Implement --enable-source-maps CLI flag

src/ast/Ast.zig

@@ -70,6 +70,16 @@ ts_enums: TsEnumsMap = .{},
 has_commonjs_export_names: bool = false,
 import_meta_ref: Ref = Ref.None,
 
+/// `#sourceURL="foo"`
+///
+/// This is a slice into the source.contents.
+sourceURL: js_ast.Span = .{},
+
+/// `#sourceMappingURL=bar.map`
+///
+/// This is a slice into the source.contents.
+sourceMappingURL: js_ast.Span = .{},
+
 pub const CommonJSNamedExport = struct {
     loc_ref: LocRef,
     needs_decl: bool = true,

src/ast/Expr.zig

@@ -3127,6 +3127,21 @@ pub const Data = union(Tag) {
         pub threadlocal var memory_allocator: ?*ASTMemoryAllocator = null;
         pub threadlocal var disable_reset = false;
 
+        pub const DisableResetScope = struct {
+            no_op: bool,
+
+            pub fn exit(self: DisableResetScope) void {
+                if (!self.no_op)
+                    disable_reset = false;
+            }
+        };
+
+        pub fn disableResetIfNecessary() DisableResetScope {
+            const no_op = !disable_reset and memory_allocator == null;
+            disable_reset = if (!no_op) true else false;
+            return .{ .no_op = no_op };
+        }
+
         pub fn create() void {
             if (instance != null or memory_allocator != null) {
                 return;

src/ast/Stmt.zig

@@ -334,6 +334,26 @@ pub const Data = union(Tag) {
         pub threadlocal var memory_allocator: ?*ASTMemoryAllocator = null;
         pub threadlocal var disable_reset = false;
 
+        pub const DisableResetScope = struct {
+            no_op: bool,
+
+            pub fn exit(self: DisableResetScope) void {
+                if (!self.no_op)
+                    disable_reset = false;
+            }
+        };
+
+        /// Prevent a call to .reset() from doing anything
+        ///
+        /// This is useful for when you may add additional AST nodes immediately after parsing.
+        pub fn disableResetIfNecessary() DisableResetScope {
+            // If we were using ASTMemoryAllocator, or if we were already disabled, then we shouldn't do anything.
+            const no_op = !disable_reset and memory_allocator == null;
+
+            disable_reset = if (!no_op) true else false;
+            return .{ .no_op = no_op };
+        }
+
         pub fn create() void {
             if (instance != null or memory_allocator != null) {
                 return;

src/bun.js/ModuleLoader.zig

@@ -743,7 +743,7 @@ pub const AsyncModule = struct {
             var mapper = jsc_vm.sourceMapHandler(&printer);
             defer VirtualMachine.source_code_printer.?.* = printer;
             _ = try jsc_vm.transpiler.printWithSourceMap(
-                parse_result,
+                &parse_result,
                 @TypeOf(&printer),
                 &printer,
                 .esm_ascii,
@@ -981,6 +981,7 @@ pub fn transpileSourceCode(
                     setBreakPointOnFirstLine(),
                 .runtime_transpiler_cache = if (!disable_transpilying and !JSC.RuntimeTranspilerCache.is_disabled) &cache else null,
                 .remove_cjs_module_wrapper = is_main and jsc_vm.module_loader.eval_source != null,
+                .parse_source_map = virtual_source != null or jsc_vm.enable_user_source_maps,
             };
             defer {
                 if (should_close_input_file_fd and input_file_fd != bun.invalid_fd) {
@@ -1030,6 +1031,12 @@ pub fn transpileSourceCode(
                 },
             };
 
+            defer {
+                if (parse_result.source_map) |source_map| {
+                    source_map.deref();
+                }
+            }
+
             const source = &parse_result.source;
 
             if (parse_result.loader == .wasm) {
@@ -1247,7 +1254,7 @@ pub fn transpileSourceCode(
                 var mapper = jsc_vm.sourceMapHandler(&printer);
 
                 break :brk try jsc_vm.transpiler.printWithSourceMap(
-                    parse_result,
+                    &parse_result,
                     @TypeOf(&printer),
                     &printer,
                     .esm_ascii,
@@ -2423,6 +2430,7 @@ pub const RuntimeTranspilerStore = struct {
                 .remove_cjs_module_wrapper = is_main and vm.module_loader.eval_source != null,
                 .module_type = module_type,
                 .allow_bytecode_cache = true,
+                .parse_source_map = vm.enable_user_source_maps,
             };
 
             defer {
@@ -2468,6 +2476,12 @@ pub const RuntimeTranspilerStore = struct {
                 return;
             };
 
+            defer {
+                if (parse_result.source_map) |source_map| {
+                    source_map.deref();
+                }
+            }
+
             if (vm.isWatcherEnabled()) {
                 if (input_file_fd.isValid()) {
                     if (!is_node_override and
@@ -2581,7 +2595,7 @@ pub const RuntimeTranspilerStore = struct {
                 var mapper = vm.sourceMapHandler(&printer);
                 defer source_code_printer.?.* = printer;
                 _ = transpiler.printWithSourceMap(
-                    parse_result,
+                    &parse_result,
                     @TypeOf(&printer),
                     &printer,
                     .esm_ascii,

src/bun.js/VirtualMachine.zig

@@ -44,6 +44,7 @@ standalone_module_graph: ?*bun.StandaloneModuleGraph = null,
 smol: bool = false,
 dns_result_order: DNSResolver.Order = .verbatim,
 counters: Counters = .{},
+enable_user_source_maps: bool = false,
 
 hot_reload: bun.CLI.Command.HotReload = .none,
 jsc: *VM = undefined,
@@ -972,6 +973,7 @@ pub fn initWithModuleGraph(
         .standalone_module_graph = opts.graph.?,
         .debug_thread_id = if (Environment.allow_assert) std.Thread.getCurrentId(),
         .destruct_main_thread_on_exit = opts.destruct_main_thread_on_exit,
+        .enable_user_source_maps = opts.enable_user_source_maps,
     };
     vm.source_mappings.init(&vm.saved_source_map_table);
     vm.regular_event_loop.tasks = EventLoop.Queue.init(
@@ -1042,6 +1044,7 @@ pub const Options = struct {
     /// Worker VMs are always destroyed on exit, regardless of this setting. Setting this to
     /// true may expose bugs that would otherwise only occur using Workers.
     destruct_main_thread_on_exit: bool = false,
+    enable_user_source_maps: bool = false,
 };
 
 pub var is_smol_mode = false;
@@ -1093,6 +1096,7 @@ pub fn init(opts: Options) !*VirtualMachine {
         .ref_strings_mutex = .{},
         .debug_thread_id = if (Environment.allow_assert) std.Thread.getCurrentId(),
         .destruct_main_thread_on_exit = opts.destruct_main_thread_on_exit,
+        .enable_user_source_maps = opts.enable_user_source_maps,
     };
     vm.source_mappings.init(&vm.saved_source_map_table);
     vm.regular_event_loop.tasks = EventLoop.Queue.init(
@@ -1252,6 +1256,7 @@ pub fn initWorker(
         .debug_thread_id = if (Environment.allow_assert) std.Thread.getCurrentId(),
         // This option is irrelevant for Workers
         .destruct_main_thread_on_exit = false,
+        .enable_user_source_maps = opts.enable_user_source_maps,
     };
     vm.source_mappings.init(&vm.saved_source_map_table);
     vm.regular_event_loop.tasks = EventLoop.Queue.init(
@@ -1341,6 +1346,7 @@ pub fn initBake(opts: Options) anyerror!*VirtualMachine {
         .ref_strings_mutex = .{},
         .debug_thread_id = if (Environment.allow_assert) std.Thread.getCurrentId(),
         .destruct_main_thread_on_exit = opts.destruct_main_thread_on_exit,
+        .enable_user_source_maps = opts.enable_user_source_maps,
     };
     vm.source_mappings.init(&vm.saved_source_map_table);
     vm.regular_event_loop.tasks = EventLoop.Queue.init(

src/bun.js/api/TOMLObject.zig

@@ -42,7 +42,7 @@ pub fn parse(
         &writer,
         parse_result,
         source,
-        .{
+        &.{
             .mangled_props = null,
         },
     ) catch {

src/bun.js/api/server.zig

@@ -1880,7 +1880,7 @@ pub fn NewServer(protocol_enum: enum { http, https }, development_kind: enum { d
                 &writer,
                 bun.Global.BunInfo.generate(*Transpiler, &JSC.VirtualMachine.get().transpiler, allocator) catch unreachable,
                 source,
-                .{ .mangled_props = null },
+                &.{ .mangled_props = null },
             ) catch unreachable;
 
             resp.writeStatus("200 OK");

src/bun_js.zig

@@ -56,6 +56,7 @@ pub const Run = struct {
                 .graph = graph_ptr,
                 .is_main_thread = true,
                 .destruct_main_thread_on_exit = bun.getRuntimeFeatureFlag(.BUN_DESTRUCT_VM_ON_EXIT),
+                .enable_user_source_maps = ctx.runtime_options.enable_user_source_maps,
             }),
             .arena = arena,
             .ctx = ctx,
@@ -194,6 +195,7 @@ pub const Run = struct {
                     .dns_result_order = DNSResolver.Order.fromStringOrDie(ctx.runtime_options.dns_result_order),
                     .is_main_thread = true,
                     .destruct_main_thread_on_exit = bun.getRuntimeFeatureFlag(.BUN_DESTRUCT_VM_ON_EXIT),
+                    .enable_user_source_maps = ctx.runtime_options.enable_user_source_maps,
                 },
             ),
             .arena = arena,

src/bundler/LinkerContext.zig

@@ -1179,7 +1179,7 @@ pub const LinkerContext = struct {
             .{ .stmts = out_stmts },
         };
 
-        const print_options = js_printer.Options{
+        const print_options = &js_printer.Options{
             .bundling = true,
             // TODO: IIFE
             .indent = .{},

src/bundler/linker_context/postProcessJSChunk.zig

@@ -26,7 +26,7 @@ pub fn postProcessJSChunk(ctx: GenerateChunkCtx, worker: *ThreadPool.Worker, chu
     const runtimeRequireRef = if (c.options.output_format == .cjs) null else c.graph.symbols.follow(runtime_members.get("__require").?.ref);
 
     {
-        const print_options = js_printer.Options{
+        const print_options = &js_printer.Options{
             .bundling = true,
             .indent = .{},
             .has_run_symbol_renamer = true,
@@ -820,7 +820,7 @@ pub fn generateEntryPointTailJS(
         };
     }
 
-    const print_options = js_printer.Options{
+    const print_options = &js_printer.Options{
         // TODO: IIFE indent
         .indent = .{},
         .has_run_symbol_renamer = true,

src/cli.zig

@@ -388,6 +388,7 @@ pub const Command = struct {
         /// compatibility.
         expose_gc: bool = false,
         preserve_symlinks_main: bool = false,
+        enable_user_source_maps: bool = false,
     };
 
     var global_cli_ctx: Context = undefined;

src/cli/Arguments.zig

@@ -108,6 +108,7 @@ pub const runtime_params_ = [_]ParamType{
     clap.parseParam("--redis-preconnect                Preconnect to $REDIS_URL at startup") catch unreachable,
     clap.parseParam("--no-addons                       Throw an error if process.dlopen is called, and disable export condition \"node-addons\"") catch unreachable,
     clap.parseParam("--unhandled-rejections <STR>      One of \"strict\", \"throw\", \"warn\", \"none\", or \"warn-with-error-code\"") catch unreachable,
+    clap.parseParam("--enable-source-maps              Enable input source maps for all files") catch unreachable,
 };
 
 pub const auto_or_run_params = [_]ParamType{
@@ -667,6 +668,7 @@ pub fn parse(allocator: std.mem.Allocator, ctx: Command.Context, comptime cmd: C
         ctx.runtime_options.smol = args.flag("--smol");
         ctx.runtime_options.preconnect = args.options("--fetch-preconnect");
         ctx.runtime_options.expose_gc = args.flag("--expose-gc");
+        ctx.runtime_options.enable_user_source_maps = args.flag("--enable-source-maps");
 
         if (args.option("--dns-result-order")) |order| {
             ctx.runtime_options.dns_result_order = order;

src/cli/create_command.zig

@@ -1430,7 +1430,7 @@ pub const CreateCommand = struct {
                     &package_json_writer,
                     package_json_expr,
                     source,
-                    .{ .mangled_props = null },
+                    &.{ .mangled_props = null },
                 ) catch |err| {
                     Output.prettyErrorln("package.json failed to write due to error {s}", .{@errorName(err)});
                     package_json_file = null;

src/cli/init_command.zig

@@ -779,7 +779,7 @@ pub const InitCommand = struct {
                 &package_json_writer,
                 js_ast.Expr{ .data = .{ .e_object = fields.object }, .loc = logger.Loc.Empty },
                 &logger.Source.initEmptyFile("package.json"),
-                .{ .mangled_props = null },
+                &.{ .mangled_props = null },
             ) catch |err| {
                 Output.prettyErrorln("package.json failed to write due to error {s}", .{@errorName(err)});
                 package_json_file = null;

src/cli/pack_command.zig

@@ -2183,7 +2183,7 @@ pub const PackCommand = struct {
 
             // shouldn't be used
             &json.source,
-            .{
+            &.{
                 .indent = json.indentation,
                 .mangled_props = null,
             },

src/cli/pm_trusted_command.zig

@@ -421,7 +421,7 @@ pub const TrustCommand = struct {
         buffer_writer.append_newline = package_json_contents.len > 0 and package_json_contents[package_json_contents.len - 1] == '\n';
         var package_json_writer = bun.js_printer.BufferPrinter.init(buffer_writer);
 
-        _ = bun.js_printer.printJSON(@TypeOf(&package_json_writer), &package_json_writer, package_json, &package_json_source, .{ .mangled_props = null }) catch |err| {
+        _ = bun.js_printer.printJSON(@TypeOf(&package_json_writer), &package_json_writer, package_json, &package_json_source, &.{ .mangled_props = null }) catch |err| {
             Output.errGeneric("failed to print package.json: {s}", .{@errorName(err)});
             Global.crash();
         };

src/cli/pm_view_command.zig

@@ -242,7 +242,7 @@ pub fn view(allocator: std.mem.Allocator, manager: *PackageManager, spec_: strin
                 &package_json_writer,
                 value,
                 source,
-                .{
+                &.{
                     .mangled_props = null,
                 },
             );
@@ -278,7 +278,7 @@ pub fn view(allocator: std.mem.Allocator, manager: *PackageManager, spec_: strin
             &package_json_writer,
             manifest,
             source,
-            .{
+            &.{
                 .mangled_props = null,
                 .indent = .{
                     .count = 2,

src/cli/publish_command.zig

@@ -967,7 +967,7 @@ pub const PublishCommand = struct {
             &writer,
             json.*,
             json_source,
-            .{
+            &.{
                 .minify_whitespace = true,
                 .mangled_props = null,
             },

src/install/PackageManager/updatePackageJSONAndInstall.zig

@@ -243,7 +243,7 @@ fn updatePackageJSONAndInstallWithManagerWithUpdates(
         &package_json_writer,
         current_package_json.root,
         &current_package_json.source,
-        .{
+        &.{
             .indent = current_package_json_indent,
             .mangled_props = null,
         },
@@ -320,7 +320,7 @@ fn updatePackageJSONAndInstallWithManagerWithUpdates(
                 &package_json_writer2,
                 root_package_json.root,
                 &root_package_json.source,
-                .{
+                &.{
                     .indent = root_package_json.indentation,
                     .mangled_props = null,
                 },
@@ -384,7 +384,7 @@ fn updatePackageJSONAndInstallWithManagerWithUpdates(
             &package_json_writer_two,
             new_package_json,
             source,
-            .{
+            &.{
                 .indent = current_package_json_indent,
                 .mangled_props = null,
             },

src/js_lexer.zig

@@ -149,7 +149,7 @@ fn NewLexer_(
         code_point: CodePoint = -1,
         identifier: []const u8 = "",
         jsx_pragma: JSXPragma = .{},
-        source_mapping_url: ?js_ast.Span = null,
+
         number: f64 = 0.0,
         rescan_close_brace_as_template_token: bool = false,
         prev_error_loc: logger.Loc = logger.Loc.Empty,
@@ -169,6 +169,9 @@ fn NewLexer_(
         track_comments: bool = false,
         all_comments: std.ArrayList(logger.Range),
 
+        sourceMappingURL: js_ast.Span = .{},
+        sourceURL: js_ast.Span = .{},
+
         indent_info: if (json_options.guess_indentation)
             struct {
                 guess: Indentation = .{},
@@ -2031,7 +2034,13 @@ fn NewLexer_(
                         if (span.range.len > 0) @as(usize, @intCast(span.range.len)) else 0;
                 }
             } else if (chunk.len >= " sourceMappingURL=".len + 1 and strings.hasPrefixComptime(chunk, " sourceMappingURL=")) { // Check includes space for prefix
-                return PragmaArg.scanSourceMappingURLValue(lexer.start, offset_for_errors, chunk, &lexer.source_mapping_url);
+                return PragmaArg.scanSourceMappingURLValue(lexer.start, offset_for_errors, chunk, &lexer.sourceMappingURL);
+            } else if (chunk.len >= " sourceURL=".len + 1 and strings.hasPrefixComptime(chunk, " sourceURL=")) { // Check includes space for prefix
+                if (PragmaArg.scan(.skip_space_first, lexer.start + offset_for_errors, "sourceURL", chunk, allow_newline)) |span| {
+                    lexer.sourceURL = span;
+                    return "sourceURL".len +
+                        if (span.range.len > 0) @as(usize, @intCast(span.range.len)) else 0;
+                }
             }
 
             return 0;
@@ -3258,7 +3267,7 @@ pub const PragmaArg = enum {
     // These can be extremely long, so we use SIMD.
     /// "//# sourceMappingURL=data:/adspaoksdpkz"
     ///                       ^^^^^^^^^^^^^^^^^^
-    pub fn scanSourceMappingURLValue(start: usize, offset_for_errors: usize, chunk: string, result: *?js_ast.Span) usize {
+    pub fn scanSourceMappingURLValue(start: usize, offset_for_errors: usize, chunk: string, result: *js_ast.Span) usize {
         const prefix: u32 = " sourceMappingURL=".len;
         const url_and_rest_of_code = chunk[prefix..]; // Slice containing only the potential argument
 

src/js_parser.zig

@@ -23922,6 +23922,9 @@ fn NewParser_(
                 .ts_enums = try p.computeTsEnumsMap(allocator),
 
                 .import_meta_ref = p.import_meta_ref,
+
+                .sourceURL = p.lexer.sourceURL,
+                .sourceMappingURL = p.lexer.sourceMappingURL,
             };
         }
 

src/js_printer.zig

@@ -456,6 +456,7 @@ pub const Options = struct {
     minify_identifiers: bool = false,
     minify_syntax: bool = false,
     print_dce_annotations: bool = true,
+    input_source_map: ?*bun.sourcemap.ParsedSourceMap = null,
 
     transform_only: bool = false,
     inline_require_and_import_errors: bool = true,
@@ -5225,13 +5226,13 @@ fn NewPrinter(
         pub fn init(
             writer: Writer,
             import_records: []const ImportRecord,
-            opts: Options,
+            opts: *const Options,
             renamer: bun.renamer.Renamer,
             source_map_builder: SourceMap.Chunk.Builder,
         ) Printer {
             var printer = Printer{
                 .import_records = import_records,
-                .options = opts,
+                .options = opts.*,
                 .writer = writer,
                 .renamer = renamer,
                 .source_map_builder = source_map_builder,
@@ -5676,7 +5677,7 @@ const GenerateSourceMap = enum {
 pub fn getSourceMapBuilder(
     comptime generate_source_map: GenerateSourceMap,
     comptime is_bun_platform: bool,
-    opts: Options,
+    opts: *const Options,
     source: *const logger.Source,
     tree: *const Ast,
 ) SourceMap.Chunk.Builder {
@@ -5702,6 +5703,7 @@ pub fn getSourceMapBuilder(
             );
             break :brk .empty;
         },
+        .input_source_map = opts.input_source_map,
     };
 }
 
@@ -5712,7 +5714,7 @@ pub fn printAst(
     symbols: js_ast.Symbol.Map,
     source: *const logger.Source,
     comptime ascii_only: bool,
-    opts: Options,
+    opts: *const Options,
     comptime generate_source_map: bool,
 ) !usize {
     var renamer: rename.Renamer = undefined;
@@ -5836,7 +5838,7 @@ pub fn printAst(
         printer.print("var {require}=import.meta;");
     }
 
-    for (tree.parts.slice()) |part| {
+    for (tree.parts.slice()) |*part| {
         for (part.stmts) |stmt| {
             try printer.printStmt(stmt);
             if (printer.writer.getError()) {} else |err| {
@@ -5875,7 +5877,7 @@ pub fn printJSON(
     _writer: Writer,
     expr: Expr,
     source: *const logger.Source,
-    opts: Options,
+    opts: *const Options,
 ) !usize {
     const PrinterType = NewPrinter(false, Writer, false, false, true, false);
     const writer = _writer;
@@ -5915,7 +5917,7 @@ pub fn print(
     target: options.Target,
     ast: Ast,
     source: *const logger.Source,
-    opts: Options,
+    opts: *const Options,
     import_records: []const ImportRecord,
     parts: []const js_ast.Part,
     renamer: bun.renamer.Renamer,
@@ -5947,7 +5949,7 @@ pub fn printWithWriter(
     target: options.Target,
     ast: Ast,
     source: *const logger.Source,
-    opts: Options,
+    opts: *const Options,
     import_records: []const ImportRecord,
     parts: []const js_ast.Part,
     renamer: bun.renamer.Renamer,
@@ -5976,7 +5978,7 @@ pub fn printWithWriterAndPlatform(
     comptime is_bun_platform: bool,
     ast: Ast,
     source: *const logger.Source,
-    opts: Options,
+    opts: *const Options,
     import_records: []const ImportRecord,
     parts: []const js_ast.Part,
     renamer: bun.renamer.Renamer,
@@ -6066,7 +6068,7 @@ pub fn printCommonJS(
     symbols: js_ast.Symbol.Map,
     source: *const logger.Source,
     comptime ascii_only: bool,
-    opts: Options,
+    opts: *const Options,
     comptime generate_source_map: bool,
 ) !usize {
     const prev_action = bun.crash_handler.current_action;
@@ -6087,7 +6089,7 @@ pub fn printCommonJS(
     printer.binary_expression_stack = std.ArrayList(PrinterType.BinaryExpressionVisitor).init(bin_stack_heap.get());
     defer printer.binary_expression_stack.clearAndFree();
 
-    for (tree.parts.slice()) |part| {
+    for (tree.parts.slice()) |*part| {
         for (part.stmts) |stmt| {
             try printer.printStmt(stmt);
             if (printer.writer.getError()) {} else |err| {

src/json_parser.zig

@@ -1014,7 +1014,7 @@ fn expectPrintedJSON(_contents: string, expected: string) !void {
 
     const buffer_writer = js_printer.BufferWriter.init(default_allocator);
     var writer = js_printer.BufferPrinter.init(buffer_writer);
-    const written = try js_printer.printJSON(@TypeOf(&writer), &writer, expr, source, .{
+    const written = try js_printer.printJSON(@TypeOf(&writer), &writer, expr, source, &.{
         .mangled_props = null,
     });
     var js = writer.ctx.buffer.list.items.ptr[0 .. written + 1];

src/sourcemap/sourcemap.zig

@@ -63,7 +63,7 @@ pub const ParseUrl = struct {
 /// The mappings are owned by the `alloc` allocator.
 /// Temporary allocations are made to the `arena` allocator, which
 /// should be an arena allocator (caller is assumed to call `deinit`).
-pub fn parseUrl(
+pub fn parseInlineSourceMap(
     alloc: std.mem.Allocator,
     arena: std.mem.Allocator,
     source: []const u8,
@@ -99,6 +99,85 @@ pub fn parseUrl(
     return parseJSON(alloc, arena, json_bytes, hint);
 }
 
+pub fn parseDataURL(
+    alloc: std.mem.Allocator,
+    arena: std.mem.Allocator,
+    source: []const u8,
+    hint: ParseUrlResultHint,
+) !ParseUrl {
+    const json_bytes = json_bytes: {
+        const data_prefix = "data:application/json";
+
+        try_data_url: {
+            debug("parse (data url, {d} bytes)", .{source.len});
+            switch (source[data_prefix.len]) {
+                ';' => {
+                    const encoding = bun.sliceTo(source[data_prefix.len + 1 ..], ',');
+                    if (!bun.strings.eqlComptime(encoding, "base64")) break :try_data_url;
+                    const base64_data = source[data_prefix.len + ";base64,".len ..];
+
+                    const len = bun.base64.decodeLen(base64_data);
+                    const bytes = arena.alloc(u8, len) catch bun.outOfMemory();
+                    const decoded = bun.base64.decode(bytes, base64_data);
+                    if (!decoded.isSuccessful()) {
+                        return error.InvalidBase64;
+                    }
+                    break :json_bytes bytes[0..decoded.count];
+                },
+                ',' => break :json_bytes source[data_prefix.len + 1 ..],
+                else => break :try_data_url,
+            }
+        }
+
+        return error.UnsupportedFormat;
+    };
+
+    return parseJSON(alloc, arena, json_bytes, hint);
+}
+
+/// Parse a sourceMappingURL comment from either a data: URI, a local file path
+/// or an absolute file path.
+pub fn parseSourceMappingURL(
+    alloc: std.mem.Allocator,
+    arena: std.mem.Allocator,
+    relative_to_source: *const bun.logger.Source,
+    path_or_data_url: []const u8,
+    hint: ParseUrlResultHint,
+) !ParseUrl {
+    const data_prefix = "data:application/json";
+
+    if (bun.strings.hasPrefixComptime(path_or_data_url, data_prefix) and path_or_data_url.len > (data_prefix.len + 1)) {
+        return try parseDataURL(alloc, arena, path_or_data_url, hint);
+    }
+
+    if (!relative_to_source.path.isFile()) {
+        return error.UnsupportedFormat;
+    }
+
+    const path_buffer = bun.PathBufferPool.get();
+    defer bun.PathBufferPool.put(path_buffer);
+
+    const path = bun.path.joinAbsStringBufZ(
+        bun.fs.FileSystem.instance.top_level_dir,
+        path_buffer,
+        &[_][]const u8{ relative_to_source.path.sourceDir(), path_or_data_url },
+        .loose,
+    );
+
+    const json_source = try bun.sys.File.toSourceAt(
+        bun.FD.cwd(),
+        path,
+        arena,
+        .{ .convert_bom = true },
+    ).unwrap();
+    defer arena.free(json_source.contents);
+
+    var log = bun.logger.Log.init(arena);
+    defer log.deinit();
+
+    return try parseJSONFromSource(alloc, arena, &json_source, &log, hint);
+}
+
 /// Parses a JSON source-map
 ///
 /// `source` must be in UTF-8 and can be freed after this call.
@@ -111,10 +190,20 @@ pub fn parseJSON(
     source: []const u8,
     hint: ParseUrlResultHint,
 ) !ParseUrl {
-    const json_src = bun.logger.Source.initPathString("sourcemap.json", source);
     var log = bun.logger.Log.init(arena);
     defer log.deinit();
 
+    const json_src = &bun.logger.Source.initPathString("sourcemap.json", source);
+    return parseJSONFromSource(alloc, arena, json_src, &log, hint);
+}
+
+pub fn parseJSONFromSource(
+    alloc: std.mem.Allocator,
+    arena: std.mem.Allocator,
+    json_source: *const bun.logger.Source,
+    log: *bun.logger.Log,
+    hint: ParseUrlResultHint,
+) !ParseUrl {
     // the allocator given to the JS parser is not respected for all parts
     // of the parse, so we need to remember to reset the ast store
     bun.JSAst.Expr.Data.Store.reset();
@@ -125,8 +214,8 @@ pub fn parseJSON(
         bun.JSAst.Expr.Data.Store.reset();
         bun.JSAst.Stmt.Data.Store.reset();
     }
-    debug("parse (JSON, {d} bytes)", .{source.len});
-    var json = bun.JSON.parse(&json_src, &log, arena, false) catch {
+    debug("parse (JSON, {d} bytes)", .{json_source.contents.len});
+    var json = bun.JSON.parse(json_source, log, arena, false) catch {
         return error.InvalidJSON;
     };
 
@@ -822,7 +911,7 @@ pub fn getSourceMapImpl(
 
             break :parsed .{
                 .is_inline_map,
-                parseUrl(
+                parseInlineSourceMap(
                     bun.default_allocator,
                     allocator,
                     found_url.slice(),
@@ -1455,7 +1544,7 @@ pub const Chunk = struct {
     pub fn NewBuilder(comptime SourceMapFormatType: type) type {
         return struct {
             const ThisBuilder = @This();
-            input_source_map: ?*SourceMap = null,
+            input_source_map: ?*ParsedSourceMap = null,
             source_map: SourceMapper,
             line_offset_tables: LineOffsetTable.List = .{},
             prev_state: SourceMapState = SourceMapState{},
@@ -1572,7 +1661,7 @@ pub const Chunk = struct {
                 var current_state = current_state_;
                 // If the input file had a source map, map all the way back to the original
                 if (b.input_source_map) |input| {
-                    if (input.find(current_state.original_line, current_state.original_column)) |mapping| {
+                    if (Mapping.find(input.mappings, current_state.original_line, current_state.original_column)) |mapping| {
                         current_state.source_index = mapping.sourceIndex();
                         current_state.original_line = mapping.originalLine();
                         current_state.original_column = mapping.originalColumn();

src/transpiler.zig

@@ -52,6 +52,7 @@ pub const ParseResult = struct {
     input_fd: ?StoredFileDescriptorType = null,
     empty: bool = false,
     pending_imports: _resolver.PendingResolution.List = .{},
+    source_map: ?*bun.sourcemap.ParsedSourceMap = null,
 
     runtime_transpiler_cache: ?*bun.JSC.RuntimeTranspilerCache = null,
 
@@ -808,6 +809,7 @@ pub const Transpiler = struct {
         comptime enable_source_map: bool,
         source_map_context: ?js_printer.SourceMapHandler,
         runtime_transpiler_cache: ?*bun.JSC.RuntimeTranspilerCache,
+        input_source_map: ?*bun.sourcemap.ParsedSourceMap,
     ) !usize {
         const tracer = if (enable_source_map)
             bun.perf.trace("JSPrinter.printWithSourceMap")
@@ -825,7 +827,7 @@ pub const Transpiler = struct {
                 js_ast.Symbol.Map.initList(symbols),
                 source,
                 false,
-                .{
+                &.{
                     .bundling = false,
                     .runtime_imports = ast.runtime_imports,
                     .require_ref = ast.require_ref,
@@ -838,6 +840,7 @@ pub const Transpiler = struct {
                     .runtime_transpiler_cache = runtime_transpiler_cache,
                     .print_dce_annotations = transpiler.options.emit_dce_annotations,
                     .hmr_ref = ast.wrapper_ref,
+                    .input_source_map = input_source_map,
                 },
                 enable_source_map,
             ),
@@ -849,7 +852,7 @@ pub const Transpiler = struct {
                 js_ast.Symbol.Map.initList(symbols),
                 source,
                 false,
-                .{
+                &.{
                     .bundling = false,
                     .runtime_imports = ast.runtime_imports,
                     .require_ref = ast.require_ref,
@@ -863,6 +866,7 @@ pub const Transpiler = struct {
                     .runtime_transpiler_cache = runtime_transpiler_cache,
                     .print_dce_annotations = transpiler.options.emit_dce_annotations,
                     .hmr_ref = ast.wrapper_ref,
+                    .input_source_map = input_source_map,
                     .mangled_props = null,
                 },
                 enable_source_map,
@@ -875,7 +879,7 @@ pub const Transpiler = struct {
                     js_ast.Symbol.Map.initList(symbols),
                     source,
                     is_bun,
-                    .{
+                    &.{
                         .bundling = false,
                         .runtime_imports = ast.runtime_imports,
                         .require_ref = ast.require_ref,
@@ -899,6 +903,7 @@ pub const Transpiler = struct {
                         .target = transpiler.options.target,
                         .print_dce_annotations = transpiler.options.emit_dce_annotations,
                         .hmr_ref = ast.wrapper_ref,
+                        .input_source_map = input_source_map,
                         .mangled_props = null,
                     },
                     enable_source_map,
@@ -924,12 +929,13 @@ pub const Transpiler = struct {
             false,
             null,
             null,
+            null,
         );
     }
 
     pub fn printWithSourceMap(
         transpiler: *Transpiler,
-        result: ParseResult,
+        result: *const ParseResult,
         comptime Writer: type,
         writer: Writer,
         comptime format: js_printer.Format,
@@ -945,6 +951,7 @@ pub const Transpiler = struct {
                 false,
                 handler,
                 result.runtime_transpiler_cache,
+                result.source_map,
             );
         }
         return transpiler.printWithSourceMapMaybe(
@@ -956,6 +963,7 @@ pub const Transpiler = struct {
             true,
             handler,
             result.runtime_transpiler_cache,
+            result.source_map,
         );
     }
 
@@ -993,6 +1001,7 @@ pub const Transpiler = struct {
 
         keep_json_and_toml_as_one_statement: bool = false,
         allow_bytecode_cache: bool = false,
+        parse_source_map: bool = false,
     };
 
     pub fn parse(
@@ -1175,6 +1184,43 @@ pub const Transpiler = struct {
                         .loader = loader,
                         .input_fd = input_fd,
                         .runtime_transpiler_cache = this_parse.runtime_transpiler_cache,
+                        .source_map = if (this_parse.parse_source_map and value.sourceMappingURL.text.len > 0) brk: {
+                            var arena = bun.ArenaAllocator.init(
+                                // Deliberately use default_allocator instead of
+                                // this_parse.allocator this_parse.allocator may
+                                // be an ArenaAllocator. or it might not be,
+                                // depending on the caller Nested arena
+                                // allocators cause the allocation to be freed
+                                // even later, so it's just wasteful.
+                                bun.default_allocator,
+                            );
+                            defer arena.deinit();
+
+                            const reset_scope = js_ast.Expr.Data.Store.disableResetIfNecessary();
+                            const reset_scope2 = js_ast.Stmt.Data.Store.disableResetIfNecessary();
+                            defer reset_scope.exit();
+                            defer reset_scope2.exit();
+
+                            if (bun.sourcemap.parseSourceMappingURL(
+                                allocator,
+                                arena.allocator(),
+                                source,
+                                value.sourceMappingURL.text,
+                                .{
+                                    .all = .{
+                                        .line = 0,
+                                        .column = 0,
+                                    },
+                                },
+                            )) |*source_map| {
+                                break :brk source_map.map;
+                            } else |_| {
+                                // TODO: failing to parse the sourcemap shouldn't cause the build to fail.
+                                // so we for now just ignore failure.
+                            }
+
+                            break :brk null;
+                        } else null,
                     },
                     .cached => .{
                         .ast = undefined,
@@ -1209,8 +1255,7 @@ pub const Transpiler = struct {
                     },
                 };
             },
-            // TODO: use lazy export AST
-            inline .toml, .json, .jsonc => |kind| {
+            .toml, .json, .jsonc => |kind| {
                 var expr = if (kind == .jsonc)
                     // We allow importing tsconfig.*.json or jsconfig.*.json with comments
                     // These files implicitly become JSONC files, which aligns with the behavior of text editors.
@@ -1220,7 +1265,7 @@ pub const Transpiler = struct {
                 else if (kind == .toml)
                     TOML.parse(source, transpiler.log, allocator, false) catch return null
                 else
-                    @compileError("unreachable");
+                    unreachable;
 
                 var symbols: []js_ast.Symbol = &.{};