* @__PURE__ */ Foo()).bar();\n");
+
+    // https://github.com/oxc-project/oxc/issues/4843
+    test(
+        r"
+/* #__NO_SIDE_EFFECTS__ */
+const defineSSRCustomElement = /* @__NO_SIDE_EFFECTS__ */ (
+	options,
+	extraOptions,
+) => {
+	return /* @__PURE__ */ defineCustomElement(options, extraOptions, hydrate);
+};
+",
+        "const defineSSRCustomElement = /* #__NO_SIDE_EFFECTS__ */ (options, extraOptions) => {\n\treturn /* @__PURE__ */ defineCustomElement(options, extraOptions, hydrate);\n};\n",
+    );
 }