node:module: implement stripTypeScriptTypes

src/ast/ast_result.rs

@@ -92,6 +92,26 @@ pub struct Ast<'a> {
     pub has_commonjs_export_names: bool,
     pub has_import_meta: bool,
     pub import_meta_ref: Ref,
+
+    /// First non-ambient TypeScript construct with runtime semantics (not
+    /// erasable by type stripping). `node:module`'s `stripTypeScriptTypes`
+    /// rejects these in `'strip'` mode, matching Node's amaro/swc strip-only
+    /// behavior. `declare` contexts never set this.
+    pub ts_runtime_syntax: Option<TsRuntimeSyntax>,
+    /// An identifier-named `module Foo {}` declaration was parsed. Node's
+    /// `stripTypeScriptTypes` rejects the `module` keyword in both modes
+    /// (string-named `declare module "foo"` is ambient and allowed).
+    pub uses_ts_module_keyword: bool,
+}
+
+/// TypeScript syntax with runtime semantics; see `Ast::ts_runtime_syntax`.
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+pub enum TsRuntimeSyntax {
+    Enum,
+    Namespace,
+    ParameterProperty,
+    ImportEquals,
+    ExportAssignment,
 }
 
 // `parts`/`symbols`/`import_records` are now `ArenaVec`s and need an allocator,
@@ -137,6 +157,8 @@ impl<'a> Ast<'a> {
             has_commonjs_export_names: false,
             has_import_meta: false,
             import_meta_ref: Ref::NONE,
+            ts_runtime_syntax: None,
+            uses_ts_module_keyword: false,
         }
     }
 }

src/ast/lib.rs

@@ -3193,7 +3193,7 @@ pub mod target;
 
 pub use ast_result::{
     Ast, CommonJSNamedExport, CommonJSNamedExports, ConstValuesMap, NamedExports, NamedImports,
-    TopLevelSymbolToParts, TsEnumsMap,
+    TopLevelSymbolToParts, TsEnumsMap, TsRuntimeSyntax,
 };
 pub use import_record::{
     Flags as ImportRecordFlags, ImportRecord, PrintMode as ImportRecordPrintMode,

src/js_parser/p.rs

@@ -242,6 +242,10 @@ pub struct P<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> {
     pub latest_return_had_semicolon: bool,
     pub has_import_meta: bool,
     pub has_es_module_syntax: bool,
+    /// See `Ast::ts_runtime_syntax`; records the first occurrence.
+    pub ts_runtime_syntax: Option<bun_ast::TsRuntimeSyntax>,
+    /// See `Ast::uses_ts_module_keyword`.
+    pub uses_ts_module_keyword: bool,
     pub top_level_await_keyword: bun_ast::Range,
     pub fn_or_arrow_data_parse: FnOrArrowDataParse,
     pub fn_or_arrow_data_visit: FnOrArrowDataVisit,
@@ -8283,6 +8287,15 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
 // independently. `compute_character_frequency` is fully un-gated
 // (lexer.all_comments + CharFreq.scan live).
 impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_ONLY> {
+    /// Record the first non-ambient TS runtime-syntax construct in the file;
+    /// see `Ast::ts_runtime_syntax`.
+    #[inline]
+    pub fn record_ts_runtime_syntax(&mut self, kind: bun_ast::TsRuntimeSyntax) {
+        if self.ts_runtime_syntax.is_none() {
+            self.ts_runtime_syntax = Some(kind);
+        }
+    }
+
     pub fn to_ast(
         &mut self,
         parts: &mut ListManaged<'a, js_ast::Part>,
@@ -8862,6 +8875,8 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
             has_top_level_return: false,
             redirect_import_record_index: None,
             target: js_ast::Target::Browser,
+            ts_runtime_syntax: self.ts_runtime_syntax,
+            uses_ts_module_keyword: self.uses_ts_module_keyword,
         }))
     }
 
@@ -9148,6 +9163,8 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
             latest_return_had_semicolon: false,
             has_import_meta: false,
             has_es_module_syntax: false,
+            ts_runtime_syntax: None,
+            uses_ts_module_keyword: false,
             top_level_await_keyword: bun_ast::Range::NONE,
             fn_or_arrow_data_parse,
             fn_or_arrow_data_visit: FnOrArrowDataVisit::default(),

src/js_parser/parse/parse_stmt.rs

@@ -1342,6 +1342,9 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
                     p.lexer.next()?;
                     let value = p.parse_expr(Level::Lowest)?;
                     p.lexer.expect_or_insert_semicolon()?;
+                    if !opts.is_typescript_declare {
+                        p.record_ts_runtime_syntax(js_ast::TsRuntimeSyntax::ExportAssignment);
+                    }
                     return Ok(p.s(S::ExportEquals { value }, loc));
                 }
                 p.lexer.unexpected()?;
@@ -1760,6 +1763,11 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
                     && (p.lexer.token == T::TIdentifier
                         || (p.lexer.token == T::TStringLiteral && opts.is_typescript_declare))
                 {
+                    if matches!(ts_stmt, js_lexer::TypescriptStmtKeyword::TsStmtModule)
+                        && p.lexer.token == T::TIdentifier
+                    {
+                        p.uses_ts_module_keyword = true;
+                    }
                     return Ok(Some(p.parse_type_script_namespace_stmt(loc, opts)?));
                 }
             }

src/js_parser/parse/parse_typescript.rs

@@ -421,6 +421,8 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
                 .insert(name.ref_.expect("infallible: ref bound"), ns_member_data);
         }
 
+        p.record_ts_runtime_syntax(bun_ast::TsRuntimeSyntax::Namespace);
+
         // S::Namespace.stmts is `StoreSlice<Stmt>` (arena slice). BumpVec → bump slice.
         let stmts_slice: &'a mut [Stmt] = stmts.into_bump_slice_mut();
         Ok(p.s(
@@ -509,6 +511,8 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
             return Ok(p.s(S::TypeScript {}, loc));
         }
 
+        p.record_ts_runtime_syntax(bun_ast::TsRuntimeSyntax::ImportEquals);
+
         let ref_ = p
             .declare_symbol(SymbolKind::Constant, default_name_loc, default_name)
             .expect("unreachable");
@@ -717,6 +721,8 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
         let prev = p.scopes_in_order_for_enum.insert(loc, scope_order_clone);
         debug_assert!(prev.is_none());
 
+        p.record_ts_runtime_syntax(bun_ast::TsRuntimeSyntax::Enum);
+
         Ok(p.s(
             S::Enum {
                 name,

src/js_parser/visit/mod.rs

@@ -1046,6 +1046,12 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
                             to_add += 1;
                         }
                     }
+                    if to_add > 0 {
+                        // `declare class` statements never reach the visit
+                        // pass, so this only fires for real (runtime)
+                        // parameter properties.
+                        self.record_ts_runtime_syntax(bun_ast::TsRuntimeSyntax::ParameterProperty);
+                    }
 
                     // if this is an expression, we can move statements after super() because there will be 0 decorators
                     let mut super_index: Option<usize> = None;

src/jsc/ErrorCode.rs

@@ -709,9 +709,13 @@ impl ErrorCode {
     pub const FS_CP_SYMLINK_TO_SUBDIRECTORY: ErrorCode = ErrorCode(325);
     /// `ERR_DIR_CONCURRENT_OPERATION` (instanceof Error)
     pub const DIR_CONCURRENT_OPERATION: ErrorCode = ErrorCode(326);
+    /// `ERR_INVALID_TYPESCRIPT_SYNTAX` (instanceof SyntaxError)
+    pub const INVALID_TYPESCRIPT_SYNTAX: ErrorCode = ErrorCode(327);
+    /// `ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX` (instanceof SyntaxError)
+    pub const UNSUPPORTED_TYPESCRIPT_SYNTAX: ErrorCode = ErrorCode(328);
 
     /// == C++ `NODE_ERROR_COUNT`.
-    pub const COUNT: u16 = 327;
+    pub const COUNT: u16 = 329;
 }
 
 // ──────────────────────────────────────────────────────────────────────────
@@ -961,6 +965,9 @@ impl ErrorCode {
     pub const ERR_MYSQL_CONNECTION_CLOSED: ErrorCode = ErrorCode::MYSQL_CONNECTION_CLOSED;
     pub const ERR_MYSQL_CONNECTION_FAILED: ErrorCode = ErrorCode::MYSQL_CONNECTION_FAILED;
     pub const ERR_MYSQL_CONNECTION_REFUSED: ErrorCode = ErrorCode::MYSQL_CONNECTION_REFUSED;
+    pub const ERR_INVALID_TYPESCRIPT_SYNTAX: ErrorCode = ErrorCode::INVALID_TYPESCRIPT_SYNTAX;
+    pub const ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX: ErrorCode =
+        ErrorCode::UNSUPPORTED_TYPESCRIPT_SYNTAX;
     pub const ERR_MYSQL_CONNECTION_TIMEOUT: ErrorCode = ErrorCode::MYSQL_CONNECTION_TIMEOUT;
     pub const ERR_MYSQL_IDLE_TIMEOUT: ErrorCode = ErrorCode::MYSQL_IDLE_TIMEOUT;
     pub const ERR_MYSQL_LIFETIME_TIMEOUT: ErrorCode = ErrorCode::MYSQL_LIFETIME_TIMEOUT;
@@ -1425,6 +1432,8 @@ static CODE_STR: [&str; ErrorCode::COUNT as usize] = [
     "ERR_FS_CP_EEXIST",
     "ERR_FS_CP_SYMLINK_TO_SUBDIRECTORY",
     "ERR_DIR_CONCURRENT_OPERATION",
+    "ERR_INVALID_TYPESCRIPT_SYNTAX",
+    "ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX",
 ];
 
 // ──────────────────────────────────────────────────────────────────────────